maric734

I started with an 89 XT that was only running on 1 maybe 2 cylinders (#1,#3). After doing some trouble shooting (which I describe in earlier post) I decided to check the wiring harness. This is where my problem was. There were factory splices in all 4 wires that feed the fuel injectors. I know it came like this because the wiring was still in factory foam rap under the carpet on passenger’s side. Why this was done is the mystery, must have to do with the different types of fuel systems (carb, spfi, mpfi) that were available. The ECM just works as a ground in this system so check all voltages at the pins and resistance or voltage of component. You can also check the fuel pump relay this way for those of you that use toggle switches for your fuel pumps!

Hi Glad to see somebody wanted to respond to this. Went to libary to get info from a Mitchel manual. Says I should have 10-12V at pins 49-52 at the ECM which I don't have. I do have 11.9V at the connector on the firewall on all 4 injectors. I checked the resistor block and resistance on injectors both fall within spec. also voltage at pin 59 is way low, should be 10-12V and is only .5V This controls the Aux Air Valve which checked out fine on resistance. The voltage test is done with ignition on and ECM unpluged, what is strange is that the voltage is different with the key, off but the wiring diagram shows a straight shot form injectors to ECM. Next thing to do is start checking the harness for shorts. What a bummer!!

New to this site and would like to say HI. Just bought my second sooby. First was a 87 GL 10 and loved it. I just got a 89 XT GL AWD, but its not running well at all. Only one or two cylinders on the passenger side fire. First checked compression and got 130 to 140 lbs. in all four. It will run fine if you supply fuel (starting fluid). Changed the fuel fillter and the pump runs fine, has good presure after the fillter. Then checked injectors. none are open or have high resistance. Then checked for current at injectors with niod test light and showed no juice. I found the ECM in the trunk instaed of under the dash thanks to this site. I get code 14 and 15 which is abnormal injector output. Does this mean the injectors are bad (all 4 at once)and why is there no current at the injector or is the ECM bad or could it be just a short in the wiring. Please and Thanks for any help.