hondahp4

I've been fighting fuel pump/pressure issues for weeks now, and I've had about enough. Maybe someone can enlighten me....

1987 Formula 242LS 454 alpha

Had a good 8psi fuel pressure one day, and next took it off the trailer and 0psi. Boat would start and run, but would die after about 30 seconds. Bad pump right? Well, went looking for another mechanical, and couldn't find one, so settled for an electric to get me back on the water for the day until i can order a new mechanical. boat ran fine all day after the electric. next weekend out, boat ran fine for 15 minutes, then started to bogg and die. turn on key to let electric pump catch up, and it would fire back up and run fine again for another few minutes, then the same thing. another bad pump right? or maybe the electric doesn't hold up real well in marine or not enough @$$ to keep up. i cross referenced the number from mercruiser, and came up with an airtex 60601. i ordered that and got it installed a few nights ago. get 5psi idle out of both the electric and mechanical. so i figured maybe the electric is hindering flow, so i removed it......get 0psi. boat starts and runs, but dies after about a minute idling.

here's what i tried:
changed water separator
tank check valve went missing many years ago (only problems)
blow from fuel line back in the tank, free flow
blow from tank line and fuel easily comes out the feeder to the carb
tank vent is free and clear and ran it without fuel cap just in case
pull the carb feeder, start it, and fuel kinda trickles out of the line. i would think it would geyser out of there. took about 15-20 seconds to fill a standard sierra fuel/water separator.
replaced the fuel line from tank to f/w separator just to eliminate any air leaks.

what am i missing? i find it hard to believe i've gone through 3 pumps and haven't found a good one. any ideas are appreciated, because i'm losing my mind with fighting this issue.

JB33

Try pulling vacuum on the line from the tank to the pump. I have seen them collapse causing a restriction. or if its easy just replace it and see if that fixes it.

EDIT i am not sure if vacuum would work. for what it costs to replace the line I would just do that.

pitts1313

Is the electric pump near the tank?

My understanding is the mechanical pump is designed to pull fuel from a distance from the tank and the electric pumps are design to push fuel FROM the tank. Hence, electric has to be mounted near the tank. Don't know if that is a concern for you. Lots of threads on here about pumps burned up that are mounted too far away. Some electric sets require a return fuel line to the tank, also.

hondahp4

i replaced the fuel line from the tank to the water separator already for that exact reason. the line from the separator to the pump is a hard line. the only one not replaced was from the pump to the carb, but its a steel braided line, but probably rubber inside.

hondahp4

the electric pump was about 6 inches from the pickup at the tank. then only about another 1ft from there to the "in" in the f/w separator. its only a p.o.s. mr gasket electric pump (from advance auto parts) made for carb engines and push 5-8psi, which is why i figured maybe it wasn't holding up real well for marine stuff. but with a new marine mechanical, its weird that the electric worked better than the mechanical

Airpacker

First, are you certain when you installed the new mechanical pump you got the pump arm UNDER the cam follower rod ? If so, remove the pump, hold the follower rod up against the cam and have someone crank the motor with the coil dosconnected. Does the follower rod move in and out about 1/2" ?

hondahp4

thats also what i thought might be wrong, so i took the pump back out and reinstalled it...no change. i took it back out again and checked the lever on the pump and theres a little wear mark (polished spot) on the end of the lever where the follower rod would touch it, so im assuming that it was in correctly. i didn't check to see if the rod moves at all. i was trying not to think about a collapsed cam lobe since this is a new motor that i just had built. the motor has maybe 5 hours on it and i've been fighting this fueling issue almost the whole time.

the collapsed cam lobe idea has crossed my mind. it is my understanding that when a cam lobe quits, it usually does it on startup. is this correct? when i first lost fuel pressure on the original pump, it was 10 seconds after i pulled it off the trailer after sitting for the night (cold engine).

tinman565

I think something is floating in the tank and getting sucked to the end of the pickup tube...or, the pickup tube has a problem. How much fuel is in the boat when this happens ? Did it run ok when the tank was full/near full ? Run a length of hose from the water seperator to a 5 gallon jug full of fuel. Check to see what your fuel pressure is then. This eliminates the tank and the pickup tube/system from the equation.

hondahp4

its got about 2/3 tank in it right now of fresh gas (less than 2 weeks). its been doing this with all different amounts in it from 1/4 all the way to full. ive been fighting the issue almost since the motor was brand new. it ran 1 day without fuel pump issues, and that was its maiden voyage.

i didn't try an external tank, but i did pull the hose off the w.s. and let the electric pump run while it was still on there. it seemed to pump ok and didn't cavitate or sputter with air, so i'm assuming the pickup in the tank is ok. the boat hadn't moved since i took that electric pump off and installed the new mechanical one.




when i push on the pump lever of the new pump i just pulled out, it seems to have pressure behind it. it'll suck my finger into the inlet side and it'll blow of off the other end. to the me it seems to be working ok, but who's to say its enough to push/pull fuel. which brings me back to this whole cam lobe ordeal. its beginning to worry me. has anybody ever seen that lobe collapse? i can't say i've ever heard of it happening, but knowing my luck....i'll be the first.

hondahp4

i couldn't take it anymore, so i just went and checked on the cam lobe. i had my wife crank it over while i had my finger holding the follower rod. it moves about a 1/2" or the length from my first to second knuckle. seems like plenty to move the pump lever. makes me feel a little better, but still doesn't fix my problem.