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Topic
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This is a 1988 Isuzu Impulse with 2.3L non turbo EFI with 5spd MT. Only 127k.
It always starts right up when cold although there is no sense that it has any fast idle provision whatsoever.
When I try to start it while fully warmed up it starts on all four then immediately dies unless I jab the throttle ever so slightly
once it initially fires then it will catch and all is fine. This car has been well maintained and recently passed California smog
even with this problem. Any ideas? Thanks.
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Try unplugging the coolant temperature sensor to see if that makes a difference. Also check fuel pressure or block the fuel return line if so equipped.
Thank you. I would not have guessed about those items. I have the weekend and will give it a shot and report back.
Today I connected a fuel pressure gauge and got a result that I didn’t expect. As I understand it most EFI vehicles develop fuel pressure at key on and from there it is what it is. On this one you turn the key and the FP does not run at all until you crank. Then it builds very quickly to about 50 psi. Upon starting it drops to about 35 at idle but as soon as you come off the TPS home position by touching the throttle it jumps back up to 50. There is a FP relay which when removed will not allow the car to run but it will always start and die unless you hold the key to crank with the clutch out so the starter goes off then it will run until you let go of the key. There is another identical relay with no identification as to what it’s for so I swapped them to no avail. An added note: at idle the fuel pressure gauge bounces very rapidly between about 25 and 45 psi. As soon as you touch the throttle it instantly smooths out at 50 until the engine returns to idle.
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