Okay...I've beaten this to death...fuel issue...

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dwarren

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Okay, "thought" I had chronic vapor lock but just can't be. Boat is just not starting intermittently, then, after hours of trying, fires up. I've replaced everything, by-passed TPI. There is no fuel coming from injectors one second, then next second, the boat is running like a bat out of hell......although.....

this weekend, same symptom. Literally ran boat for 5 minutes to go across canal. Started up no problem. Died within a minute and would not start.

STarter fluid worked every time. Fuel pump is brand new, all filters brand new.

After a bit, it started and I figured what the hell, took it out to hit the fuel dock. Came off plane and motor stalled again....no start since. I am way low on fuel on that tank but this issue has been around since I had a half tank so not really understanding what the issue could be.

1996 Crusader 350 EFI (Throttle Body not MPI).

What should I replace next sensor wise and could this possibly be a pick up issue in the tank (no cross manifold to feed from separate tank btw)
 
I would borrow a 6 gallon outboard tank and connect it to the fuel sep inlet. remove and plug the existing line
 
Yeah, that's my next trick but the connection is going to be tricky. May take a run over there today......
 
I remember your other thread about this and how you eliminated so many possibilities. Got to wondering, what are the safeties on that electric fuel pump? What if an oil pressure sender hiccuped, confused the ECM, downhill from there. I ask this NOT knowing detail of how the system works.
 
Good points, I bypassed all of the senders and TPS but not the oil sensor.....you may be on to something. I did unplug and plug in both sides of ECM just to do it and killed battery power all together to "cold boot" as a last ditch effort.....
 
Check to see if you have 2 plug in relays. One on the back of the engine above the transmission. Might be labelled starter relay but it controls the electric fuel pump on startup. The second relay is labelled fuel pump. I had very similar problem of engine dying until finally a no start condition. By luck swapped the starter relay from other motor and started right up and has not stalled again since. I bought 2 relays and replaced them both. 26.00 each
Hope this does it for you. Took me 4 weekends go find this.
 
This is a long shot in the dark guessing here but...try to jump across a shift interrupt switch when no start condition is present and see if it makes any different. Shift interrupt switch provides a ground connection to various systems, if the switch is intermittently open or not fully grounded, beside your timing is messed up, your fuel pump may not get a good connection on ground circuit. Just a thought.
 
Okay....so....was able to replicate issue on a cold motor.....sputtered and died almost immediately...so
*Much lower in fuel now so problem seems more prevalent
*Decided to remove the fuel line from the tank and stick it direct into a 5 gallon can of fuel. Fired right up and stayed fired up..
*Fortunately, had access to pick up and check valve so removed from fuel tank.....perfect...no clogs, no rust etc.
*Replace pick up without check valve to isolate. Reattached fuel line to tank and ....nothing.....
*Put fuel line back into 5 gal tank....fired right up...

So....this narrows down that there's "something" in that tank. I'm not seeing any fuel being sent to throttle body at all so for some reason, it's just not getting any fuel.....or.....there's gunk at the quarter of a tank mark (ish). Again, this seems to have gotten worse as the fuel got lower now that I think about it.

Any suggestions? I'm pretty happy it's not injection related but not sure where to go next. Do I throw a ton of fuel treatment and some premium fuel in or do I siphon entire tank?...I'm just confused as to why "nothing" is coming out at all.
 
A few possibilities come to mind:

Did you take a sample of fuel from the bottom of the tank and let it settle in a clear container to see if it is phase-separated or smells like varnish?

Did you carefully inspect the pickup tube and it's threaded connections to look for small cracks that will only allow the pump to suck air rather than fuel? This would be high on the list of suspects if the problem increases as tank level lowers as there is greater "head" height to overcome and holes may be uncovered 1/2 way down or so.

A scan device might be able to check the operation of the IAC valve in the throttle body , but in the meantime you could remove it to see if the operation feels "sticky".
 
Okay, not so convinced that I fixed it but I added about 15 gallons of high test and she started right away.....I added two treatments for water and fuel injector and ran it hard for an hour. STarted and got me home with no issue with only one quick stall versus no restart at all. Next day, I added another 40 gallons of high octane and ran it crazy.

So far so good......may not be the total "fix" but we'll see.
 
The fuel pick up tube may have pin holes in the tube at the below the midway point. Or maybe a cracked tube.

If the tube rusted out over time and has any holes, it will suck air from within the tank and lose the prime and the capability of pulling fuel from the tank. You may have solved your issue with stating that you added 15 gallons of fuel and all seems to be okay... Albeit perhaps when the fuel sloshes around in the tank to the point of exposing the rotted tube and pulling air.

Pull that tube and inspect. Good luck.
 
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