Hello everyone. New to the forum here.
I have a 1994 Mighty Max with the 3.0L V-6. The truck belonged to my dad but has been sitting and not driven or started since 2006. The truck is in good shape and my son wanted to drive it so we have been working on getting it going. We changed all the belts (including the timing) and hoses, changed the oil, replaced the fuel tank and fuel pump, replaced all the filters, and installed new valve cover gaskets.
Today, after replacing the fuel pump we were finally able to start it. It was a little reluctant to start (which I expected) but it finally did. This is where I noticed the first problem.
When the accelerator pedal is pressed the engine is very slow to respond and increase RPM. After running for a few minutes it gets better but when the engine is shut off and then started again the problem returns.
The next problem I noticed was that the engine won't idle. My son has to keep his foot on gas pedal just a little bit for the engine to run. I see a screw that looks like it is an idle adjustment screw but not sure. This is a fuel-injected engine.
The last problem is harder to explain. When the RPMs are raised occasionally a thump can be heard. I have about come to the conclusion that it is back-firing or maybe back-firing into the intake. It isn't constant but it is pretty consistent one the RPMs are around 2000 or so (no RPM gauge so I have to approximate). Could this just be from a sticky valve because of not running in 8 years?