Jlk111205

My 88xj drove horrible today. It idles fine occasionaly, drive it keeps sputtering skipping like its gonna shut off.. Im guess fuel issue? I have new fuel filter, have not swapped the fuel pump , nor injectors . Any ideas? It may not be fuel related at all

cruiser54

Borrow/rent a fuel pressure test gauge from a parts store. Check the pressure.

Jlk111205

Yea ill do that for starters lol I can hear my fuel pump come on wen turn ignition on. My wife thought bout selling but its good jeep all new parts, and plus wouldn get much for jeep that hardly runs. Lol not much else to be replaced and the motor.is new with around 50k on it

cruiser54

Better off testing the fuel pressure than listening to your wife. LOL.

Jlk111205

Lol I kno right . I got new fuel lines . Filter full tune up. Thinkin bout replacing the injectors also, that would prob help . Even tho I had the motor replaced the injectors still original. May need fuel pressure regulator?? ,imma,see bout testing the pressure tho .

Jlk111205

Either way it could use all that bring original. 250k+ miles on the body and chassis lol wouldn hurt to give it some fresh parts lol

cruiser54

www.precisionautoinjectors.com. Price is for a set of 6.

New distributor cap, plugs, rotor and wires?

Jlk111205

Wat about the crank sensor? Wad told thatll make it act up bad also

cruiser54

Here's a way to test it:

Renix CPS Testing and Adjusting
　
　
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
　
Revised 11-29-2011

tjwalker

1. Follow cruiser's advice above. Tuneup the engine.

2. Verify fuel pressure. For an 88, you should have 31 psi at idle. Then disconnect the vacuum line leading to the fuel pressure regulator (be sure that line is pulling good vacuum and is not wet with fuel) and the pressure should jump to approximately 39 psi.

Start with this..................

Jlk111205

Ok. It has fresh tune up. Omly bout 4months old. I have a vacuum line that doesnt conmect to anything it stops and is located almost at my battery. Wen its blocled off of course it idles low sometimes runs bad, un block it idles lil high and sometimes runs better. I have vacuum leak in brake booster box too which messes with my vacuum, wen applying brake pedal all the way down it idles low. I was informed I can buy a obd1 cable for about $30 & use a obd2 tester to read a code if have any. I noticed my o2 sensor had broke apart from the wire and I dnt have a check engine light.. Time to timd I have "maintenance light come on . But last time it was on was bout 6months ago, I have bulbs in my info center . Was thinkin maybe still b a code? But am still tunin up the engine I kno jist becausr I have a newish motor doesnt mean everytging is new. I can tell wats new and wats not. . Lol this is gonna b interesting

Jlk111205

Installed crank sensor for starters my oem one was shot

cruiser54

There are no stored codes you can retrieve on a Renix as it is pre-OBD. There will not be a check engine light either.

Seems odd that you have a brake booster leak but uncapping the vac line near the battery changes the idle. If th ebrake booster is leaking you would have little or noeffect when uncapping the line near the battery.

Jlk111205

Yea wat does that vac line connect to? The one by the battery? Ive took everywhere to b looked at and no one knows. Cant even find it in the haynes manuals, I have a hissing sound comin from the rear by gas tank also??

cruiser54

That vacuum lines runs to a vacuum reservoir in the front bumper on the passenger side.

The hiss you hear from the gas tank is probably the fuel pump making noise.