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1986 GMC S15 Wont start

Tiny
DERBYGUY74
  • MEMBER
  • 1986 GMC S15
  • 6 CYL
  • 2WD
  • MANUAL
  • 171,428 MILES
My truck wont start. It has spark and fuel to the throttle body but the injectorswont pulsate fuel. If I spary starting fluid in it it runs fine for a minute.
Sunday, March 21st, 2010 AT 8:18 PM

12 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Hook up a noid lite to the injector/s harness and see if it flashes if so the injector/s is the problem no flashes could mean power input or the computer injector/s ground drivers-
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Sunday, March 21st, 2010 AT 8:28 PM
Tiny
DERBYGUY74
  • MEMBER
  • 8 POSTS
Noid lite?
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Sunday, March 21st, 2010 AT 10:18 PM
Tiny
DERBYGUY74
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  • 8 POSTS
The ecm b fuse blew and when I put a new one in it blows imedeitley. I checked the wires that go to the fuel pump and they were fine. The ECM B fuse is the fuel pump. What else runs off that fuse?
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Sunday, March 21st, 2010 AT 10:22 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The fuel pump relay, oil pressure switch, fuel pump and computer
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Sunday, March 21st, 2010 AT 11:59 PM
Tiny
DERBYGUY74
  • MEMBER
  • 8 POSTS
The manual says the ECM I fuse is the computer and that fuse is fine.
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Monday, March 22nd, 2010 AT 12:31 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Mit1 says it powers the items I've mentioned earlier I viewed the electrical diagram/schematics
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Monday, March 22nd, 2010 AT 7:27 AM
Tiny
DERBYGUY74
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  • 8 POSTS
Is the fuel pump relay under the hood? There are 3 relays under the hood.
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Monday, March 22nd, 2010 AT 12:27 PM
Tiny
DERBYGUY74
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  • 8 POSTS
So I looked at the three relays under the hood on the drivers side fender and the middle relay looks like it fried because the plug and bottom of the relay are black. I cant read the numbers on the relay so I cant cross refrence tot see if it the fuel pump relay.
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Monday, March 22nd, 2010 AT 2:32 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
S15 2.8 liter the FP relay is located on left front fender panel behind AC compressor relay-Sorry no pic available.
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Monday, March 22nd, 2010 AT 3:28 PM
Tiny
DERBYGUY74
  • MEMBER
  • 8 POSTS
Ok. I have replaced the fuel pump relay, ignition control module, computer and oil pressure sensor. It still blows the ECMB fuse even when the computer is unplugged and the key is off.
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Thursday, March 25th, 2010 AT 5:58 PM
Tiny
RASMATAZ
  • MECHANIC
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Time to break out the circuit tester and check for direct short to ground from the fuse all the way to the pump
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Thursday, March 25th, 2010 AT 6:34 PM
Tiny
DERBYGUY74
  • MEMBER
  • 8 POSTS
I know its not the wires from the fuse to the pump cause they are brand new. I did end up finding a common problem with these trucks. The wires that go from the computer to under the hood to the engine. The wires run along the firewall behind the motor rub on the back of the block and short out but is very hard to see anything.
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Thursday, March 25th, 2010 AT 11:15 PM

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