05 22v with MP 340 5.7L Wont Start - Diagnosing

[WHammond]

I have a 2005 22v with a MP 340 HP (5.7L MPI) with the MEFI 4 ECM and G-Force fuel pump that won't fire up. The starter will turn the engine over fine, it just won't fire. It seems to me like it's just not getting fuel.

2 weeks ago we were riding normally, and at the end of the day it just cut off while idling back to the dock. I haven't been able to fire it up since.

What I have done/verified so far:
-Voltage at battery and starter is fine, boat cranks and turns over fine, just won't fire up.
-Spark has been checked and verified between the coil and the distributor, and on every plug wire/plug.
-Fuel is getting through the LP tank to the HP tank, and from the HP tank to the fuel rails.
-Fuel filter attached to the HP tank (g-force) has been replaced, needed to happen anyways.
-Fuel pressure at fuel rail after priming the ignition was measured to be 58-59 psi. The manual states "fuel pump pressure-39 psi", but i'm assuming that's operating pressure and it drops when it's actually running?
-Fuel was bled out of the fuel rails via pressure gauge (priming the ignition definitely pushes fuel through), and there is no water or debris in it.
-Checked the 15A fuses in the fuse box on top of the engine, replaced 2 that looked sketchy.
-Using a Noid light, every injector wire harness has been verified for power and was triggered by the ECM commanding fuel.

Any ideas or suggestions? Next I assume it's something mechanical with the injectors and they are clogged, or something is clogged in the rails. I just think it's strange that everything would go out at once instead of it running rough, or firing and struggling to run if that's the case.

[hairball]

This happened to me a couple yrs ago. My issue was a cross firing distributor. I know you have spark at the plugs but my symptoms were the same. Distributors are cheap. My other thought would be a clogged fuel rail from old gas or trash in the tank. I'm sure some other guys on here have a better diagnosis.

[lee]

When you turn the key to the run position, do you get a beeping noise?

[ericinmich]

Is there compression? If you have fuel and spark, that is the only thing missing (if fuel and spark is happening at the correct time).

If it ran fine and wouldn't start, compression problems aren't likely though. Maybe cam timing jumped, or ??

[JCP]

Hit it with some starting fluid, if it fires you are not getting fuel.

[Stingreye]

-Fuel pressure at fuel rail after priming the ignition was measured to be 58-59 psi. The manual states "fuel pump pressure-39 psi", but i'm assuming that's operating pressure and it drops when it's actually running?

When I was troubleshooting a problem that turned out to be bad gas I was checking fuel pressure and I think too high of fuel pressure could be a bad fuel pressure regulator but I am no mechanic and have no clue if a faulty fuel pressure regulator would cause it not to fire.

[WHammond]

When you turn the key to the run position, do you get a beeping noise?

Hit it with some starting fluid, if it fires you are not getting fuel.

@lee. yes, I get a continuous beep noise when the key is in the run position. It turns off while I try to crank.

@jcp I was planning on trying this tomorrow to see what happens.

[ChrisSnow]

If your fuel pressure is too high the injectors won't open.


If the numbers you quoted are correct It could be that your pressure regulator has given up. It's a standard automotive part. Somewhere I may an email from marine power with the GM part number

Sent from my HTC One_M8 using Tapatalk

[ChrisSnow]

Just found the info,

its a GM 12568878 which is 4 bar or 58.8psi, so your readings are perfect.

From memory the crank position sensor triggers the injectors, so it could be that sensor has issues, the injectors should have 12V at all times but the ground gets switched by the ECU.

does your exhaust stink of unburnt fuel? if it doesn't then look for fuel issues, if it does then look at ignition issues.

[UNSTUCK]

The last thing to really check is compression, but I don't think that is the problem. If the noid lights were flashing, that means the crank sensor is ok. If there was any issue with the distributor cross firing you should get some pops and some point. My guess is that you ran bad fuel through it and that has clogged the injectors. I would remove them and take them somewhere that can flow test them. Even that seems odd though, to happen in the middle of running it. Usually that happens during storage.

You did a great job of running through all the right tests first.

[SKSailboatshop]

after cranking and it not firing pull a plug, is their evidence of fuel? can you also verify spark?


edit: and i know its the obvious but did you verify the safety switch is functioning correctly?

sometimes its the simple things

[boatwakes]

If the issue happened at idle, it's possibly the IAC (idle air control valve) and an easy check: hold the throttle open in neutral (like a carbureted engine) and see if it fires. If so it will most likely die again when brought back to idle. Replace the IAC and enjoy.
As a note, high fuel pressure has no effect on injectors opening. The injectors open due to ignition signal from either the crank position sensor (if so equipped) located on the starboard lower side of the timing cover, just behind the balancer, or from ignition signal from the distributor (depends on the distributor type). Crab cap uses external crank position sensor, all others use distributor signal. High fuel pressure will, however, cause the injectors to stay open too long thus causing terrible mileage and fuel dilution in the oil. You are correct that the fuel pressure drops while its running but will show high when you prime it.

[WHammond]

Tried starter fluid in it today. It would pop off but then nothing. Definitely have spark to ignite the starter fluid, it just seems like there's absolutely no gas in there. How could I check for a cross-firing distributor?

Neutral safety switch is still working fine, it won't start or crank at all if I trip it intentionally. I'm able to crank and turn the motor over fine.

Planning on pulling the fuel rails next to see if something has jammed up in there, then the injectors after that.

[hairball]

Tried starter fluid in it today. It would pop off but then nothing. Definitely have spark to ignite the starter fluid, it just seems like there's absolutely no gas in there. How could I check for a cross-firing distributor?

Neutral safety switch is still working fine, it won't start or crank at all if I trip it intentionally. I'm able to crank and turn the motor over fine.

Planning on pulling the fuel rails next to see if something has jammed up in there, then the injectors after that.

Just gotta buy one like $20

[hairball]

Just the cap that is