It did this once before and the temp sensor front and center was bad, this time not.
I have a factory manual and best I can tell this thing should run. It sets no codes on ecm and the check engine light does not come on. When the aldl is jumpered it gives me code 12 only. Unless I induce a code by short/open temp sensor or unplug tps, or something like that, then it catches it and will display the proper code.
here are some statistics:
4.5v map sensor voltage output measured on pin at ecm
.5v tps reading at idle swings to about 4.8 smoothly while cycling to WOT measured on pin on ecm.
3.3 v across manifold temp sensor, measured on pin at ecm. Sensor reads about 3.5k ohms around 65 deg.
fuel pressure is 12 psi at TBI input.
plugged noid light to injector connectors and it pulses when cranked. Not on solid.
performed test on 4pin connector from distributer with test light to pulse the injectors / noid light and that worked fine.
I tried the ecm in a buddys 91 w/4.3 and my ecm ran his engine fine.
changed the ignition module because thats what gives the pulse to the ecm to fire the injectors. No help.
It has great spark and new tune-up
I did replace the distributer pickup coil with a junkyard unit not long before it started these shenanagans because the old one died and I had no spark. That fixed it and it ran fine for a couple of months after that.
It looks like you could take a shower under the injectors. I have seen the injectors operate properly making a nice cone shape of fine mist. They now are making almost a solid cone, Their really puttin it out!
Injectors do not leak a drop when unplugged from wiring harness.
Is it possible they can go bad and put out too much fuel but still switch on and off perfectly?
I am at wits end as my mom used to say. :Cry:
have the same problem?
Friday, March 23rd, 2007 AT 7:23 PM