wolf E Cakes

So I've been having trouble starting my xj after its been running for a long time and is hot. It was so bad tonight it wouldn't even crank at all. At first I though my battery was dead but all the lights were bright and electronics were working just fine. So I started doing some research and it brought me to the fuel system. My fuel pump is running just fine you can hear it engaging and running when I turn the key. So in my readings I found that it could be the fuel psi?? Anyone have this problem at all if so was it a simple fix like the fuel pressure regulator because that's what I have come to at this point to change first.

HudsonN

While there are a few possibilities, one of the first things to consider is a faulty "coolant temp sensor".

It provides input on temperature to the computer, which then can decide on the proper mixture, etc. for a quick start. What the computer decides on for a cold engine is a lot different than a hot engine.

They CTS can be tested, but testing is kind of a PITA. Refer to a service manual for more information, or many guys just swap them out as they aren't that expensive.

cruiser54

Does it take a long time to start or does it start and run poorly?

s346k

if it won't crank, the issue is not fuel related. i'd be looking at electrical connections and giving a second look at the condition of your battery and starter.

highmileage

grounds
starter
battery
connections
and being a Renix the ignition switch on top of the steering column can and will burn up, and cause all sorts of uncool things to happen.

wolf E Cakes

When its really really hot like after wheeling for awhile it wont even crank at all. Let it sit for a few minutes 10-15 it will start really hard like 5 very slow cranks. let it sit about an hour it will start up a lot easier and over night it starts right up no problems.

randall L

Test your CPS. If that's not it.......we'll go from there. I have "years" of experience with HNS. (hot no start)

If she won't even turn over when hot that's a different. If she turns over but won't start or starts rough then clears up it can be narrowed down to some other items to check.

Let us know.......

wolf E Cakes

What is the CPS?

wolf E Cakes

Yeah it doesn't even turn over at all when its really hot. I'm going to test the starter here in a little bit. I had my other truck jumped to the battery last night and still it wouldn't crank at all. I'm not too sure if the starter was engaging or not my other truck is way too loud to hear over.

randall L

CPS is the Crankshaft Position Sensor

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 the upper mounting hole to 3/8" from the stock 5/16", or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.



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wolf E Cakes

It's an automatic transmission. Thanks for the info ill start with the starter then start check cps and the cts and see what the reading are.

randall L

If she doesn't even turn over it's electrical. Check all connections, starter, alt, batt, GROUNDS BIG TIME CHECK, relays......

I had a bad ICU (ignition control module) once & it would turn but not start. Under yer coil. All that can be checked with a multimeter.

You should read "Cruisers Tips" for more info. Links under his signature (pink & green links)

77olds

Starter might be getting cooked. I had that problem with my old Cutlass - the headers practically wrapped around the starter and it would NOT want to crank after a long drive.

just one possibility... but could be a LOT of things.

cruiser54

Somehow I missed the "no crank" comment in the first post..........

wolf E Cakes

So just an update I figured it out. The starter was burning its self out there was no ground wire connected it was on its last strand so I rewirded the ground and replaced the starter and it starts right up now.