The last 2 times I've ran my boat its bogged down to an idle after running on plane. The first time I was running for maybe 2 mins when it did it. Today I ran about 20mins before it acted up. It seems to be a fuel issue I think. There's no backfire or black smoke when it does it so I don't think it's ignition related. My gas cap is vented good(I took it off today and still did it) fuel filter is new and carb is clean. The motor is stock except for exhaust and stainless valves and a little intake polishing. Any help is appreciated

Any bubbles in your air filter?
Sounds to me like you have an air leak.
Also, could have a dirty carb/jets, causing you to run lean.

Does it crank right up after it bogs down?
Do you have a primer bulb?

No bubbles in the filter. It doesn't die when it happens just goes to an idle and won't rev up. If you shut it off and let it sit for a min it'll run fine again for a bit then do it again. No primer bulb. Is the vacuum fuel pump junk on these motors?

Sounds like a fuel delivery issue for sure.

I know a lot of guys throw inline pumps on their motors. I don't think I've got vacuum problems. I checked my valves but putting solvent in the ports to make sure they weren't leaking after I lapped them in. Should I try an inline electric pump? Or Use this as an excuse to get a mikuni carb? It runs really good for a big heavy boat when it ain't acting up. It's only got 40hrs on it btw

You can try an inline electric pump.
That's what I did, and the second I hooked it up and turned it on, I found that my fuel filter itself had a crack in it that wasn't noticeable.

The reason I said to try a primer bulb, is cause they are $20, as opposed to $50-$70 for an inline pump.
but hey, that's your pennies, not mines!

I've got a primer bulb I can try. I Took the carb apart when I did the valves and it was clean. Also noticed it had 2 diff main jet sizes which I didn't understand

What psi pump do these motors like? 3-5? I'll put the cheapo plastic filter before the pump

They do have 2 different size main jets and you need the low pressure pump about 3 psi. I had a buddy that was having fuel issues with a new 37 EFI and it was because of a clear inline filter that he had added that was too restrictive. It was brand new and looked fine but wouldn't let enough fuel thru.

I don't think it's running lean. I've got one of the all plastic universal small engine fuel filters on mine. I'll try a new filter and inline pump and see how it does. Do you just cap the vacuum port goin to the factory pump and remove the factory pump or pump through it?

Pump through it

Also, make sure you don't have the hose clamp too tight for the plastic fuel filter, causing it to kink.

I personally like to use the metal fuel filters for vehicles.

Collapsed fuel hose?

Black pushlock fuel line. Msha approved stuff

Try the e-pump, report back.

Vent fuel tank lid


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Where is your fuel tank located? In the front of the boat or rear?

Fuel line could definitely be the problem. The marine line is crap. The liner on the inside will collapse and starve the engine. Seen it go bad in less than a year.

My tank is in the back of the boat. I put a new electric pump ,filter, and new fuel line on. Gonna take it out tomorrow and see how it does. Thanks for everyone's input btw

I've got an aluminum spun fuel cell. The kind you usually see in the bed of ratrod trucks. I put a different cap on it that vents good. Yeast ersatz when it acted up I took it off and it still did it so it can't be the cap

Yesterday not yeast ersatz! Damn spell check

I know this is off topic but how in heck do you post pics off your phone?

You have to make them smaller. My phone takes huge ass pics. You cannot upload them. Make them smaller and it is all good.

Its actually pretty simple, if you aren't on tapatalk, and have an iphone, just attached the image, then post it.

This is the only pic I have of my fuel cell

Well I ran 7 miles up river before I it happened again.when it f$&ks up it'll idle smooth and rev to 1500ish before it starts to cut out. I stopped on the bank and let it sit for a min then headed back and never messed up again. Must be somethin in the carb floating around then clogs a jet maybe?? I'll take it apart next week and try again next weekend.

Yup

Do you have fresh fuel in the tank?
Old fuel? Put a can of seafoam in your tank and run it.
see what happens.

Ya fresh premium gas. I had the carb apart a while back and it was clean. The only thing I can think of is somethin got in the carb that's too big to pass thru the jets and is clogging one. It's just aggravating when you spend a lot of time and money on a boat and shit like this happens. Could the governor be screwing up?

I'll double check the carb again maybe somethin got in the fuel line when I had it off. I use it mostly for bowfishing so running at night isn't a prob. The only thing I've ever noticed at night was the exhaust glowing red

Is it a true fuel cell. If it is they have a foam liner inside seen them come apart. Also not ethanol friendly

There's no foam in my tank at all

Sounds like you're loosing a cylinder when it gets hot from the spark plug boot arcing to the metal air dam. You can wrap them with electrical tape to test it but that usually doesn't last long. Next time it does it, pull each plug wire, one at the time and see if it'll crank. The NGK - LB05EP boot is a permanent fix.

https://www.amazon.com/NGK-LB05EP-Resis ... B001KOL5SG

Ok thanks will. I'll run it at night and see if it's arcing. Maybe I could spray water on the boots to see if it'll cut out. I won't be able to be on the water till this weekend