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<!-- BEGIN TEMPLATE: ad_showthread_firstpost_start --><!-- END TEMPLATE: ad_showthread_firstpost_start -->I have a 91 chevy k1500 5.7l tbi auto 4x4... I bought this truck a couple of months ago with 167,000 miles on it and it ran fine... Now it sputters and seems like its either flooding its self out or missing while driving... If the map sensor is pluged in it will not idle or run properly while driving. If i unplug it it sometimes idles fine but runs like it missing while driving it... I have replaced the plugs, wires, cap, and rotor thinking this will fix the problem. Tested the tps, map sensor, and egr valve and all of the work properly and replaced them thinking that maybe it was human error but still the same problem. Replace the coolant temp. Switch hoping that it was sticking open or closed but that didn,t work either. Pulled the catalytic converter off thinking that maybe it was starting to clog really bad but nothing... Im really confused and thinking about sending it to a shop but don't want to pay the money... Kind of broke... Any ideas or suggestions of any kind would be appreciated... Thank you...

 

Have you tried replacing the fuel filter or doing a volume test of your fuel pump?

 

I replaced the fuel filter... Same thing. I pulled the injectors out put new filters in them new gaskets and o rings and same thing... I havent checked the fuel pressure yet...seems like its getting plenty of fuel but looks could be decieving...

 

does this only happen after warmed up? have you checked the coil resistance compared to a good coil?

 

You Need To check Fuel Pump Pressure. Make sure when you check The pressure It remains constient.

 

Hi SGTBRYAN.WISE1,

Welcome to the Chevy forums.

Borrow some gauges. Get a small notebook and start writing down the results of your tests. Use the resources you have at hand. Somebody at the fort has a compression gauge. Do a compression test. It might be as simple as a blown head gasket.It could be a collapsed lifter or a bent pushrod. Turn that back in, borrow a timing light. Does the engine backfire at all?

Before you start the engine, see if the distributor is loose. Pull the cap, look at the rotor. Make sure neither has carbon tracks or cracks. Check the timing. Re-coat the plate on the bottom of the ECM with dielectric grease. Also just look at the timing mark under the light, see if it's steady or skips around a bit. Turn that back in, borrow a vacuum gauge.

Before starting the engine, check all your vacuum hoses very carefully. Don't forget the vacuum advance on the distributor. Hook up the vacuum gauge, see if your engine reads solid pressure under acceleration, or if it flutters or drops way down.

That's how I got my Rambler fixed when I was in the Navy in San Diego back in '82. If your problem survives all these tests, then you may want to consider letting a pro have a crack at it. Best of luck.

 

So i did a fuel pressure test on the fuel pump last night and when you turn the key on (not running) the pump will go to 3lbs and drop back to 0lbs. With the truck running it only gets 3lbs of pressure. So im going to replace the fuel pump tonight and see what my results are...
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So I went with my gut instinct and decided to replace the fuel pump and problem solved... every thing is back to normal... thanks to every one for their advice...