Instant shut off!
 

Hey everyone, hope your all enjoying the summer. I had a funny thing happen today. I pulled up t oa dumpster and shut the truck off. Climbed in, turned the key on and as soon as it fired , it shut off. I tried for the next 10 minutes every few minutes to try and re-fire. It finally did. So, on the way home from work... i was driving and at about 1700 rpm, it shut off for about 1/2 second then back on and i made it the rest of my 15 minute drive home. Its a 99 with 310,000 kms.....Does the 99 have the on/off key code dispaly? Any ideas what i could try? I put a new fuel filter on 6-7 months ago.. Help!!!!!

My truck engine shuts off as soon as it fires up. It doesn't do it much in warm weather, it happens more in the winter. I found out that the ECM is actually shutting off 12v power to the VP44. I haven't figured out why the ECM is doing it.

In your case, monitor the 12v supply to the VP44 and see if it is being turned off.

The 98's and 99's won't do the odometer code reading, you will need a scanner or a programmer to retrieve those codes. Does the tach go dead instantly, or does it slow down with the speed of the engine? I have a hunch it may be a crank position sensor, but I'm not sure if it would kill the engine or just put it into limp mode. If the crank sensor fails, the ECM thinks the engine has stopped running and will kill all other accessories.

When it does restart, does it fire up normal, or is it a hard start and a lot of smoke? If its a hard smokey start, I'd be looking at a fuel system malfunction, if it fires up relatively easy when it does start, I'd look for electrical gremlins. Either way, get those codes, will give you a direction to investigate.

Good advice guys.....I posted all my codes yesterday and people have commented. Looking for more advice on which ones to do first for order of importants. Thanks averyone.