Poor idle and stalling need Help/Ideas

Nate288 · Jan 10, 2016

Im working on a friends 2001 2WD 2.5L 5 Spd Ranger his fuel pump went out so i replaced the whole assembly along with the filter the truck will start however it runs and sounds like a tractor when I give it a good rev the engine sounds fine but when the RPM's return to the idle range the truck starts to die also the fuel gage isn't working after the new pump was put in what I've done so far checked the fuel pressure its @ 65psi at idle, changed the IAC, changes TPS, checked for vacuum leaks and is reading around 18inHg, oil and coolant are fine and are at a good level, ignition is fine and will be pulling the plugs out tomorrow and once i get the tool will do a compression test, cleaned the MAF, and no codes or CEL light. I'm running out of things to check and ides unless anyone else has some clue as to what my be going wrong here?

RonD · Jan 11, 2016

I assume the truck was running fine prior to the fuel pump dying?

You should have a Low Fuel level warning light if fuel gauge is not working?

You have 65psi while engine is running, and it should stay above 50psi when engine is off.
It should hold pressure for months, not minutes, days or weeks........months
If pressure is dropping when fuel pump is off then you could have fuel leaking into engine cause rich mix.
This can be from a leaking injector or Pulse Damper vacuum hose(rear of fuel rail, check vacuum hose for fuel)

18" of vacuum is a bit low at sea level to 2,000ft, what is your altitude?

Nate288 · Jan 11, 2016

Hello thanks for the reply and no the truck was never really running right before the new pump but it was at least drive-able. We are right at sea level
and I'll recheck the fuel pressure when the truck is off and inspect the fuel rail

zolar1 · Apr 12, 2016

I too have poor idle but no stalling as of yet.

Things that affect idle are:

1) Fuel pressure (maybe clogged fuel filter, bad fuel pressure regulator)
2) Ignition coil - mine had 5 cracks and a hole in it!
3) Injectors
4) MAP sensor
5) MAF sensor
6) Spark plugs bad, worn out, wrong gap, wrong plugs, related other.
7) Spark plug wires.
8) Bad IMRC control valve if you have one
9) Bad EGR or EGR pipe or clogged EGR passage
10) Bad head/head gasket.
11) Bad Cylinder Head Temperature Sensor
12) Bad ground 'somewhere'
13) Bad battery/alternator
14) Bad PCM

A vacuum leak can cause problems with your symptoms as well.

Long list but probably more than I posted.

Z7What · Sep 27, 2016

I bought a 01 2.5L about 3 months ago and it was running like shit when i bought it. The issue was a few things. The check valve in the fuel pump was bad which was causing the fuel pressure to drop to zero within seconds of shutting the truck off. I ended up replacing just the pump. This helped the starting issue, the biggest help was replacing ALL 8 plugs with CORRECTLY GAP MOTORCRAFT PLUGS. There was 3 different brand plugs and not a single one of them were Motorcraft plugs, they also were gapped anywhere between .010 - .024 TO LARGE. After installing a new set of correctly gapped Motorcraft plugs and a set of wires the truck instantly was 100% better.

Wayne

Poor idle and stalling need Help/Ideas

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