1998 Isuzu Rodeo - 3.2L No Start

[bmadison31]

1998 Isuzu Rodeo 3.2 V6 Starts great when cold if you shut it off it may or may not restart for a couple minutes. When it will not start there is no injector pulse but spark is okay. I have checked the two ecm grounds. I have replaced the ecm. I have tried new crankshaft position sensor. Nothing makes any sense. All help would be appreciated.

[ricmorin]

When it is in the no-start condition, check for your 5v reference signal. Something may be pulling it down intermittently. Also check computer powers and main relay. Is there a CEL prove-out during the condition?

[bmadison31]

There are no check engine lights. The 5v reference to the crankshaft sensor is good. I havn't checked it to anything else.

[bmadison31]

The injectors are loosing the ground signal from the ecm. The power wire from the main relay is always hot.

[steven kiser]

I'm shooting from the hip here. i'm remembering an issue along these lines and these vehicles had HUGE issues with the wiring harnesses for the engine. i believe the ground in the harness was something like a static strap and would disintegrate. I'd check the signal from the cam and crank sensor from the sensor to the pcm. look for oil in the plug. i may have a harness kicking around in my room full of stuff that i should have thrown out. p.m. me if you pinpoint it as the harness and give me the par # and I'll take a look. i can't say for sure because it was about three yeas ago and because of back order issues the customer got rid of the car. when it finally came in even though he owned it he didn't want it. i usually save harnesses for the plugs so i may still have it. if we're lucky it hasn't been cannibalized.

[bmadison31]

I found a TSB referring to the sheilding wire interfering with the splice for the 5V ref to the crank sensor. I opened up the harness found the splice and the repair had already been made. I taped it all back up per the TSB's instruction. I still have to shy away from any wiring problems with crank sensor since spark is always present. I'm only loosing injector pulse. (My TPS sensor is not in clear flood mode)

[steven kiser]

i believe cam sensor controls the injector timing. when vehicle will not start have someone crank while you wiggle the harness. check to see what side of the injector plug isn't functioning. is it the power or the negative trigger pulse

[bmadison31]

Problem solved bad MAP sensor. Tapped on sensor vehicle would die. Never threw a fault code though guess because it quit running everytime it had a problem

[steven kiser]

thanks for posting fix