90 not getting fuel through injectors


javatrooper
04-11-2009, 06:06 PM
My 1990 trooper is getting fuel to the TBI but the injectors are not spraying. The trooper died suddenly as if it were electrical. Anyone know how to test to see if injectors are getting a signal from the ECU? How can I test to see if ECU is getting electricity? I swapped ECU unit and no change. Anything inside the TBI that is blocking flow? What do I look for? Any advise is well appreciated.

fourwd1
04-13-2009, 04:00 PM
You should be able to see the signal for the injectors with a voltmeter. Either by sliding the probe in beside the the connector pin, or by disconnecting the plug to an injector and connecting directly.
Same for the power to the ECM. You'll need as wiring diagram to determine which pin on the ECM connector. The only diagram I have is for my 00 Trooper, so I can't tell you which pins on the ECM.

gesellman
04-13-2009, 10:48 PM
Add a brand new ground to the block.
I had the same problem, only it was only one injector which did not work. I added a new ground to the block and it started running fine again. Also, there are several ground wires bolted to the side of the intake manifold. Take them off clean them and put them back.
Check the wiring harness coming out by the battery and towards the firewall and see if moving them around gives you juice to the injectors.

sassee
05-08-2009, 09:11 PM
It's always the grounds! The torque convertor in mine was locking and unlocking constantly at highway speeds. I thought I had some serious issues. Turned out to be bad ground. Found it by accident when disconnecting the battery to weld on my new sliders. Has run fine ever since.

Ernie

javatrooper
05-10-2009, 08:54 PM
Found the problem. Turns out that the fuel pump and the injectors were not getting voltage. I could get the injectors to spray with the fuel pump hot wired and the injectors hot wired, but the injectors were not getting signal for the computer. So after stripping the wiring harness on my parts car and following the wire from the injector, I found the hidden relay on the passenger front fender under the L bracket. It was the brown relay. Swapped relays and she fired right up. Only took me 5 days to figure it out. It took so long to find it because the wire from the injector is spliced inside of the harness to another wire of a different color. Thanks all for you suggestions. For some reason I was not receiving you email replies. Just noticed them today while checking the forum.

Add your comment to this topic!