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Steve-O
January 8th, 2021, 09:53 AM
A friend of mine has a '93 YJ with the 6 cyl and auto trans. He's unable to start it right now -- it will crank but won't start. When he pulls the key out, he can hear the fuel pump continuing to run behind him and will only stop if he unplugs the battery. He said he recently replaced the fuel pump, so what electrical problem could be causing this? I'm going to tell him to check his fuel lines and that he should probably do a pressure test at the fuel rail ('93 is MPI). Thanks for any advice you guys can give!
Jim
January 8th, 2021, 01:08 PM
Was it running before he changed the fuel pump?
Steve-O
January 8th, 2021, 01:40 PM
Yes it was. More to the story: the old pump kept blowing fuses which is why he replaced it. Immediately after replacing the pump, the Jeep wouldn't start and pump runs nonstop, even with the key out, UNTIL he puts the key into ACC, then the pump stops. I thought this was really bizarre, I don't think the pump should be able to run at all until the key is at ACC (or does it have a "always on" line to the battery to be able to operate when the Jeep is off?). When I turn my key to ACC, I heard the pump run for a second or two then it stops. Seems like there might be 2 different issues here: whatever was causing his blown fuses, and now whatever trouble he created for himself by replacing the pump
DaveO
January 8th, 2021, 01:42 PM
Did he "burp" the fuel line at the schrader valve on the engine's fuel rail to be sure fuel is making it to the engine? If it has one...


edit - with the weird electrical issue - I try to figure that out first.
Jim
January 8th, 2021, 01:58 PM
Are you certain as to saying pump running in ACC vs RUN?

I think ACC should have no fuel pump power. When turned to RUN from OFF/ACC, my fuel pump turns on for a few seconds and then shuts down.

1) I'd see if fuel is being pumped to the engine bay - Dave's schrader valve test would be easy. Caution when opening the valve.

2) It seems quite possible to be an electrical issue. I'd check computer connections. He might wish to check this web page. No telling if it's related - just tossing it out.
www.jeepforum.com/forum/f12/how-repair-your-ecu-591031/