Car shut off completely while driving and has no spark

BASASSGS

MEMBER
1999 GMC SUBURBAN
5.7L
V8
4WD
AUTOMATIC
236,000 MILES

I have replaced alot of things on this beast. New crank sensor, ignition module, coil, distributor, cap, rotor, fuel pump, oil pump all within the last 6 months. I have had issues with the fuel pump more than a few times in the past. Now fuel pressure is good and there is an electrical problem. 14 days ago I put in a new distributor, cap and rotor. My mechanic told me my old distributor was causing the check engine light to come on. New distributor fixed it. Then 10 days ago I did a trip over the desert and on my way home car shut off while on freeway. Had it towed home and turns out the brand new cap was bad. Replaced dist cap and she fired right up. Now last night same thing happened except this time no spark from coil ( as we rolled to a stop I noticed the Tach was going crazy up and down). Replaced the coil and ignition module and still nothing. Towed home and now this morning with a hei spark tester I noticed the coil is sending intermittent spark while key is in on position and the tach is going crazy, but when you turn the key to start, no spark.

4 Replies

RANDICO

MECHANIC
174 POSTS

Key on engine of and the coil produces spark? The cam and crank sensor are Hall-effects. It produces a on - off signal, With the key on something is giving it ground. The fuel pump relay gives power to the crank position sensor. For now replace the fuel pump relay. You have a wire issue somewhere along the harness. There is also a fuel pump prime connector should have a green tab on it. This wire is used to activate the fuel pump and to test fuel pressure should be along the battery . Make sure that fuel pump test connector is not grounded or has a ground test lead attached to it.

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Tuesday, April 22nd, 2014 AT 10:58 AM

BASASSGS

MEMBER
2 POSTS

I replaced the crank sensor and the intermittent spark from the coil I was getting while the key is on stopped. Now the truck fired up and started no problem. My concern is how does a brand new cap go out after 5 days of usage then a week later a 4 day old crank sensor goes out. Am I getting bad luck with cheap parts or is there something wrong inside my truck making these things short out.

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Tuesday, April 22nd, 2014 AT 11:15 AM

HMAC300

MECHANIC
48,601 POSTS

Cheap parts will do this especially sensors. If they are made in china especially. If you buy a brand name part like standard or borg warner if they are made in another compay they are made to their specs same thing with light bulbs. The dist cap could have been many things or the coil wire may have been bad as I've seen this several times dist cap screw up by getting wet which if you have a/c on yours you should make sure that the a/c line going over cap is wrapped so as to not drip water on it and give you the same problems as it will. That is the only thing ican think of at the moment

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Tuesday, April 22nd, 2014 AT 12:03 PM

RANDICO

MECHANIC
174 POSTS

What you have going on is nothing out of the ordinary, This condition is popular and you will end up replacing the crank and distributor cap as a hobby. Replace the fuel pump relay.

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Tuesday, April 22nd, 2014 AT 1:05 PM