Old Mercury 7.5 hp 2 stroke outboard engine. Will it run? Sitting for years

Is this motor a lost cause or will I get it running? I check out this old Mercury 2 stroke outboard motor to see if it has what it needs to run. I recently purchased an old Mercury 7.5 hp 2 stroke outboard engine from 1971 that had not run in years. Will this engine run? Can I get this old 2 stroke outboard running again? I cover the process I use to evaluate an old engine and the tests I do to see if it has the potential to run and what to check before you start spending money on parts. Testing an outboard motor isn't hard and you only need a few special tools to do the basic tests to see if it will run.
In this video I show you how to do a compression test, how to use a spark tester and step-by-step process of troubleshooting and evaluating an old 2 stroke outboard motor to see if it will run. I show you how to check for spark on an outboard engine. I show you how to use a compression test gauge and what the results mean when checking an outboard motor. I show my process for troubleshooting fuel issues and how to follow a logical path to identifying fuel and carb issues on older outboard motors.
#2strokeoutboardmotor #mercury2stroke #willitrun
Do you need a compression test kit? amzn.to/3dmydHr
Do you need a spark testing tool? amzn.to/3axd1wH
Do you need a Mercury fuel adapter? amzn.to/3bhUN1g
As an Amazon Associate I earn a small commission from qualifying purchases.
Timestamps:
00:00 Introduction
00:41 How I got this outboard motor
01:45 Basic things to check first
02:26 Removing the engine cover and looking over the engine
05:10 What an outboard engine needs to run
05:53 The tools we will be using
07:00 Removing spark plugs and performing a compression test
13:00 Testing for spark on both cylinders
16:27 Overview of a 2 stroke outboard motor fuel system
19:45 Replacing old worn fuel lines
24:38 Old style Mercury fuel connector
27:50 Testing to see if fuel flows past the fuel pump
29:50 Initial start test
32:50 Checking for fuel in the cylinders
34:11 Final start test
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[@toddparfitt7571]

I've got a Mercury Model 110-9.8 hp 2 weeks ago. Great video, I'm inspired! Thanks Wayne!

[@WayneTheBoatGuy]

That is awesome! good luck

[@capitalisticcommie]

Just got my 9.8 a few days ago. What connector do you use? I’m totally new to this.

[@davidamoritz]

Dude I just got the same motor many will not work on it but I found a shop.

[@74nova36]

Lol I just got my 1968 110 9.8hp last week. Where did you find the fuel connector for this one all I’ve got on mine is a narrow piece of sliver pipe coming out

[@ethanedwards9838]

@@74nova36did you ever find out?

[@androsborsato]

The face of a man when an old outboard runs for the first time. Priceless.

[@samuelthomas9758]

Kemp

[@Daviddickson]

I only hope I get to have the same look when I test mine after 15 years. 😊

[@Anonymous99997]

Back in the early 70s, the summer camp I went to had motor boating classes where we completely rebuilt a Mercury 9.8. Pretty heady stuff for a 12 year old, but that experience makes me appreciate what you are doing here.

[@pjimmbojimmbo1990]

In the 70s, there was no such thing as a Merc 9.9, however there was a 9.8, which wasn't much different than this 7.5. The much later 9.9 was pretty much a different engine

[@Anonymous99997]

@@pjimmbojimmbo1990 omg. Go to the dictionary and look up Troll and you will see your comment as an example.

[@pjimmbojimmbo1990]

@@Anonymous99997 There was no 9.9 Merc prior to some time in the late 80s or early 90s. So you were either mistaken, or full of Fecal Matter

[@motorv8N]

Such a familiar sound. I learned to operate a ‘78 7.5 Merc as a kid. Loved that motor and put hundreds and hundreds of hours on it exploring the local lake growing up. Still have both that motor, disintegrating wiring harness included, and the ‘72 Springbok tinnie we hung it on these fifty years later.

[@chadbussey8305]

Wayne, I just bought a 10hp evinrude sportwin "60's model". It was a spontaneous purchase, very unintelligent purchase considering I'm neither a mechanic or very...well that point is already established. I have been doing some amount of studying and gaining a small amount of confidence. I have not completely finished this video yet but I felt compelled to express my appreciation for your video. I appreciate your no nonsense method of instruction you remind me of Joe Friday "just the facts". I was almost shocked to see nearly immediately somebody insulting you for exactly the reason I came to thank you for. Anyway, ignore the trolls, I prefer my education instructive not entertaining. 😊

[@JCinematic]

Excellent video Wayne! Well put together and very informative for people who are new to this.

[@MakeItMike]

I just got a 1984 4.5hp mercury. Can't wait to see if it runs.

[@jeffselano2300]

Wayne, thanks for the great video. Very well done, thoughtful and the basic explanations are great. Appreciate you. Keep up the good work.

[@nickxmaiden9406]

Got so much info from this video!! Thanks for the content

[@jamiecook3966]

great video buddy, these pieces of history need to be looked after. From a way better time in our lives.

[@alanloudermilk3422]

Awesome video, thanks!

[@lionelhulbert1687]

That was a great help to me thanks

[@craiglitchfield1526]

Hi Wayne, that Mercury fuel connector is from the spitfire ww2 fighter planes, after ww2 they had thousands of them surplus and Mercury brought them all, appariently they are the best designed fuel connector ever made.

[@pjimmbojimmbo1990]

That old Style Fuel connector was the best that Mercury ever had, they later switched to the problem prone OMC style. Maybe they figured they could sell more replacement Fuel Hoses

[@jcaprada]

Thank you so much for this video Wayne. I was just given an aluminum jon boat with a 1973 Mercury 110 9.8 hp, almost identical to this except it seems like the fuel pump and carb are together in one piece. Just got a lot of hope on my old engine and went ahead and order the compression and spark testers from your links. WIll follow up on this comment soon hopefully with great news, fingers crossed. Thanks again, from Atlanta, GA

[@WayneTheBoatGuy]

Good luck! These things can be a can of worms sometimes and other times they can be quite rewarding!

[@danevans9347]

great video!

[@allenletondre1561]

You pull like my grandmother

[@markcollins5026]

Man. and my Uncle John 😅 !

[@Alfredo5883]

Excellent! Immensely learned something from this video as I am a beginner. Great thanks Brother for sharing. I am def' subscribing

[@chrisandlane]

Excellent video!

[@WayneTheBoatGuy]

Thank you very much!

[@darrylmcleman6456]

I had an engine (85 Evinrude ) in 1970 It was not new but about 5 years old and it had those Glow-style of plugs.The dealership was calling them glow plugs. CHEERS from Western Canada

[@WayneTheBoatGuy]

They are an unusual plug that’s for sure!

[@dustinweaver3032]

I've got a 7.5 mercury myself. It still runs good.

[@greghudson1489]

I don't think I've ever seen a more thorough trouble shooting demonstration. Thank you! I have a 1970 9.8 version of that outboard motor, and am working some issues. Two summers ago it would start but only run at idle speed (stalled/choked out when revved). I found the old metal gas tank was full of rust which had clogged up the carburetor. Cleaned and rebuilt the Tillotson carburetor and installed new spark plugs. Replaced the gas tank & line with a new poly tank. The ignition/stator was replaced with a new one only a few years ago as the original had disintegrated wires like the one you taped up. Fuel lines to and from the fuel pump have cracks but are not leaking. (I'll replace them. but have to get the elbow fittings, because the OEM lines are crimped on brass on the line ends.) Now I can't get the motor to start at all. There is gas coming out the carburetor after several pulls.

[@WayneTheBoatGuy]

If you’ve definitely got spark, and fuel is dripping out of the carb there’s only two things left to address. First, be positive the fuel is relatively new (especially if you have ethanol blends like I have here). Second, if the fuel is good, I think it’s gotta be something in the carb. They have all those passages and if there’s any tiny dirt or gunk at all anywhere in a passage, they don’t work. I’d blow through every passage in that carb one more time with compressed air. Good luck!!

[@greghudson1489]

@@WayneTheBoatGuy Thanks...

[@greghudson1489]

- Fuel lines all replaced. - Fuel pump rebuilt. - Did a compression test like you did but only get 50 Psi on each cylinder. **Still won't crank, even with starter fluid sprayed into the carburetor. - I'm not certain the plugs are firing... I watched a video about testing the coils. The primary, post to post gave .4 ohms (too high?), and the spark plug tower to either post showed nothing. Could the coils both be bad? - My engine has the Thunderbolt ignition, which I thought was a "no points" ignition. Am I mistaken about the points?

[@staffanfogelberg6816]

​@@greghudson1489I'm in the same boat...did you manage to get it running?

[@sureshabreu3171]

Thanks much this is so helpful

[@lomgshorts3]

A 1971 Mercury 7.5 hp will not have electronic ignition unless it was updated with special ignition parts. Chances are it still is magneto fired direct spark to plug. I had a 15 hp Mercury in 1970 that ran well and probably was the same ignition system. You will probably have to rebuild the carburetor, replace the magnetos and spark plug wires and spark plugs to start with. Replace all gaskets, oil in the lower unit, and any seals there. Replace the impeller in the lower unit or "leg". Reassemble everything and test in a barrel filled with water. So you got spark on both magnetos? Replace both magnetos anyway, because magneto insulation degrades over time - especially if the engine hasn't been run in more than 5 years. And, go through the carburetor, too (especially if it hasn't been run in a long time, gas gums up carbs when it wasn't run dry when they stopped using it way back when). Use a torque wrench to tighten those plugs, the head is aircraft aluminum and relatively soft! Strip those spark plugs out of the head and you will have to use helacoil inserts to replace the threads! You CAN replace hoses easier by heating them with a hair dryer so that they are flexible enough to fit easily. Use spring clamps to fix them in place if there is room enough to use them. Told you about the carb being blocked by old gas that was broken down by time! You were lucky the gas pump was free, but the blocked carb got you. Yes, scraping out the carb was an option, but a rebuild kit is the only reliable option to make it reliable. Bring oars in case the carb fails. Hope the gaskets on the carb weren't messed up by you, or you might never get it started. So, you got it started! Replace that impeller immediately or you probably will burn the motor up - it only takes seconds to do that at full speed. "Tweak" the outboard? No "tweaking" until you replace the impellar, rebuild the carburetor, and REPLACE the fuel pump! Then you probably will have a reliable outboard that will take you somewhere - and bring you back. Best wishes!

[@sharonbraselton4302]

buy mini tug vuag 15 hp 21 mph

[@markcollins5026]

man. and that's all folks !

[@mckessa17]

I have a 1968 Mercury 9.8 hp, its cool and runs well.

[@WayneTheBoatGuy]

awesome

[@Beautifultruthofficial]

very enjoyable.

[@pjimmbojimmbo1990]

71, the last year where the Decals were Red. The years 68 thru 71, had the best looking Cowl Decals, that Merc ever had

[@ourv9603]

YEARS AGO, I worked at a marine dealership as a mech. Every year, the weekend before 4th of July many, many, many, many customers would bring us their boats & motors expecting us to have it ready for the 4th weekend which would be in 4-8 days. We always found their boats & had not been winterized. After last use last year the boats were simply parked with not a second thought to next year. Needless to say, every year we had a lot of unhappy customers whose boat was not ready for the 4th. !

[@byustim]

Hi Wayne, you have a good video..it makes me also want to try what you are doing.. :)

[@WayneTheBoatGuy]

It's never too late to start trying and learning!

[@markburley3418]

My aluminium boat is yet to have a motor (Rowing my kids around the lake for the moment means I don’t require boat registration), so I found this video useful in the form of relaying it to my attempts at my self repairs on my car.

[@WayneTheBoatGuy]

You might consider an electric trolling motor next - silent and simple!

[@Nobamaable]

I had an early 70's Mercury 7.5 as a kid in the mid 70's. It was mounted on my 14 Jon boat my Dad bought from Sears. It ran around 25 mph with my young ass in it, and would porpoise really bad at speed, so I had to sit on the floor of the Jon boat for safety. It had a blue stripe on it instead of your red stripe. What a great engine!

[@sharonbraselton4302]

12 foit game fisher beter

[@juanpabloramirez6565]

I have 2 of that's 4hp 1969 both start after decades good engines run nice only clean carburator and impeller change

[@WayneTheBoatGuy]

Very nice!

[@sharonbraselton4302]

2 4 hp elrrc outbard cheapee

[@pclabs2]

Thanks for the detailed explanations, Wayne! I'm going to repair a 1983 7.5HP Mercury with (apparently) similar issues and I was looking for hints. Cheers from Sicily!

[@WayneTheBoatGuy]

I hope it goes well! With these particular motors, if you have a spark you're off to a good start.

[@sharonbraselton4302]

buy new 9.9 10 amp 12 vilt akternateé 120 watts charg8ng

[@pjimmbojimmbo1990]

Mercury must have bought enough of the Wire with the Decomposing Insulation, to string it between the Earth and Moon several times.

[@gregdenman2342]

Great video, very easy to follow, but 80 ish to 90 psi will be a motor that is hard to start when cold. Those are center fire plugs and there is no gap to adjust, only heat range .Get a spark tester that has the clear glass or plastic. Spark should be as blue as possible and should snap (that's the air being ionized). That ignition system is a Thunder Bolt system as was an in between system before fully transistorized ignition. AKA hard to find parts if you don't know the year of the motor Check the serial number online to see year of motor if you have to order parts. It's not a vacuum line it's pulse line. Vacuum is constant but a pulse system uses the piston of the motor to create a pulse wave to move the diaphragm of the fuel pump back and forth to draw fuel from the tank. That fuel pump is a non oem (original equipment manufacturer) and appears to be a universal fuel pump, but may still work as it is still a pulse pump. Always try to use the highest octane available as it is non ethanol and years ago fuel had a better quality, so older motors ran(better??) differently so stick to 91 to 93. Yes, many extra dollars but you will be way ahead if you leave you motor sitting around in your living room, like I do...because I can!! You can use low pressure fuel line, don't go for the sale of fuel injection hose(more$$), these outboards need only 2-3,4 psi, maybe not even. Late 60's Mercs like 4 hp,7.5hp and 10hp used a non standard fuel connector that Wayne is showing you, again check your serial number with iboats, oldmercs.com or other. Only for Mercs, OMC motors different. My mercury 9.8 twin has a serial number 1995660 and that means as far as I can tell it's a late 67 to 68 model, requiring this special connector..... 35 plus dollars NON standard!! You can always convert any fuel system to another standard system, it's just that the standard fuel tank connector would not physically fit into the hole of my 67/68 motor A ratio of 50 to 1 is 50 parts gas to one part oil that's 2.6 oz oil to 1 gal gas, but 40 to ,1 to free up those old rings, so 3.2 oz per gal gas, and back after 2-3 hours run time to 50:1 NEVER LESS THAN 50 TO 1. Use 2 stroke oil for TC WC. That's two cycle, water cooled. Water cooled engines run colder than air cooled two stroke engines...when possible. He should have pulled the recoil to have the fuel pump actually pump fuel out of the outlet to see the function of the pump itself, but still good to show everything is holding pressure. The recoil on top of the motor needs lube..watch other vids to see the work to disassemble the recoil before attempting this......that spring is a 6 foot long clock spring aiming for your eye....safety glasses!! Wet plugs?? Got gas. Too much?? Fouled. Check carb. That's the vent hole, as in over flow, too much fuel in carb and no place to go....needle and seat. Finally, that's a bad fuel pump because he removed the choke and it stalled. Great video for newbs, not dissing Wayne, just commenting to add additional comment

[@donalphin5058]

P

[@donalphin5058]

L

[@outboardguys7426]

Hi i fixed this motor to, great engine!

[@WayneTheBoatGuy]

Yeah it's a solid runner.

[@bradywiggers7382]

Yep, I have this one too. Just don’t let it sit or else it will kill the ignition system. Then you have a $700 problem.

[@vvgfg5531]

Great video! I have the exact same one I just finished repainting and looks like new. Do you have any idea where the zinc anode locations are? can't seem to find any info online anywhere!

[@jeepsinaus]

What a great video. Any follow up vids on this motor?

[@WayneTheBoatGuy]

I think I did an impeller video with it - but it was a long shaft that was too heavy for my little boat so it's no longer mine.

[@tuomashayrinen4763]

Bar is the international unit for pressure. One bar is about 14,7 psi. Atmospheric pressure is about one bar depending on weather, altitude etc.

[@tobyforest665]

Hello awesome motor i have the same kind anyway i would like to share with you a couple things one i always check for spark if it has spark and was sitting for a year or more i do the what i call the one litre half full of mixed gas trick i drill a small hole about the centre of the cap or hammer a nail threw it just enough so that it will squirt strait into each cylinder make sure you give each cylinder a good squirt then as fast as you can put plugs back in give it a pull keep choke on hand on primer ball works for me hope that it does the same for you have fun keep up the great vids.

[@SleeperBBQ]

working on a late 80 merc now US 301 very familiar with it

[@sw-ls7zn]

On the spark part the tester you buy inst really needed you can put the plug while plugged in to the black cable and put it against some metal

[@jerry38732]

Hi Wayne, I think that fuel pump is an add-on. The squeeze bulb on the tank hose should push gas into the carb.

[@WayneTheBoatGuy]

My 6 hp Evinrude had a vacuum fuel pump like this one, but my 2.5 Merc is gravity fed because the tank is on the engine. I can't see a carb sucking up gas without gravity or some type of pump.

[@teaeff8898]

Im sure someone has tried to get that motor running, with those plugs in it and some of the wires look new-ish. The pull-cord recoil needs attention. The Merc fuel connector never leak! Two things: the bulb should be at the end nearest the motor, and the impeller definitely needs replaced as that should be a stream coming out not a dribble. Our boat had a 1960s 50hp Merc ran for… oh 40 years before my father bought a 4-stroke Merc. I’ve got my grandfathers 1954 Mercury Mark 5. Has had the impeller replaced. Still runs. Great motors.

[@sharonbraselton4302]

whaler 15

[@gracelutherangreenwood7499]

I just picked up a 1970 Mercury 7.5hp. This video is so very helpful. Thank you! *I have to re-wire though. All of the wiring was damaged. I can’t find a suitable wiring diagram anywhere. Would it be possible for you to trace the wires (stator to coils, ground, kill switch, etc)? Pictures work great. Video is even better.

[@WayneTheBoatGuy]

If I still had this engine I would be happy to help. A good resource is Marineengine.com

[@sbxxxiii]

The priming bulb is much easier to get firm if you have it hanging vertically under the motor.

[@74nova36]

Could I see the video of the impeller change on this unit? Is there a link

[@meesau2112]

You should first try putting some gas in the carb. If it runs for a second will tell you if you have spark and enough compression to run motor. Great video

[@WayneTheBoatGuy]

Great point - That is a nice way to cut to the chase!

[@godofrock]

I always keep a 12 pack of cold beer around and bet my friends that if they get it started they can have the beer. Works every time! No work for me and I get a running outboard for under $20.

[@InspiredByEverything]

GENIUS! I am trying this!!!

[@sharonbraselton4302]

buy 12 volt çooler

[@socomsmith3241]

Bar means it's time to crack a cold one lol !

[@Whalermansteve84]

They are called gapless plugs.. my 1987 25 Merc used them .. it actually ran better then the ones that come pre gapped , I don’t know how , but it seemed to start on first pull vs the gapped ones

[@WayneTheBoatGuy]

Nice!

[@sharonbraselton4302]

chef had ner y 25 12 foit carolina skiff 228 watt akternatir ekrruc stat power trim tillt

[@patpacheco3296]

Hi I have a merc 9.9 110 from the late 60's early 70's. How or better yet where can I get a new prop? I have the serial number of the engine. I mean I have looked and looked, even went to a store that sold boat parts. Everyone including myself just gets confused. Any direction would be greatly appreciated.

[@florianborkenhagen9434]

Good Video. But always perform a Compression Test at WOT for exact meassurements.

[@WayneTheBoatGuy]

I've only ever used a compression test to verify two things: 1-that there is 'some' compression and 2-if there's multiple cylinders that the cylinders are somewhat similar

[@shawngibbon8198]

Also, there isn't enough water flowing out of the discharge suspecting a worn water pump and leaking prop shaft seals which are common for those age of units

[@andysinn8655]

Those little Mercs will run forever if taken care of and not left outside for years.

[@antonioesposito6802]

Ciao posso sapere quanti giri hai compiuto per la carburazione?

[@Alan-tn6de]

I just got one for free same exact model, where did you get the fuel connector?? Nice informative video

[@WayneTheBoatGuy]

I got my connector at West Marine but they’re also on Amazon.

[@todddenio3200]

I have had for many years an old Mercury mark 6, then a year ago I bought a boat that has a 93 Mercury 9.9 2 stroke on it which after I got it and test fired it without the lower unit on it for impeller replacement and it ran great, so some jealous SOB sabotaged it by taking a screwdriver and breaking out the ignition trigger and breaking one of the flywheel magnets. There were screwdriver marks on the broken trigger and the screwdriver was laying there too. But today I had a model 75 given to me that supposedly runs great but I will find that out in a couple days when I have time. I also had someone offer to sell me an old Mercury 110 (possibly including a 2nd one that also is supposed to run). They were offered to me for a “make an offer” price but I have no clue what to offer him as he’s never actually ran them since he bought them a couple years ago, so actual condition is unknown. I’m thinking about going to get them on payday. 2 of my Mercurys have been converted to Evinrude style fuel connections

[@sharonbraselton4302]

75 hp huñter edude 27 sail biat 25 moh

[@sharonbraselton4302]

cabinn cruseer 115 hp outbard

[@jonhutchens9770]

Wayne, a great product to use to repair wire cracks or damage is Liquid electrical tape. You brush it on and it dries to a waterproof flexible coating. Obviously if the wire is damaged too much, time to replace. The liquid is better than heat shrink in my opinion.

[@WayneTheBoatGuy]

That sounds like a good option for this particular wire - thanks!!

[@youdonthavetoreadthispost.5850]

I like to solder every connection first.

[@InspiredByEverything]

This is a great tip. I'm going to add some to my onboard tool kit in case I need to do some quick first aid out on the water.

[@zahoor3160]

hello friend i would like to ask you about a mercury 7.5hp that i have removed the upper head and like there is three small triangle sorry for that like i don't know how it's called but yeah there is three small triangle and i was wondering like how to put them in the right place

[@libsrmarxist]

I've got a 20hp mercury which is exactly like the one you show in this video except it's 20hp. Pull start broke... not the cord the "spring " came unhooked from the lip it's supposed to catch when you pull it. The problem I have is I didn't realize the nut and bolt were reverse threads and ruined the bolt and nut when I removed the pull start assembly. Can't find replacements.. where can I find them?

[@WayneTheBoatGuy]

Have you tried looking up the part number on the exploded view diagrams on the Mercury parts site? That part number can then be used on eBay and other places to find the part you need.

[@jeffshorts6052]

Great video I just acquired a 7.5 I believe it’s a 1974. No spark great compression. I’ll probably have to pull the flywheel and look for points. Also the wires are kinda hard and crumbling. Can you send me the links for parts.

[@chrisandlane]

I know this comment is old, but did you find a usable link for those parts?

[@jeffshorts6052]

@@chrisandlane no not yet

[@sailingpittsburgh]

I never saw that type of spark plug. Do they have a name for that type? Advance Auto and Auto Zone have tool lending programs where you can get a compression gauge for free by putting a deposit on it and getting the deposit back when it is returned. This was a very nice video on how to trouble shoot a two stroke engine. Thanks.

[@WayneTheBoatGuy]

I think they’re called a “surface gap spark plug” - I often forget about the tool lending programs! That’s a great tip!!

[@vladimirlopez7840]

Quite a few older outboards used that type of plug

[@Whalermansteve84]

They are called gapless plugs

[@bnich56]

You should have mentioned about the fuel filter !

[@coleanderson7290]

Hi I just got me a new 7.5 mercury 2 stroke and I’m not sure but I believe it’s a 1970-1980 somewhere between there but not 100% sure but I was wondering how I can tell what the gas to 2 cycle oil ratio is for my engine or is it the same as yours 50:1?

[@sharonbraselton4302]

yes it chuef had 6 hp 10 hp 25 ho 135 hp waverunn 2 sterikes thats right

[@oldmadbear007]

With a good quality for the screwdriver you can turn the motor over to start them number two very important take the prop off that way you don't get air bubbles what's a messy water pump up and you won't get water everywhere

[@WayneTheBoatGuy]

I didn't think about pulling the prop! Thanks!

[@sdanville]

So, what did you pay for it ? and Happy New year.

[@MustangBurger67]

Thank you for making this video. I had received this exact outboard and seemed to be having the exact issues that you had. I do have one question though, how do you get to the impeller and replace it?

[@MustangBurger67]

Never mind I just noticed you did a video on it.

[@WayneTheBoatGuy]

Glad you found it! That impeller fits in there TIGHT!

[@richardwernst]

New to your channel on this older video but it drives me crazy when folks take a motor (outboard or otherwise) and just start turning it over (other than small movement to see if frozen). Please put some oil in the cylinder before doing compression test or anything else. Yes, oil will artificially raise the compression but it may save the rings and cylinder from scoring due to having NO lubrication. Also, when doing a compression test, the throttle should always be wide open (and choke off, of course). Having not wide open WILL affect the compression readings. Assuming you've grounded the plug wires (can, but not guaranteed, damage the coil/ignition system if left ungrounded while spinning the motor), you can even put it in gear so you can open throttle wide. Otherwise, most outboard won't let you pull/crank them if they're in gear. Hoe this is helpful

[@WayneTheBoatGuy]

Great tips! Thank you for sharing

[@billyeldridge1929]

Hey got a question I have a 1995 mercury 115hp outboard it has the flat nose spark plugs in it I was told I could switch those to the standard type spark plugs is that true please help

[@WayneTheBoatGuy]

I'm sorry, I'm really not sure if you can switch out the spark plug types.

[@andytinline7717]

1 BAR (pressure) is about equal to the atmospheric pressure on Earth at sea level, If you want to get a more accurate reading pull the rope 5 times on each cylinder. This gives you a better average reading

[@WayneTheBoatGuy]

Nice tip! Honestly I was expecting them to be much lower and not within 5 psi of each other.

[@gilfredooquendo9969]

I need to hire your services for my mercury

[@WayneTheBoatGuy]

I'm just an amateur - watch enough KZbin videos and you can give it a whirl!

[@MrRinksclass]

Wayne. I have exact same motor. My Fathers old one. I am having trouble with the throttle engaging to full. Any suggestions would be great.

[@WayneTheBoatGuy]

See if there's a way to adjust and lubricate from the handle to carb first. Chances are some components of the mechanism needs lubrication, adjustment or repair/replace. My old Evinrude had a very worn arm (not sure of the part name) on the carb which had been modified at some point to keep it operational. Good luck!

[@sharonbraselton4302]

chief had pr9ble buy newer oiutbard

[@the2120company]

hello what year is this unit, I got into one and is issing ignition, magneto etc, wonder how could I get parts for it

[@WayneTheBoatGuy]

I think mine was from 1969-71 but i no longer have this engine.

[@billv3617]

Just got a 1973 mercury 7.5 hp for my fishing boat still waiting on fuel line connector till I see if it runs this video should help diagnose any problems thx

[@WayneTheBoatGuy]

Yeah that funky fuel connector is key! Good luck!!

[@billv3617]

@@WayneTheBoatGuy the motor I got has freyed wires coming from the Stater what is an easy way to remove flywheel I’m getting a gear puller tomorrow but how do y remove nut without flywheel spinning, of course the I got from said it ran fine lol

[@billv3617]

@@WayneTheBoatGuy where can I get points for my 73 Mercury 7.5 hp

[@Happy11807]

Bought a 70’s 7.5 Merc.a year ago Carb,and impeller were full of crud ! $35 dollars later and a little elbow grease it runs great! These motors are usually bullet proof with any kind of care!

[@douglasdingwall4915]

When storing your engine for the season you should disconnect the fuel line while running and let the motor run out of gas then you won't have old fuel gumming up the carburator....my motor starts right away every spring when I do it.Been doing it fo 40 years. After it starts turn off the choke....it is only needed for the intial start. I have a 2000 6hp merc and push the choke back in a just a second or two after it starts....not needed the rest of the day.

[@pjimmbojimmbo1990]

It would be smarter to add some Fuel Stabilizer to tank, run the engine to get the Stabilized Fuel into the carb, then with it still running, spray fogging oil in the carb, to coat the Bearings in the crankcase. I am referring to 2 Strokes. 4 Strokes? Who cares how they are stored, they are gutless wonders.

[@theoryxboi]

You should have sprayed oil in the cylinders. The oil helps for sealing and compression.

[@WayneTheBoatGuy]

I had never considered that - but it’s certainly not a bad idea, especially on an engine sitting for a long time.

[@ct1762]

well its really to lubricate the dry and probably spot-rusted cylinder walls

[@drummer0864]

put an O-ring inside and out side of your spark tester to hold the electrode so it doesn't move.

[@WayneTheBoatGuy]

Neat tip! I have a whole box of them sitting around

[@johnwigren4429]

I have a Mercury 110 it's probably the same years as yours. What kind of oil do you use to mix with the gas?

[@WayneTheBoatGuy]

TC-W3 outboard 2 stroke oil is what I use. Good luck! kzbin.info/www/bejne/bWOUn4inhdSJrJo

[@craigkaschan4822]

If you have to ask that I don’t think you should be on the water.

[@sharonbraselton4302]

best merçy outbard 2 strok 135 v6 merçy 135 uptuñed 110 hp

[@mr.v.2434]

Hi also I own a Mercury 35cv but I have some problems where can I find the spare parts?

[@sharonbraselton4302]

buy sçout 145 hybred eltric troolíng moter 8 hours 8 mph 64 mioe ràñge

[@kennethstafford2152]

Hello could you help me rewire my 1976 mercury 4.5 hp outboard. I need to know the schematic for points, condenser, and coil. Any assistance you can provide would be greatly appreciated sir

[@WayneTheBoatGuy]

There might be a diagram on the Mercury parts web site or MarineEngine.com

[@kevinle1268]

lets just appreciate that this guy replies to every comment

[@WayneTheBoatGuy]

Not EVERY comment. 😜

[@craigkaschan4822]

Used to have a few of these in 9.8 they don’t like salt water.

[@WayneTheBoatGuy]

good to know!

[@InspiredByEverything]

Is there any reason we wouldn't use inline fuel filters on these motors?

[@WayneTheBoatGuy]

People do add them!

[@Thonglover37]

weird air filter , just a little raster xD mine has a problem that it will run full speed with in neutral , but in gear i cant go full throttle and will go off

[@PapaMav]

That OB see the water? Still in operation?

[@WayneTheBoatGuy]

I didn't have a boat at the time that was well suited for it. It now has a new home.

[@TheYeddy87]

I have a 1969 mercury 7.5 what size is the fuel connector? Help please

[@WayneTheBoatGuy]

It might be the 'standard old style' Mercury connector

[@gemale]

Hi Wayne. I need some help to protect my money. Bought a motor from market place and guy said it’s almost new and working but since I bought it’s not even seems to be working. Can I bring my motor to you and you can help. Thanks

[@WayneTheBoatGuy]

I would try to find a real outboard mechanic local to you, or watch a few more KZbin videos and start playing with it yourself. Sometimes if we're lucky, the problem is something really simple.

[@nequea.5539]

I didn't see a fuel filter, they don't come with?

[@markrusso6401]

Dam ,, I started drinking again

[@MrMatthewkirby]

What happened to your 1977 Datsun?

[@WayneTheBoatGuy]

Lol - It got totaled in 1986

[@johncooper6246]

Hey Wayne! I'm just waiting til you drop something and smash that glass tabletop, Ha Ha. Just kidding, but seriously...

[@WayneTheBoatGuy]

That table won’t die!

[@chriseisele9969]

Did you change the lower unit gear oil

[@WayneTheBoatGuy]

I wasn't going to bother if it didn't run!

[@chriseisele9969]

what year mercury

[@seniorLu48]

I have never owned a Mercury, just how good are Mercury?

[@WayneTheBoatGuy]

I honestly don't have an opinion one way or another. It seems like the older Evinrude/Johnsons are more common, more desirable and may be easier to get parts for.

[@loganvick3385]

The indoors is the perfect place to run engines!

[@WayneTheBoatGuy]

Lol - The garage door was open!

[@loganvick3385]

@@WayneTheBoatGuyok😂

[@bradmartin9913]

I could really use a video on how to remove and clean out the carburetor

[@WayneTheBoatGuy]

I hear ya! It's challenging to get the camera close enough when working on carbs. Usually there's only 4 nuts to remove that are on studs. It often seems that two of them are easy to get and one or two are next to impossible. And cleaning it out is tricky because there's so many tiny little passages that have to be clear. Carb cleaner spray, soaking if necessary and compressed air are very useful as you clean a carb.

[@sammyrothrock6981]

That impeller definitely needs replacing

[@WayneTheBoatGuy]

And that is what one of my next videos was!

[@mckessa17]

Ya your impeller is shot.

[@semajekrad6922]

A bar is 14.5lbs per square inch .96 atmospheres Or 100Kpa

[@youdonthavetoreadthispost.5850]

I just sold a 2006 15 horse merc two stroke for half of what I paid for my 9.8 4 cycle Tohatsu. Small outboards can be like money in the bank.

[@sharonbraselton4302]

mercy has 4 ßtroke 9.9 and 15 hp buy miny tug biat honda 15 4 strokes

[@preparedtrucker6815]

I can't get the cover back on what am I doing wrong please help

[@WayneTheBoatGuy]

I think this one requires being over a 90 degree angle to hook the one side - but it's been a while

[@preparedtrucker6815]

@WayneTheBoatGuy I got it figured out apparently one of the little hooks bent a tad just had to Bend it back

[@preparedtrucker6815]

@@WayneTheBoatGuy do you need to use any special oil for an outboard motor

[@CrystalMaxey-cp1sf]

What compression test kit did you use?