96 K1500 Cranks but won't start

Discussion in 'General Chevy & GM Tech Questions' started by mattress67, May 8, 2009.

  1. mattress67

    mattress67 New Member

    1996 Chevy Silverado K1500 4WD, 5.0 WILL crank, but will not start. No fuel pump noise when key turned on. Now I recognize a quick diagnosis would be that the fuel pump is the culprit, but keep reading. When key is turned on, none of the normal starting lights come on (check engine light, airbag, and batt). With the key in the "on" position, none of the gauges seemed to be powered -- fuel quantity, oil, and batt voltage (only the gear indicator is illuminated (P)). Though when key is moved to ignition, engine cranks normally -- won't start though. Radio, fans, windows, all accessories also work. When key is moved, no clicking is heard from any of relays under hood. All fuses checked good.

    There is a history of the common fuel pump problem (engine quits unexpectedly -- 3X in two years), but problem seems to resolve itself in a 24 hour period (in one case after a tow), so I really question whether it is the fuel pump. Seems to be more inline with the starting sequence logic, perhaps VCM/PCM/ECM? Any help would be greatly appreciated
  2. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    Get yourself a buddy to lay under the gas tank when you are cranking on the motor, if you give the middle of the tank a good whack with a hammer (where the pump is) it should get it to turn over, its an old trick, and it works as I did it for a month two summers ago on my burban until I could get the new pump in. Have you chacked all electrical connections for the battery to starter to grounds for looseness and corrosion. Thses are at least free tests.
  3. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    I would pull all the fuses one at a time and visually inspect them for corrosion and of course continuity. You have an electrical problem up front somewhere.
  4. cascott325

    cascott325 Epic Member 5+ Years 1000 Posts

    did you also check any connections from your ignition? could be a pinched wire, a bad guage cluster, a burnt wire, could be a lot of things. fuses maybe?
  5. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Yep, and these trucks are famous for bad ignition switches! Good point.
  6. daddytech

    daddytech Epic Member 5+ Years 500 Posts

    it seems like it's a lose connection somewhere to me the whole checking for corrosion on the connections is a good start, you might also try something else simple like changing out the fuel filter, if it is clogged up it will act the way you are describing yours is right now , one thing to consider too is that if you used an aftermarket replacement part when you replaced the fuel pump that may be part of your problem too. that and the thing i learned the hard way is if you run your vehicle much with half a tank or less the fuel pump does not get cooled properly and can shut down on you again also. that is what happened to my 89 silverado and changing out the pump is not something i care to do again any time soon so needless to say the truck hasn't had less than half a tank since i changed it out.
  7. mattress67

    mattress67 New Member

    Problem solved for now...

    Thanks guys excellent advise. After two days of research on the Internet, as well as your help (I really did not want to change a fuel pump), I traced the problem to the fuel pump relay (for now). Although, it wasn't as simple as just changing the relay. In fact, the first thing I did was to change the relay but remember that I mentioned that when I turned the key on, I would get no gauge lights (check engine, batt, etc.). So, with the key in the on position, I wiggled every connection under the hood. When I went back to look at the dash, bingo, I had gauge lights. So, I proceeded to start the vehicle. Around the third attempt it would start. Now I mention this because my research educated me on a few things. The best info is that when you turn the key on, although you should hear the fuel pump whine for 2 seconds, it's absence doesn't necessarily mean a bad fuel pump. There is a back up to the fuel pump, and that is the oil pressure switch. Initially during the start (again after I got the gauge lights back) the oil pressure was indicating zero. Around the third attempt, the oil pressure would raise, and the truck would start. I hope this helps those who have the "hard starting" issue, as well as those who don't hear the fuel pump when you first turn your key to on. To fix the hard starting issue (or starting after oil pressure build up), I went back to the fuel pump relay. I replaced it, and now everything works fine.

    I honestly believe that a lot of people first change the fuel pump only to find that the fuel pump is not the culprit. I've also read posts where people have changed CPS's, and PCM's with no luck. Bypassing the fuel pump relay (I used a jumper over the relay early on) told me the fuel pump was good, and the lack of gauge lights led me to check all connections. So for me, it was a combo of loose connections (which I am not sure I've permanently solved), and the fuel pump relay.

    Thanks again!
  8. daddytech

    daddytech Epic Member 5+ Years 500 Posts

    well I am glad you got that figured out and it's not often that the electrical side of it is the issue for people. that is actually kind of rare but I'll be sure and check with people in the future to make sure wheather or not they are also having the electrical problem also or not before suggesting changing anything major like the pump. Jumpering the relay is a good step but some people might jumper the wrong thing or leave that in place as a permanent fix so i personally usually do not mention jumping any electrical connections at all. I know i would hate it pretty badly if someone did jumper something and make thier problems worse instead of better.
  9. mattress67

    mattress67 New Member

    I agree with you about making the problem worse by using a jumper to bypass the relay. For me, I had the electrical schematic in hand. And you're right, it's an easy thing to screw up which could possibly fry your PCM. Finally, you wouldn't be able to keep the jumper in place. The bus is hot wired to the battery and the fuel pump would run continuously. In short, buy a new relay and use that in place of a jumper. If it's not the problem, you can always return it.
  10. daddytech

    daddytech Epic Member 5+ Years 500 Posts

    very well said, good job and thanks for posting your resolution on here.

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