98 Northstar, cranks/backfires/no start
98 Deville, Northstar. Just died one day. Cranked,
but no start, with backfires and random hits and
misses. Discovered ICM was cracked and failed.
Replaced the ICM, loaded the fuel system, fired up
and ran for about 4 seconds, died. Tried to start
again, more hits and misses and backfires. Fuel
pressure is good (52 lbs), and I'm getting spark.
Weird thing is, it ran like a top for about 4 seconds,
then died. Reseated and cleaned the intake flap
behind the ps pump, all good there. Is there a learn
for the replaced ICM? What could cause this? Ran
perfect for 4- 5 seconds. Thanks guys and gals!
Run a compression test. If all cylinders test very low or zero it's jumped timing. If this is a higher mileage car and the head gaskets have already been done it might be worth fixing if it's in otherwise good shape. If the head gaskets haven't been done it may be time to move on. All Northstar engines blow head gaskets sooner or later. HTH. -Jim
Thanks, Jim! I'll get my hands on a compression tester and check it out.
You're welcome. Glad to help. Usually when backfiring is involved it's a timing issue. Especially since you have spark and fuel. Keep us posted. -Jim
The thing that gets me, is that it ran great for 4 - 5 seconds before it died. Checked on the forums, and it's extremely unlikely it's timing. It's an interference engine, so there would be all kinds of racket from valves hitting pistons. Going to check cylinder pressure next.
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