fuel pressure issues - pulling my hair out!!
 

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.

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.

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.

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.

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

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" ?

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).

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. :drink:

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.

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.

Needle valve on the carb float sticking closed or the float sticking? I still like the idea of something in the tank. What was the issue you had with that?

Sir...listen...its gotta be from the w/s back. Here's the theory: first, cant be anything in the carb...because that wouldnt change what is showing on the pressure gauge...and you said it ran fine all day after you installed the electric pump. Second, the electric pump that you are thinking cant keep up..HELD UP ALL DAY...as you stated earlier. Thirdly...let go of the lobe idea. You said it has pressure sometimes..and sometimes it doesnt. If the lobe was wiped out, it wouldnt have any at all...ever..lol. Please disconnect the hose coming from the tank to the water seperator. Put a 5 gallon jug of gas into your bilge (somewhere safe) and put the hose into it. Fire the motor on the muffs...and record your fuel pressure. If you get good pressure, you figured out most of your problem. If its still zero....sell the phucking boat. :drink:

do you think it would run if the needle valve/float was sticking? it does start up and run for about 1 min until (i'm guessing) the float bowl drains. it seems like its getting some fuel, just very little and not enough.

i will definitely try the fuel tank suggestion i got earlier, but i warrantied the fuel pump today, so ill get the new one on wednesday. i'll try it then when i get the new one.

If everything in the carb was seized up....YOUD STILL SHOW PRESSURE ON YOUR GAUGE !!!
It's only running till the bowl is empty cause YOU DONT HAVE A SIGNIFICANT AMOUNT OF FUEL GETTING TO THE BOWLS.
If your gauge reads zero...you are not getting fuel to it...let alone to the carb.
I know your frustrated sir...but think rationally. If you cant pump gas into your truck...but your squeezing the trigger...something from the handle BACK is not right. Your truck ran when you drove it up to the pump right ? Itll run some more when you figure out how to get gas in the tank. If it aint coming outta the handle...then something is wrong from there back.
You stated earlier that the boat ran fine all day with the electric pump...and you worked on/checked the water seperator system. So that would tell me that those things are fine. Your not getting fuel TO THEM. :drink:

i agree with you on everything, BUT why would the electric pump make 5psi by itself, and the new mechanical make 0psi? are electrics usually a bit stronger than mechanicals?

ya know, another thing just crossed my mind......dont the pickups in the tank usually have some sort of screen or filter on the end of them? with the new ethanol fuels, i've heard of those collapsing or deteriorating enough to hinder fuel flow.....confirmation?

i still have the new pump, so i'll stick that back on and give the 5gal tank a try. if good, ill see if i can get into the sending unit hole and see anything on the end of the pickup

ok, tinman (....tail between my legs.....:lolhit:).....you were right!!! queue the "i told you so!!!"....go ahead, say it, i deserve it.

i put the fuel line from the tank in a gas can and vroom 7psi.

now my issue is, what is causing that pickup to not flow correctly? i did however have another pickup in the tank. im not sure if it is a return or a second pickup. the 242 could be ordered with twin smallblocks, so i'm guessing it might be a pickup for the other engine. it was capped off, so i switched my barb fitting to the other fitting and vroom, still 7psi. does anyone know what is on the bottom of these pickups? is it a stone type filter or a screen or something along those lines?

the problem may have been found, but as far as i'm concerned its not fixed. if i run it on this other pickup, i could run into the same problem in a few miles down the lake. are there any 242 experts out there that can tell me if that second fitting is a return or a pickup? can i use it the way i did? btw i was previously using the starboard side fitting, but now am using the port.

No "told ya so's" from me sir...as I've had my share of problems too. I'm glad you got it going. I dont know about your tanks setup without seeing it. You may be right about the extra one being for another motor. Your almost there !!!! :drink:

pull the pickup out of the tank. It probably has a crack in it up at the top where it goes into the fitting. If you pull it out, it would be easy to do leak check on it.

Thanks again for your suggestions and help! I'll see if I can snap a picture of it today when i get home from work.

i know there's an elbow that unscrews off the fitting, but i'm not sure if the pickup will come out with it. it looks like the pickup is welded into the tank, and the elbow just screws onto it. I'll see what i can find when i get home tonight..

kvogt - i'll bet you're right that there's a crack in it. i know i can easily blow back into the tank through the old pickup, so its free flowing, but probably drawing air into the pickup once the fuel level goes down. come to think of it, when i left the dock the last time i had a full tank of gas. once i ran a few miles and burned some gas, thats when it started to die. and it gradually got worse as i high-tailed for the dock. ill be willing to bet that as the fuel level dropped below that crack, that it started drawing air, and thats what causing my intermittent pressure issues

the pickup tube presses in the bottom of the fitting, seen them plastic and aluminum..some have a small filter on the end..that could be the issure right there...

if i unscrew the 90* fitting from the tank, will the pickup tube come out with it? if not, how do i get it out? will i have to take the sending unit out or something in order to get to the tube?

The pickup tube should come out with the 90° fitting. I had a problem with my '06 292 fuel tank pickups. The pickup tube was hard plastic with a press fit over a barb fitting on the bottom of the 90° fitting. I believe ethanol in todays gas over time caused the plastic to swell slightly. This allowed air to be sucked in the gas line (especially with low fuel levels) and cavitate my fuel pump. Ended up getting new pickups with welded stainless pickup tubes from the gas tank manufacturer. Problem solved. Good luck!:drink:

if you take the fitting out and tube does not come out you have found the problem...but would not run at all...

ok guys, this boat is going to be the death of me......pulled the boat out this weekend (i know, June and my boat hasn't been dewinterized yet....shame) and have the exact same problem i had last year....again, no fuel pressure!!! this time while cranking my fuel pressure gauge says 5psi. as soon as the engine starts, it drops to 0.5 at idle and 0 at anything off idle. did the exact same troubleshooting as last year including putting the pickup in a gas can to rule out that again. if i pull the carb feed line off and crank it seems to be pumping fine and filled a 20oz bottle in around 6 pumps, but must be losing pressure once the carb starts feeding off it. i was thinking the fuel pump again (maybe the diaphragm has a pinhole), but there is no fuel coming out of the bleed line that goes to the carb. i'm yet again stumped by this fuel system....

Try checking for leaks in your fuel lines between the tank and the pump.

i have replaced the line from the tank to the pump, which would be suction side of the pump. that would be the only one that would draw air. if anything else was leaking, then it would be on the pressure side of the pump and would leak rather than draw air. it would have to be a pretty hefty hole to bleed 5-7psi of fuel pressure to zero and i would notice fuel leaking. the odd part is that it builds pressure when the engine is cranking but not running (pulled coil wire to distributor), but loses it when the engine starts.

the fuel pump is less than a year old, so i wouldn't think it would be bad, but its the thing i'm aiming at right now. i warrantied the old one the other day, so i'm waiting on a new one to come in later this week to rule it out.