I friends kid has a '90 2.9 ranger and wanted me to check it out, in the last 8 months they replaced the fuel pump and filter,cat converter, and ox sencor it ran good until last week. The icm module was bad so I replaced that but all that got was a smooth idle and better smelling exhaust. Now it idles ok but cuts out @ 2000 rpm like its starving for gas, the fuel pressure is 35 psi but drops off to 0 after the ign. sw. is shut off. Iam not sure if the fuel pressure reg. is sticking or not it seems to be working properly, also there are no leaks in the fuel line that I can see, I did find a loose clamp on the fuel filler neck and repaired but psi still drops off, it also has a new gas cap. I just found out that he ran it out of gas and over heated it i don't know if that will have anything to do with the problem or not but thought I'd throw that in. Any body out there can think of anything that might help it wikll be greatly appreciated.
Frank '92 F-250 4x4

 

Clogged pick-up screen in the tank? A kink in the fuel line? Maybe air starved? I'm reaching here. One of the real veterans will pick up soon. I'm just trying to flex a few brain cells.

 

You might have better luck on the engine forum...my EFI experince is with GM systems, maybe there are simlarities?

Pinch the return line and see if the system holds pressure...it shouldn't leak down that fast...should hold pressure and slowly bleed to zero after 10-15 minutes.

Smell the crankcase oil, if it smells like gas, then you're probably pulling it through the diaphram in the regulator...you can also pull the vacuum line on the regulator and see if it smells like gas as well.

If the regulator is fine, I'd suspect a fuel injector(s) as the problem, one stuck open/not seating properly and all the fuel is bleeding out through it...thing is when this happens while it's running (again-I'm in GM mode) yuo wind up dumping too much fuel into one cylinder...the O2 sensor reads this as a "rich" condition and shortens the injector PW...thereby robbing the other cylinders of fuel...so you wind up with more of a lean condition.

Where abouts are you located? If nearby, my scantool (SnapOn MT2500) will link up with your truck if normal TS'ing doesn't solve the problem.

 

I have a scan tool and nothing showed up. but a fuel injector does soud possible I was just hoping for something else. I try that and let you know what happens. We're in Smartsville along hwy 20 next to Timbucktoo and Moony Flat. That might tell you how well we can get expert help and parts.
Frank 1950

 

Heck...just drove by there the other day

Monitor you Inj PW...should be, IMO around 2.0...plus/- a bit while watching the O2 sensor voltage...which should swing in the 450mv range back and forth at a fast idle unless you have heated O2's?), if your scan tool can change to O2 crosscounts, you can watch that too.

So if the O2 is "acting" right, but PW is way too small, should get you headed in the right direction (too much fuel in one cyl)...to narrow it down (if that's the cause), just diconnect an injector clip (one at a time) and see if your scanner results change.

Again, I'm approaching this from a GM EFI point of view, so all discalimers apply

 

Run some cleaner through both the injection system and thfough the fuel system. Do one, then the other. Crap, my oldtimers is in full wing and I can't remember the name of that stuff . . .
It should smoke like a steam engine on the injector clean through the intake.
look around there's threada on the internal cleaning.



It may not be throwing a code, the O2 sensor could be subject. I had one do that in a '88 2.9.

Good luck

Rich

Ah! Sea Foam is the stuff.

 

The injector cleaner can't be run through the intake...taht would just do the valves and topend...you have to have the setup thatt goes inline with the fuel rail in order to clean the injectors...pretty sure there are kits for it now...we just use to pull'em apart, dip in ChemTool and cycle the heck out of them with compressed air. Cheap and effective, but messy as all get out

There is a real good guy who does great work on injectors, and is honest enough to tell you to replace/rebuild/etc...his name is Rich and if my old timers memory is correct, he's at cruzinperformance.com...used to be he'd charge about 80 or 90 bucks to clean and flow match a set fo 8 injectors

 

My 1989 2.9 Bronco II had a bad intake gasket. Defectively thin from the factory. It sounds like it might be the same problem to me. They are known to be great motors except for that minor flaw from the factory. You might want to check to see if there was a recall for such and that the work was done on your unit. Ford might fix that one for free if this is the case.