I have a 1991 xj6 that will not start. It will run intermit but will not run for long. The only thing the vcm shows is pro fail. I have checked and it has fuel pressure and spark and the injectors show a signal with a node lite. This is confusing me as if you have spark fuel and compression you should have a running engine. Any help here would be nice. No other code show up. I am going to probe the ecm again for missing signals or power.

thanks,
Hugh

 

Hugh:
Welcome to the forum! Don't forget to introduce yourself in the New Member section.

I'm not sure what "pro fail" means, and I'm wondering if you are reading it correctly. Pad fail, perhaps? Does the VCM display a number also?? Perhaps I've just not run across that one yet...

My second thought is whether you know (i.e. have kept it on a fuel pressure gauge) to be sure the system is keeping 40 psi whilst running, not just at start up.

Scott

 

Thanks Scott
I have good pressure, all the right signals at the ecm and starting to wonder about the spark quality. I pulled the plugs yesterday and they were fowled good cleaned and replaced after a no start pulled a couple and found fuel fowling. So today will be spent looking at the spark delivery. Crazy car will run backwards just a bit after you let off of the key?? but this only happens on sometimes.

Thanks for the help,
Hugh

 

Hugh:

I'm still wondering what the VCM is showing you. Once you shut off the car, turn the key to position II (without engaging the starter) and press the VCM button, assuming the check engine light (CEL) is on, it should give you a fault number. Please check and report back!
Scott

 

I finally got a code 14 the coolant temp sensor is over voltage. I confirmed this and it is showing battery voltage when the key is in run position. When it is being cranked it shows 2.1 volts??? I check compression and spark at the plugs I have both. I am wondering why do I have 12 volts on the temp sensor? it is pin 2 on the ecu and why does it go to normal during cranking? and why would it not at least run?

This one is about to get the boot.

Hugh

 

You have a fuel issue. Could be a intermittent fuel pump.