Repair

Tiny
GKC
  • MEMBER
  • 1991 BUICK SKYLARK
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 75,000 MILES
1991 buick skylark. Starts then dies. Have a new fuel pump & coil pack w/mod check ok. How can I test or find what may be wrong?
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Friday, February 25th, 2011 AT 9:25 PM

15 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
How long since a tune-up? Any applicable mil codes?
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Friday, February 25th, 2011 AT 9:29 PM
Tiny
GKC
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Every year gets new oil & oil filter. Only has 73,340 miles. Within the last month, new air filter, new water pump, new plug wires, new thermostat, and ran fine for weeks after all that. Then while driving, it was like you turned the key off, then on, made it to the garage. Where now all the engine will do is start, run smooth for 2 - 3 seconds then nothing. How do you check for "mil" codes and what else could possibly be done to "tune" it up. Someone said that it was the fuel pumpj. I replaced it. Same results. If it is a sensor of sorts. Which one and how do you "test" the sensor to see if it good or not?
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+2
Friday, February 25th, 2011 AT 11:15 PM
Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
Cross the a&b terminals in the aldl. Count the flashes to get the codes or go to an autoparts store to have them read. Of if you find the codes come back to the site here and lok under obd 1 for whih light code you got.
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Saturday, February 26th, 2011 AT 12:05 AM
Tiny
GKC
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  • 8 POSTS
I used a GM code reader (should jump the terminals) and the only code flashed was a 12. Which according to the manual "no distributor signal to ECM" system PASS. Is there a break in the wire loom? I took the Module that is attached to the coil packs to AutoZone where they put it on their tester and said was good. I watched as he did test and all green lights showed for the test. So now what do I do with the code 12?
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Wednesday, March 2nd, 2011 AT 4:31 PM
Tiny
JDL
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Code 12 may only mean diagnostic mode. Use a gage and check fuel pressure. Not only look for correct pressure, see if it holds after pump shuts off.
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Wednesday, March 2nd, 2011 AT 6:25 PM
Tiny
GKC
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The new pump activates for a few seconds each time you turn the ignition on. But no not much pressure and with the key on the pressure goes to near zero.
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Thursday, March 3rd, 2011 AT 4:18 AM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Some of the national brand autostores used to loan out a fuel pressure gage, check with engine cranking. Check voltage and ground at the fuel pump connector, engine cranking. Gray wire is voltage for the pump motor. Black wire is ground, where applicable.

Engine cranking, use a noid lite, check for injector pulse.
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Thursday, March 3rd, 2011 AT 3:50 PM
Tiny
GKC
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In the past years at first start sometimes the engine would faultier for a moment then recover during the shift from park to Drive/reverse then keep running fine. Now today with the pressure at near zero and no voltage to pump after engine stalls. What could the problem be. What/where is the relay to keep the fuel pump running?
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Thursday, March 3rd, 2011 AT 5:43 PM
Tiny
JDL
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When the problem occurs, use a voltage tester, check for voltage at fuel pump/injector fuse in fuse box. Should go hot/voltage with key on. My info shows an oil pressure switch in parallel to the fuel pump relay. One can't effect the other, once you crank it enough to bring up oil pressure that o/p switch should close and the pump runs. That is why I'm asking about that fuse.

The relay shows to be number 3 on the firewall. Note picture.
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Thursday, March 3rd, 2011 AT 6:15 PM
Tiny
GKC
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Thank you JDL for the graphics. Can you make it larger?
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Friday, March 4th, 2011 AT 5:00 AM
Tiny
JDL
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This is about as good as I can get it.
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Friday, March 4th, 2011 AT 4:03 PM
Tiny
GKC
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First I'd like to say thank you. And I have looked all over the internet to see if I could find that diagram. Because I cannot read it. Too fuzzy. But I think the problem lies in the fuel pump RELAY. The fuse must be good or it would not run the pump with ign key on. So the pump does run, the engine does start for a sec. I believe that the relay is not working correctly. I would check the voltage ((as in your last post)) but you will have to lead this blind dog to the exact location of the RELAY and if there is a separate "fuse" for when the engine is "running". It looks to me that the "fuel pump RELAY" is on the engine side of the firewall & closest to the steering column. Correct? I have attached a photo of what looks like 4 relays on center of firewall are one of these the pump relay? ((And one of the engine area))
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Monday, March 7th, 2011 AT 5:21 PM
Tiny
JDL
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You may be right about the fuse, but, because you have an oil pressure switch in the fuel pump wiring circuit, parallel with the relay, just a redundant power supply to the pump. The pump should run even without the relay. Maybe a problem with wiring circuit? There is a link below, it is free, has component locations and engine wiring diagrams. When the link comes up, you click on technical resourses, There is a user agreement, click agree. The next page asks year--make-- model, just follow the links. I can't guarantee that all that info is correct? You can look at the wiring colors at the connector for fuel pump relay to make sure you have the correct relay.

Showmetheparts. Com/airtex/
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Monday, March 7th, 2011 AT 6:07 PM
Tiny
GKC
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Well, the best thing is I sold it to a backyard mechanic that replaced the timing sensor down on the crankshaft. It still ran rough BUT better then before AND kept running and did not die. Later he replaced the injectors, then it ran smooth and strong again. So that anyone reading this can have the ANSWER TO THE PROBLEM THAT WAS ONCE INQUIRED ABOUT HERE.
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Wednesday, March 28th, 2012 AT 2:41 AM
Tiny
JDL
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Sounds good to me.
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Saturday, September 15th, 2012 AT 6:18 PM

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