Still running way rich.

The vacuum on my 87 waggy 4.0 is pulling strong at the fpr. When I remove the vacuum, there is no change in idle. Does this mean the fpr is bad? Is there a way to test the fpr?

 

The best thing would to do is get a fuel pressure test gauge on it to see what pressures are and do the test. I don't recall the specs its suppose to be exact at, but when its running and you pulling the vacuum line off the pressure should go up about 10psi. You sure you don't have any vacuum leaks? Another thing when you pull the vacuum line of the regulator does any fuel come out of the regulator or the line itself

 

No fuel is present when the engine is running and I pull the vacuum hose.

I do not think there are any vacuum leaks. When I put my hand over the throttle the engine dies.

The Jeep has no trouble starting or idling, but backfires like crazy if you add any pressure on the accelerator.

Checked, and or replaced everything I can think of besides the fpr. TPS (new and adjusted), MAP, IAC, EGR, grounds, O2, rotor, plugs, wires, and cap are all good or new.

 

firing order?

 

Yep. Checked and double checked.

 

Do the fuel pressure test.

 

AutoZone has the pressure tester for $45.00. They rent it for $150.00 plus deposit.

Is it better to just buy a new FPR for $54.00?

 

Test the pressure. Probably a pump issue anyway.