Code for OBD-I

[Aaron285]

Induction?

 

[bobbywalter]

All of your intake tubing. False air can whack timing wct.

 

[Aaron285]

Induction is all perfect. I really think the alternator has something to do with the problem. I had an issue months ago when I first started the truck up in December and it would not start if the battery was not at exactyl12 V, a little under and the fuel pump would not work and it would not start. I think the voltage is a little low like 10-11V and its causing problems with the fuel pump and /or the coil pack. I will keep you guys posted after I get the new alternator and re test drive the truck. My fingers are crossed and I'm going to pray every night before bed!! lol.
Thank you all for the help. This forum is greater than Google, Youtube, etc. for anything Ford Ranger. Ive been a member for about 5 yrs but been using the forum for about 12 yrs.

 

[bobbywalter]

Well....low voltage and corrosion hold hands allot.

The wires can look good on the outside and be corroded and resistive.

When is the last time you looked at the sending unit connector? I have seen corrosion there on the power pin cause volume issues under load....less then 10 v at pump. Hell I have seen em corroded right to a nub.


Do you have a fuel pressure gauge you can watch under load?

Try this. Start it up. Rev it up a bit....then shut the key off and then back on so it don't stall all the way. See if it has more rpm after that....or all the way off then back on while coasting in gear maybe.

There's several potentials with these systems...it's why in only recommend swapping complete known working 4.0 setups as a whole. There are a myriad of changes and calibrations and wiring differentials.

 

[Aaron285]

I don't have a way to check fuel PSI while driving. While driving underload is the only time motor Boggs down. I can sit in the driveway and rev it up till the cows come home and its sounds great/ smooth. It is the worst in 3rd gear. I can go thru 3/4 RPM (4000 RPM) range in 1st shift to 2nd and go thru about 1/2 RPM (3000-3500) range but then right when I put into 3rd and let out clutch to re apply power, Boggs and truck shakes. Sending unit is brand new, just put in 2 weeks ago along with new tank, sending unit plug and wires are good. Motor was fully rebuilt at machine shop. Only parts on the truck that are old are the electrical components that bolt to motor (alternator, IAC, MAF, Etc.) Motor ran/idled in donor truck before I took it out but had low compression in 2 cylinders.

Im just guesstimating the RPMS, my tach and entire dash doesn't work correctly or really at all. Only MPH works.

 

[bobbywalter]

There is a reason I wanted you to do the key cycle.

It may be as simple as pin 30 needs ground issue.

But if the maf is bad or wrong or in the wrong application there will be load issues.

May be a combo of things ...may just be chaffed wiring that shorts causing timing or fuel cutoff because at that load the engine moves a certain distance.....

The 90 to 91 don't have NGS...or cmp....or egr...and run bap sensor.....so if pcm is looking for other things that are not there....maybe that's why it's cutting fuel or timing....

Might be a bad pcm. I would have to have it to see what it is doing.

 

[Aaron285]

what and where is the 30 pin?
None of the parts are wrong, but maybe bad. Also maybe a wire short somewhere. The Motor and all harness's under the hood are off the same donor truck, which was 91 4.0 auto 2wd, The dash was out of a different 91 4.0 auto 2wd, and all other chassis electrical/lights are from the original truck/frame which is 89 2.9 manual 4x4. And the ECU/PCM is new/ refurbished from parts geek.com for a 91 4.0 manual 4x4. I posted pics of the old PCM and the current/ new one.