HELP! DESPERATE! Car starts but than instantly Dies unless I keep holding the starter

THe car is doing something super weird. Its a 1990 XJ 4.0L I6. When I go to start it, it fires right up but as soon as I let go of the starter it immediately dies. Even when I rev the gas while the starting is engaged the car will rev up but as soon as I let go of the starter and return the ignition to "ON" the car will die. Sometimes when if I keep the starter cranking even tho the engine is already firing for like 6-7 seconds it will eventually run on its own. Its super weird. Sometimes it starts normally. Does anyone have any ideas? IACV?

well a guess would be to check your ignition switch, since you said it dies right away in the run position. prolly need a wiring diaghram though. someone might know how to by-pass it to keep it running temporarily. i am sure someone will chime in with a similar problem that they have solved.

Kal said:

THe car is doing something super weird. Its a 1990 XJ 4.0L I6. When I go to start it, it fires right up but as soon as I let go of the starter it immediately dies. Even when I rev the gas while the starting is engaged the car will rev up but as soon as I let go of the starter and return the ignition to "ON" the car will die. Sometimes when if I keep the starter cranking even tho the engine is already firing for like 6-7 seconds it will eventually run on its own. Its super weird. Sometimes it starts normally. Does anyone have any ideas? IACV?

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Check the ballast resistor. When starting the fuel pump gets full voltage, but it gets fed through this resistor to drop the voltage a bit after it's started.It's up front, drivers side, on the firewall, next to the airbox. It's about 1/2" square by 2" long. If it's cracked or broken you'l get these symptoms. Try jumping across it with a short wire and see if it keeps running. It could be a bad ignition switch, but the ballast resistor is a common problem.

Re: HELP! DESPERATE! Car starts but than instantly Dies unless I keep holding the starter

Here is the thing tho. Once its running on its own it runs tottaly fine, accelerating etc no problems so I doubt its the fuel pump resistor. It is only an issue to get the thing to run on its own right when you let go of the starter on start up. I guess it is possible its the ignition switch but I was thinking about the idle up control on start up being the cause. I too am thinking it could be the ignition switch.

Re: HELP! DESPERATE! Car starts but than instantly Dies unless I keep holding the starter

Jump the ballast resisitor, just as a test. The balast resisitor can be a sometimes thing. I cut one end off of mine and put a male/female end on it, makes testing easy. It will likely screw up sooner later anyway.
If the IAC is sticking closed, you can often kind of coax the motor to life. And sometimes after the TB heats a little, the sticky stops and it works just fine.
It kind of sounds like you have a bad contact in the ignition switch though.
You can back pin the large yellow wire going to the Ignition control module (under the coil), hook up a volt meter and watch what the needle does during start and when the key is released.

Re: HELP! DESPERATE! Car starts but than instantly Dies unless I keep holding the starter

Replace the Power Relay AKA power latch relay.

langer1 said:

Replace the Power Relay AKA power latch relay.

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Also check the fuel pump relay.