Engine/Transmission (1994 - 1998) looks like a i need a pcm!

[WDimig]

ok guys lets start from the top, about 2 weeks ago, i put a FASS fuel system on my truck, i did not disconnect the battiers, i really didnt think i needed to, but i guess i should have, anyway, went to start the truck, truck was just cranking, no start, though maybe some air in the line, cracked a few lines loose, no fuel, i checked the solenoid to see if it is pulling up, it was not pulling up, i tap on the relay that controls the solenoid, it pulls up, but it does it violently, at first i didnt think that was right, it kept doing that, and then it finally pulled up on it's own, soo i decided to drive the truck home, and i was going to replace the relay, soo im driving home, and i hear a loud click from the engine compartment, first though was the solenoid was acting up or something, then i notice a loss of power, and smoke coming out from underneath the truck, great the solenoid is bruning up, so i pull over as quickly as i can, the solenoid is toast, after it cooled down, i took it off and zip tied the run lever up to get home, while driving i noticed that i had no tach, spedometer, and the truck was not charging, i was hoping that it was just somethng to do with the solenoid and the relays being bad, i replaced the solenoid, and both relays, and still had a no start issuse, it didnt occur to me about the blue fusible link, i check that, sure enough i was burnt, sooo i replaced the link, still the solenoid is not pulling up when i crank the engine, soo i did some reading, basically come to the conclusion that it is either the crank position sensor, or i took out the PCM, i replaced the crank sensor, still have no solenoid pull. ok now my question, is thee soemthing else on gods good green earth that i am missing, or did i really fry the PCM, is there anything else i can be checking to see if it is wrong. thanks for your help guys, im stumped on this one, and getting frustrated.





wes



sorry for the longggg post:-laf

 

[DPapworth]

Look two pages down at the thread entitled "electrical questions". The issues are similar -- no fuel solenoid, tach, speedo, or charge.

Fuse 9 powers the fuel solenoid hold coil, among a host of other things. When fuse 9 blows, you lose all these functions. The fuel solenoid hold coil is not controlled by the PCM at all.

The fuel solenoid pull-in coil is controlled by a relay tied into the start circuit and a fusible link. The PCM is not involved.

Replacing the PCM will not affect the fuel solenoid. You probably don't need a PCM. The fuel solenoid should work, and the engine should start and run, even if the PCM is removed from the truck. The tach and speedo and alternator won't work without the PCM, but the engine and fuel solenoid should.

I'd gently suggest putting away the parts replacement shotgun and doing a little troubleshooting. Turn the ignition on, but don't try to start. Push the fuel solenoid up manually. Does the solenoid hold coil hold the fuel lever up, or not?

If not, troubleshoot the power supplied to the hold coil, including fuse 9.

If the hold coil works, shut the key off. Then get a helper and watch the fuel lever while the helper attempts to crank. Does the lever pull up, or not? If not, then attach a test light to the white wire, and see if power is supplied to the solenoid pull coil during crank.

 

[RobertP]

no the solinoid never even tries to pull up. i will be checking powers and grounds tonight. also will check on that control fuse. thank you for your response.

 

[WDimig]

Update!

ok, spoke with robert, got home and checked the #9 fuse, sure enough it was blown, replaced the fuse, engine still cranks but does not start, with the key on i went out and manually pulled up the solenoid, the hold coil is working, it stayed up, went back in the truck started, and i had tach spedo, and it was charging! soo i got one problem solved, but i still dont have power going to the pull coil, i brought home the trusty multi meter, me and rob are going to go poke some wires here shortly. will keep you posted.



wes

 

[WDimig]

ok did some testing last night, we found a bad ground at the fuel shut off relay connector plug, we just need to find where the ground is bad at.



wes

 

[Rams-n-Hogs]

Glad to see you're getting it figured out, Wes. I didn't know about fuse #9, but since I know about it, now, I'll bet I don't forget, if it ever happens to me.

 

[WDimig]

It's Alive!

yup truck is up and running, we decied to make 2 new grounds for the fuel solenoid relay circuit, we took one ground to the driver's side battery, and another on the body right below the firewall, soo i can assure my self that i will never have a grounding issue again with that circuit. truck runs strong, havent really gotten to drive it but a mile or 2, but i notice a big difference in power, and smoothness with the FASS installation. will post more results once i have them. !Oo. Oo. Oo.



wes