Would someone check my MAP math?

[aw12345]

It would be a good idea to try and borrow a ecm from a same year same engine YJ. Fuel pressure readings taken while not under a full load do not mean much, The pressure jumping around a bit should not make it stall. You have an electric problem related to ignition, could be a bad component or a wiring problem. The ecm contains the ignition module when it runs try heating the ecm with a drop light, hair dryer or something simular, just don't go crazy. Move wires around near the coil, distributor etc, you did change the crank sensor right?

[Jeeperator]

Pull the distributer cap and check out the rotor and cap. I had a rotor tab break off and it caused the jeep to die but it tried to run for a while somehow. Man the spark had to be jumping over an inch. Make sure there not much play in the dizzy up and down and side to side.

[Jason]

Art, I have not yet replaced the CPS. Look's like that is next. I had it off to inspect it and on the outside it appears fine but it is a sensor. I did move around the wires coming out of the ECM on the firewall thought to myself, I hope that's not the problem. I had just replaced the cap, rotor, and plug wires a couple of months ago so I don't suspect that but they don't make parts like they used too. I'll look there again.

[6spdYJ]

Also sheck the connections to the module inside the distributor. This guy is what triggers the start point of your injectors. If it's falky, so's your fuel supply.

[Jeeperator]

Yea I replace my cap and rotor with autozone cap and rotor and it failed in less than a month. I got a replacement cap and rotor at autozone again and it failed in a couple of days again.The little tab kept breaking off. I put a cap and rotor form napa and havent had a problem yet.

[aw12345]

Here is something worth trying when it acts up set a baggy of ice on the crank sensor, if it behaves again after a minute or so the sensor is bad

[Jason]

You're kidding? This seems like that muffler bearing thing my Dad had me go look for when I was a kid.

[Jason]

Look what I just found from another board;

"you can have good fuel pressure even with a bad crank sensor. When the ignition is first turned on, the pump should prime the fuel rail, then shut off until the ecm receives the rotation signal from the crank sensor. So the initial priming will occur, but a bad crank sensor will prevent the fuel pump from coming back on while cranking due to lack of rotational pulses supplied by the crank sensor"

30 seconds of fuel during the prime?

The thread goes on with;
"If the crank is bad it will not send a sync pulse. If the sync pulse is not received the ECU will not pull in the relay for the fuel pump. It depends on how the crank sensor fails. Sometimes you get the crank to fail from heat it will come back and function normal until it heats up again. Fuel pump primes(ASD and fuel pump are functional), valid fuel pressure, along with a valid check engine light(That tells you the ecu is getting power) gets you to checking the spark and seeing if the distibutor pickup(cam sensor) is functioning. Its not the only answer by a long shot but its the most common."

[aw12345]

putting ice on the crank sensor gives you a quick answer on the above

[Jason]

and the ice test for the most part is free. I like free.

[Jeeperator]

I think the ice is for the mixed drink you going to need if you cant figure this out LOL.

[aw12345]

I think the ice is for the mixed drink you going to need if you cant figure this out LOL.

Don't worry about ice Beau, you go make your Jeep huff and puff some air lol

[Jason]

We have a clogged catalytic converter and really high fuel pressure. So high it may have killed the fuel pressure regulator and that is an expensive little bugger.
There really is no reason the cat should go bad. Something else has caused this. Excess fuel is always a culprit. Remember the backfires?
Now to diagnose the fuel pressure. I may have pinched the return line when I dropped the tank a couple of weeks ago and that would cause the higher readings.

[Jeeperator]

I there a return line on a yj? a tj dont have one.

[aw12345]

YJ does