I have a 2000 2.5

I changed the vacuum hose from the throttle body to the valve cover, replaced the AIC valve, then cleaned the throttle body and the MAF sensor. After all that it idles very smooth , but if I rev the engine, after it drops to a lower rpm, it then idles rough for about approx 4 or 5 seconds, then goes back to smooth. I did all this while the tank was 1/4 full.

I just filled the tank, and I rev the engine, and after it drops RPMs its completely smooth - no rough idle. I did this multiple times - same result. I'm thinking the pressure of a full tank pushes the gas through better than a near empty tank - I guess.

So I think my issue revolves in some way around fuel. I went and bought a fuel filter which I will install this Saturday; this is where I'll start cause its cheap and likely needs changing anyways.

If changing the fuel filter does not resolve it, then do fuel pumps, when they are getting old, work better on a full tank?

Is there any other fuel line parts that should be replaced starting with cheapest or most likely first?

Do i sound like i have a clue and going in the right direction?

Thanks for any help.

Darryl

 

Not at all.

Your fuel pump *could* be overheating when the tank is low which *could* result in a drop in fuel pressure. Not 100% certain on that but it's a possibility.

FWIW, my 4.0 does the exact same thing you describe regardless of fuel level. It will stumble for a few seconds around 500 rpm then suddenly comes alive again. No rhyme or reason for it and I've never been able to figure out the source. Truck has about 150,000 on the clock and it's been doing this for quite some time but has never left me stranded.

IMHO, if the thing runs then I'd wait for something to actually break...but that's just me. I'd rather save my money rather than blindly throwing parts at something that I have no idea what the solution will be.

My .02

 

Your fuel pump has to work less because of the high fuel level. Filter could be partially plugged causing a restriction.

Easier to clean the IAC valve which controls idle and meters air around the throttle plate. A 15 minute job, you won't get dirty and it just might really need cleaning. My 2000 2.5 did.

 

Thanks for the replies. The initial repairs i performed solved a major inability to idle smooth, and it would stall at stop lights. So at this point I got off cheap just buying a vacuum line and AIC valve, because it runs pretty well now. The line replaced is shown in bidwell's picture from the throttle body to the valve cover - just replacing this line cured most of the problem. The old line was deteriorating and had huge cracks.

I'll change the fuel filter saturday and see what that does. I got this truck with 159,000 on it; I've put very few miles on it myself. I wish my engine was as clean as bidwell's picture; although for 159,000 mine looks pretty decent.

 

Mine just turned 159k too.

 

i wish the exterior of my truck looked as good as yours does. The color of my truck is a burnt copper or something like that; the color had to grow on me. Also has a tan interior with black trim, again had to grow on me. But getting the truck running good was a lot easier thanks to this forum. I was just reading that the 2000 fuel filter has some odd clips that have to be taken off carefully - break them and you apparently won't find replacements.

 

Well, I changed the fuel filter today; wow, that was easy. Clips came off without any problems. No fuel shot out at me. But has the same problem as before. Oh well, I'll keep dinkin around with it.

On another issue: I fixed the front sagging bumper. Not quite as easy as a fuel filter replacement. But came out fairly nice and straight.

I used this forum to resolve both issues above - awesome resource.

 

Try a can of SeaFoam in half tank of gas. It's ten bucks and just might clean something.

 

yea...this is directed to the OP... how many miles are on your truck anyway

 

I'm new here; what does this mean "this is directed to the OP"?
I have just short of 160,000 miles on the truck.

 

means its directed to the original poster...your fuel pump might be on its way out

 

Would having the pressure checked at the fuel rail determine if the pump is going out?

 

that will also help you to see if theres a clog/restriction somewhere

 

Hmmm, I'm still searching for the issue on my ranger, and so not having squirted starter fluid on a running engine, I was a bit hesitant; so I waited till a friend could help - we literally doused the engine in the correct locations, and there is apparently not a single vacuum leak. I then floored the engine to show my friend that it would idle bad after flooring it, and it idled bad and killed itself; my friend jokingly said: "well; don't floor it", because otherwise it idles just fine most the time.

That evening, and all day today, the truck is running great. I can floor it and it idles great just after (not something it did prior). I find it hard to believe that starter fluid sprayed on the engine would fix it, but we didn't do anything else other than change the tow ball to a shiny new one. So, at this point I guess I'll see how long it last.

 

well, still trying...

As posted earlier in this thread, i was told to try sea foam in the tank. So i did. Can't say it runs like new, but something good seems to have happened; it seems to have more responsive power on demand now. There must have been some crap or something in the tank making it's way to the injectors, or the injectors were dirty, or I have no idea, but that sea foam is great stuff so far.