Hard starting ... AM only ??? HELP!

[gr8lite]

I understand about the fuel pressure issues. That is ok.

My concern is more with the Delay for the pump to run on initial "power up". Does the CPS control the ECU , ie: tell the computer when to "turn on " the pump?
Is the ECU the black boxed part on the drivers fender beside the air box? Can a ECU from any 4.0 be used to test this ?

About the bleed down issue. I was told by a local expirienced factory Jeep tech , that the return line hose / clamp on the sending unit can become loose or broken and allow a loss or seal.

Thanks to all here for the great info and help!!!

 

[Digger87xj]

When you turn the key on, the CPU runs the pump for 2 to 3 seconds and shuts it off. (fuel prime) after that, (within the same key cycle) it turns on the pump only after it sees a cranking signal from the CPS.
Normally this is sufficent to raise fuel pressure to start the engine.


With your failing pump, You need to cycle the key 2 or three times before you crank or you will have long crank times.

By key cycles i mean: turn the key on, wait 5 seconds, turn it off, wait 10 seconds, turn it on, wait 5 seconds, turn it off, wait 10 seconds and then on the third key cycle crank and start the engine.
What you are doing here is rebooting the CPU to get it to run the prime cycle again to get fuel to the rail before you crank the engine over .


As far as fuel pump prices, any aftermarket parts store carries a fuel pump for your jeep... you just need to call around to find the right price.

 

[gr8lite]

I don't feel as I have a failing pump. I have a delay issue in getting the power to the pump at initial "key on". Today at lunch I unplugged the ECU cleaned and dielectric coated the contacts. It seemed to make a difference. We'll see for sure tomorrow maorn after sitting all night.
If I were to disconnect the battery for an extended period (say 12+ hours) will any harm be done ? Will this "reset" and programs within the ECU ?
Thanks alot guys for all the help.

 

[gr8lite]

OK now I am incredibly discouraged !!!!!!!!

I replaced the fuel pump , double checked the connections ........

Low and behold ...The Same Freakin Problem !!! Turn the key on it takes on the average of 1 min to 1 1/2 mins for the fuel pump to "pump up" the system!

Anyone here ever showed pics of thier burned XJ? LOL

HELP PLEASE !!!

 

[Durango-Bob]

Interesting thread. One question, did you ever do the morning prime like was suggested? Key on for 5 sec's and then off for 10 sec's, repeat? If you did, did it start after the third cycle?

 

[gr8lite]

Oh yes I certainly have tried that , makes no difference. Does anyone here know if the computer itself could be "holding" a code to retard the signal to the fuel system? This Freakin Jeep is useless !


HELP !

 

[Yucca-Man]

Oh yes I certainly have tried that , makes no difference. Does anyone here know if the computer itself could be "holding" a code to retard the signal to the fuel system? This Freakin Jeep is useless !

Do the OFF-ON-OFF-ON-OFF-ON trick with the key to display codes through the Check Engine light http://allpar.com/fix/codes.html Or you could disconnect the battery and clear codes before you try starting it.

 

[gr8lite]

OK now I am on the verge of Suicide ! I just changed the freakin CPS (thats a nice location) ! No change! WTF?

OK Recap: 1994 XJ 4.0 5 speed

When starting vehicle turn key to on position and the fuel pump does not trigger to pump up the system. Sometimes it takes 1 min sometimes it has taken 20 mins!
I have replaced the following in the last 400 miles :
cap , rotor , 8mm wires , splitfire plugs , O2 sensor , CPS , fuel pump relay

Does anyone , PLEASE , have any idea what it is? Help me out here this is my GF's lifted XJ she is ready to sell it! Seroiusly She loves it but she needs reliability. This is just crazy!!!

Thanks to all!

 

[Durango-Bob]

Could be a bad fuel pump relay even though you changed it not long ago. Or even the wrong one?

 

[csr_011]

Check all your grounds.
Cory

 

[gr8lite]

BTT HHHEEELLLPPP Please..................................................



XJ is now for sale!

 

[gr8lite]

OK after about a 3 min wait I got the junk fired up. I shut it off , then proceeded to do the on / off / on trick. I got the light to flash a code but it doesn't make any sense it was 2-5-5. What the heck is that. There are no 25 codes or 255 codes or 2 codes. Helllllllllllpppppppp!

 

[Yucca-Man]

OK after about a 3 min wait I got the junk fired up. I shut it off , then proceeded to do the on / off / on trick. I got the light to flash a code but it doesn't make any sense it was 2-5-5. What the heck is that. There are no 25 codes or 255 codes or 2 codes. Helllllllllllpppppppp!

I'd recommend redoing it and counting again then. You're right - no '2' codes.

 

[gr8lite]

ok I am sorry it was different I got a 12 and a 55
12 = battery of computer recently disconnected

55= end of codes

So I am still screwed !

Thanks Guys for all the help , I guess I am gonna throw in the towel!
Again thanks to all !

Want to buy a XJ .....cheap !