While driving last week our Ranger died as if it had run out of gas, so I figured a pump had gone bad. This past week I have traced the wiring, checked the inertia switch and relays. I pried the cover off the fuel pump relay and manually closed the contacts which made the pumps come on and work. I have checked voltage into the computer and checked port 22 which the wiring diagram says connects to the fuel relay and it stays hot all the time. I read somewhere that the computer was supposed to supply power to the pumps for few seconds and then switch to ground to complete the relay circuit. Does anyone have any insight on this issue?

Thanks in advance,

Larry

 

I believe the computer energizes the fuel pump relay for 2 seconds when you first turn the key on, after that the computer requires an RPM signal from the ign system to keep the ground circuit to the relay closed.
It sounds like you are not getting the signal from the ign system. A thorough check for spark is in order. The signal originates in the distributor goes to the ign module which then triggers the coil.
Do you have voltage available at the coil primary coming from the ign switch?
If you have either a test lite or voltmeter see if you have a pulsating voltage at the other end of the coil winding which should trigger the coil to produce the spark voltage. If you have the pulsating voltage , the coil is suspect.
If you don't have the pulse the problem could be in the dist, wiring, or the ign module.

 

Hanky,

Thanks for your reply and additional insights. I did check all those different things and finally broke down and bought an OBD I reader when I kept getting erratic readings with my voltmeter. The reader acted like there wasn't anything connected to it so I pulled the computer and opened the case up after seeing some rust on the case where the cover goes to protect the edge connection on the circuit board. I could not see any physical damage but decided to replace it anyway. I found a water leak along the lower edge of the windshield and plan on having the windshield re-bedded this week. In the mean time I covered the computer with a plastic film when I installed it. I reconnected the battery, then ran through a diagnostic check with the reader and got a response back with the following codes; 10, 15, 21, & 24. The pickup started right up and is running smoother than it did before the old one failed. I am researching the codes and will make the necessary repairs. I am hoping that making the repairs will help the gas mileage, currently I am averaging 16-17 around town.

Larry

 

If you disconnect the reader when it is giving you the codes, it should erase them.
The 10 code appears to be a separator code.
The 15 Said there was a problem with the ECA
The 21 code said the ECT test was out of range
The 24 code said the ACT " " " " "
When you have multiple readings stating such as out of range , it is usually a poor ground somewhere in the computer system or supply voltage problem.
You may have found the problem in the computer with the moisture problem.
Usually we clear the codes and then rerun the tests after the corrections have been made, in this case the moisture problem.
Not sure what you mean with "replace". Did you install a different computer(ECA) or did you reinstall the original ECA?
Was the replaced ECA new or used?

 

Don't know if this will help anybody now or in the future, but this is a couple of issues and resolutions for a couple of drivability issues I had with my 1988 Ranger S/C XLT 4X4.

Was driving down the road and just died like it had no fuel. NO FUEL was right. After pulling my hair out for about 3 days, I found that the engine would start if I sprayed fule into the intake. I found the ground disconnected at the battery. This ground goes to a 5 or 6 point splice. One of those grounds goes to the CPU. The disconnected ground was causing the injectors NOT to inject fuel. I butt spliced the ground wire back together and WHA-LA, the truck fired right up.

The small ground coming off of the battery post had a twist lock fuse type connector on it that failed and caused the ground to lose connection even though the connector was still intack. Ford used this type of connector for assembly line ease.

I also had an issue with low mileage with no codes being generated. This was caused by a bad O2 sensor. Every now and then I would see black smoke coming out of the tail pipe under light loads. Replaced the O2 sensor and I went back to running 24-27 MPG on the highway.

 

Mr. Common Sense,
Thank you for joining me in trying to help this gentleman. Some people are reluctant to accept assistance and I am not one of them. Please feel free to add anything you think I could have overlooked, and I appreciate your assistance.
Thank again, hanky

 

Hanky...No problem...

LarryT..Follow the small ground wire from the battery post. It will go down by the right side inner fender to a nulti-point BUTT splice. These will be the main grounds for your CPU/Ignition/Fuel delivery systems. Check to ensure that the splice is not "GREEN". The 1st generation Rangers/BII's had a tendacy to leak around the windshield as you have found. Also, they tend to leak where the roof and pillar seams meet at the windshield (Sometimes rust under the sealer).

 

Hanky,

I installed a rebuilt (Cardone) ECU and immediately was able to acquire codes; something I could not do with the old one. My reader acted as if there was nothing connected to it.

I know the ground wire you other fellows are talking about and had already replaced it when I installed a new battery a few months ago. I am a anti-corrosion nut and replace any suspect connection when installing a new battery. I rarely replace an end on a battery cable or connection, preferring to replace the entire cable/wire as needed. This practice has held me in good stead through the years and doesn't cost that much. I recently replaced a battery in one of my vehicles that had been in use since 2003.

The truck seems to be running better each day and I will pull it into the shop this weekend and recheck codes now that the truck has been in operation all week.

I would not be surprised that the truck might have a bad O2 sensor. I don't drive it and my son usually only tells me about any problem when the truck won't start.

Thanks again for your responses.

Larry

 

The computer usually requires some time to relearn and adjust to your driving habits. Glad we were able to be of some help. Appears you solved all your problems, keep up the good work!