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Sudden starting/idling problem

Discussion in 'Trucks and Trailers' started by TracStr400, May 4, 2001.

  1. TracStr400

    TracStr400 LawnSite Member
    Messages: 48

    I have a 1987 3/4 chevy truck. It is the Throttle body fuel injected 350. My problem is I went out the other morning to go to work and started it up. Well every time I turned the key it would fire maybe one or two pistons and then shut right off. The only way I could get it to start up and stay running was to hold the throttle down a bit and turn it over. Then I had to keep on the throttle to keep it going. Eventually I eased off and let it come to an idle by itself. When I opened the hood and checked for anything obvious I could smell gasoline. Then for a few days afterwards it didn't have any problem. So I just thought maybe i had got ahold of some bad gas because i went somewhere new. But it did it again today with gas from my usual place. This time it never really came out of it. It idles three or four hundred rpms lower than it should and barely stays running, especially in gear "automatic" while stopped. It runs fine going down the road. I put a two inch body lift on this truck a day or two before this problem occured. I have checked all electrical wires and fuel lines and none seem to be stretched or cracked. Maybe it's just a coincidence. I would really appreciate any ideas as to what might cause this random problem. Thank you.
  2. 85w/350

    85w/350 LawnSite Member
    Messages: 244

    Crap gas = clogged fuel filter maybe thats it?
    O^2 sensor - really messes with idle if its bad.
  3. Alan

    Alan Member
    Messages: 1,185

    I've got an 88 S-10 that does the same thing. It's been doing it for four years now, ever since we've had it. Not very often, but sometimes it just will NOT fire up. When it does that, hold hte throttle half open and crank until it lights, then keep the revs up for a few seconds and then it runs fine. Might be weeks before it does it again or it might be the next time you start it. I'm living with it.
  4. DMC300

    DMC300 LawnSite Senior Member
    Messages: 325

    I'll have to agree with "85" and say change the fuel filter,you should check the O2 sensor next.Good luck,let us know what you find.
  5. TracStr400

    TracStr400 LawnSite Member
    Messages: 48

    Thanks for the replies guys. I can't imagine it is the fuel filter because I just changed it three weeks ago. So I'm kind of leaning towards a bad O2 sensor. Thanks again for your input.
  6. 85w/350

    85w/350 LawnSite Member
    Messages: 244

    Yeah then I'd check the O^2 sensor next. If the o^2 sensor is bad you will also notice a decline in gas mileage because it adjusts the gas/air mixture and the extra gas it may be calling for would be that really strong odor of gas you smell. Also maybe check for a burnt plug wire or wire thats not connected completely. This would be the most obvious at idle. Even though you changed the fuel filter three weeks ago sometimes you might be suprised what loosens up from within your gas tank every now and then and makes its way through the system and clogs it again. Good Luck!
  7. MTCK

    MTCK LawnSite Senior Member
    from Idaho
    Messages: 254

    I'm not sure if you have dual tanks or not, or even if this would apply with a fuel injected truck or not (fuel pump in tank?) but on my older carburated truck, with dual tanks the tank selector valve is on the inside of the frame rail on the passenger side about even with the middle of the cab. This valve apparatus has about about 9 hoses going in and out of it if I'm not mistaken. They are held on with metal clips, the kind that you pinch with a set of pliars to remove. Now, if you do have this setup, and you just put the body lift on, I'd look closely at this. I don't believe in coincidences (sp?) and I wouldn't be suprised a bit if you knocked a line loose here or just PARTIALLY pulled one of the clips off the end of the hose. This could get you some air in your system that would cause a lot of problems. It can be a real bi*ch trying to work on these, and I suggest you enlist the help of a friend with small hands or bribe offspring with promises of candy. Good luck.

  8. mike reeh

    mike reeh LawnSite Member
    Messages: 229

    maybe Im crazy but the O2 sensor should have nothing to do with it on a cold start, the ecu should be in open loop, besides the o2 sensor does NOTHING until its GOOD and HOT

    Id check fuel pressure first and go from there..


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