i have 95 explorer with 4.0
it started to have this bad hesitation when you take off, it runs fine once you get going, but i has died on me a couple of times taking off, it has never done anyting like this befor. i have changed fuel filter, spark plugs, wires, added fuel treatment, checked all vaccume lines, and dont know what to do from here, if anyone know what i need to do please let me know, cause im getting very frustrated!



thank you

 

Off the top of my head, I'd suspect the IAC

 

Check your fuel pressure. A blown FPR (fuel pressue regulator) will often have fuel in the vacuum line.

Fuel pressure should be 35-45 KOEO and 30-40 KOER.

 

what is IAC ?
im not familar with that.

 

where is the FPR located ?
does the scanner test the fpr? or do i have to do it myself?

 

You will need to put a fuel pressure gauge on the fuel rail to test the FPR. The fuel rail is what distributes the fuel to the injectors--there is usually a valve stem (schrader valve), like on a tire, to attach the gauge.

The FPR is usually located on the fuel rail. It will usually have two fuel lines attached--one for the supply and the other for the return to the tank. It will also have a vacuum line.

A bad FPR will not necessarily throw a code. The computer might see it as a rich condition, bad O2 sensor or a bad Cat.

When it is hesitating, does black smoke come out of the exhaust?

 

thank you ,ill check the fuel pressure and regulater and see what happens.
but im not sure if their is fuel smoke when it hesitates, i havent seen it yet.

 

Never hurts to pull the codes as well. If it is the IAC -Idle Air Control valve, located near the throttle body and looks like this:

http://www.justanswer.com/uploads/Ha..._IAC_valve.gif

...then it should throw a code which is stored in the computer. Not all fault codes will trigger the Check Engine Light, so just because you haven't seen it come on doesn't mean there aren't any codes stored.

Possibly it's a problem with the MAF, either a dirty filament or gone bad. Codes will tell you that as well.

 

I have the same prob with my explorer, but it got to the point where it just dies out every time you give it gas. Black smoke, and lots of carbon on plugs.

 

Could be a couple of things. Right off the top of my head I'm thinking the Fuel Pressure Regulator. Pull the vacuum hose and see if there's any gas in it. There shouldn't be, if there is then the diaphragm is leaking and sucking raw fuel into the manifold, but without allowing enough fuel pressure to the injectors.

If there's no fuel in the vacuum hose, check the pressure anyway. It should be around 35-40 psi.

And check those codes.

 

In consideration of the problem and what you have done to try to fix it (first post), it's time to pull codes.