Hello All,

I have a 1992 3.0L 2WD ranger with an issue I am trying to diagnose. I tried starting my truck the other day and could not get it to idle. I could get the truck to fire for maybe a second and then die. I began thinking it was fuel related - either fuel pump or fuel filter. I used some starting fluid and the truck fired right up and began to idle normally (very smooth no knocks). Upon revving the engine around 2000-2500 RPM the truck immediately chokes out almost like when there is no air flow being detected by the MAF and a check engine light came on in the dash. I double checked the MAF was plugged in and that there were no holes in the intake. I also checked all of my vacuum lines and they all seemed to be in good shape I plan on checking for leaks with some smoke here shortly. I have ran the truck with vacuum leaks before and they never caused an issue like this.

I tried to hook up my OBD1 reader to the truck with no luck yet on engine codes. I think my reader bit the dust.

I did find something I had not noticed before under the hood while diagnosing. When I turn the ignition on I can hear the fuel pump turn on. From under the hood there is a hissing like similar to letting air out of a tire around the alternator/A/C accumulator/left valve cover area, but I do not smell fuel or see any leaks. I don't know if this is normal. Also I am unsure if the fuel pump is supposed to constantly run or shut off when it reaches pressure, but the fuel pump will continue to run as long as I have the key in the on position. Have any of you heard of something like this or have any ideas on a good place to start eliminating potential issues? Any help is greatly appreciated.

 

It reads like computer has failed, well a capacitor in the computer, happened to my 1994 a few months back, replaced the 3 capacitors, $5, and all was well again

The fuel pump staying on and engine not running well was the symptom

Fuel pump should come on and then go off after 2 seconds, its a timer, there is no fuel pressure sensor on a ranger

MAF sensor is there to detect the WEIGHT of the air, not flow, the computer is programmed for a 3 LITER engine, so computer already knows exactly how much air is coming in at any RPM and throttle position
If "extra air" is being sucked in then the WEIGHT of the air from MAF sensor is incorrect so fuel mix is incorrect, Lean, but engine still runs

On a 1992 3.0l Ranger Spark is a separate system from engine computer, so the fact it started by manually adding fuel means spark is not the issue

Just to take it off the table so you don't was time on non-fixes, I would pull out the computer and open it up
You will see 3 Blue or Black capacitors, these can leak after 20+ years, usually easy to see the residue, blue ones seen here: Ford EEC-IV

Replace with Black models, they last longer

More info here on capacitor replacement if needed: http://support.moates.net/capacitor-...-ford-a9l-ecm/

 

Thanks for all the information! That is definitely where I will start. Just as a side question, when you had the bad capacitors in your computer did that cause parasitic battery drain as well?

 

No, but it could, I just fixed it when engine didn't start and was acting up when it did start, so maybe over 2 days, so never noticed drain on battery

My thread on it is here: https://www.therangerstation.com/for...y-1994.187821/

 

Okay I finally pulled the ECM. It was not looking good. Then I opened it and it actually looked decent at first glance. Then the closer I looked the less i has confidence in fixing it. Should I just bite the bullet and get a replacement?

 

looks like its got some corrosion but nothing a little contact cleaner wouldn't fix up, its a non-residue spray then use q-tips to clean surfaces
You can also use Isopropyl alcohol, almost no water in it and cleans off corrosion(water)

I would replace the blue capacitors, the kind you need is on their sides, get Black ones, they last longer than the blue ones, few cents more, literally cents

Don't see any other major issues, these things were built to last, lol

You can rinse/spray the whole board off, both sides with the Isopropyl alcohol or contact cleaner and let it dry

 

Thanks! Ill give it a go and let you know how it works out. I appreciate you taking a look!

 

Just an update - that did the trick, she is running like a champ again. I also checked the battery for a parasitic drain with a multimeter and it seems to have resolved that too. Thanks again!

 

Good work

Thanks for the update and the FIX