C4 spark testing
#1
4th Gear
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Location: South Jordan Utah
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C4 spark testing
This may sound dumb but I bought a 1990 C4 that didn't start. Ok they told me it has water damage and was totaled. When I looked into it the water damage was minimal but the engine had thrown a rod. How do you throw a rod parked at the Beach?? Anyway after a rebuilt engine I've gone through most of the electronics, new ECU, relay's, distributor cap roter wire's +. The engine will crank over, fuel pressure up, but won't start? I've tested voltage to the ECU the Fan's come on the vats light goes off when cranking but have no spark, checked all fuses (twice) in line fuses (twice) power to the distributor cap.
I don't know what else to check, is there something I've missed??
I don't know what else to check, is there something I've missed??
#2
Instructor
This may sound dumb but I bought a 1990 C4 that didn't start. Ok they told me it has water damage and was totaled. When I looked into it the water damage was minimal but the engine had thrown a rod. How do you throw a rod parked at the Beach?? Anyway after a rebuilt engine I've gone through most of the electronics, new ECU, relay's, distributor cap roter wire's +. The engine will crank over, fuel pressure up, but won't start? I've tested voltage to the ECU the Fan's come on the vats light goes off when cranking but have no spark, checked all fuses (twice) in line fuses (twice) power to the distributor cap.
I don't know what else to check, is there something I've missed??
I don't know what else to check, is there something I've missed??
#4
time to dig out the FSM. start with the basics. question - how are you checking for spark?.
Last edited by Joe C; 01-09-2018 at 08:44 AM.
#6
Safety Car
This may sound dumb but I bought a 1990 C4 that didn't start. Ok they told me it has water damage and was totaled. When I looked into it the water damage was minimal but the engine had thrown a rod. How do you throw a rod parked at the Beach?? Anyway after a rebuilt engine I've gone through most of the electronics, new ECU, relay's, distributor cap roter wire's +. The engine will crank over, fuel pressure up, but won't start? I've tested voltage to the ECU the Fan's come on the vats light goes off when cranking but have no spark, checked all fuses (twice) in line fuses (twice) power to the distributor cap.
I don't know what else to check, is there something I've missed??
I don't know what else to check, is there something I've missed??
#7
4th Gear
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C4
Ok I pulled up the codes and it says the ECM is bad so I ordered a new one and I'll see what that does 🤔.
#8
Does it start if you give it a sniff of gasoline in the air intake? If it turns over. Your problem is fuel delivery. Don’t assume spark. Try and eliminate the cheap stuff. Spark is super tricky. What code did you say you got?