Fuel Issue...IRCM....

[BSTDLXY]

hopefully you guys can help me out. I purchase a mocha 1991 with 110k for $500. Owner kept it sitting for 6 years. He said it had a bad clutch and was going to use it as a parts car, yet he never took any parts off. So i bought the car, gave it the normal tuneup, plugs, wires, valve cover gaskets, fluid change, tires... My problem lies with the fuel delivery. the inertia switch was disconnected and the fuel pump was being powered by the trunk light. So i started to try and figure out the reasoning, and the ircm has a date on it from 2001, so i know this part is not stock. I searched on the forum about the ircm and based on what i am reading (correct me if im wrong) J code which is what i have is for an automatic car. So i assumed they replaced the wrong part and thats why the car sat for so long. So i went and got a M code ircm, hooked everything up and my only problem is when i turn the key on, the fuel pump doesnt prime for the 1-2 seconds that it should, and the car wont start, however if i put power to the inertia switch for a few seconds and prime it myself, the car will start and once its running the car will power the fuel pump itself. So i know the fuel pump works and the car runs, i just cant figure out why it wont prime for the 1-2 seconds it needs to start on its own. Please help.

 

[Off Road SHO]

The Computer (PCM) commands the CCRM fuel pump relay to run for 1-2 seconds. Maybe the previous owner also had problems with the PCM and swapped it out with an incorrect version. I have spares if you need one.


Was that the SHO on Craigslist that didn't have a title?


Tom

 

[BSTDLXY]

It was on craigslist, but it wasnt the one without a title. this was the mocha that had 2 small pics of it on a trailer. If the pcm was wrong or broken wouldnt the car not run at all?

 

[rbruso]

Where in AZ are you? Maybe you're near someone who can come over with a bucket-o-parts and try to figure it out

Is the car a California Emissions model? It will have an EGR valve on the intake between the throttle body and the firewall? If so, I have a '91 computer. I also have a B9B or B9B1 in the shed. Can't remember which.

Pull the glove box and check out the code on the back of the computer.

(from an old post)
B9B - 89
B9B1 - 90
LOS - 91

 

[BSTDLXY]

It is a california car. Im going to pull the computer out later and check the numbers, but if this helps its a 1991 california car built 02/91

 

[rbruso]

You usually don't need to pull the computer to see the code. You might have to unbolt the little brace, but if the computer has been swapped it's possible the brace isn't there anymore.

Of course, there might be another culprit. Looking at the wiring diagram for the 1991, there are TWO feeds to the inertia switch: one from the IRCM and one from the computer. Doesn't the fuel pump get primed during startup as a function of the IRCM? If so, it's possible the fuel circuit in or from the IRCM is bad, but the feed from the computer is good. Or the other way, if I have it backwards

Diagram here, fuel pump in the upper right area:

 

[projectSHO89]

The feed from the IRCM/inertia switch as shown in the wiring drawing to the PCM isn't to run the system, it's to provide running status to the PCM. IOW, it's an input to the PCM, not an output.

IRCM/CCRM info is in a stickied post in the Electronics sub-forum. This post tells how it works: http://www.shoforum.com/showpost.php?p=739231&postcount=19

 

[rbruso]

Any updates?