OK. THis is going to be a long winded post...
The back story:
A week after buying the MJ I had to have it towed. It had melted the fusible link to the fuel pump/injector circuit. With the help of Langer1 I got it running in the wee hours of the night (thanks Langer, still owe you lunch)
I replaced the fusible link with a fuse holder, and I had been using a 20A fuse. I put another fusible link in and it does the same thing. RIght nw I've got the fuse in for troubleshooting purposes.
THe problem:
At WOT the motor will stop running at 3500 RPM. It always blowes the duse/link on the fuel pump circuit. I can rev past 3500 RPM if I'm below 80% throttle. I don't think it's anything mechanical. Replace the fuse, it will start right up.
WOT is fine below the 3500 RPM mark.
Troubleshooting:
I pulled individual injectors and ran on 5 injectors until the cutoff point. No change.
I don't have a fuel pump ballast resistor, for what that's worth.
Wiring harness seems to be in ok shape. I pulled back all the loom on the injector harness and there's no damage.
I know the fuel pump wiring is good, in the troubleshooting when it died I inspected every bit of it.
I'm at a loss as to what to look at next. I'm thinking it might be the fuel pump, but that doesn't make sense. It always runs at the same current draw and the regulator returns the extra fuel.
Someone with more experience just point the newb in the right direction. I'm handy with a multimeter.
Thanks.
1987 MJ 4.0 Engine is most likely from a 90, ECU is orginal 87 unit. Injector year unknown. Fuel pump unknown.
The back story:
A week after buying the MJ I had to have it towed. It had melted the fusible link to the fuel pump/injector circuit. With the help of Langer1 I got it running in the wee hours of the night (thanks Langer, still owe you lunch)
I replaced the fusible link with a fuse holder, and I had been using a 20A fuse. I put another fusible link in and it does the same thing. RIght nw I've got the fuse in for troubleshooting purposes.
THe problem:
At WOT the motor will stop running at 3500 RPM. It always blowes the duse/link on the fuel pump circuit. I can rev past 3500 RPM if I'm below 80% throttle. I don't think it's anything mechanical. Replace the fuse, it will start right up.
WOT is fine below the 3500 RPM mark.
Troubleshooting:
I pulled individual injectors and ran on 5 injectors until the cutoff point. No change.
I don't have a fuel pump ballast resistor, for what that's worth.
Wiring harness seems to be in ok shape. I pulled back all the loom on the injector harness and there's no damage.
I know the fuel pump wiring is good, in the troubleshooting when it died I inspected every bit of it.
I'm at a loss as to what to look at next. I'm thinking it might be the fuel pump, but that doesn't make sense. It always runs at the same current draw and the regulator returns the extra fuel.
Someone with more experience just point the newb in the right direction. I'm handy with a multimeter.
Thanks.
1987 MJ 4.0 Engine is most likely from a 90, ECU is orginal 87 unit. Injector year unknown. Fuel pump unknown.