Fixing my sons truck for school.

[Greasemonkeydad]

I’m trying to fix a problem with my sons 2001 Ford Ranger 4x4 with a 4.0 V6 and an automatic. It’ll run perfect one trip at any speed with zero problems at all, and then the next trip it’ll hardly want to leave the housing development.
When the problem happens it’s at maybe a quarter throw in the gas pedal and the truck hesitates and acts like it wants to die. If you ease the throttle/RPMs up you can slowly get up to speed. But you can’t put your foot in it at all or acts like it wants to die and has even seemed to have backfired through the engine once.
I grew up working on old Chevy naturally aspirated engines and these newer computer driven engines baffle me.
We’ve replaced the TPS, EGR, O2 sensors, Mass airflow sensor, spark plugs, wires, coil, ran injector cleaner through it. I have also heard of a possible plugged catalytic converter so we drove it on the freeway and got it good and hot (Vegas temps at night are still at 95 degrees right now) and then got off the freeway and immediately looked at the catalytic converter‘s and they weren’t glowing at all. There’s been no strong smell of gasoline. I’ve been leaning toward fuel pump or possibly injectors, I don’t know what else to check. Any help is greatly appreciated

 

[rebuild83]

Try a fuel pump and filter

 

[Dirtman]

Try a fuel pump and filter

Kind of a drastic step to spend $300 on a fuel pump and remove the bed on a guess...

But you ain't wrong that the fuel filter should be changed, they cost like 15 bucks and take 5 minutes to change. It definitely could be fuel delivery related.

Check fuel pressure (if you don't have a guage alot of auto parts stores will loan you one for free). Pressure should be 65psi at idle and drop a tad when you hit the throttle. Also worth getting a vacuum guage because you can use that to test for a clogged/restricted exhaust.

 

[CrabGuy]

Probably not the cause but as they say on the German car forums 'check your grounds'. Bad grounds can manifest themselves as the strangest problems. Even corrosion under the battery cable insulation has caused more frustration that I like to remember. Go for that fuel filter change 1st and hold off throwing Ford dollars at 'possible' problems.

 

[Greasemonkeydad]

Man I really appreciate all the replies. I should’ve mentioned that I replaced both fuel filters also.

 

[Bgunner]

When my fuel filter started to get plugged I ran into a very similar situation. at times it ran fine but while driving, at times, it would loose power but still run. I third the fuel filter recommendation.

Check engine light on?

 

[dirtymike]

2001, what code is it showing.

 

[Uncle Gump]

I moved you post to the 4.0L forum...

I have to ask... does it matter if the vehicle is fully warmed up or does it seem to do it cold?

 

[Greasemonkeydad]

I moved you post to the 4.0L forum...

I have to ask... does it matter if the vehicle is fully warmed up or does it seem to do it cold?

Seems to do it hot or cold really. The kid that owned it before us put a cold air intake on it and there was a vacuum leak there after the mass airflow sensor. We literally about an hour ago finished removing the cold air intake and installing a new OEM air filter housing, filter, duct, and crankcase breather hose. We started it and while it was idling it began to chug and died. We restarted it and it ran so we decided to run it around the block and halfway through that five minute trip it started chugging again and actually died driving through an intersection after a green light. Start it back up and drove it home barely easing on the gas pedal. He’s been driving it to school in the mornings here in Vegas where the temperatures are around 75-80° in the morning. He hasn’t had any trouble in the mornings. It’s strange to say the least. Any help is greatly appreciated.

 

[Greasemonkeydad]

And thank you for moving the post to another section. Much appreciated.

 

[Greasemonkeydad]

2001, what code is it showing.

Hey bro sorry for the late reply. As soon as the engine light comes back on we’ll go have it read and see what it says now since we just replaced the cold air intake with the OEM intake. Put the code a week ago was saying PCV valve, which we replaced weeks ago.

 

[dirtymike]

check your fuel pressure regulator, Dont know where it is on a 2001.

 

[Uncle Gump]

With most drivability concerns... you really have to start with fuel pressure. If it's out of range... everything is off.

I believe your 2001 has a returnless fuel system. Meaning the pressure regulator is in the tank. Either way... invest in a cheap fuel pressure gauge or rent/borrow one from the local parts store. With the symptoms you describe... it is exactly where I would start the diagnosis process.

 

[SenorNoob]

The aftermarket intake and known leaks would have me looking at the MAF sensor. I bet it's dirty. That a fairly cheap fix too. Cleaner is like $10, if it works. I've had to gently scrape mine with a toothpick before.

 

[Greasemonkeydad]

Trucks fixed fellas! Literally just got back from a test drive after changing the fuel pump. Ran like a champ. Pressure test showed it was only running at 20 psi and it was intermittent at that.
Can’t thank you guys enough for all the advice. Much appreciated