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View Full Version : fuel problems??? (long)


themud
April 18th, 2004, 20:45
Ok so I went and did the 99 manifold swap to my 95 it wasnt really that hard at all and cleaned my for now stock throttle body and had my injectors cleaned and flow tested and now I have this crappy long start up time???? I dont know whats causing it it seems to take like 7 or so seconds of straight cranking before it turns over then when it does its real weak running for like 2 or 3 secs then goes back to normal...Im thinking the pump is going out because if I start it then after a minute or so then turn it off and restart it it starts right up??? I just cant figure this one out :huh: am I just not getting enough fuel all around?? or is it a IAC motor finally going on vacation or maybe just the pump is finally dying on me didnt have any of these problems before hand and it usually started on the first or second rev of the motor before...lets hear them ideas!!! :yelclap:

Bryan C.
April 18th, 2004, 20:55
I would say check your fuel pressure drop after you shut off the engine. It should hold at least 30psi for 5 minutes after shut off. Sometimes what happens is all the fuel runs back into the tank when the Jeep sits for an extended period of time if the one-way check valve inside the pump is bad. Just use a fuel pressure gauge and see how long the pressure holds. If it drops to 0psi quickly, try pinching off the rubber hose that goes to the fuel pimp and then see if the pressure holds. This will tell you if the pressure regulator on the fuel rail or the fuel pump itself is bad.

Bryan

Eagle
April 18th, 2004, 22:33
I would say check your fuel pressure drop after you shut off the engine. It should hold at least 30psi for 5 minutes after shut off. Sometimes what happens is all the fuel runs back into the tank when the Jeep sits for an extended period of time if the one-way check valve inside the pump is bad. Just use a fuel pressure gauge and see how long the pressure holds. If it drops to 0psi quickly, try pinching off the rubber hose that goes to the fuel pimp and then see if the pressure holds. This will tell you if the pressure regulator on the fuel rail or the fuel pump itself is bad.

Bryan

What he said.

It sounds like the fuel rail isn't holding pressure when parked for extended periods. When you start, do you wait a few seconds while the fuel pump runs up the pressure? How long does it run? How long does it run on a hot restart?

themud
April 19th, 2004, 10:08
What he said.

When you start, do you wait a few seconds while the fuel pump runs up the pressure? How long does it run? How long does it run on a hot restart?


I actually thought this could be the problem so I purposely tried to pressure up the fuel rail I let it sit with the key on for like 10 secs that made no differnce what so ever as far as helping the starting problem....I cant actually hear the pump running to pressurize the rail(this might be a bad sign) well at least not from the drivers seat...I cant hear it either on a hot restart I just know that it fires right up like nothing is wrong??? It once and a while also just starts up like its normal but those times are very rare like twice so far...As far as the fuel pressure guage Im gonna grab one on the way to work and hit it tomorrow...keep em coming... :dunce: