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View Full Version : Help determining why truck is cutting out while driving.



joegreen
08-04-2016, 03:55 AM
Truck is a 1978 chevy k20 with a tbi swap. Today I was driving home and all the sudden the truck cut out and I coasted maybe 30ft then the engine picked back up again. It did it again a half mile later. I managed to get back home. Luckily I was only a few miles from home. Anyway in the driveway I managed to get the truck to do it again. I noticed that once it stalled if I turned the key off then back to the on position after maybe 10 seconds I could not hear the fuel pump turn on. I tried doing the on off thing for a few more times until I heard the fuel pump kick on then the truck would start again. I have had the exact symptoms of the truck stalling while driving from a bad icm. How can I definitely determine whether the fuel pump is going or if the icm is the culprit. Can a fuel pump intermittently work?

MQQN28
08-05-2016, 12:59 AM
Hi there.
I had a similar problem with my hot rod when I first put it on the road. It has delco fuel injection on a flathead. It uses the the delco 808 all custom stuff. It would cut out as you say then come good.
You symptoms are similar. My problem was not helped by being a custom it did not have a CEL light to read error codes. I installed a fuel pressure gauge and that helped to show it was a fuel delivery problem. I then installed a surge tank not the answer. I put the cel light on the system and found when the car went over a bump it flashed. Should of had this at the start.

I then decided to take the ECM out and inspect it. As soon as I opened the case I saw a problem on the circuit board. It was a loose surface mount resistor. Common problem with these units in Australia. I repaired this problem solved. The signal from the dizy tells the fuel pump to turn, when this part moved it lost the signal.
So your problem maybe similar. The signal for the fuel pump may be missing. I replaced the ECM also as I did not know how good it was.