K1500 Blazer 5.7 V8
Car runs great at first start up but after 10-15 minutes it gets a rough idle and really stutters, spits & chokes upon initial acceleration. It runs fine once up to cruising speed. It gets especially bad if I am towing an extra load. Do I check exhaust system, pcv valve, etc? I have already done sparks, wires, cap & rotor and fuel filter. All helped in overall performance but none eliminated stated problem.
Any thoughts?
Thanks,
Chad
Hey Chad,
I think the first thing I would do is check the computer codes, read the current computer scan data and check fuel pressure.
I kinda suspect you have a lack of fuel pressure problem, but would really need to manually check the fuel pump pressure with a hand held gauge to be sure. You have already replaced all the other components I would suggest you try.
You can sometimes kick start a weak fuel pump by banging on the bottom of the fuel tank with a rubber hammer or your fist as the problem is occurring. Hopefully you can power brake the vehicle to duplicate the problem in your driveway to try this test. If the engine RPM changes at all, you probably have a fuel pump problem. (don t run over anyone)
You might also want to look inside the distributor and make sure there is nothing rubbing against the inside of the cap or any signs of sparking on the sides of the cap, and that the rotor is firmly in place. I have seen the distributor shaft get worn out and cause problems. You should not be able to move the distributor shaft from side to side with your bare hands.
Other things to look at:
1. Is there an under hood vacuum leak somewhere
2. Is the ignition timing set correctly, no excess slack in the timing chain
3. Is the EGR system working correctly
4. Does the MAP Manifold Absolute Pressure sensor work properly
5. Does the Oxygen sensor work properly
Blessings,
Austin Davis