One bad injector??

dbmart

New Member
Hello all. Having a problem where I am banging my head against the wall. I have one injector(CYL 1) that's stuck wide open. I replaced the spark plug and verified that the cylinder is getting spark. I replaced the injector in question with a brand new one and I still am getting the same issue. I am able to build fuel pressure when cycling the key on when injector #1 is unplugged. As soon as its plugged in or if cycling the fuel pump with it plugged in, my fuel pressure drops to 0. I know its stuck open because I've shot liquid fuel out of the spark plug hole about 3 times now trying to figure out this issue. I can read 12volts on one prong of the injector plug, and I read .64 volts on the other. I was under the impression that the ground side of the plug is what fires the injector from the injector driver. Maybe a short? Car was running perfectly one day, parked it, and this issue appeared next day. I am stuck on what to do next and would appreciate any input! If it helps-lightly built motor-80lb injectors(chipped)-warlboro 450-hotwire kit.
 

dbmart

New Member
Picking up a noid light kit from autozone tomorrow as I don't have one. I'm assuming there will be no pulse but I guess I'll find out.
 

hensleyt

Active Member
Sounds like a injector harness problem or the plug to the harness . I got a intake onetime that the wires were badly cracked.
 

dbmart

New Member
I will report back my findings later today when I get a chance to work on it. Thanks for the suggestions. If an injector driver is bad I would have to replace the ECM correct? Hoping it's just the injector ground wire somewhere along the line to the ECM. Fingers crossed!
Thanks
 

TIMINATOR

Active Member
As I remember, the injectors are continously supplied with voltage. Easy to check. The computer driver grounds the other lead to operate it. If you have a shorted to ground wire on that side the injector will stay open. Or you need a computer. Somebody should have a stock computer cheap, or to borrow for diagnostics, rather than you buying a rebuilt one.
TIMINATOR
 

dbmart

New Member
Well I only got to look at it for a few minutes this afternoon and will dig deeper tonight. That is my understanding as well. I tested the hot side of all the injector plugs and they all get 12v with key on. I'm sure reading voltage for the ground side has no bearing, but they all read about 100mV give or take except injector #1 which reads 600mV. I will take apart the harness tonight, check resistance and for shorts and will continue on towards the ECM if I cant find anything in the wires themselves.
 

dbmart

New Member
So I decided to take a look at the ECM and found nothing immediately questionable. Took off the intake side of the fuel injection harness and tested the resistance through each injector plug and got the same readings. Checked continuity to ground. I pulled up the engine harness side(female connector) and found some shiny wires with broken insulation. Managed to separate them out and sloppily rig up the fuel injector harness and she fired. Held fuel pressure and ran rough for a good minute before smoothing out but was/is firing on all cylinders. Guess it was a short after all. Thanks for the help fellas I appreciate it.
 

Buick Mark

Active Member
Hello all. Having a problem where I am banging my head against the wall. I have one injector(CYL 1) that's stuck wide open. I replaced the spark plug and verified that the cylinder is getting spark. I replaced the injector in question with a brand new one and I still am getting the same issue. I am able to build fuel pressure when cycling the key on when injector #1 is unplugged. As soon as its plugged in or if cycling the fuel pump with it plugged in, my fuel pressure drops to 0. I know its stuck open because I've shot liquid fuel out of the spark plug hole about 3 times now trying to figure out this issue. I can read 12volts on one prong of the injector plug, and I read .64 volts on the other. I was under the impression that the ground side of the plug is what fires the injector from the injector driver. Maybe a short? Car was running perfectly one day, parked it, and this issue appeared next day. I am stuck on what to do next and would appreciate any input! If it helps-lightly built motor-80lb injectors(chipped)-warlboro 450-hotwire kit.
Its an old time problem, but check the injector wiring that runs by the EGR valve, it likes to melt thru.
 
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