Low money and high dreams

OK so I brought my Jeep to a mechanic/tire place. So after they balanced my tires my Jeep wouldn't start. The mechenuc said weak spark but its has ran fine for months without a problem. all it does is turn over. Fuel pump kicks on. Just no catch catch.any suggestions on what could be the cculpret

RTorrez1

Start by having it checked for any stotrd codes.

cruiser54

89 has no codes.

Test the CPS output.

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.




Revised 01-26-2013

DFlintstone

It's the connector at the back of the manifolds with wires going down to the bell-housing/cps. (it's a three wire plug, with only two wires). Sometimes just un/re-plugging it will make it start to get you home. (I've only had that happen/work while it was hot)

You also might check that for some reason someone didn't bump that brittle little tube from the throttle body back to the MAP sensor, with the green connector, up there on the firewall. Just sneezing on that could cause a no- start! Seriously.

Low money and high dreams

well wont this cause no spark instead if a weak spark. Assuming the guy knows what he's talking about.