Installing Holley Sniper EFI on a Boat

I installed the Holley Sniper EFI Rochester 2GC kit on my 1984 OMC 3.8L Wellcraft. The kit cost more than the boat was worth but now I have the reliability of EFI and no more carburetor issues! It took me most of the summer but we were able to take it out on the lake and test it.

[@yoster77]

Putting this on an old OMC stringer drive - you deserve an award!! Thank you for keeping this ol' girl running. It's just so cool to see someone convert a boat of this vintage to EFI. Also - really good angle/shots of it running. Thank you for that! Would love to see more of it!

[@fordtechchris]

Thank you! I'm going to try to get an update video of I can get it on the water a little more this summer. I need to do some tweaks and fine tuning still, so hopefully I can catch that on video.

[@darronlemell224]

Good to see a old stringer drive. I love the old omc's long live the stringer!

[@fordtechchris]

Ha ha, yes! I'm a fan of anything older and sometimes obscure.

[@brik4evr]

Hello. I have a 95 Larson Cabrio 250 5.7 tbi. Had issues with the Rochester so I bought a complete Holley 4150 Sniper with Htyperspark distributor and coil setup. Mounted the electricals on the transom well up and away from moisture. I do pull the boat out usually but have left it moored for a couple of weeks at a time over the summer. Been working well right off the wizard but I've since learned to do minor adjustments like IAC to 7 %. So far so good. I did find that I had to eliminate the prime because if there was a stall, the unit flooded. My trick. unplug the fuel pump relay. Crank it over, and it'll start but quickly re-plug the relay and she will run. Nice to know out in lake erie. Also, I run 3 batteries. I don't believe that the sniper makes more power but the plug and play of it was amazing. Had my riser drilled to accommodate the O2 sensor one side but seems ok. ECM goes into learn mode at 160 F. On line halp is great but tough for me to absorb without multiple viewings. Considering installing check valve under the holley pump as it is mounted about 8 inches above the tank using the old mounting hardware and am warned that this elevation will burn the pump. I'm guessing that this is because the pump will be sucking air straight off, hence the check valve. I did securely wrap wires and plugs with electrical tape and sprayed the tbi unit itself with clear coat paint spray.......to stop the oxidization of the polished unit. My only concern is....... I can make a carburetor work but if this unit messes up, I'll be paying a tow. Feel like carrying a carb, and electrical components on board just in case as I do a raw water impeller. Oh, I grease my exposed electrical connections like on the fuel pump. Wiring direct to the battery Is Important.

[@fordtechchris]

Thank you for the huge interest in this project! Hit the SUBSCRIBE button so you don't miss Updates on this project or Future EFI Conversion projects! (My 1974 F-250 460 has a bad carburetor 😉) And Thanks for supporting my Channels Growth!

[@5635randy]

Really good job Holly does make filter that would eliminate need for return but you did great job. Love how you worked through each problem with sound solution.

[@chrisking7255]

I’m a marine mechanic currently "12yrs" and before I owned a motorcycle/atv/snowmobile shop for 8 years, I could clean/rebuild pretty much any types of carbs blindfolded and with a single hand easily… but with nowadays shitty fuel quality if fuel stands still in the carb bowl even for a very short time "3-5 weeks" the fucking fuel turn into jelly/grainy varnish and clogs pretty much every jets/little fuel circuits and even float needle port … so carburetors are now a fucking pain in the ass to have of your power sports machines unless you use them every single week!!! Fuel stabilizer are ok for season storage only I wouldn’t run every fuel tanks with stabilizer in it !! Now I’m converting both of my boats Mercruisers to efi and plan to diy convert my Banshee / yz250r to efi also !!! Great video btw man keep up the good work 😎😎

[@brik4evr]

SEA FOAM !!!!!

[@bensboats]

Dude. Seriously awesome video! I have a 1982 Cobalt with this same OMC 3.8L V6 and stringer drive. Good work saving the old stuff!

[@fordtechchris]

Thank you! It can be frustrating, but it is fun keeping old stuff running.

[@jamesal0]

I held my breath when the gopro went under water - great video.

[@fordtechchris]

That's funny! Thanks

[@kari53]

A trick that you can use to true up that manifold is to get your self a piece of mable slate. Homedepot has them 5/8 thick by 5 inches wide at various lengths. Then 3m spray glue your sanding paper down. The resurface is within most engine specs for heads. Just remember gasoline/petrol return lines in a boat are illegal. EFI for boats have differant fueling requirements and are designed with no return lines. If coastguard sees that it will be flagged. Insurance can be canceled if they get wind of it.

[@fordtechchris]

That's interesting, I hadn't come across that. I would prefer a returnless system, but it was hard enough to find this one. Looking at doing a returnless in my truck though

[@mysticvalley2003]

Dude I don't know what your thinking but your exhaust manifolds & risers are rusted out which reduces your cooling that probably led to the cracks on your exhaust manifolds.The problem is if the ports on your risers or exhaust manifold continue to become blocked your engine will run hot and eventually warp your heads. See ya later engine...all 4 of your ports on your manifold / riser need to be open....google replacement part and you'll see it. In salt water the life expectancy of risers is approx 5 years. Another tip if you want your boat to look new, wash it, then prime & spray it with Rust oleum boat paint with an air compressor....its cheap paint but will give you boat that wow factor for a long time

[@fordtechchris]

Yeah, the boat was destroyed in the SF Bay. Used as a fishing boat. I bought it for $500 with a rotten transom and no floor. Replaced all that and the engine mostly ran descent the last few years. But as a full time mechanic, I absolutely can't stand wrenching on things anymore. I legit have to drill exhaust manifolds every day at the Ford dealer. This is as enthusiastic as I can get over this cheap, outdated and obsolete boat as I can get. Maybe you've never looked in to parts for the early OMC stringer engine, but they are unobtanium. Heck, I never even replaced the spark plugs while I had the manifolds off, I loath wrenching that much, lol. Thank you though, I'm sure you're on to something about the rust though.

[@austinflick1453]

Salt for sure will eat up a motor without a closed cooling system but your manifolds don’t look any worse than 20 year old boats I’ve taken apart that have always been in fresh water.

[@fordtechchris]

@@austinflick1453 I'll keep flushing it with Ford VC9 iron cleaner. As long as it's not overheating, I'll be happy.

[@user-ul7cq7ss6v]

Your a bad ass

[@alexpaun3153]

Can you help with some advice on how would I know which model I would need ? Currently rebuilding a mercruiser 3.0 140 hp - Would love to get this fitted instead of the carburetor

[@fordtechchris]

You're going to want to find out what kind of carburetor is on the boat and then research Holley's direct fit Sniper for that model. In my case it was a Rochester 2GC. But they also have Carter and 2 barrel Holley's too

[@chandlerclaussen1885]

Did you buy a fuel line and fitting kit or just piece it togrther? If you bought a kit which one did you get and have you had any issues with it?

[@fordtechchris]

I just pieced it together with various summit and jegs AN fittings and a roll of braided fuel line.

[@Toolmaker76]

We have a 1982 boat and considering the MEFI sniper. Currently has a rochester q jet and is trouble free, it's a stringer OMC 260 mechanical shift. Would you do it all over again? We just replaced the 40 year old original engine last year due to internal engine corrosion in the water jacket. I overheated it cracked a head. I found out after, the previous owner would remove the water pump on the front of thenegine and clean out the block. It's also raw water cooled and was well maintained, it would run at low power just fine but WOT or towing I struggled to keep the heat down, did the thermostat and risers too. Great video. I have a set of exhaust elbows and engine mounts that would work for you boat...

[@fordtechchris]

If it runs fine with the carburetor, I wouldn't mess with it. This was mostly an experimental project for me, but has taken a lot of tinkering and it still isn't quite right. I'm pretty sure a bad thermostat was my problem all along. I'm not certain I'll keep the boat much longer either.

[@nickg7205]

The location where you installed the coolant sensor is very poor. It's reading the cold water entering the engine, not the warm coolant exiting the engine, which represents the true engine coolant temp.

[@fordtechchris]

The water pump had a hole already tapped, so it was convenient. I would much rather have it in the manifold coolant crossover, but I found with marine-ized engines you don't get as many options. I have noticed the Sniper reads very consistent with the temperature gauge in the dash though, so I think it's pretty accurate.

[@Brian-mp2mv]

Is this Sniper EFI a marine unit? Looking for Sniper EFI for 1991 Mastercraft ProStar 190 with 351windsor to replace a Holley 4160

[@fordtechchris]

It's not, but I'm the literature it says it's marine compatible. But there are so many coast guard rules, you may be in violation with aftermarket EFI

[@Brian-mp2mv]

@@fordtechchris Agreed, I know my Holley 4160 still has the Coast Guard mandated and approved spark arrestor air cleaner, and marine specific non-sparking starter. Weird though that I don't see that my alternator is spark proofed marine grade.

[@lawman390]

Hello where did you purchase your EFI kit? I have a 5.7 liter V8 4bbl carb. Mercruiser. I'm looking to install on my boat.

[@fordtechchris]

It wasn't a complete kit. Mostly due to shipping problems the lastt few years. I peiced it together from Jegs and Summit

[@atiaimesui2199]

Nice work bud, are you in nor cal?

[@fordtechchris]

Used to be, but moved to Idaho.

[@chrisking7255]

I love that Evinrude sealing compound your using man btw … I’m a certified BRP Evinrude, Yamaha Marine, Suzuki Marine and Mercury Marine outboard technician , but I only use Evinrude Sealing compound ,triple-guard grease Ect… the best chemicals imo 😁

[@KaoticFdr1]

how did the O² sensor last? I'm so worried about spending the money on something like this for my engines only to have to run open-loop if I ever pull the trigger.

[@fordtechchris]

Sadly we only got it out three times before winter hit and I put the boat away. But the sensor is not exposed to any water in the exhaust, so it should be as reliable as in a car.

[@austinflick1453]

Exact same concern I have on my boat. But I did forget the water jacket doesn’t always go all the way around the exhaust so I’ll take mine apart to see what I find. Good video!

[@guglielmodicarlo4139]

wouldnt it have been possible to just put a return into the fuel feed, like a t, to return the fuel ?

[@fordtechchris]

I was initially going to do that. Figuring that system is under vacuum anyways. I tried researching if anyone else was tried it and couldn't find anyone doing it. My biggest concern was circulating warm fuel over and over again through the system. In the end it really wasn't too big of a deal to return to the tank. I know every fuel injected vehicle I've ever worked on also returns to tank for fuel cooling, so I figure better safe than sorry with vapor lock or other problems out on the water.

[@mattwoody1089]

Is there any o2 sensor to hook up

[@fordtechchris]

Yes, it needs an O2 sensor to run the best

[@mattwoody1089]

@fordtechchris hi where do you locate it on a wet exhaust

[@fordtechchris]

@@mattwoody1089 if you watch the part where I had the manifold off, I found a dry spot where it wasn't jacketed. There are adapters for more popular boat engine types

[@djrowe007]

The only problem I see with this is that this Holley TBI is not coastguard approved. I looked into getting it for my 4.3L with a 2gc and they don't make it in a marine version. They also said that the fuel pump had to be at the lowest part of the fuel tank. Did you have issues with fuel delivery when gas was low? I'm looking into the conversion kit from 2gc to 2300 sniper. That is the fuel return line you drilled into the tank?

[@fordtechchris]

I initially ordered the 2300, but it was not going to fit at all. It was all kinds of wrong for the Chevrolet engine. I'm sure with enough fabrication it could work, but the 2gc version was far easier to adapt. The mounting flange was the first no go and I didn't have enough room to try to get the adapter to fit. I had hours of footage into trying the 2300 that I cut because it didn't contribute to the finish project. That's why the video starts off a little weird. I swore I had found somewhere that it was coast guard approved. It shuts off the fuel pump when the engine stops and the fuel pump is approved for sure. Not sure what other safety features it would need. Carburetors are required to vent into the throttle but these don't have bowls to vent. I almost never run my fuel tank below half. The hole I drilled is the return. The pickup goes all the way to the bottom and the pump sits roughly at the half way level maybe lower once the boat is on plane. I have not had any performance issues yet.

[@Wingnut353]

@@fordtechchris Both of them (2BBL and 4BBL) are coast guard approved... only the smallest one isn't. You just have to make sure you have the spark arrestor installed.

[@brik4evr]

My holley fuel pump is mounted above the tank about 8 inches. still working well but am considering a check valve under the pump , as, I think the problem is with sucking air before prime if the fuel flows back into the tank. I'm nervous about installing the pump as low as the tank because that is bilge territory and I made use of the old existing mounting hardware from the old TBI. I did route a return line well out of hazards way.

[@guglielmodicarlo4139]

never seen an engine move like that for tilt, what is that?

[@fordtechchris]

It's the old 80s OMC stringer drive system. They're all but obsolete. The Cobra drive quickly replaced it for obvious advantages.

[@joebarrios3579]

what fuel pump did you use, and what is the rated psi and gph?

[@fordtechchris]

The Holley 12-920, 60psi at 80 gph. I got it from Summit Racing.

[@bigray3360]

How is the unit doing? Still working good?

[@fordtechchris]

I haven't had a chance to dewinterize it yet. We only got it out three times after I installed it, but it was running great. I fixed the temperature issue with a new thermostat. I'm hoping it does great this summer because I want to do some more fishing soon with lots of start stops, extended idling, etc. Hopefully I'll get an update video sometime this summer.

[@jaymorgan8017]

Did you consider buying a new manifold ?

[@fordtechchris]

Very briefly. But that's a big job and would have added time and cost. In the end the original one worked out fine.

[@eriksnider7777]

We're did you connect shift interrupter

[@fordtechchris]

It did not have any provisions that I saw for a shift interprer. I might need to research that better?

[@eriksnider7777]

Still able to get out of gear

[@fordtechchris]

@@eriksnider7777 yeah, it seemed to shift in and out no problem.

[@shaynelhta]

Is that a marine fuel pump?

[@fordtechchris]

Holley's website lists the 12-920 as "United States Coast Guard Approved Certified to ISO 8846, SAE J1171 Requirements"

[@raymondvalles3494]

Is there anyway you could dm me I have this exact motor but I know nothing about it and I can’t get it to run right…

[@fordtechchris]

Im sorry, I can't help you with the diagnostic over the internet. I'm far too busy

[@MrDubaux3]

Hydronic motor mounts ,,,, whaaaaaaaat

[@fordtechchris]

They provide the trim adjustment on the old OMCs. The out drive doesn't have a flexible shaft to the engine so it must be fully down.

[@MrDubaux3]

I have a 94 omc/Volvo p 4.3 v tec just replaced gimble and RE aligned motor , I need this on my motor mounts lol

[@fordtechchris]

@@MrDubaux3 oh, ha ha!