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

[gr8lite]

OK stock powered 94 XJ. Only in the AM first startup of the day. It cranks for quite a while ( 20-40 sec) then starts and runs very rough sometimes stalls. The rest of the day it is fine. Any Thoughts ?

[Eagle]

Random thoughts:

1. How old is your O2 sensor?

2. Are you letting the fuel pump run until it shuts off before you crank the engine?

[RichP]

Cracked distributor cap

[Ramsey]

i had a 94 that did the same thing, i fixed it by getting a 99. actually, i never did figure out what was wrong with it.

[Ed in North Ga.]

I go by Eagles rule-
I double prime mine.
turn key until pump cuts off, turn key off, return key until pump cuts off again. usually the second time is enough to bring the pressure up to full...winter time sometimes takes 3 turns.

without primeing, about 15 seconds.
with primeing, about 5.

[gr8lite]

I will try the key on / fuel pump test. However this has not always been the issue. This rig has been fine since last May. This has just started. I don't think the manner in which the key is turned has changed. It was fine all winter. Good call on the cap, I will check it! I wasn't thinking outside the FI system. Thanks for all the help guys , we'll see what happens.

[RichP]

I will try the key on / fuel pump test. However this has not always been the issue. This rig has been fine since last May. This has just started. I don't think the manner in which the key is turned has changed. It was fine all winter. Good call on the cap, I will check it! I wasn't thinking outside the FI system. Thanks for all the help guys , we'll see what happens.

I had a 66 mustang, chased that cracked cap for almost 3 months on an off. condensation got in it over nite thru the crack. Once the moisture was cooked of it was fine.

[Sparkman]

Most if not all FI systems don't use the O2 sensor data until the engine has gone closed loop. The engine runs open loop when starting and until it warms up to a certain temperature.

Your problem sounds like a coolant temperature sensor to me. The PCM thinks the engine is warm, so it doesn't supply enough fuel to start the cold engine.

I have owned hard starting engines where the only problem was ignition related.

[Eagle]

Most if not all FI systems don't use the O2 sensor data until the engine has gone closed loop. The engine runs open loop when starting and until it warms up to a certain temperature.

Good point.

If it isn't the distributor cap, the next thing I'd think about is the CPS. Usually they just fail, but sometimes they do strange things for awhile before giving up completely.

[Digger87xj]

FUEL PUMP

there is a check ball in the fuel pump that holds the fuel in the line.

When it starts to fail, fuel drains back to the tank overnight and you have to wait for fuel pressure in the AM

To check for this, install a FP guage and start the engine, shut it off and watch fuel pressure over a 20 min period... If it falls off more than 10 psi, the check ball is bad and needs replacement.


To check for this if you have no guage, in the AM, turn the key on then off for ten seconds, then on again.... do this 3 times then crank the engine after the last time. If it starts right away, replace the fuel pump.

[gr8lite]

Digger and ED sounds like you may have got it. I had her try the turn key on / off / on then it fired right up! I figured it must be losing pressure somehow after she called back to update me. We'll attempt a fix real soon! Thanks to all who contributed. I will post with a fix if I can find one! :wave1:

Thanks Guys !

[Matthew Currie]

Another possibility if it's running very rough after starting is a dribbling injector that floods it when it sits a long time. Does it smoke when you start?

[ZmOz]

It cranks for quite a while ( 20-40 sec)

Don't ever run your starter that long. It is designed to run for 15 seconds MAX. If you have it on for 40 seconds it will be way overheated...

[2offroad]

sleep till noon?

[gr8lite]

Well this issue is beginning to be a big pain! When the key is turned to the on position there is almost a 1 min wait for the fuel pump to "pressurize" the system. Sometimes the key must be turned on / off / on a couple times at the 1 min interval to get it to pump.
It almost acts like there is a poor connection to the in tank pump. Does anyone know where if any there is a connector in the wiring to the in tank pump? The price for the pump is outraegeous! Is there a good source for less than the dealer (holy crap) price? Thanks to all !

[jneary]

digger87 is probably right the fuel pump bleeds back and takes a while to bring the system up to pressure after long shut offs.

[Matthew Currie]

digger87 is probably right the fuel pump bleeds back and takes a while to bring the system up to pressure after long shut offs.

Yes, but I suspect there's something else wrong, because it should only cycle for a few seconds, and a couple of 5 second cycles should bring it up. I'd check the voltage at the pump and the pressure out of it, and don't forget the fuel filter.

[jneary]

well he can always put a fuel pressure gauge on it after shutting it off in the evening and see if it starts when the fuel pressure comes up to spec or after that

[gr8lite]

In the am , turn key to on position, wait in the on position for as much as 1 min before pump cycles (for 5 sec or less). Sometimes you must turn key on / off / on a couple times at the 1 min wait time before the pump runs. If the fuel filter were "clogged" would that make the pump sense pressure ? Therefore NOT run? Boy I really thank all of you helping me out on this one.This is my GF's rig. She is really getting fed up with this and wants to take my CJ.HELPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPp !!!

[jneary]

you should get fuel pressure when the key is turned on and while cranking, once fuel pressure is achieved, see how long it takes to bleed off. i think about 5lbs in 15 minutes is bad, but i cannot remember the specs on that.

[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 !