bigmouthbass

since about a week ago when driving down the road my jeep is fine until i give it more gas to speed up then it kinda stutters as it tries to speed up. only did it when i was going around 55 mph. as the week drew on it has now happened anytime i come to a complete stop and then accelerate it starts stuttering. i have replaced the fuel filter and that didnt help any. what would be causing this. this is my daily driver so i cant afford to have it break down on me.

VTJeep

I'd start assessing electrical/ignition system. Make sure ever connection is clean and tight, then move to the sensors- the TPS might need to be adjusted. There's a great write up by Cruiser54 on it. Could be iac valve (I think you have one), or maybe o2 sensor.
Does it ever backfire at the manifold?

cruiser54

Ever changed the plugs, wires, cap and rotor like should be done every 30,000 miles?

bigmouthbass

no i havent ever changed wires. bought it a year ago and now is the only time i have had any issues. guess ill look into that tomorrow and go from there
im still learning about these things so i go in baby steps

bigmouthbass

also i dont get any check engine lights. i always thought if it was electrical it would make the light come on

cruiser54

Al the more reason to take a giant step and put all new tune-up parts in. No gimmicky plugs either.

CEL will not tell you a plug, wire etc is bad. Back to basics here.

DFlintstone

90 won't have a check engine light. I'm pretty cheap myself. I once suggested to my neighbor he just gap his plugs, no need to buy new. Years later he told me when he hit 80,000 miles he went ahead and changed them...even though they seemed fine! (hopefully there are no moving parts!)
Don't buy platinum's, and if you have them, can them.

If you have a DVM you can rule out the CPS in a couple minutes. That trickster can do about anything.

bigmouthbass

whats that mean

cruiser54

It means do this in Flintstone lingo:



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

bigmouthbass

new wires and plugs in. also had a small leak at gas pressure sending unit??. i think thats what my BIL called it. replaced that o-ring and drove arounds the block and seems to be running right now. will see when i hit the highway tomorrow on the way to work. thanks for all suggestions

DFlintstone

The fuel pressure regulator, with the vacuum line going to it probably. Goad you gotr'. (DVM is digital volt meter)