96 Jeep Cherokee not start

[xjoffroad]

Wifes grandma cherokee wont start unless you have your foot on the gas. Once it turns over it sputters for a few seconds then idles. I checked the IAC and cleaned it yesterday. It started fine until this morning and still have issues.

Fuel pump comes on and has fuel at the rail. Obviously has spark because it does start with gas pedal down. Suggestions?

 

[JOOP]

What's the PSI on the fuel rail?

 

[xjoffroad]

Fixed it. The IAC valve was a defect from autozone that I bought yesterday.

 

[JOOP]

Glad you figured it out. :awesomework:

 

[xjoffroad]

well i guess i didnt fix it. put the new IAC in and it started right up and drove fine the rest of the evening. tried to start it this morning and all it did was crank. put my foot on the gas and it started right up. someone said the CPS was bad, but wouldnt that make the cherokee unable to start?

throw out some ideas please. this is pissing my off :booo:

 

[zukkev]

Coolant temp sensor (for the computer)? TPS?

 

[Lead Foot]

Most likely not TPS but still possible. When you hold down the gas all the way on a cherokee while cranking it tells the ecu it is flooded and to not send fuel through the injectors. Check your fuel pressure, you might have a bad fuel regulator and its flooding out the engine. So when the ECU quits sending fuel it decides to start up but once started it goes off info sent from sensors and if the fuel pressure is too high the ECU cant cut back far enough on fuel. Especially since it doesnt even double check the air/fuel ratio till the engine warms up and starts taking readings from the O2 sensor.

 

[xjoffroad]

Most likely not TPS but still possible. When you hold down the gas all the way on a cherokee while cranking it tells the ecu it is flooded and to not send fuel through the injectors. Check your fuel pressure, you might have a bad fuel regulator and its flooding out the engine. So when the ECU quits sending fuel it decides to start up but once started it goes off info sent from sensors and if the fuel pressure is too high the ECU cant cut back far enough on fuel. Especially since it doesnt even double check the air/fuel ratio till the engine warms up and starts taking readings from the O2 sensor.

wouldnt say I was holding the gas down all the way. more like pumping it while it was cranking.

 

[WA-Wheeler]

fuel filter? i would test the pressure on the rail first... just to rule it out......my .02 cents :awesomework:

 

[Lead Foot]

fuel filter? i would test the pressure on the rail first... just to rule it out......my .02 cents :awesomework:

If you dont have a gauge atleast make sure the regulator isnt stuck closed and not allowing excess fuel back to the tank through the return line. Just see if any gas comes out of the return side of the regulator when the fuel pump is running.

CHECK FOR VACUUM LEAKS EVERYWHERE. Double check to the map sensor. Sometimes that little line likes to blow off if theres any sort of backfire or stutter in the engine.

 

[WA-Wheeler]

MAP SENSOR!! thank you :awesomework: yes check that, my old 88 Cherokee died because of that

 

[skinny_pedal]

Do you have access to a scan tool?

 

[xjoffroad]

Do you have access to a scan tool?

yes and there are no codes :booo:

 

[skinny_pedal]

yes and there are no codes :booo:

Can you pull live engine data or is it just a code puller?

 

[xjoffroad]

Can you pull live engine data or is it just a code puller?

its just a basic snap on code puller