Will not start

[Cougar_Marauder]

03 Trilogy tuned at Lidio. Aeromotive Stealth fuel pump. Boost-a-pump (dialed down low), relatively new spark plugs, JLT CAI

A few days ago I put the battery back in the car and it fired right up. I made a few short stops and it fired up fine each time...until it didn't. After about a 20min drive it sat for about 30-45min and then it wouldn't start anymore. Turns over fine. After a tow home I checked all fuses, they look fine. I noticed I wasn't holding fuel pressure at the rail (I have a permanent gauge at the Schrader valve) so I swapped out the FPRS and now I have good pressure readings but still no start. I took out a plug and it showed good spark. It was drenched in fuel though. I took out all the plugs and sprayed with carb cleaner and left them out of the car over night in hopes any excess fuel would evaporate from the cylinders. Put it back together and still no start. I tried holding the pedal down while starting too. The anti-theft light does not blink when turning over and the check engine light isn't on either. I tried all 3 of my keys.

I am definitely getting fuel, maybe too much? Could I be flooding myself out every time or maybe never recovered from being flooded the first time (when FRPS failed)?

I haven't tried cam or crank sensors yet but shouldn't the injectors stay off if they were bad?

I looked for the infamous crimped wire bundle running around the cam cover but nothing seems too tight or bent in that area but it is difficult to be sure since it's hard to do anything back there.

Any ideas would be appreciated!

[RubberCtyRauder]

Check fuse for boost a pump..which is inline fuse type . Assume you hear fuel pump when key turned on position?

[Cougar_Marauder]

Fuse on Boost-a-pump looks OK. Yes I can hear the pump hum when turning the key on.

[RubberCtyRauder]

Could be FPDM, I swapped mine for a modified one due to trilogy etc. Some other members with more knowledge hopefully will shed some light on those other sensors that might be issue.

[Cougar_Marauder]

I put a modified FPDM from RacerX back in 2014. I can see if I can find the old one just to be sure...

[JimP]

Pull the line off of the fuel rail pressure sensor, see if you smell fuel. If it failed and the diaphragm ruptured you could be flooding the engine.

[Cougar_Marauder]

I found the FRPS to be bad initially but I replaced it. Today I cleared out any gas that may have been sitting on the cylinders and now it kind of stumbles but wont start, it wont even stumble unless I hold the pedal down to the floor. I checked for engine codes and have a P0190 and P1233. I never cleared them initially so i'm not sure if they are from the initial failure or on-going. I still have to find my old FPDM and try that.

I just came across this thread: https://www.mercurymarauder.net/forums/showthread.php?t=103178&page=5
but nobody ever posted a solution. It sounds very similar to my problem.

[decipha]

if the check engine light isnt on at key on then thats a major problem. The check engine light will be on when the ecu is powered up and the engine isnt running. Verify that first. Usual culprit will be the exu relay.

based on what youve posted i would suspect your frps to be your issue and as u suspect it still hasnt cleared out from being flooded.

first things first, no doubt the oil is saturated with fuel. Go ahead and change the oil and filter. Remember modular engines can only run motorcraft filters otherwise youll hurt the engine.

the cam sensor isnt needed to run but the crank sensor is, u can easily see if its working by logging and verifying the ecu sees an rpm while cranking, if not then crank sensor is most likely culprit

otherwise

Charge the battery overnight so its fully charged
remove the fuel pump fuse or disable it some way
pull all the spark plugs and disconnect the coils
set the charger to crank and turn the engine over for a minute or so to get any fuel vapors out

put NEW plugs in her gapped accordingly
hook everything back up
then try to crank her with the pump still disabled
after u have verified shes cleared out re enable the pump

hopefully success otherwise u need to do a compression test

possibly investigate the ignition switch

[Cougar_Marauder]

Thanks decipha, I did pretty much as you said and also installed my stock FPDM and it fired up. I guess I never experienced a vehicle that will flood so badly!

:burnout:

[decipha]

Happy to hear it, good thing you caught it in time. I have seen ALOT of modular engine destroyed when the frps fails. There use to be an aftermarket rupture disc you install on the frps that prevents fuel from getting sucked in the engine when the frps fails. It might be worthwhile to look for one for peace of mind. If you do find them please do let me know as I'll prob put one on my marauder just in case.