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Need help with NO START problem

Discussion in 'Truck & Equipment Repair' started by B&E snowplowing, Feb 21, 2010.

  1. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    Hey all,
    I have a 1995 GMC 2500 5.7litre TBI, The truck won't start. I have replace the fuel pump, sending unit, fuel filter, and fuel pump relay. Still no go...I have checked for spark at the coil, and plugs, all good spark. If I give the truck a shot of quick start it will fire up for a second then dies, I can hear the pump running when I turn on the key, and it is getting fuel at the throttle body. I am so confused. :dizzy:

    Any ideas would be great. I use this truck as my back up but with the approaching front, I would like to have it running.

  2. creativedesigns

    creativedesigns PlowSite.com Addict
    Messages: 1,929

    Is there a blockage in the exhaust somewhere? Perhaps a mouse nest?
  3. ahoron

    ahoron Senior Member
    from here
    Messages: 422

    check fuel pressure, sounds like a weak pump
  4. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    I don't think so. Let me give you the low down.... The truck wouldn't start so I changed the fuel filter, still wouldn't start so I went to change the fuel pump, but broke the lines going into the sending unit, so I replaced the sending unit as well. Truck fired up no problem, was driving it one day decided to get a coffee, was going through Tim Hortons drive thru, truck just died and would not restart, had to tow it home, where I checked for spark which I have, and replace the relay. Still no start and I'm really confused.

    So I don't think the exhaust is plugged. Oh ya about 3 months ago I replaced the Y pipe and O2 sensor.

  5. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,415

    Do the injectors pulse fuel when you crank the engine?
  6. leon

    leon Senior Member
    Messages: 872

    truck trouble

    I think you may have ice in the fuel lines,
    my second guess would be a plugged
    catalytic converter, third would be a broken
    timing chain which the yuckiest problem
    if your unfamiliar with gas engines in vehicles.

    I would park a salamander in front of it for an
    hour to warm the little monster up for further checking

    Last edited: Feb 21, 2010
  7. Mr.Markus

    Mr.Markus PlowSite Fanatic
    Messages: 5,779

    Had this happen once.... Mine was a fuel station mixed up there diesel and Gas stumped the hell out of me. Luckily they called (Paid with visa and they tracked me down) and the hauler paid the repairs. Not saying this is what it is just check. I deal with both fuels so sometimes the difference isn't always on my nose.
  8. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159


    When I turn the key I get fuel from the injectors, and I'm not to sure about the timing chain, but if I give it a shot of quick start, or pour a little gas down the throtle body it will start and run, then quits. If it was the converter, wouldn't it at least start until it warmed up then quit.:dizzy: I don't know really has me stumped, and for some reason, I can't seem to find a place on the fuel line to attach a pressure gauge to see what the pressure is.

    My neighbour said it might be the crank sensor......does that make any sense???
  9. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,415

    It doesn't have a crank sensor.

    You need to confirm correct fuel pressure. A good fuel injection pressure test set, like a Snap On, will have the correct fitting to tee in at the back of the throttle body to check fuel pressure. It's not uncommon for the fuel pressure regulator spring to fail on those TBI's.
  10. leon

    leon Senior Member
    Messages: 872

    that would be a possiblity too but it would not start if it was out of position,

    I would lean toward the plugged converter- the 2 crazies on car talk have talked about your problem many times.

    The plug in car computers are very inexpensive to buy now and I think you can buy a very basic one for under $100.00 USD at NAPA thses days.

    The purchase will not be wasted money in any case.
  11. Evanbrendel

    Evanbrendel Senior Member
    Messages: 181

    if it runs when you dump fuel in it then its a fuel probeblem like a pressure regulator or injector probeblem. sugar in the gas tank?
  12. Proplower85

    Proplower85 Junior Member
    from NH
    Messages: 14

    I would say start back at square one. I have the same motor have no running issues aside from it being a 21 yr old truck and the motor is tired. Your pump may be running but it may not be picking up fuel due to fuel level or ground level. Check your fuel pressure if it isn't starting without ether or added gas then your injectors aren't spraying enough fuel of no fuel. I would say check power at the injectors as well as you may be only spraying from injector. Even though you replaced the fuel pump that doesn't necessarily mean that the pump wasn't faulty outta the box. Hope this helps. A TBI is a pretty basic system however GM could have done better things with it it was an experimental motor that they didn't have much problems with... More reliable then the vortec in my own opinion..
  13. Reliable Snow and Ice

    Reliable Snow and Ice Senior Member
    Messages: 981

    dumb question but did you change ur fuel filter??? that would cause what ur talking about
  14. the_experience

    the_experience Member
    Messages: 75

    I'm with this guy. You need to make sure you have proper fuel pressure. TBI trucks will not run below 9 psi at the TB and 10 psi makes them happier. Did you check voltage drop when you replaced the pump? Corroded wires and connectors will drop the voltage enough to kill pumps and drop fuel pressures.

    Are you sure you're getting good injector pulse? These trucks were known for losing ignition modules (often they would have spark still but no impulse). This would be the TBI version of a crank sensor.

    Does opening the throttle a little help at all? A bad coolant temp sensor will usually allow it to start if you do that though the symptoms you're describing don't particularly sound like one to me. Still...a TX-3 is what...like $15?
  15. 00bluegtp

    00bluegtp Member
    Messages: 71

    When you did the pump was there rust in the tank? Where did you get the pump from? What about the connections to the because low voltage kills thenm very quickly wich sounds like your issue. Aftermarket fuel pumps are made like ass beleive me I have experience where they work for like 10-15 miles and then crap out. Get a fuel pressue guage and get it on there and let me know what you come up with.
  16. sjcolwell22

    sjcolwell22 Junior Member
    Messages: 7

    I would check fuel pressure first and then go from there. If your getting good fuel pressure check the injector pulse with a noid light. Are there any codes ?
  17. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Can you explain that?
  18. truckboy

    truckboy Junior Member
    from texas
    Messages: 23

    sometimes batteries need to be replaced. try to get a jump if that works then see if the alternator can charge it better.:alien: