I've got a similar problem. I've got a CPS on the way. TPS checks out ok. I've never installed the CPS -is it difficult? Seems like a long reach from under the jeep to the transmission. Is there another way?

Thanks

 

I just did mine, and I have the two bolt style. At least 12" of extensions, a swivel, and long 11mm socket. I had a flashlight in the engine bay that shined down to the bell housing that gave me a clear view. Just be careful and do the top bolt first as it allows the CPS to stay in place to keep the bell housing itself "closed" so the bolt won't fall in. I ended up loosening a bolt enough to grab it through the engine bay and unthread by hand to also prevent it from falling in. All in all, very easy just takes patience and some stamina

 

What's your present CPS output voltage?

 

Make sure your motor is cold I've had to change mine in the dessert on a blazing hot motor

 

okay put my baby back together and it runs good. i have 30psi at the fuel rail. my engine runs smooth now hasnt ran like this for a long time. i installed a new fuel pump assembly with fuel sender. i also installed a new cps.

 

Good to hear

 

Hey, you got it! Well done

 

Yeh, forgot about that part. My jeep hadn't been able to start for a week, so obviously it was cold

 

Thanks for the tips. I've got lots of extensions but I don't know about patience!!

 

It's about a 50/50 chance of starting and when it has, I've checked fuel pressure, 39 PSI w/o vac and 32 PSI with vac, compression over 140PSI on all cylinders good, spark good. Problem is, when it doesn't start, it just won't start! I will check the CPS during cranking but I've also got a problem with #1 cylinder not firing even though I have spark, compression and fuel pressure. I'm thinking a clogged injector. I'm hoping to take the rail off and clean these.

Always something!

 

Check the CPS output voltage at the connector with it unplugged when it happens again. Here's something you should definitely do on your 87 anyway since the CPS signal travels through the C101:
Renix Jeep C101 Connector Refreshing
　
The C101 connector on 1987 and 1988 Renix Jeeps was a source of electrical resistance when the vehicles were new. So much so that the factory eliminated this connector in the 1989 and 1990 models. The factory recommended cleaning this connector to insure the proper voltage and ground signals between the ECU and the fuel injection sensors. We can only imagine how this connector has become a larger source of voltage loss and increased resistance over a period of almost 25 years. The C101 connector needs to be cleaned at least once in the lifetime of your vehicle. Chances are it’s never been done before.

Almost every critical signal between the engine sensors, injectors, and the ECU travel the path through the C101.
The C101 is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the bolt and pull the halves apart. You will find the connector is packed with a black tar like substance which has hardened over time.
Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth.
If you have a small pick or dental tool tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter. Apply a true dielectric grease, not the stuff that came with your brake pads, to the connection and bolt it back together.
　
　
Revised 11-29-2011

 

Thanks CPS came today but will have to wait for weekend!

 

Do the C101 refreshing anyway.