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imtheboobman
11-13-2009, 06:52 AM
fuel pump runs on cranking position but not on run position
any ideas?
thanks rob

Nutbar
11-13-2009, 08:51 AM
Year and engine info might help

imtheboobman
11-13-2009, 11:40 AM
'89 4L

Happypants
11-13-2009, 02:19 PM
fuck this same thing happened to a buddy of mine in his 89 xj, he had to run constant power to the fuel pump relay cause something in the ignition or something fucked up and to keep the truck running he had to hold it in crank position,

Trailjunkie
11-13-2009, 05:04 PM
fuck this same thing happened to a buddy of mine in his 89 xj, he had to run constant power to the fuel pump relay cause something in the ignition or something fucked up and to keep the truck running he had to hold it in crank position,
what he siad. could just be the relay

Nutbar
11-13-2009, 06:14 PM
Most likely the ballast resistor is fried. It is a little white ceramic block mounted on the drivers inner fender near the air filter box it will have 2 wires going to it (89 the wires should be orange with a black tracer). Unplug the wires from the ballast resistor and hook them together and see if it will stay running.

They put in the ballast resistor to drop the voltage to the fuel pump so the pump was less noisey when running, but when cranking the fuel pump has a jumper going to it that supplies it with full battery voltage so you get maximum fuel pressure for initial start up.

imtheboobman
11-13-2009, 06:33 PM
checked the ignition switch, will check the resistor tomorow,let ya know
thanks all rob

imtheboobman
11-18-2009, 07:50 PM
changed the resistor today, it runs great, thanks nutbar for the advice