ok fist off lets get this out of the way, it is a Chevy 350 5.7 4 bl with an auto transmition

Ok this started after I was able to get my idle problem fixed, happens only when engine has been running and getting up to normal temp, 180 to 195, but lets start from this morning, started her up and let her warm up took off everything was running great idled great when warming up when under pressure and sitting at a light she ran great without any problems, but about almost into the parking lot sitting at a light she was having trouble, so I popped her in to neutral and she picked right back up, light turned and I put her into gear and took off, now got into the parking lot and as I'm backing into the spot she died, started her back up and WOW, nice back fire. Didn't bother putting her in gear was already in spot and running late as is,

Second thing, replaced carb brand new, brand new engine coil, brand new 180 degree thermostat, changed coolant 65/45 (water/coolant), after this I have now idea what to do please help,


Joe

What kind of choke is on the new carb? Is it working correctly? Backfire usually means unburnt fuel is igniting in the exhaust system (unless it's backfiring through the carb). If your choke isn't opening up as the engine warms up, it can create a rich condition, causing the bad idle and backfire. [img]images/graemlins/grin.gif[/img]

Fuel filter?

I Second Ted, Fuel Filter.

I have the choke coil, and it seems to be working just fine, when the engine warms up it keeps the butterfly open to allow the right amount of air in, would it hurt anything if after i got the jeep started to drive home without the choke coil hooked up, and see if that makes any change, i am just stumped

I have checked for vacuum leaks and cant find any, the fuel filter is brand new,

i can useally watch my my oil pressure gauge, and when it is running good i can keep it about 40 psi sitting at a light a soon as it is hurting it drops to about 20 psi, and that is when it has trouble keeping up

again i am lost at where to go from here, i cant think of what to do next, i am sure that it is a minor fix but cant figure it out

Joe

I was wonder if at by any chance that it could be the fuel pump, while under pressure it can not supply the carb with enough gas, and while in nuetral it can, this is just a thought that ran through my mind,

Please help, I have no idea where to start fixing this problem, I have tried everything that i could think of,

Joe
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Second thing, replaced carb brand new, brand new engine coil, brand new 180 degree thermostat, changed coolant 65/45 (water/coolant), after this I have now idea what to do please help,


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I have to ask this!!!!!!!!!!!
Was the above work done before or after the problem?
The carb could be loading up at idle. I wouldn't think the fuel filter would be the issue if you take it out of gear and it clears up.

The carb was replpaced after the problem, It was acting up, and since the carb was causeing a few other problems, I did not think that rebuilding it for a second time was going to clear up, i figured i would start fresh,

I did not think it was the fuel filter either. but the problem is still there and i have no idea how to fix it

Joe

Have you had a vacuum gauge on it? What did it tell you?

Where did it backfire? Intake or exhaust? Or could you tell?

I'd look for a vacuum leak and check the timing.

I have to assume you've tried turning the idle mixture screws properly.

What kind of carb?

Step 1 - check to make sure the EGR Valve doesn't have vacuum on it at idle. You replaced the carb, could have got the hoses mixed.

In gear there's a little more load on the engine, and it's slower - suspect lean condition since it dies easily hot.

2 - Get it hot to the point it won't run in gear, choke the carb off a little at a time with your hand or a CLEAN rag.
If the R's increase or at least it smooths out, it's lean.
You might want to get someone to help - so you can try that test "in gear" without getting run over. (Embarrassing when it drives over your foot - and painful.)
Let us know what it does.

A. If it is lean, spray some BURNABLE carb cleaner around the likely spots, carb base, manifold gaskets and Tees, including brake booster. Dribble a few drops down the carb to test the carb cleaner- if it "likes it" it's burnable. Most carb cleaners won't react - Gumout seems to work, but there is better. Or use starting fluid - but be careful - it flashes easy. If little or no reaction takes place you might as well "bark at the moon" - it's not going to find the trouble! It has to burn like gasoline in the engine.
B. If holding your hand over the carb did not help, - it didn't "like" it, then look elsewhere.
3. Disconnect the vacuum advance - make sure it's timed properly with the advance disconnected. If fact, test drive it with the advance hose plugged. It will not hurt anything - see if it helps. Timing way off can create your symptoms.