rocketknight03

I have all ready checked out my injector relay and replaced it doooo to corrision. But the problem lies furrer up stream somewhere. my only idea is a bad ecu now. since the power come in and goes out to start the injector relay. I get power to starter, but only power to pump when cranking.,,, none when key to acc. any help would be great! no fuses blow either. maybe some other relay i dont know about~>? i just wish this was a nissan... i know i know

BlueKitsune

Did you check your injector dropping resistors yet to make sure their fine? Also your fuel pump wont run with the key in on when you have no oil pressure or power from the alternator (basically the motor has to catch before the pump will run with the key just in on) And it will not run in acc sense that just puts power to the clock, radio, and AC.

rocketknight03

but it will prime the pump when key to on for fuel pressure. gonna check the drop resistors tomorrow. currently ripping into my dash to fix the mess of a wiring someone did. solder....is that soo hard to do... any other ideas would be grand. i'm new to the L series.

theramz

The '78 need the alternator to turn for the pump to work in the start condition. After the engine starts and the key is on the oil pressure sender completes the circuit to continue running the pump. On the '75-'77 needs the start position to run the pump. After start the afm flap must be open to keep the pump running. Depending on what year you have, the circuit is not complete after "start."
You should have power to the injectors with the key on. The ecu grounds the circuits to batch fire the injectors. That's why there are two sets of resistors. Each set fires every other rotation.

rocketknight03

you mean the drop resistors, and there is just two coloums but a tottal of six.... this is just tooo bizzare! i was running, and then just died idle'n. then no re-start. and no more power to pump or injectors? any of this sound like somthing common? didn't have enough time after work today. tomorrow, voltmeter and ohm testing "HURRAY" and the dorp R should be at 6 ohms correct?

BlueKitsune

No air movement/Alt power, Or oil pressure = none running fuel pump while the key is "On" but it should run no matter what when at "Start"

You know did you check your fuses and fuseable links yet to make sure one didnt get fried?

theramz

You still havn't told us what year you have. It could be as simple as the contacts on the ecu or the wiring harness. The correct manual for your specific car will step you through the entire fi system. As for the resistors either they work or they don't. Blue is right in that the pump is working in the start position but it should start when you try it again. You can buy a cheap fuel pressure gauge to make sure you are getting 35 psi all the time. Might be as simple as a clogged filter which would give you enough static pressure for a start but not continuously or a restart.
You can remove the small wire from the strarter and turn the key to start. This will run the pump but not the starter so you can listen to the pump run or check the pressure. If the pump sounds weak or the pressure is low it won't run.

rocketknight03

76--- tested the drop! 6ohms, great! injector relay good! ya! body grounds good! ecu grounds GOOD! no power output from ecu..... SAD looking like a fried ECU, guess getting it running was too much from the old beast! lol this car has been sitting since 97

theramz

ECUs aren't usually intermitent. The starting leads me to believe a there is a weak ground which will show good with a tester. Test the ground from the ecu plug negative pin to the battery -, not chassis ground. You still need to test the fuel pressure.

rocketknight03

the solder inside the ecu remelted. have new one in hand. but with the old one plug back in. EVerthing good toooo goooooo, swaping ECU tomorrow. anyone have an idea of the fuseable links in engine bay amp valve?

theramz

As far as I know there is only one way to melt solder. Theer is one pin on the harness plug for battery ground and one for positive. They are both red. The factory connectors near the battery made it impossible to reverse them. Since your harness has been tampered with you should ckeck it thoroughly as per the fsm for possible shorts to ground or other wires.

rocketknight03

when any of the millions of resistors inside a ecu go bad,,, or build up any crude on the termials. they make more resistors' so more heat, the hotter they get. the better chance of a damaged solder point. they usely turn brownish.thanks again for the help guys..