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reddragon
Bone Stock
Posts:42
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| 02/26/2009 2:55 PM |
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i have a 86 chevy k-5 blazer that will not run. The truck has a chevy 350 with a holly 750 carb everything else is stock. It takes bout 5 min to start and when it does i have to hold the gas pedal. If i let go of the gas it dies. it backfires, stalls, and sputters. the first time it did this it was a vacuum leak. then the next day i go to start it up it does the same thing as before. i cant see anymore leaks. Does anyone know what it might be? I think it could be the fuel pump but i dont know for sure. |
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Rob |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 03/03/2009 9:17 PM |
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| does it continue to do this after the vehicle has warmed up, or does this only happen when the engine is cold? |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
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'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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reddragon
Bone Stock
Posts:42
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| 03/03/2009 11:57 PM |
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| i cant get it to warm up. if i let go of the gas it dies. |
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Rob |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 03/04/2009 9:57 AM |
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Generally speaking, if it's backfiring, then it's a timing issue or you have sparkplug wires crossed.
Questions:
1) Is it backfiring through the tailpipe, or through the carb?
2) When it's running (while you have the gas pedal held), is it running rich? Is it blowing black smoke or is it smelling really rich?
Rick |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
- - - - - - - - - - - - - - - - - - - - -
'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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ChevyMan0784
Lift & Lockers
Posts:699
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| 03/04/2009 10:49 AM |
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| Ok, for one... That 750 Holley, its way too big for a stock 350. Try a 600. Two, I can almost guarantee your timing is off. Three, a Chevy fuel pump is about 35 bucks at Kragen/Checker/Schucks/O'Rielly. So the most important thing here, is getting a different or new carb of the 600CFM calibur. 750 is far too big. I am running a 670 and have 400HP. You do not need that big of a carb, it is flooding your motor. I gurantee it. Start there. Once you do that, do your timing, if it still wont start, do a fuel pump. And that will fix it. |
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gimmie fuel gimmie fire gimmie that which I desire-James Hetfield
*Never give an Irish man good cause for revenge.
*Guns dont kill people, but they sure help!!
*98% OF AMERICANS SAY 'OH S**t' BEFORE GOING IN THE DITCH ON A ICEY ROAD.
THE OTHER 2% ARE FROM ALASKA, AND THEY SAY, 'HOLD MY BEER AND WATCH THIS |
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reddragon
Bone Stock
Posts:42
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| 03/04/2009 11:27 AM |
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it sounds like it backfiring through the through the tailpipe. it does smell rich and their is smoke coming from the tail pipe but it isnt thick black smoke. |
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Rob |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 03/04/2009 8:58 PM |
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It's definately a timing issue... whether it's directly related to the distributor being off or not is something you'll have to figure out, but the timing is certianly off. What clued me into this, is that it's difficult to start as well as it won't run right, which makes me almost certain that the timing is off. Put a timing light on it and see where it is and adjust accordingly.
To ChevyMan's point, I agree - the 750 CFM carb is far too large for your truck. You really should downsize that carb to match your motor.
Rick |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
- - - - - - - - - - - - - - - - - - - - -
'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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reddragon
Bone Stock
Posts:42
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| 03/04/2009 11:43 PM |
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| ok thanks. what would be the reason for the timing to be messed up? could it be because its old? im looking round to get a smaller carb. found one but i will have too rebuild it. |
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Rob |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 03/06/2009 9:05 AM |
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Timing can become off for a variety of reasons. If this is something that has gotten worse over time, then it's likely just a late tune up thing.
If this is something that happened all of a sudden, then it could be the following:
1) The timing chain is slippy and the cam gear has jumped a tooth.
2) The distributor hold-down bolt loosened up and the distributor rotated during heavy acceleration or during starting
3) The vaccum advance or some other timing control mechanism has failed
At least that's all I can think of right now.
Rick |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
- - - - - - - - - - - - - - - - - - - - -
'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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