Engine cranks but no start?

LESMESS

MEMBER
1990 CHEVROLET SILVERADO
5.7L
V8
4WD
AUTOMATIC
73,000 MILES

Last time truck driven it bucked several times rather violently when accelerating. Thought it a fuel issue. Then truck set for a month while I was in hospital. Now cranks but never fires a lick. Engine does not appear to have adequate spark (weak yellow orange) and does not appear to be getting fuel. New coil, ignition control module, distributor cap, rotor, fuel pump relay, fuel filter. Still weak spark no fuel. Seems something is interfering with the ECM start routine but I can't figure out what. The manual indicates this model does not have a crankshaft sensor. Could it be the ECM? Any help appreciated.

6 Replies

HMAC300

MECHANIC
48,601 POSTS

Have the ignition module checked in dist and check resistance of pickup coil in dist may be bad. auto parts can check ignition module. When you turn the key to the on position without cranking the engine over can you hear the fuel pump run in the tank for 5 seconds?

https://www.2carpros.com/articles/car-cranks-but-wont-start

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Friday, July 8th, 2016 AT 7:18 AM

LESMESS

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6 POSTS

Thanks. Ignition module is brand new (realize could still be bad). I believe acceptable ohm range for pickup coil is 500-1500. Mine checked out at 824 ohms.

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Friday, July 8th, 2016 AT 7:38 AM

LESMESS

MEMBER
6 POSTS

Any other thoughts? Anyone?

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Friday, July 8th, 2016 AT 7:41 PM

HMAC300

MECHANIC
48,601 POSTS

Check coil wire for resistance all plug wires/coil should not have more than 5000 ohms per foot check coil reisistance as well. Then check wires from pick up coil to module in dist sometimes these go bad also if internally mounted coil check for a bad or broken coil piece

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Saturday, July 9th, 2016 AT 6:21 AM

LESMESS

MEMBER
6 POSTS

Pickup coil was bad and apparently not sending signal to ECM to fire ejectors. Replaced pickup coil - now ejectors are firing and spraying gas into throttle body. Still no start. Spark at plugs is only yellow-orange instead of blue/white. Does not appear to be hot enough to ignite compressed gas. New coil, new ignition control module rotor and distributor cap. Nothing else spark related to replace except plug and coil wires. Could old bad wires be knocking the spark from a new coil down to the point it is not hot enough to ignite gas? Thanks.