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1996 GMC Pickup Died and Now Won't Start


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djdavis75
User

Nov 29, 2014, 6:44 PM

Post #1 of 14 (1843 views)
  post locked   1996 GMC Pickup Died and Now Won't Start  

My vehicle is a 1996 GMC Sierra SL C1500 2WD Pickup with a 4.3L V6 engine and automatic transmission. The truck has about 180,000 miles on it. I've had some problems with it in the past which can be read here:

http://autoforums.carjunky.com/...p_Wont_Start_P35678/

I know I ended up putting plugs, wires, cap, rotor, camshaft position sensor (One in the distributor.), and a coil on it. Anyway it's been running great for years since that time I had all the problems with it.

On Thanksgiving day we started the truck and moved it into the yard to load/unload some stuff as we were about to drive it on a trip. We started and moved it twice, short distances both times. We then checked the oil, power steering fluid, and added some antifreeze to the overflow tank (It has a slow water leak.). After that we headed out on our 130 mile trip, but after about 4 or 5 miles the truck cut out a couple of times and died. It has not restarted or even attempted to start since. We finally towed it back home and started working on it.

The starter works and engine turns freely, but we did notice some arcing on the starter. We replaced the starter and the arcing problem is solved. I don't think that has anything to do with my main problem, but thought I'd mention it. We've checked for spark from the coil wire and the #1 cylinder wire and the ignition system seems to be totally dead. When cranking it doesn't hit even a little bit.

Here are some things we've tried to fix it/diagnose it:

(1) We've checked the fuel pressure, it's in the 55-60psi range at key on and while cranking.
(2) Checked to ensure I had power across all fuses in the Fuse/Relay Center under the hood.
(3) Replaced cap and rotor. (I've had trouble with moisture/corrosion in the distributor cap on this truck before, it was corroded.)
(4) There is 12V to one of the connector pins at the coil with the key on.
(5) Did an Ohm test on the coil according to the repair manual and it seems good, and the readings are almost identical to a coil on another vehicle.
(6) Tried another ignition module (One by the coil.) from a working vehicle.
(7) Tried a different cam shaft position sensor from a non-working vehicle (So it could possibly be bad).
(8) Tried a new coil wire.
(9) Unplugged and inspected the connectors on about everything ignition system related.
(10) Charged battery and cleaned terminals.

The computer had 3 error codes when I hooked it up:

(1) P1864 TCC Ckt (Think this was a transmission code of some sort.)
(2) P0175 (Think this means the fuel mixture was too rich, which might have been caused when the ignition system failed.)
(3) P???? (I didn't write it down, it's always set, says my catalyst efficiency is below threshold. It's been setting this code a long time.)

I cleared the codes on Thanksgiving after I read them, and since then the computer hasn't reported any error codes.

I'm at a loss on what to do next, I figured it was just a corroded cap/rotor, but that didn't fix it. I can't figure out why I have no spark, no error codes, and nothing seems to fix it. Any help would be greatly appreciated.

Thanks,
David


Tom Greenleaf
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Nov 29, 2014, 9:17 PM

Post #2 of 14 (1826 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

Unsure of how you tested for spark and question results and parts swapping.


First thing I'd see if this will respond to priming throttle body with starting fluid. I don't trust your fuel pressure results either and that's critical. Your range was correct but was it accurate? Was it delivered or just pressure at rail? I say verify that first then worry about if spark or not,


T



djdavis75
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Nov 29, 2014, 9:51 PM

Post #3 of 14 (1822 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  


In Reply To
Unsure of how you tested for spark and question results and parts swapping.


Tested spark several ways...

(1) Inserted plug in #1 wire and grounded outside of plug to engine via contact. Plug didn't spark.
(2) Inserted screwdriver in #1 plug wire and held very close to exhaust manifold, no spark.
(3) Inserted screwdriver in coil wire and held close to engine block, no spark.
(4) Did test 3 with spark plug wire attached directly to coil.


In Reply To
First thing I'd see if this will respond to priming throttle body with starting fluid.


I'll try it tomorrow.


In Reply To
I don't trust your fuel pressure results either and that's critical. Your range was correct but was it accurate? Was it delivered or just pressure at rail? I say verify that first then worry about if spark or not,


Fuel pressure was tested with a fuel pressure gauge at the port on the line on top of the engine, I don't know any other way to test it.

After cranking I could smell gas around the engine with top off air intake butterfly.


Tom Greenleaf
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Nov 29, 2014, 11:39 PM

Post #4 of 14 (1813 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

OK - Out of all that try the priming it test. Others still inconclusive and you just proved it with telling me about the screwdriver and spark testing. Fine, let's get some REAL info.


Fuel: Smelling it isn't proof it's where it belongs.


Let me know how the suggested test works,


T



Hammer Time
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Nov 30, 2014, 5:25 AM

Post #5 of 14 (1801 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

You're fuel pressure is low and on this engine, that is enough to cause this. This engine is very pressure sensitive. The fuel pressure spec is 60 to 66 PSI. Look for a section of rubber hose in the return line and try pinching it off to see if the pump is capable of going any higher. If not, replace the pump.



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Tom Greenleaf
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Nov 30, 2014, 6:22 AM

Post #6 of 14 (1798 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

You tell me HT - I did find spec of 55-60 was the range for '96 4.3 but didn't specify if Vortec here or at look up? I thought most were as you posted for those, any engine and wouldn't start if specs were off that much and this game is over if so - lower pressure than it can run on,


T



Hammer Time
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Nov 30, 2014, 6:25 AM

Post #7 of 14 (1793 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

FUEL PRESSURE
  1. Ignition "OFF" for 10 Seconds.
  2. With ignition "ON," engine "OFF" and fuel pump running, pressure should be 415-455 kPa (60-66 psi).




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
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Nov 30, 2014, 6:59 AM

Post #8 of 14 (1791 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

In fairness to OP for this the spec is available WRONG and I thought it was wrong. No info would be more helpful than wrong.


Doubting it I suggested priming it for a reaction and if that reacted would have dug harder to prove what was correct. Sorry to OP that the info you seemed to find was wrong as well which would send someone on to some other issue wasting time, parts not needed for what is now clear. Pressure too low.


Just a note of minor interest: Had one unfortunately intermittent but ran always but part time would be just harder to start and less power than usual then go away by the time any testing could happen. Finally, just caught it absolutely sure showing just 58 PSI max and once was enough and the diagnosis finished. This issue is NOT intermittent which actually helps to peg it down but wrong info sure didn't help!


T >>>> See if this shows on edit what I found.............Complete with typos in it!


*****************************************************************

1996 GMC Truck C1500 1/2 ton P/U 2WD 4.3L SFI 6cylThe Fuel System Pressure

55-61 PSI (Pounds per Square Inch)Vent the fuel tank vapors by loosening the fuel cap.Position the ignition switch and the A/C system in theoff position. Install a fuel pressure gauge to thevehicles fuel pressure valve.Confirm that no leaks are present, and with the keyon, engine off verify the PSI reading on the gauge.



(This post was edited by Tom Greenleaf on Nov 30, 2014, 7:07 AM)


Hammer Time
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Nov 30, 2014, 8:00 AM

Post #9 of 14 (1782 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

I'm not sure what you are trying to say here Tom but the spec I posted is absolutely correct. This is info issued from the factory service manual.

You may be looking at the Mitchell info which happens to lump both SFI and CFI fuel systems together and only give you the spec for SFI which is 56-61, however that is not the system used in this engine.

Again I state the fuel pressure spec for this engine is 60 - 66PSI.

Please stop confusing the poster.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
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Nov 30, 2014, 2:08 PM

Post #10 of 14 (1763 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  


Quote
We've checked for spark from the coil wire and the #1 cylinder wire and the ignition system seems to be totally dead.


I'd be more concerned as to why there is no ignition coil output.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Hammer Time
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Nov 30, 2014, 2:11 PM

Post #11 of 14 (1761 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

True



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



djdavis75
User

Nov 30, 2014, 3:25 PM

Post #12 of 14 (1754 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

I tried starting it again today, the exhaust smelled like raw gas. We tried spraying starting fluid into the intake and it made no difference.

Finally we put a coil off a junked out truck on it, and it started right up. So it was a bad ignition coil, even though it checked good by the service manual's testing method.

Thank you to everyone for your assistance with this problem, it is appreciated.


Hammer Time
Ultimate Carjunky / Moderator
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Nov 30, 2014, 3:32 PM

Post #13 of 14 (1752 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

Glad you got it resolved.

I'll close this now as solved to keep the spammers out



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
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Nov 30, 2014, 4:10 PM

Post #14 of 14 (1746 views)
  post locked   Re: 1996 GMC Pickup Died and Now Won't Start  

How comes I never get lucky when I do swaptronics? My luck was so bad that I had to go buy expensive test equipment...Mad

Ya, service manual tells you to ohm check it, which unless it is an open circuit, is a inconclusive test. Best way to check ignition coils is with a scope, IMO, because a coil might check perfectly fine with an ohm meter, but fail in real world conditions.

Glad to read you got it on the road again Smile





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Nov 30, 2014, 4:22 PM)






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