Weird gt40 miss/stumbling - please help! |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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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 |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Kyle,
Make sure you boat today on a lake that does have other traffic or, at the very least bring a paddle with you. I sure hope what you did solves the problem. Good luck with it. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
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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 |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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Turns out I am still not in the clear. The issue returned as I was just letting the boat run. Upon further inspection, I found that it seemed as though the coil was shorting out with key on engine off at the distributor cap. So I replaced the TFI module thinking that it was leading current to the coil potentially when it shouldn’t be. This did not resolve my issue. With the key on and engine off, sometimes the coil will send a signal to the distributor and it will register on the tack making it look like engine RPMs are bouncing all over the place, and the boat isn’t even running. I’m starting to think that maybe it is the ECM given how intermittent this problem is. This weird interrupted signal will also cause the engine to not run correctly because the voltage from the coil is erratic.
Thoughts? Kyle |
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3734 |
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It does not sound like the pressure regulator is at fault at all in your boat.
Sounds like electronic gremlins. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
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I hate it when Carnac gets it wrong
Have you checked the ground connection from the ECM to be clean and tight? Also maybe unplug and check the cleanliness of the connections in the big connector to the ECM. I figure they're both easy and cost nothing. |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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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 |
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tryathlete
Platinum Member Joined: April-19-2013 Location: Lake Villa, IL Status: Offline Points: 1797 |
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Kyle, a new distributor is pretty cheap, and it sounds like there’s something going on there, and if it were me, I’d do it just to get my boat back up and running. I don’t think you have to worry about timing if you get it close enough (mark position of old distributor and especially rotor). ECM controls timing on the GT40. Others may argue against swapping parts for good reason, but that’s what I would do.
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Why in the world would you change the whole distributor unless the distributor has to come out to change that module ?
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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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 |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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I have not taken one apart yet but in reading it looks like you do have to pull it to change that. Seems crazy. I did find this though- sensor troubles Kind of sounds like your trouble with the erratic tach and all, interesting reading anyway
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
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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. |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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So I got the boat to run today and had it running for about a half hour on my lift after replacing the distributor with a spectra fd14 from O’Reillys. The interesting thing is that I still expect that maybe I have a bad ecm. I set the initial timing of the new distributor by unplugging the sprout connector and timing it to 5 btdc. As soon as I did this, I turned off the engine, plugged in the sprout, and it would crank, fire once and die. I then disconnected the sprout, and ran the boat. It ran fine. As it was running, I reconnected the sprout and it would immediately die. Disconnect sprout, and it would run fine timed at 5btdc. After this, I disconnected the battery on a whim while I took a phone call. After my 30 min call, I reconnected the battery and started the boat without the sprout connector. After running for 5 minutes or so I reconnected the sprout connector and it stayed running! Not sure if the computer was reset by the disconnect and had to “re learn” something By running the boat without the sprout for a short period, or if this is a fluke thing that it is now only working for a little while, with my fear being that it will go back to doing as it had. Good to know that at least for now I can disconnect the sprout if it starts running poorly in order to limp my way home at 1000 rpm or less. The downside is I have no way of testing the sprout circuit of the ecm when engine is running poorly without a breakout box. I can only check continuity with ground for a short.
Think I need to find an ecm?? Kyle |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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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. |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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Yeh Gary I noticed that too while looking. I’ll have to look at the PN thread but if I recall the D1L1 ecm May also be a usable replacement. I’ll have to double check on that.
Thanks, Kyle |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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My suspicion was confirmed this afternoon. Coming back from work I ran the boat for another 15 minutes on the boat lift without issue then randomly the erratic behavior came back. The engine quit, I removed the sprout plug and the boat ran fine. I believe the ECM is definitely sending a strange signal to the TFI causing the boat to run poorly. I’ve been studying the GT 40 manual, and I can’t think of a different explanation. That being said, I also bought a code reader off of Amazon so we will see if the ecm has thrown any codes once I receive it sometime today or tomorrow.
Kyle |
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lewy2001
Grand Poobah Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234 |
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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. |
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If you're going through hell, keep going
89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Good to know Mark.
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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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 |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
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Just a thought or maybe a question
You mentioned that you replaced the TFI module What is the part number of the replacement and what color is the casing gray or black? |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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Hey Ken, it is the black module CBE40 and crosses to the Napa TP29 module and the oem ford part number.
Kyle |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
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That's a number and color I came up with too. |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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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 |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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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 |
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tryathlete
Platinum Member Joined: April-19-2013 Location: Lake Villa, IL Status: Offline Points: 1797 |
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Kyle, I am curious if you made sure the multipin connector is in good shape. I think you saw a lot of corrosion in there. What’s your confidence that connector is doing it’s job?
The SS sure is going to be good for the long haul once you get this settled. I spent a lot of time chasing my ignition switch a few years back. It almost made no sense to replace it, but when I decided to do so, the issues went away. |
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kylem428
Senior Member Joined: May-31-2005 Location: United States Status: Offline Points: 263 |
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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 |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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What tune is the new ECM ? 290 or 300? Just curious
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