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350 running poorly

Discussion in 'Chevy Trucks' started by gophergus, Jan 26, 2003.

  1. gophergus

    gophergus Junior Member
    from midwest
    Messages: 2

    during the recent cold snap, below 5 degrees at night, my 350,tbi V-8 has started to act up. it is fine while warming up but after, it cuts out, stalls and is hard to restart. i have spent some time out in these temps trying to figure it out. i found two cracked and leaking vacuum lines, this made it run better for about 2 hours then it went back to acting up. i did replace the cap and rotor in july. it has backfired up through the throttle body a couple of times, but the timing checks fine. i am probably missing the forest for the trees but my frozen brain has refused to think about it any more. any suggestions would be appreciated.
  2. long0

    long0 Senior Member
    Messages: 247

    You say it's a 350 with TBI, so i am assuming it's a GM somewhere between 88 & 98.

    I'm thinking bad fuel. I've had problems with TBI in cold weather also, the injectors jell up, almost like diesel does. Try adding a liter of Alcohol to your fuel. It eliminates any water that might be in your tank.

  3. wyldman

    wyldman Member
    Messages: 3,265

    Sounds like a fuel pump.When it's running OK,use a timing light,with the pickup clamped on the coil wire to watch the fuel spray from the injectors.Now do they same when it acts up.If the spray patter nis poor,or little or no fuel,then it's probably a fuel pump going bad.

    The proper way would be to use a fuel pressure gauge,but it's not easy to hook up on that truck (no fitting),so the timing light works too.
  4. BigRedBarn

    BigRedBarn Senior Member
    Messages: 133

    For what it's worth, my brother just spent $1200 on getting his 2002 Chevy 1500 Z71 repaired due to comtaminated gas. GM will not pay for the repair, as the gas had crud beyond belief in it, and some water, too.

    My brother gets his gas only at Mobil, always the same store (and has the receipts to prove it, and he's gonna use 'em, too).

    Service engine light came on, then the engine was running rough. Luckily, the comtaminants didn't get into the injectors, because that would've doubled the cost. They had to drop the tank and clean it out. Replace the fuel pump. Clean out the injector rails. And more I can't remember.

    I don't know if you might have this problem, and I don't want to scare you. But, the Chevy dealer has so many of these repairs in-house right now they can't keep up, and they claim it's not all the same gas retailer or brand.

    If I can make some recommendations: Always use an Isopropyl alcohol dry gas, never that other, cheaper stuff (can't remember the chemical name). Don't try to get just a few more miles out of a gas filter.

    A backfire through the carb/TB implies timing. Were you working on the engine maybe and accidently bumped the distributor? Is the distributor loose (free to rotate)? I did that once, and it took me a while to figure out what I did.

    My old 92 GMC had the 350 with TBI. It never did run right when cold for some reason. Always seemed low on power, too, in cold.

    I've never been a fan of TBI, but I guess it was a way to get the benefits of fuel injection into production quickly. I can't even remember how bad it was to have to deal with a carb on an engine anymore. Remember having to warm up an engine for 20-30 minutes before you could drive away? Now, just twist the key and slam it in gear regardless of temperature.

    Just my feeble 2¢.
  5. Mike Fronczak

    Mike Fronczak Member
    Messages: 64

    Sad part is at least with the older trucks you can work on them. I just bought a '86 K20 because my 2002 2500HD keep breaking down (once a month) and the dealer can't get it fixed, tired of paying subs. I'd rather let that truck warm up 20-30 min than pay out $ 400, for a sub. I look undr the hood of the 2002 can't veven see the spark plugs. Both have good/bad points.
  6. Earthscapes

    Earthscapes Senior Member
    from WNY
    Messages: 577

    LOL Mike,,,,, i'll trade my 02' for 3 90-92' K2500's(big block's preferred,but will go with 350's) .
    Anybody up for it ??
  7. Grshppr

    Grshppr Senior Member
    Messages: 268

    Earthscapes, how about a 78 Dodge with a full tank of gas? I'll even drive.......er.....trailer it over to you as a trade. :cool: :D