ECU/PCM opinion
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Tuned
Joined: Jun 2011
Posts: 355
Likes: 1
From: CNY
ECU/PCM opinion
This past weekend I picked up my first EFI/computerized project truck. The owner's dad bought it in '87 and it was very well taken care of and he had a decent amount of history on the truck. It's an F150 XLT Lariat 300 w/ a 4 speed OD. Long story short, it ended up sitting for the past year and a half.
I towed the truck home, siphoned out the bad gas, installed a new starter and solenoid, put in a new fuel filter, and then dropped in a battery. It fired right up and ran great...for about 2 minutes.
It will crank, I have spark, and I can hear the fuel pump under the cab hum when I turn the key. It sounds like it wants to start but just won't quite catch.
Edit: I also can't seem to get the truck to flash any codes for me.
I pulled the ECU/PCM to see if maybe it fried up and this is what it looks like:
A close up....
I've never really messed with these, but that brown doesn't seem ok. Does this look like it fried?
I towed the truck home, siphoned out the bad gas, installed a new starter and solenoid, put in a new fuel filter, and then dropped in a battery. It fired right up and ran great...for about 2 minutes.
It will crank, I have spark, and I can hear the fuel pump under the cab hum when I turn the key. It sounds like it wants to start but just won't quite catch.
Edit: I also can't seem to get the truck to flash any codes for me.
I pulled the ECU/PCM to see if maybe it fried up and this is what it looks like:
A close up....
I've never really messed with these, but that brown doesn't seem ok. Does this look like it fried?
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Yeah that doesn't look good, darkening of the PCB substrate suggest overheating but it could just be dirt. The strange thing is where the PCB is dark, that is the J3 connector where a tuner or chip would be connected, but if there was one plugged in there the paste would at least be scraped off all the pads somewhat. So maybe it is just dirt, the opening in the case where that connector is should be sealed with metal tape, was it sealed or was the area open to the elements?
What does the other side of the PCB look like?
What does the other side of the PCB look like?
Fleet Mechanic
Joined: Mar 2014
Posts: 1,926
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From: Saskatchewan Canada
If you look carefully at the legs of the IC close to that discolored area, you will see the same sort of discoloration. I don't think that was from heat. There is a coating on most PC boards for environmental protection called a conformal coating and sometimes this can discoloration with age. I expect what you see would easily clean up with a good board wash, but I also do not think what you see is any sort of problem.
There is a lot of troubleshooting to be done before you should even think about faulty ECU's.
There is a lot of troubleshooting to be done before you should even think about faulty ECU's.
Thread Starter
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Tuned
Joined: Jun 2011
Posts: 355
Likes: 1
From: CNY
Thanks guys.
Conanski - here's what the cover looked like and the other side.
I just figured I'd check the ECU because it's fairly easy to get to and I can't pull any codes (which could just be user error.) I'll get out my Haynes and start going through every piece now I suppose.
Conanski - here's what the cover looked like and the other side.
I just figured I'd check the ECU because it's fairly easy to get to and I can't pull any codes (which could just be user error.) I'll get out my Haynes and start going through every piece now I suppose.
New User
Joined: Nov 2016
Posts: 16
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Buy, borrow, or rent a fuel pressure gauge, and get a reading from the fuel rail ahead of the regulator. Will bet a pump gave up the ghost. or the tank pickup mesh is clogged. Or both.
A pump can sound like it's working, yet be pumping bupkis.
A pump can sound like it's working, yet be pumping bupkis.
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Tuned
Joined: Jun 2011
Posts: 355
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From: CNY
Well I was able to pull some codes - 22,23,67, and 82. In relation to 22 my MAP is missing lol
Im going to get a fuel pressure gauge and check on the rear pump. Will the truck run without the MAP?
Im going to get a fuel pressure gauge and check on the rear pump. Will the truck run without the MAP?
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Thread Starter
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Tuned
Joined: Jun 2011
Posts: 355
Likes: 1
From: CNY
Thanks for the help everyone. It was a compound issue of rear fuel pump not working and timing out 180 degrees. Truck fires up for a quick second now, but my TPS is way out of spec. Should be good once the new one is in.
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
Not right, it's probably the most important sensor in the system so I'd suggest you get another and hook it up.
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Tuned
Joined: Jun 2011
Posts: 355
Likes: 1
From: CNY
Well got the TPS in and no luck. I have fuel and spark and new air filters. Distributor wires are set correctly. It fired up momentarily last night. Now it only cranks.
Has a code 82 which I believe is something to do with the air diverter/smog stuff? I don't think that would keep it from starting.
Any guidance would appreciated because I'm at a loss at this point....
Has a code 82 which I believe is something to do with the air diverter/smog stuff? I don't think that would keep it from starting.
Any guidance would appreciated because I'm at a loss at this point....
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Tuned
Joined: Jun 2011
Posts: 355
Likes: 1
From: CNY
I put two brand new fuel pumps (one in tank and one in line) and another new fuel filter in. If I spray starter fluid into the throttle body it'll fire up, but if I give it throttle it dies or if I leave it alone it dies shortly after firing up.
Idk if one can install a TPS sensor in upside down?
Idk if one can install a TPS sensor in upside down?
Thread Starter
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Tuned
Joined: Jun 2011
Posts: 355
Likes: 1
From: CNY
Finally got my hands on a fuel pressure gauge. No fuel pressure at the rail, and I have juice to the injectors. Followed the lines back and the in tank fuel pump isn't putting out anything, but I can hear it working. Looks like I'll be dropping the tank again and investigating 