Mercury OptiMax Fuel Pump Clean-out

Mercury/Mariner OptiMax fuel pump clean-out. The gray fuel line apparently suffered from ethanol decomposition and deposited debris into the fuel/water separator and fuel pump module. The engine would turn over, but would not start. NOTE: check the fuel pump fuse on the right side of the engine first. I believe the debris clogged my low pressure fuel pump motor, causing an over-current flow, which blew the fuse. Hopefully, this video will provide some insight into what you can expect when you do this clean-out procedure.

[@papaduck2443]

I like how this video is 5 years old but people are still commenting on it as of recent. I have that exact motor and year on my bass boat. Its been running like a top up until about a week ago. I turned the key and it fires up, runs for a second and dies. If I keep the key turned for several seconds it will stay running and runs fine when it is running but I found it wierd that it all the sudden wouldnt stay running when I turned the key. I immediately thought, its not getting enough fuel. Of course I googled it and here I am. I replaced that grey hose last year when I went to replace the primer bulb and noticed how the hose was flaky inside. I also added a water seperator/filter just after the gas tank and before the engine. I think if I change the red filter and clean that out it may do the trick but I think Im gonna pop that top off and replace that rubber seal as well. Great video, great info! Was so glad to see someone was finally working on the exact same product I own right down to the model year. Thanks again!

[@aaroncondon871]

Good video!! I had a similar problem with what now is a VST tank. I checked my fuses before I started getting involved with replacing the pump . Due to constant cranking the fuse for the pump and fuel injectors had blown. That's a good reminder to check the fuse block after any repair because it's always something simple that you can beat your head against a wall over. Thanks for sharing!

[@rik0715]

Thank u so much for this video. I boat died at the lake this weekend. Imagine the sight, a little jet ski towing a 21’ pontoon lol. I need to order the filter tool before i break all the ears. Hope this fixes my boat too

[@EricsBBQAndMORE]

Thank you for this video! I had great success making this same repair saving me hundreds of dollars! I plan to post a video in hopes to help others like you did. I will give you all the credit and link to your video! Again, thank you!

[@ronmitchell8929]

Thanks! Just the video I needed. I started out with a busted primer bulb. Replaced the bulb and line. Still a no go. I took apart the primary pump. Inside you'll notice two plungers on springs. One of my springs was broke in half so I put a kit in. Still a no go. I followed your video and cleaned the box out and 👍👍. Just a note that black plastic float will saturate after 10-15 years and will not float at the proper level so it's a good idea to change them. Also the needle valve that hangs on it make sure you check it out good. The seat it goes in is bad about corroding and collecting trash. When you sprayed carb cleaner in there you probably cleaned it out and didn't even know it. Again thanks for the help. Having worked on boats and cars for over 40 years this set up is like a cross between a carburetor and fuel injection. Car engine just use a fuel pressure regulator to return the excess fuel pressure back to the gas tank. Very interesting.

[@RoosterMclaren]

Thanks for your value added comment You two are saving me mucho dinero. 🤞

[@Happy-Hunter89]

Got water in my engine and this video helped me get back up and running. Thanks!

[@Devil7414]

the best and the most informative video on youtube

[@patrickcobb4483]

I had a symptom of 1/2 to 3/4 throttle it spudders & struggles to get on plane. I have new plugs & quite certain of no water in my fuel. Its a 2006 200 Optimax with 280 hours. Thank you so much for your time showing this. I ordered a primary pump & looking forward to disassembling mine to get it cleaned up. 🍻

[@wewetree8816]

Hey Patrick, How is your boat running? I have similar problems. Was the spuddering making a loud noise (jumping rpm) or was it subtle and/or lack of power?

[@tylerdavis6439]

I'm in the same boat.. redid all new fuel lines,bulbs,rebuilt the low pressure fuel pump... but never completely took apart the this separator tank completely. Just drained it from the bottom screws. Someone please help lol Might rip apart the tank tonight just to see. But I have twin 2007 225hp optimaxs. Start and idle flawlessly.. when I plane off and run for like 2mins. She starts to surge

[@handyallaround5776]

excellent video , very good tip about arrows lining up

[@sesmarias]

Great video. You help me to save time and money, because I had same problem on my Mercury 90Hp Optimax from 2006. I am in PORTUGAL. Thanks a lot!

[@RichBrownsChannel]

Glad it helped

[@leohenderson9631]

This is a great video. My motor would run at about 2000 rpm but any higher and it would just die. I watched this video and cleaned out my vst and fuel pump and now it is great. Thanks much for the great video.

[@RichBrownsChannel]

Glad to hear it!

[@barrynelms564]

Great info.....I think you gave me all the info I need, my 115 Optimax has been up all winter, started on first try, cut off, started again-cut off after a couple of min.-started again-cut off...I do not have a manual so was not sure what all I am looking at...downloadedone on line but could not find it in trouble-shooting..added NEW GAS but the motor will not fire or start,.,..the shrader valve on one side deposits gas and air, the other side only air, so I figure there is a blockage---and we could not get the fuel filter cap off--thanks for all your great info...going to the local Merc and get that tool.

[@sweetfordfx4]

Very good and informative video. Thanks for this.

[@richardfrost7601]

Very helpful video, thanks for sharing this.

[@RoosterMclaren]

You’re my hero. Can’t wait to try this.

[@garylcarrier]

Great job! Excellent video!

[@Commonsense167]

What an excellent video you really pay attention to detail and thank you so much. I think this is what's wrong with my motor and I am definitely going to try it much appreciated

[@stevena9512]

Great video, I have an Optimax I need to get torn down and figure out why I have no compression.

[@raytiernan6321]

Rich, that was one of the best videos I have seen on youtube, very informative! Thanks

[@jaywoodgarage8447]

Did one of these before and glad I did versus spending the big bucks on a new one. They're between $6-800 from the dealer vs about $25 to just rebuild and clean!!

[@davidfritch6954]

Thanks for the video!

[@ufoDziner]

Thanks for such a detailed video. I had a similar issue, except mine would idle, but wouldn't accelerate beyond 2000 RPM, then it would quit. I had a bunch of gel in the fuel screen/water trap that I cleaned out at the lake, but that didn't solve the problem. After watching your video, I tore into mine. WOW, what a mess! Gel everywhere, and the screens on the bottom of the pumps were >80% blocked! I cleaned it all out and re-lubed all the o-rings. Testing on Saturday, but the quick driveway test says that it should be WAY better. Thanks again!

[@RichBrownsChannel]

ufoDziner To damn kewl when it fires right up.. : ))

[@7x779]

+ufoDziner Any update? Hows' it run now?

[@ufoDziner]

+Beulah Lips The boat ran great for a one trip after this. On the trip prior, I had a compressor overheat warning. It appears that if you get one of those, the compressor is done. In my case it failed on the next trip. Turns out that my fuel rails were practically rusted closed as well. So, after having the injectors cleaned, replacing the fuel rails, and a new compressor, it runs like a champ!

[@7x779]

ufoDziner who cleaned the injectors and how much was it? Did you also clean the air injectors or just fuel injectors?

[@ufoDziner]

+Beulah Lips I had European Marine do the work (they cleaned both). They seem to be about the best that I could find. What I paid is much more than most because I had to replace almost everything. They'll give you a quote. I highly recommend them.

[@rsieveke1]

I have the Same motor... Same problem. FYI the price of that seal is now $19.00. Thanks for posting the fix.

[@paulenglefield3489]

rsieveke1 you guys got it lucky just paid £23 so about $31.22 in the UK

[@wayne1959]

I agree with paul below..in aus that would be a $50 part..optimax spark pugs are $37 a piece here and I can buy them ex the states for $12..luckily the NGK guy here can sell them to me for $15

[@lildavidjax]

VERY informative! Bet this our problem! THANK YOU!

[@abdulazizal-assaf9588]

thank you for this video

[@donashvini6546]

Thanks for the videvo !

[@PattersonProspecting]

Awesome job thanks for the info.

[@peterogryzlo5675]

Thanks for showing th part no for the high pressure seal. Even at 12.50 they are hard to find,

[@fuckerfreak]

I have the same problem with my 100HK 2stroke Mercury. I will do the same thing, to see if it fixes the problem, thanks for a great video! Greetings from Sweden! :)

[@RichBrownsChannel]

Before you do anything, I suggest you disconnect your fuel line and pump gas into a clear container to see if there is water in your tank.

[@markcasey2517]

Mate. This is a fantastic video. Well done and thank you.

[@philnorton6095]

VERY GREAT PRES/ON THE PROBLEM / AND IT WILL HELP ME AS WELL THANKS.

[@okskeeter278]

Man this video helps! Thanks for posting.

[@RichBrownsChannel]

Glad it helped!

[@wayne1959]

good video.Thankyou

[@mtsaz100]

Also, I would strongly recommend using marine gasoline additives for ethanol and to preserve the gas. Don't use car products they are not the same--they work- but the marine products are made for marine engines, ie outboards in particular.

[@martinfromseacity2010]

Good video

[@josephfreeman1427]

Today I was having the same problem so I used an external tank that I had off my small boat and the gas tank has a check valve people that have big boats make sure you have a check valve in the fuel line. With the small tank I can get the fuel pump to prime beautifully and the primer bulb would stay hard. With the original fuel line that came from the fuel tank in the boat the primer bulb would not stay hard there has to be an inline check valve inside that fuel line somewhere on your boat you have to install it so when the pump Primes the line stays hard in like a car.

[@randy1ization]

bought a opti from a friend who had continual fuel problems,, he didnt believe in marine stabil..I have used it since buying the motor and no fuel system issues.

[@TomBurris]

this is awesome. about to do the same job. this was a great help

[@RichBrownsChannel]

Tom Burris Tom, make sure you check the fuel pump fuse first. It is on the other side of the engine. Thanks for watching. : )

[@TomBurris]

Rich Brown Thanks. We have fuel. Starts and runs. From time to time it acts like someone pulled the throttle back and bogs down. Found some black tar in the filter area. The filter felt a little heavy even though it looked ok. I think the tank is delevering some varnish a little at a time. I inherited the boat and they ran ethanol.... SMH.... Put a filter in it and am going to run a bottle of cleanr thru it. Crossing fingers.

[@7x779]

+Tom Burris "the ran ethanol... SMH...." Do we have a choice? Where can we get non ethanol fuel? Not in my city of 2 million.

[@TomBurris]

+Beulah Lips we live outside of baton rouge, la..... lots of non ethanol options. it is crazy to run ethanol if you have options. i understand it is hard to find for most

[@7x779]

Tom Burris sounds like you could have clogged injectors either air or fuel or both. The Mercury dealer told me you can use a mercury product product called quickclean take the fuel filter out suck the gas out of the well and fill quick clean in there and put the filter back. Then run engine at idle with pure quick clean and use another product in a spray can called power tune spray the power tune into the intake of the air pump also while it's running at idle. Then turn it off let it soak for a while and repeat

[@akowned1]

How did it get through the onboard fuel filter?

[@sgray2052]

Awesome !!!! Thanks :).

[@MednickClub]

Can you tell me what is that hose on the min 3:27 because my hose was broked accidentally and i dont know if it is my problem or low pressure fuel pump goes bad..

[@markzanetti6228]

thanks a million for this video.

[@paystar1961]

Great video ... Can anyone help ? My 75HP DFI Optimax pours gas out the overflow of the VST into the water ... Engine runs fine. I have pulled apart VST and cleaned a couple times. I have replaced the needle on the inlet and put new fuel filter in the VST. Gas still pours out the overflow when engine is running.

[@mtsaz100]

Assuming the VST is ok- no leaks in it, and the float /valve is properly set so its not just filling up and overfilling- I would make sure I do not have a restriction in the hose from vst to fuel rail. Did you check the fuel/air pressures? They should be 10psi difference- that will at least tell you if the proper fuel pressure is being delivered to fuel rail.

[@Jubi316]

I can tell you they charge 600 for them electric pumps at dealer but you can actually buy the exact pump off amazon for 19.99 I have done it a bunch !

[@greauxpete]

FamilyMann what part number do you look up on amazon? Have a link? could use it right now.

[@okiefish7066]

ohhhhhh yes....the dealers are the LAST place you want to locate parts!

[@outland4]

Do you have a refence part?

[@7x779]

So how did it run at full throttle now?

[@stevegabes146]

Also I would say that your oil tank is to low it needs to be absolutely full, open the cap when the boats running and let it fill, had problems with that letting my boat run as well

[@clintonhuffaker8252]

I don’t see where you have talked about fuel injectors. I am in San Antonio and love to drop bye so you can look at my boat. One of my cylinder does not fire. Spark plug are good and coil is good. Left main tank has junk in it and needs to be cleaned out. Right tank in good. Boat will not go above 3,200 rpm.

[@bubatrilis5200]

thanks

[@paulenglefield3489]

Hi did the new rubber seal at 19 minute push all the way onto the top of the pump or should it fit half on to seal into the top housing ?. Cheers

[@RichBrownsChannel]

Paul, I again had to do this cleanout two weeks ago. I replaced both seals. I noticed that the old seal was compressed only half way, so I believe it only goes in half way.

[@steelhammer365]

Hello, i was wondering how the to take off the fuel line from the high pressure pump outlet to the fuel rail? just remove the 8mm bolt and pull the fitting out? just want to make sure im not going to damage anything. thanks

[@RichBrownsChannel]

The rubber hose coming out of the high pressure side is held on with a clamp. Unscrew the clamp, use pliers to twist the hose and gently pull the hose off.

[@jca2908]

May I ask... did you notice if the elec. low press fuel pump when turned upside down and back went click click. sounds like there is a small one way ball valve in there. Mine does so, was just wondering??

[@RichBrownsChannel]

jca2908 I did not notice anything like that...

[@randyspringston380]

Nice job. I was wondering if you know if the fuel rails are supposed to be hot to the touch?the right side is noticeably warmer, can't hold your hand on it. I have a 2011 mercury 150 pro xs optimax.

[@RichBrownsChannel]

Never tried touching them...

[@randyspringston380]

@@RichBrownsChannel thanks for answering

[@wolfpackflt670]

my optimax runs rough at "wake" speed and will run WOT for about 1 minute and then drastically lose power and almost stalls unless i back up the throttle...what is going on?

[@jca2908]

Mine does exact the same.... did you solve the problem?

[@steveduncan131]

I have a Constant alarm goes off around 4K then it runs ruff any suggestions where to start Thank You

[@EricsBBQAndMORE]

Check your impeller

[@duramaxbradentonsaltwaterf9471]

thats exactly what went wrong with my 225hp mercury optimax. ethanol ate up line and clogged my high pressure fuel pump.

[@mikiefitzgerald7113]

what was it doing when that happened?

[@duramaxbradentonsaltwaterf9471]

eventually wouldnt start. took to mechanic and he replaced hose and high pressure fuel pump 800$

[@0Jackhammer0]

Did you have to pre-fill the bowls upon reassembly or did pulsing the key switch on/off for the pump to turn on fill it?

[@RichBrownsChannel]

my boat has a primer bulb. I prefilled.

[@victormanuelgonzalezgarcia7543]

i need to know if this motor is 2 o 4 stroke and what oil i have to put in the reservoir ,my motor is optimax 115hp ,year 2006

[@RichBrownsChannel]

It's a two stroke. Use any two stroke oil for outboards.

[@larrythompson5617]

So, what do you think contributed to this issue?

[@randylea6058]

i need a housing gasket

[@randy1ization]

it took big gonads to go that deep.. thanks for the vid

[@kawscottyoung]

What should the fuel pressure be at the schrader valve just above the high pressure fuel line on the fuel pump module?

[@RichBrownsChannel]

I really don't know. I don't have a manual. I suggest you call a boat shop and ask them.

[@papabits5721]

Scott Young did you ever find out fuel pressure

[@theherbalist2892]

I can't get the cover off my VST. I broke and completely removed the HPFP o-ring (shown around 6:30 in this video), but the VST cover still won't detach from the HPFP. It seems like it's somehow connected up top where I can't see (don't want to lift too much and break the wire). Am I missing something?

[@RichBrownsChannel]

There is a hidden screw next to the engine block, one of those that holds the cover on...

[@RichBrownsChannel]

If it isn't that screw, then the rubber "cork" I mentioned may be holding it in.

[@theherbalist2892]

Thanks for the reply. The "cork" was corroded and keep the HPFP nozzle stuck in the VST cover. Had to pry against the metal housing of the VST with a screwdriver to leverage it out.

[@randy1ization]

if you get polarity mixed up, the pumps will run backwards

[@outlawshinemaker]

always use startron fuel stabilizer blue bottle from orielley auto .

[@harrysachs2646]

The Notorious Angler better yet non-ethanol fuel.

[@MrMrwilem]

12.50 for 1 inch of fuel line hose. damn

[@mtsaz100]

THE OLD hoses. Not the new grey hoses--but the original mercury ones were prone to this. I would never buy a cheapo hose---they collapse and that is an even worse problem.

[@brian3.2]

Can the vst cause bogging and random shutdown?

[@RichBrownsChannel]

It could be any of several things. If you can't pin point the cause, take it to a shop.

[@dutcharduino2806]

Sounds like Blue Jays in the background the whole time causing a ruckus

[@RichBrownsChannel]

Good call. They are BlueJays. The Texas Hill Country has lots of them.

[@bobkreiser967]

how do you get that hose off on the right side at the bottom?

[@RichBrownsChannel]

Remove the bolt, then pull

[@dozer8065]

The dreaded mercury fuel line. This goes out too everyone if you own a mercury outboard and the fuel line has a clear liner trash it!! I usually will run Moeler or even a brp fuel line. When i service or work on a boat and it has that fuel line...i automatically replace it.. matter of fact its protocol at the shop.

[@JoeTayMetal]

Will a bad pump cause fuel to leak down and out of the lower unit?.

[@Wolfpack1254]

Dude is a mechanical genius.... what a memory, should take him to Vegas to count cards at the blackjack table... how's he get everything back together correctly? So the originating problem is ethanol deteriorating fuel lines over the years, and causing bits of rubber to clog up the fuel pump.... I still don't understand how an electronic fuel pump and all those wires can sit in gasoline inside the VST and bottom of the carb housing without causing a fire.

[@marymichaels5434]

Wolfp

[@purewaterswva.5409]

No air for combustion

[@melostmo]

So, what's the deal with my fuel pump cutting out ??? Turn the key to ON , the pump runs a few seconds then stops. Turn key to OFF, & then ON , pump runs a few seconds then stops ! is this normal ? Motor will not stay running

[@RichBrownsChannel]

I've not experienced the symptoms you describe. This past weekend, my motor would be running fine, then would choke and die. I had put an in-line filter in between the primer bulb and the engine, turns out air was leaking in at that filter. Check your hose clamps, make sure they are tight.

[@melostmo]

hi Rich, & thanks for posting this great video & replying. Maybe you can help me, before I go nuts. .. If you were to remove the cover on your Optimax and turn the key to ON without starting, you can hear the fuel pump running, OK. But does it continue running ? or does it stop ? like mine does ? eta- when I jump the pumps to a remote battery they keep running like normal , as if to say both pumps seem fine. I've done all the clean out work as described in your video

[@RichBrownsChannel]

If you get in your car and turn the key to acc, without trying to start, listen carefully and you may be able to hear the fuel pump come on, then stop when good fuel pressure is achieved. I'm sure the Optimax fuel pump system works the same way. The pumps only work when fuel pressure is needed. They probably work almost constantly when the engine is running.

[@EricsBBQAndMORE]

I bet if you take your fuel box apart you will find that you need to replace the little rubber piece shown in this and my video. It could just have a crack not allowing the fuel to pressurize.

[@melostmo]

RB - good point .. reckon I couldn't figure why the pump would stop when the fuel rail was still not pressurized.

[@brandonrobbins7036]

You got a part number on that filter?

[@RichBrownsChannel]

Search Amazon for Mercury Optimax fuel filter.

[@RichBrownsChannel]

Include your engine horsepower and I strongly suggest you get the filter removal tool.

[@cadillacescalade1]

1000000 👍

[@kylewalker7072]

when you see all that junk in the vst, the pump is done

[@felpgonzalez8436]

Necesito comprar las dos bombas de gasolina para mi motor tendrán un distribuidor de confianza que me comparta y el modelo de las bombas

[@RichBrownsChannel]

Felp, los dos motores están disponibles en Amazon. Si se encuentra en los EE. UU., cualquier distribuidor de embarcaciones con un departamento de servicio puede obtener los motores, pero serán más costosos.

[@morgancure1604]

so you don't take the bfuel pump out

[@RichBrownsChannel]

There are three fuel pumps. Low and high pressure pumps inside the VST, and the primary pump just in front of the VST. If there is a lot of gunk or dirt inside the pump chambers, I would take them out, clean them and the chambers, and apply 12 volts to verify they are working.

[@RICHJMS]

It's 90% not trash . It's you fuel pump has low pressure

[@helpAmerica1]

The $12.50 PART was failing in ours, starves the engine of fuel.

[@helpAmerica1]

same here

[@RobertSmith-vv5on]

What did you change? Mine is having same problem. 200 hp mercury

[@kodibassInsideoutboards]

Very good vid-bro, sub'd / liked. thanks

[@RichBrownsChannel]

+kodibass Glad you liked it, thanks for watching.

[@t.j.3873]

You ain't gonna be fishing long if you dont put some water to the lower unit to cool the engine off .. Also the rubber impeller is spinning at idle at 750 rpms and burning it without that water .. So your next job is gonna be a water pump impeller.

[@davidjessee7701]

20:39.. Water coming from. The pee hole ... Dosent show the gear case so you dont see the muffs.. But its has a water hose on.. This guy was too meticulous not to hook up the water... Good try though

[@tonchido]

unscrewing red filter is just fine with screwdriver or any other flat and fat tool if the filter is original quicksilver,they are hard plastic comparing to surrogate filters from other companys,so now we need fuel rail and injectors

[@mitchduncan2140]

Wrong! Mine was original Merc. Did same thing as in the video!

[@rebelroy11]

Here's a link to a video I made showing the high pressure pump running constantly. Video is nearly 1:00 long and HP pump still running so I just cut the video. kzbin.info/www/bejne/Y528qGCvjtF0qpY Also here's a link the engine "running" and dying. Then struggling to start. lol. kzbin.info/www/bejne/iYmUoIWMe7qlqbc Took it out 2 different times and ran fine until time to leave then wouldnt stay running "if" I got it started. Trolled most of the way back both times and got it started. 2nd time hot I had to put the hot foot to the floor to get started after it died (after running fine all day). Now it starts...or doesn't and if does it wont stay running or idle unless it give throttle. Any ideas?

[@EricsBBQAndMORE]

Ok, here is my video, doing the same fix, thanks again! kzbin.info/www/bejne/aXSyoJuQhth5pKM

[@williamriley2528]

Never use ethanol Blended fuel in any small engine only use it in a car and truck... only then if it's going to be driven daily... in the winter use Heat gasoline additive every time you fill up the tank...! Only use non ethanol fuel in small engines period...!

[@highvelocity123]

Fuckin Ethanol...Absolutely destroying marine engines. Change your in line filters often. I have a big in-line filter and one on the engine that I replace every year...

[@rodney6165]

the best and the most informative video on youtube

[@RichBrownsChannel]

Glad you think so!

[@t.j.3873]

You ain't gonna be fishing long if you dont put some water to the lower unit to cool the engine off .. Also the rubber impeller is spinning at idle at 750 rpms and burning it without that water .. So your next job is gonna be a water pump impeller.

[@RichBrownsChannel]

Sorry to disappoint you, TJ, but I'm not stupid. The engine has a running water hose attached.

[@t.j.3873]

Hey just pointing out what is seen , your video with the motor running no water pissing out the back. Didnt call you stupid or dumb , why so touchy?