Weird gt40 miss/stumbling - please help!

So I charged the battery yesterday, then disconnected the hp fuel pump line from the rail, attached a hose, and pumped out about a gallon of fuel into a can to make sure things were working. I re-hooked everything up and re did the rail pressure test which I posted about yesterday - same result.
I finally got it to run this morning by pulling the neutral switch on the throttle lever and opening up the throttle all the way. It sputtered and then fired up and ran smoothly. This was with the alternator disconnected. I then shut it off, hooked up the alternator and fired it up again. Smooth idle and 14v on the dash gauge. I am now thinking I had a few things going on - low voltage caused by the failing alternator issue from before, and a batch of bad gas or water in the gas, and a flooded engine. I cleared up the water issue by running fuel through the pumps in to the aux tank, then I cleared the flooded engine by starting in neutral WOT, and the voltage was normalized by a charged battery. Before all this the battery was showing 12.5 across the leads but I’m starting to think that maybe the ECM wasn’t getting the voltage it needed to run well and was causing the erratic behavior.

Going to fill up with premium and a can of sea foam and use the boat for the day.

I appreciate everyone’s thoughts and insight in to what to look for. I’m still stumped on the low fuel pressure at the rail after the key switch is off but I guess if it runs well maybe I won’t worry about it. I suppose I could check the pressure now that the engine has run and provided vacuum to the FP regulator. Maybe that’s the trick in getting it to hold pressure after replacement.

Kyle

This guy thinks you're gonna be OK



Most fuel injection systems have a "clear flood mode" which is doing what you did.

Full throttle while cranking cuts the signal to the injectors till the engine is running.

Gives lots of air and no gas to clear the flooded condition.

Good luck

It does not sound like the pressure regulator is at fault at all in your boat.
Sounds like electronic gremlins.

Okay new theory - bad distributor. The reason I think this- coil is making a tic tic buzzing noise when the key is on and engine is off. I have a constant 12.5v at the purple wire but the green feed wire voltage coming from the TFI is erratic. The TFI is also new. My understanding is the PIP sensor feeds cam position info to the computer to inform timing. I believe while the pip looks good (not moving) it is providing a faulty signal or shorting out. If I test the blue gray signal wire from the distributor for continuity to ground, there is measurable resistance indicating a partially connected circuit. This is then informing the computer to fire the coil at erratic times causing the rough running condition when I can get it to run.

Is there an easier way to test this without a breakout box connected to the ECM or do I need to jump in and replace the distributor? Oreilley has a remanufactured cardone that fits a 92 f250 5.8mpfi which is what I’ve been using as a cross ref. Vehicle for parts. It’s less than $100 but then I introduce error in having to reset the timing.

Kyle

Why in the world would you change the whole distributor unless the distributor has to come out to change that module ?

Thanks Gary. I was under the impression that you had to disassemble the whole distributor to replace the pip sensor/ staror and most opt to replace the whole distributor instead from a cost and effort standpoint. Are you under a different understanding?

Kyle

if you're gonna replace the PIP sensor , you might as well replace the stator too and if you're gonna replace both, you might as well get one of the rebuilt distributors mentioned earlier in the thread because the only way to do the stator or sensor is by pulling the distributor out, removing the gear and taking the shaft out from the top.

Pretty much complete disassembly and reassembly of the distributor.

And with the Spectra everything related to the sensors is new, clean and not rusty.And you get a new cap and rotor too. (edit took out my wrong Dorman reference)

You'll have to plug the vent in the cap or use the cap you have..

People usually use RTV for that it seems.

You have 3 options then if you think it's bad, 1- get yours fixed, 2 use a ecm and a chip like the PN guys figured out or 3- get a hold of Erik and see if he still has the one from the engine he's parting out.

PN ECM thread
Prices on used C1A1 Mustang ecm's have skyrocketed lately, someone must have seen that now there is a use for them,I paid under 90 for one a year ago.

here are some-
1-C1A1

2-D1L1

The D1L1 was thought it might work but not sure if anyone tried it since the C1A1 was so readily available

Gary S wrote: The D1L1 was thought it might work but not sure if anyone tried it since the C1A1 was so readily available

I can verify that the D1L1 works fine. I purchased 2 from an Ebay seller near you Gary (encortempw) they were US $35 each in Nov 2017. Purchased the chip and programmer from Moates. Not as much fun as my Megasquirt but I wanted something almost factory if I ever decide to sell the Sport.

Got my code reader tonight. No codes with the key on engine off test and no success with getting it to read for the key on engine running test. I had to jumper the single wire to ground for the koeo test so I expect maybe i need to clean the contact for the koer test since that wire needs to be connected to the reader. It’d be nice to know if maybe my oil pressure, knock sensor, or temp sensor are throwing a faulty signal causing the ecm to erratically adjust the timing and being the root cause of my issue but I guess so long as I replaced everything else I’ll find out as soon as I swap the ecm this weekend. Thanks to Erik for having one available and being willing to ship it expeditiously. Hopefully the end of this saga is near, though I have learned a bunch that I otherwise likely wouldn’t have taken the time for.

Kyle

Hey Ken, it is the black module CBE40 and crosses to the Napa TP29 module and the oem ford part number.

Kyle

Thinking I’ve found a smoking gun. When I disconnected the ecm today to check the spout circuit continuity with ground to see if there was a short, pin #1 came out with my harness ecm connector. This is the keep alive power feed which allows the computer to store fault codes in memory. Now there is no surprise as to why I wasn’t getting anything with my code reader. A little water came out of the connector boot when I undid it, and there is visible corrosion on the outside of the ecm box - indicative of the connector and associated contacts having been partially submerged. I would expect that this is not the only circuit to be faulty. When I open up the ecm, everything else looks okay on the circuit board; however, where you could plug in a chip there is a greasy whitish substance which I am assuming is there to prevent the circuits from shorting out. Once I get on a computer I’ll post a few pics.

Kyle

New computer came in today and I installed it over lunch. Boat cranked and started right up, idling steady at 650 rpms. In neutral it also is operating smoothly through higher rpms. Boat idled for approx 20 min and everything seems okay. My only minor concern is that on 2 occasions, after idling for approx 10 min, the engine quit like you turned it off. No sputter or anything. Just stopped with no warning. On both occasions it fired right back up and idled fine, so not sure what this was about.

I will be water testing more this weekend so hopefully everything stays in order.

Kyle

In looking at the harness connector and the pins on the ecm- new and old, they looked good but maybe I should disassemble, spray contact cleaner on the harness plug making sure all the contacts get a dose, and re-assemble with dialectic grease to ensure solid contact. Any reason not to use the grease and just clean the contacts?

Kyle