jteck10
1/2 ton status
got it, i'll do that today as well
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TBI fuel injector trouble?
- Thread starter jteck10
- Start date
jteck10
1/2 ton status
well first test of (hopefully not) many.
replaced the thermostat back to a 195 from a 180 because its 6 bucks and an easy job and peace of mind
plus if thats going to make the truck run rich and not normal, why not.
then let the truck run for 20-25 min, ran fine then shutoff. still no codes thrown
so started with the first diagnostic, put my phone at the fuel pump on the chassis and turn the key
heard it prime no problem, multiple times - so that means i should rule out the fuel pump. correct?
i did notice the ground wire to the frame looked ok, but like it could be cleaned up
ill clean that up in the morning just in case.
next up - fuel pressure test, fuel filter, and relay test tomorrow
video for prime noise and picture of ground wire attached
replaced the thermostat back to a 195 from a 180 because its 6 bucks and an easy job and peace of mind
plus if thats going to make the truck run rich and not normal, why not.
then let the truck run for 20-25 min, ran fine then shutoff. still no codes thrown
so started with the first diagnostic, put my phone at the fuel pump on the chassis and turn the key
heard it prime no problem, multiple times - so that means i should rule out the fuel pump. correct?
i did notice the ground wire to the frame looked ok, but like it could be cleaned up
ill clean that up in the morning just in case.
next up - fuel pressure test, fuel filter, and relay test tomorrow
video for prime noise and picture of ground wire attached
If the pump primes, the relay works, the ECM is commanding the relay to run the pump, pump is good, wiring to the pump is good. That doesn't mean there isn't an intermittent failure there somewhere, but the circuit does operate properly. You can start the truck and unplug the relay, if the oil pressure switch works and it keeps running, your problem almost certainly isn't the relay or the oil pressure switch since either one will keep it running until you turn the key off.
From the pic that ground looks great, often the entire area is rusted to hell. Pretty unlikely the ground is the issue, but can't make things worse. I like to hitstuff like that every electrical connection with dielectric grease when I reassemble.
From the pic that ground looks great, often the entire area is rusted to hell. Pretty unlikely the ground is the issue, but can't make things worse. I like to hit
What transmission do you have?
If it's one of the "E" transmissions, check the Torque Converter lockup.
4L60E, I don't remember what others have that torque converter lockup. If it stays in "lockup" when you come to a stop, it will stall the engine. Then disengage, as soon as you cycle the key off and on.
If it does turn out to be this, you can unplug the "lockup" plug and run without it, then fix it at you convenience.
Just my thoughts, as you've checked, and rechecked lots of the usual.
Let us know.
PS: this is one of the myriad of reasons I hate the "E" transmissions.
If it's one of the "E" transmissions, check the Torque Converter lockup.
4L60E, I don't remember what others have that torque converter lockup. If it stays in "lockup" when you come to a stop, it will stall the engine. Then disengage, as soon as you cycle the key off and on.
If it does turn out to be this, you can unplug the "lockup" plug and run without it, then fix it at you convenience.
Just my thoughts, as you've checked, and rechecked lots of the usual.
Let us know.
PS: this is one of the myriad of reasons I hate the "E" transmissions.
This would be anything with lockup, which includes the 700.
I forgot all about this as a potential issue, but either its not possible or exceedingly uncommon with the 700's.
If it's only stalling coming to a stop, I could see that being an issue. If it happens under steady throttle, I don't see that being the issue. That stalling issue occurs when the converter doesn't unlock and wants to continue to propel the vehicle forward. The act of using the brakes stalls the engine in that case.
At speed, momentum would prevent it from feeling like it stalled, as the engine would still turn, even if not firing.
jteck10
1/2 ton status
perfect, this is what i'll try today when i get some time - thanks!
jteck10
1/2 ton status
What transmission do you have?
If it's one of the "E" transmissions, check the Torque Converter lockup.
4L60E, I don't remember what others have that torque converter lockup. If it stays in "lockup" when you come to a stop, it will stall the engine. Then disengage, as soon as you cycle the key off and on.
If it does turn out to be this, you can unplug the "lockup" plug and run without it, then fix it at you convenience.
Just my thoughts, as you've checked, and rechecked lots of the usual.
Let us know.
PS: this is one of the myriad of reasons I hate the "E" transmissions.
so this is a new one i havent heard yet.
i have the TH700r4 transmission, and the stall isnt occuring when i come to a stop, i could be moving and truck turns off, but ill keep moving.
It's not the converter staying locked up. It's locked up under light load/cruise conditions under normal operation. At least some automatics can have a problem where the clutch solenoid fails and the converter stays locked up when it should unlock, which stalls the engine when you come to a stop. But only when coming to a stop.
jteck10
1/2 ton status
finally had some time to get out and try these
i started the truck, not warmed up yet, and undid the relay - truck then turned off.
i replaced the relay, removed the oil pressure switch, and the truck started right up
safe to say the oil pressure switch needs to be replaced, correct?
I put a 180 degree in my TBI truck one time, and It did not stop a my truck from running. It will cause the truck to go in and out of closed loop, which causes the OBDII/ECM to go bonkers with the fuel mixture, but that is about all.
I am not sure that's a valid test for the oil pressure sensor.
It is my understanding the oil pressure switch is there to shut the pump off if the engine stops running after an accident. So unplugging the sensor should shut the pump off
It is my understanding the oil pressure switch is there to shut the pump off if the engine stops running after an accident. So unplugging the sensor should shut the pump off
jteck10
1/2 ton status
so back to square one
i'll have to try and do the fuel filter/pressure test tonight or tomorrow and see what i find there
Time out.
We've been all around this, and gotten nowhere
Fuel pressure ??
Vacuum leaks ??
I head one of you say "it runs, and just shuts off" . Well, "just shuts off" is an electrical issue.
We've been all around this, and gotten nowhere
Fuel pressure ??
Vacuum leaks ??
I head one of you say "it runs, and just shuts off" . Well, "just shuts off" is an electrical issue.
All it takes to damage one of these ignition modules, is a stray static discharge.
jteck10
1/2 ton status
the shop i had i towed to replaced this ignition control module. when it shuts off, all my electrical stays on. dash lights and CEL comes on too.
jteck10
1/2 ton status
to add to my frustrations, i tried installing the oil pressure sensor and goddam if its not a bitch to get to.
with it being 9pm here and too dark to see anything i called it quits and put everything back together
as i was trying to get pliers behind the distributor and behind the vacuum pump i loosened the stud the oil pressure sensor screws into.
now it wont even start and the oil pressure jumps around.
Looks like i need to take the Vacuum pump off to be able to better get to that oil pressure sensor, and re-tighten down or replace the stud it goes into as well
pics of sensor and vid of no start
with it being 9pm here and too dark to see anything i called it quits and put everything back together
as i was trying to get pliers behind the distributor and behind the vacuum pump i loosened the stud the oil pressure sensor screws into.
now it wont even start and the oil pressure jumps around.
Looks like i need to take the Vacuum pump off to be able to better get to that oil pressure sensor, and re-tighten down or replace the stud it goes into as well
pics of sensor and vid of no start
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It is. Not sure where that myth started (Fords?) but it's never been true for GM:
"*** UPDATED BY TSB 893206E, DATED OCTOBER 90
When the key is first turned ON, without the engine running, the control module will turn the fuel pump relay ON for two seconds. This builds up the fuel pressure to normal operating pressure. If the engine is not started within two seconds, the control module will shut the fuel pump OFF and wait until ignition reference pulses are present. As soon as the engine is cranked, the control module turns the relay ON, which powers the fuel pump. The control module continues to power the fuel pump during engine operation. If the fuel pump relay fails, it is backed up by the oil pressure switch, which continues to operate the fuel pump as long as oil pressure remains above 28.0 kPa (4 psi)."
Your battery sounds like it's about dead. FWIW, if you deep discharge a starting battery, you have pretty much destroyed it. They do NOT take being discharged well at all. Watch the voltage on it, don't try and start it if it's going low, wait for it to recharge.
Is that switch/sender the three wire combo? Something is definitely up in that circuit, but if you don't have things threaded down tight, it may be a ground issue. Oil pressure switch/sender has no bearing on the truck running (obviously with the relay working properly).
At one point those adapters the sensor threads into weren't available, not sure about nowadays, but be VERY careful not to break it. Most (all?) of them were brass and it doesn't take much to crack them, especially too much torque.
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that bulletin came out 6 months after I left my last GM agency. Thou we did have TBI trucks in our fleet. Plenty of Fords too, and they did have a cut off switch.
jtech10 unplugged the relay and truck ran. He reconnected relay, then with truck running, he unplugged oil pressure switch and truck stalled. After reading the the bulletin, I would say the relay is bad.
Is late and want you 2 to proof read this.
jtech10 unplugged the relay and truck ran. He reconnected relay, then with truck running, he unplugged oil pressure switch and truck stalled. After reading the the bulletin, I would say the relay is bad.
Is late and want you 2 to proof read this.
"that bulletin came out 6 months after I left my last GM agency. Thou we did have TBI trucks in our fleet. Plenty of Fords too, and they did have a cut off switch."
https://ck5.com/forums/threads/fuel-pressure-relay-question.324927/page-2#post-3625396 "diagnostic aids" spells out that it's a redundancy for the relay. That diagram is from the '88 F-body line, but all GM injection from at least 1985-199? was the same in regards to relay/oil pressure switch operation.
But regarding the OP...the truck *died* when he unplugged the relay, indicating the switch or wiring for the switch is bad.
Theoretically this means the relay COULD be intermittently bad (if the switch isn't providing power, and the relay fails, it would stop running), but that doesn't seem to be a common failure mode for them.
https://ck5.com/forums/threads/fuel-pressure-relay-question.324927/page-2#post-3625396 "diagnostic aids" spells out that it's a redundancy for the relay. That diagram is from the '88 F-body line, but all GM injection from at least 1985-199? was the same in regards to relay/oil pressure switch operation.
But regarding the OP...the truck *died* when he unplugged the relay, indicating the switch or wiring for the switch is bad.
Theoretically this means the relay COULD be intermittently bad (if the switch isn't providing power, and the relay fails, it would stop running), but that doesn't seem to be a common failure mode for them.
my bad, got it backwards.
