Fuel Delivery Problem - I think? - 76' 36C Gasser

[ohiohatteras]

Hey Guys....looking for some insight.....First off let me tell you that I have not put any ethanol fuel in the boat based on what I have been told by the marina gas station owners.

Anyway, my 1976 36C started acting up last weekend.....the starboard engine ran fine to 2500 RPM's, but then when you push it past that point,it starts to spit and sputter.
It did it again this weekend too....so I tried switching the fuel tanks around and pulled fuel for both engines off just the port tank and the stbd engine ran fine. And when I switched it back it started running crappy again. So I'm guessing I got something clogging the pick up in the stbd tank????
So my question is....Is there something I can add to the fuel/tank to clean it out or is there a filter on the pick up that might need replaced? And if so, how do I pull the pick ups?

Any and All $.02 requested/appreciated!

 

[67hat34c]

Are you able to buy non ethanol gas where you are?

Is there a check valve near the tank? Possibly that has failed.

 

[Pascal]

check the anti syphon valve at the top of the fuel pick up. it's a CG requirement on gas boats and with age they get sticky.

you can also check the tank vent, if it clogs, the fuel pump can't suck fuel out under vaccum but usually you'd have noticed it the last time you filled up the tank.

 

[krush]

I agree, check the anti siphon valve first. Most people just knock the ball/spring out because the valves are such a PITA.....whether or not you are comfortable doing that is up to you.

 

[67hat34c]

Pascal is right on. Pascal do you think my 67 34c has antisyphon or ck valve? Betting it is original equipment from the looks of the fittings. No inspection plate so I can only see it from the side.

 

[Pascal]

it should have one, I'm not sure when the USCG standards requiring a valve came in but it's been a while. Some boats have a solenoid valve instead of the ball/spring thingy... unlikely on older boats though.

it's easy to check, the fittings should come off and disasemble easily.

Maynard had that problem last year on his 36, he was just about to rebuilt the engine before checking that...

 

[garyd]

O.K. first thing to do is get a gas tank with a hose hook it directly to the carbuerator (both need to be clean with clean fuel)so it can gravity feed the carb. Start and run the engine. Then hook it up to the intake of the fuel pump start and run the engine. Then hook to up to the fuel filter start and run the engine then hook it up to the first joint after the tank pickup and start and run the engine.

Where ever it stops thats your problem.

 

[Pascal]

well, he's already tried running on the other tank and it runs fine so the problem has to be between the tank, pick up or valve.

start with that anti syphon thinghy... if not then move on to the pick up.

 

[MikeP]

If any portion of the fuel tank is above the level of the carburetor than you must have an anti-syphon valve per USCG/ABYC. Without the valve or some other automatic POSITIVE fuel shutoff when the engine is not running, the ONLY thing preventing gasoline from syphoning into the carb and then into the intake manifold, filling any cylinders with an open intake valve and then running over and spilling into the engine room itself is the needle and seat in the carburetor. I would not suggest trusting that one little item to save you and your boat.

 

[Pascal]

and even if the tank is below the carb, if you get a fuel hose getting loose it will syphon out if the hose tip falls below fuel level...

 

[ohiohatteras]

check the anti syphon valve at the top of the fuel pick up. it's a CG requirement on gas boats and with age they get sticky.

you can also check the tank vent, if it clogs, the fuel pump can't suck fuel out under vaccum but usually you'd have noticed it the last time you filled up the tank.

Thanks for all the replies.......Now, can somebody please tell me where the anit-siphon valves are?

 

[Beckytek]

Mine are right at the top of the tank after the elbow. It's only a small thing and looks like a coupling. I disconnected mine and just blew through them to clear. I had some strands of fiberglass in there. Ron

 

[ohiohatteras]

Mine are right at the top of the tank after the elbow. It's only a small thing and looks like a coupling. I disconnected mine and just blew through them to clear. I had some strands of fiberglass in there. Ron

Thanks Again! I'm gonna check it out this Friday.
Any ideas why the engine runs fine up to 2500 RPM's...cuz there's definately a big load on it after 2000RPM's....

 

[67hat34c]

I am going to look at mine this weekend if i go there. I doubt there is one though. From what i remember it has original copper tube out of the tank with the small brass shut off valves, all look original. Dont remember any other components. Been wanting to install inspection plates over the pickup unit anyhow. Prior owner had deck re done and they covered them over.

 

[ohiohatteras]

I started right at the point where the 2 lines seperate and took the on/off valve section out and what do ya know...it was clogged with what looked like little pieces of varnish. Cleaned it out and re-installed it and the boat ran great! Never got to the anti-siphon valves...and don't think I have them anymore????
Also....Anybody know if I can add another set of Racors before the fuel manifold to try to prevent this in the future?
Thanks

 

[67hat34c]

Almost sounds like ethanol issue.

 

[yachtsmanbill]

FWIW... my Roamers' anti syphon device was a pin hole at the top of the pickup inside the tank. The copper pipe cracked right there and presented a vacuum leak. Put two check valves on from a late model searay. I also installed whats called a "gas sock" from Ford on the end of the pickup. you can make one out of brass or SS screen too... ws