charlesebow

Ok, so the other day I was driving down the road and my 88 xj died(4.0, manual trans). It would crank but not start. Towed it home and the next day tried to figure it out. I have refreshed all grounds in the engine bay, after doing this I am able to crank the jeep and it will start but dies after like 2 seconds. So I tried a jumper on the wires that go to the ballast resistor and still dies after about 2 seconds. occasionally when it starts if I pump the accelerator I can keep it running for about a minute, but if I try to hold the throttle down it just dies. I am not sure what to do now, thinking it must be the CPS at this point? Any help or ideas are appreciated.

Radi

I'd check your fuel pressure before changing the CPS. Bad fuel pump can cause similar symptoms.

hypedonmonster

if jumping the ballast doesnt help i would definatly remove the cps and clean off all the old clutch material off the magnet on the cps then put it back in. thats what happened to my bro's 88 4.0 5speed. and my 88 4.0 auto (my replacment cps came outa another 88 4.0 5speed). so just clean it off and that will probably fix your problem, if it doesnt let me know and ill give you more possible solutions.

charlesebow

Ok, I found that the wires to the cps had basically been melted in half. Bought a new CPS and installed it last night, now it will start but will die quickly unless I pump the gas. If i try to just hold the accelerator down it bogs down and dies. Not sure what to try next, could it be TPS?

cruiser54

Hint, hint. Fuel pressure check is in order.

If you're dying to check out the TPS it's never a bad idea. Got a meter?


RENIX TPS ADJUSTMENT
Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up.
IMPORTANT NOTE: Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed.
MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body. This manual transmission vehicle TPS provides data input to the ECU. The manual transmission TPS has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Adjust the TPS until you
have achieved this percentage. If you can't achieve the correct output voltage replace the TPS and start over.
AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles—FOR ENGINE MANAGEMENT RELATED ISSUES.
However, the automatic TPS also has a square four-wire connector clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.
FOR AUTOMATIC TRANSMISSION RELATED ISSUES. Check the four-wire connector side of the TPS.
If you have ENGINE issues check the three-wire connector side of the TPS. For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
Revised 05-20-2012

hypedonmonster

Ya, adjust your tps and see what that does. If that doesn't work, check your fuel pressure and if its low i would jump the ballast resistor. This will give your fuel pump 12 volts instead of 10 volts and it may just fix your problem. The resistor is only there to quiet the fuel pump. You may even have a clogged fuel line or a dirty pick-up sock in your tank.