After welding floor boards cranks no start

Tiny
CLENZER72
  • MEMBER
  • 1989 CHEVROLET CAVALIER
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
I had to weld the floor boards (battery disconnected of course). Once finished it would not start. Tested fuel pump relay, works fine, but when trying to crank it clicks then un-clicks. Looking at wire diagram seems to tie into oil pressure sensor? Basically relay works bench tested, in car will not stay engaged.
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Friday, February 2nd, 2018 AT 4:25 AM

5 Replies

Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
  • 1,853 POSTS
Yes, it ties into the oil pressure switch just as an override if and when the fuel pump relay will not work for some reason after cranking the engine over enough that the oil pressure builds to 4 psi, the fuel pump will run.
But that is not why the fuel pump relay is clicking off and on.
First of all, are you sure you have twelve volts at the battery?
If so, remove the fuel pump relay and make sure that twelve volts is reaching the relay socket. One of those spots in the socket will only be hot when the key is first turned to run for about two seconds, that is the one you want to test but while you are there go ahead and confirm an additional spot has twelve volts with key on run, that should be coming from the fuse #8. Then if all okay, check the ground. If it is marked it will be the C pin or black/white wire. With an ohmmeter to that C pin and a metal ground or the negative battery post it should read under 5 ohms.
If all okay, try a new relay.
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Friday, February 2nd, 2018 AT 8:14 AM
Tiny
CLENZER72
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Thanks. I have done all the tests.
It is an odd four prong relay, I am 99% sure I can swap with a standard relay. Unless there is something special I do not know?
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Sunday, February 4th, 2018 AT 11:14 PM
Tiny
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No, not really, just remember where you get the relay from.
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Monday, February 5th, 2018 AT 6:33 AM
Tiny
CLENZER72
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  • 14 POSTS
Thanks for your help.I've used my power prope and applied power and ground to the pump and hear. Nothing. Dropping the tank I guess is next!
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Thursday, February 22nd, 2018 AT 5:44 AM
Tiny
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The hard part is really getting all the gas out of it, cause each gallon will weigh about 7 lbs and with anything over just a few pounds will make it difficult to maneuver around the tank once it's lowered.
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Thursday, February 22nd, 2018 AT 6:02 AM

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