cherokeeyed

1988 Renix Cherokee


List of things already done:


Throttle body cleaned
IAC Cleaned
IAT Cleaned
TPS adjusted to spec
Butterfly Adjusted to spec
CTS Replaced
CPS Replaced
C101 Connector Cleaned
Grounds refreshed (.5 Ohms pobing B on TPS)
New Plugs Gapped to spec
New Rotor in distributor
No Vacuum leaks


It's like the Jeep is out of time but from what I understand these are automatically timed. When you floor it, it doesn't have full power, it will bog and when revved in neutral it will backfire and occasionally pop..


I've been dealing with this thing for 4 weeks... Someone has to have some info.

tjwalker

Job #1 is to verify fuel pressure. I didn't see that on your list. Backfiring is often due to an imbalance in fuel/air ratio. Verifying fuel pressure is one of the first things a technician would check if you took it to a shop. Must be done with a fuel pressure gauge which can be rented inexpensively from many parts stores; call around for availability. There are other possibilities to be sure, but gotta rule fuel pressure in or out before moving on......

For an 88, you should have 31 psi at idle. Then disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi. Be darn sure that the vacuum line is not wet with raw fuel, which would indicate a ruptured fuel pressure regulator.

Good luck and keep us updated!

cherokeeyed

Checked fuel pressure a couple days ago. 31 @ idle and with the key on and engine off. I didn't check it with the regulator vac line off but the regulator vac line DOES NOT have fuel in it.

I think this issue has something to do with my starting issue as well which is when its cold it won't start.

PDEM87

Question. How can you have 31 at idle with the engine off? With just the key turned on, the pressure should be closer to 39 and it should hold after you turn the key off. If you start it and let it idle, pressure should be about 31. Pull the vacuum line to the regulator and it should jump up to around 39. You might want to double check to be sure you're ok.

freegdr

Have you checked the map sensor line for cracks yet ? Also confirmation of vacuum to it when idleing .

cherokeeyed

That's what I meant I don't know why I typed 31 twice..

PDEM87

By the way, I must commend you on your perservierance with learning the Renix system. I too am on my first Renix and they are not easy. Had a 96 xj before the 87 I have now. Very different!

cruiser54

No plug wires?

cruiser54

With the engine running, get a voltage reading on each terminal of the fuel pump ballast resistor.

Batman33165

Hey guys I know its a little off subject but that ballast resistor... what's the cons and pros?

And why some people just bypass them instead of buying a new one?

cruiser54

It was put there for one purpose only: Keep the fuel pump quiet.

Supplies 12 volts to the pump on cranking and drops the voltage to about 10 when running.

Bypass it. Pump too loud? Hook it back up.

Batman33165

Ok, thanks cruiser...