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Unread 03-12-2013, 10:24 PM   #1
JESSERIDER
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jeep 4.0 cranks but will only start after may tries

My jeep sat for three months I would start it about once a week but not much driving. I've replaced the battery with an optima yellow top. Now when I try to start it it will crank but only start after many tries and pumping gas pedal. I've take off the air intake , tried starter fluid , I just don't know whare to go from here. When I do get it started and driving it will start right back up , but if it sits for over a few hours it will crank but not start again=/

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Unread 03-13-2013, 12:29 AM   #2
seattle_yj
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Quote:
Originally Posted by JESSERIDER
My jeep sat for three months I would start it about once a week but not much driving. I've replaced the battery with an optima yellow top. Now when I try to start it it will crank but only start after many tries and pumping gas pedal. I've take off the air intake , tried starter fluid , I just don't know whare to go from here. When I do get it started and driving it will start right back up , but if it sits for over a few hours it will crank but not start again=/
Keep that yellow top charged with a battery tender brand charger when not in use for over a week. I blew through two of them by letting them sit.

Anyway, on to your issue. Will it start once you pump the gas a few times? Or hold the pedal down? I would start with inspecting the fuel pressure because it is a simple check. You can rent a fuel pressure gauge from auto zone for free, or buy one one line for <50 bucks. Your fuel psi should be 40. When you first flick on the key and the fuel pump primes, you should see your psi at 40. If it falls rapidly then you have a fuel leak.

Once you do get it started, pull the vac line to the FPR, if there is fuel coming out is it, you have a bad regulator and it needs to be replaced. This is another simple test.

How do your plugs and such look? Good time to change them if they are old.
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Unread 03-13-2013, 12:38 AM   #3
JESSERIDER
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Its really hit and miss. I will pump the hell out of the gas and get nothing , and then somtimes it starts up. After a good drive ill turn it off and it will start right back up again but if I let it sit for a while its back to the problem. I am checking plugs , cap , rotor tomarrow in the morning. I hear a lot about csp sensor but it dose start after many , many tries. There is a valve stem of sorts on my injector rails and when releasing it gas squirts out so the fule is there. Have not checked inhectors but recently ran lucas injector cleaner through it along with a few tanks of gas.
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Unread 03-13-2013, 09:45 AM   #4
seattle_yj
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Quote:
Originally Posted by JESSERIDER
Its really hit and miss. I will pump the hell out of the gas and get nothing , and then somtimes it starts up. After a good drive ill turn it off and it will start right back up again but if I let it sit for a while its back to the problem. I am checking plugs , cap , rotor tomarrow in the morning. I hear a lot about csp sensor but it dose start after many , many tries. There is a valve stem of sorts on my injector rails and when releasing it gas squirts out so the fule is there. Have not checked inhectors but recently ran lucas injector cleaner through it along with a few tanks of gas.
I would check the pressure anyway though. If its off by 10 psi it will not start correctly. I would eliminate that first.

Your right it doesn't sound like cps.

So once it's running does it run correctly and idle correctly?

And you have no cel codes correct?
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Unread 03-13-2013, 09:51 AM   #5
biffgnar
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Bad flow back valve in the fuel system. When it sits for some time all fuel drains back into tank. When you start it takes a few seconds for the pump to make up for that. When you turn it on again right after stopping fuel hasn't had time to drain back so still works. Not an uncommon problem. Most people just live with it.
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Unread 03-16-2013, 07:10 AM   #6
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Quote:
Originally Posted by JESSERIDER View Post
My jeep sat for three months I would start it about once a week but not much driving. I've replaced the battery with an optima yellow top. Now when I try to start it it will crank but only start after many tries and pumping gas pedal. I've take off the air intake , tried starter fluid , I just don't know whare to go from here. When I do get it started and driving it will start right back up , but if it sits for over a few hours it will crank but not start again=/
What year Jeep is this 4.0 in?
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Unread 03-16-2013, 09:10 AM   #7
JESSERIDER
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Thinking its the ASD relay and its a 99
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Unread 03-16-2013, 10:13 AM   #8
biffgnar
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Originally Posted by JESSERIDER View Post
Thinking its the ASD relay and its a 99
What makes you think that? If ASD relay were bad the jeep would be dead. AS = Auto Shutdown. That is the circuit commonly used to make hidden kill switches.
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Unread 03-16-2013, 10:54 AM   #9
JESSERIDER
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That's what the shop said , I've worked on it for three days straight and can't find the issue. Between work I just ran out of time
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Unread 03-16-2013, 12:11 PM   #10
biffgnar
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Originally Posted by JESSERIDER View Post
That's what the shop said , I've worked on it for three days straight and can't find the issue. Between work I just ran out of time
Did you read my prior post? If you use search function, plenty of threads discussing similar circumstances to yours and the fuel flowback valve.
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Unread 03-16-2013, 12:51 PM   #11
JESSERIDER
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Yes , and that's a majority of what I read also. As well as the crank postistion sensor. The thing is I have pressure in my fule rail for a long time afrter shutting off the motor. Even turning the key in on position so the fule pump can fill the lines dosnt work. It just phantom starts and after sitting for more than an hour or so its back to square one. I have to move in three days and without a ride I lose my job. Between all the stress and how busy I took it to the shop and still havnt got a final anser
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Unread 03-20-2013, 11:08 AM   #12
JESSERIDER
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Ended up being the ASD relay belive it or not....runs like a champ again.
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