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'95 c1500 350tbi
Verify that the IAC is working, and the coolant temp sensor is providing valid data all the way to the computer.it gave some grief starting. Had to hold the throttle down slightly to maintain a smooth idle.
I assume that it cranks, but doesn't run. Previous day's poor running may have fouled the plugs.-Attempted to start the truck the next day, no dice.
11V on the supply side. Nobody remembers to check for voltage on the ground side.-checked the voltage at the fuel pump harness, pump has 11v with the key on. Good spray from the injectors when cranking.
Not a waste of time, but not all that helpful, either. A .035 gap in atmospheric pressure is no test of an ignition system's voltage capacity. The ignition system has to fire a .035 or larger gap, with the gap under compression pressure many times higher than atmospheric. Simulating this requires an enormous gap.-checked spark by pulling #1 and #3 plugs, good arc across the gap. Measured the gap at .035 as per my manual.
CLEAN THEM, or replace them. "Fouled" is no good. Carbon conducts electricity.Plug is carbon fouled, but nothing extreme.
SOMETHING is wrong if the plugs get fouled in 10km. Oil burning? FAULTY O2 SENSOR(s)? How old is the O2 sensor? Kinda thinking there is only one on this vehicle.-Cap, rotor, plug wires, fuel pump, spark plugs, starter, ignition coil, all less than 2 years old and with less than 10km on them.
Probably want to get one.-No scan tool to read obd1 data on hand
"Codes" can be helpful. The real diagnostic power is in the data stream, and the bidirectional control...and that takes a scan tool.no codes showing with the jumper wire/CEL.
Define "good".Theoretically, if you have good compression, air, fuel, spark....should fire off.
Define "good".
I'd have said he needs:
1. A burnable air/fuel mixture
2. Compression pressure between 100 psi, up to perhaps 200 psi.
3. Spark across the plug gap, at the right time
4. A reasonably free-flowing exhaust
Ok, compression that is close to even with all 8 cylinders. Not 100 on a couple and several at 150 and a couple at 200. IMO, the good to go compression would be 150 to 160 and all close to that range. The free flowing exhaust is great but will not hinder it from firing off and starting. Depending on the lack of free flow, it could idle fine and starve for power on acceleration, or start and if completely blocked, start to strain and falter asap and then die.Define "good".
I'd have said he needs:
1. A burnable air/fuel mixture
2. Compression pressure between 100 psi, up to perhaps 200 psi.
3. Spark across the plug gap, at the right time
4. A reasonably free-flowing exhaust
Fouled plugs are the "silent killer" of engines that won't start.Long story short, got her running again!
the #2 and #6 plugs were particularly nasty... ...the fouled plugs might not be jumping the gap under pressure... ...After cleaning all the plugs, I held the gas pedal down while starting to clear any potential flood from my earlier failed attempts and she fired up and idled around 400 rpm.
Absolutely could be the root cause. There's many different kinds of problems that a faulty ignition module, or faulty communication between the computer and the ignition module could cause.I'm still stuck wondering why they got so fouled in the first place.
After more reading in the service manual and on the forum, I have discovered the ICM. After the test procedure, my error is "IC Bypass circuit open, faulty connections or faulty DI control module."
Obviously this is an issue to be fixed, but I'm not 100% sure of the effect this would have on the truck.
Could this potentially be at the root of my problems, or am I barking up the wrong tree?