sudden death with no restart

[jbland83]

Doing 65mph down the eway on my way home from work and the truck dies. As it's rolling it starts back up and all is fine for a min. Dies again and this time doesn't start back on it's own, so I stopand start it back up and again all is fine. Half mile down the road it dies again and will not start.

Unplugged chip - no change
changed pcm fuse after unplugging fuel bowl heater - no change

I have no tach, oil pressure, or wts light

I'm sitting here waiting on tow and al info points to dead pcm. Trying to confirm. Thoughts?

[NoRalPh]

First, what year is your truck?

What fuse did you replace? Was it blown? Look at ALL the others too (esp #30-19-22)

If you have no WTS than yes, sounds like the PCM isn't running BUT, with those restart symptoms, sounds like fuel delivery too (a blown fuse or dead PCM doesn't run and die again)

Fuel - pump runs? Fuel refilling filter housing? Tank below 1/4?

[jbland83]

manufacture date of late 99.

I swapped out the 30 amp under the dash for the fuel bowl heater/pcm. Also checked all fuses with one of those cheap, light up fuse testers. Everything tested good.

fuel tank is full. Fuel bowl is full, even checked for water. I'm pretty sure the pump was running, but I'm going to go double check that in a few mins.

thanks for the reply.

[NoRalPh]

Remember the pump only runs for 15-20sec after you turn the key on (if the engine isn't running). Open the yellow lever on the fuel bowl and see how much comes out from the metal tube behind the pass ft tire. Close it and turn the key on for 20 secs and see if that bowl refilled with fuel or not (do it couple of times maybe..)

Do you still have no WTS though? 'Cause you gotta fix That or the pump isn't going to run at all!

[ToMang07]

Originally Posted by NoRalPh

Remember the pump only runs for 15-20sec after you turn the key on (if the engine isn't running). Open the yellow lever on the fuel bowl and see how much comes out from the metal tube behind the pass ft tire. Close it and turn the key on for 20 secs and see if that bowl refilled with fuel or not (do it couple of times maybe..)

Do you still have no WTS though? 'Cause you gotta fix That or the pump isn't going to run at all!

That's the key right now! If the WTS light is coming on/off like normal, the PCM is fine. No WTS means you probably have a bad fuse still.

[jbland83]

no pump and no light still. Went back and checked all fuses again, and they are all good.

[jbland83]

replaced fused 19 22 and 30 to be on the safe side. still nothing.

[jbland83]

So any ideas as to how I would check the pcn without having a known good one to swap in? All fuses are good, and its getting some power cuz my chip turns on. Is there a way to bench test it to see if its turning on or responding?

[NoRalPh]

Boy, not that I know of...

But, again, the last thing I would want you to see is to replace it, find it's not powering-up and then find a power issue like a fuse/relay/connection.

Because, in most cases, that's what it is (I'm not saying your PCM can't be just bad, just want you to be 100% sure before you make that call)

And what are you doing with your chip still connected? Take that thing Off because it's a common problem for the PCM to get "confused" by programming. Any way to get some sort of a Scanner on it? Even a cheap crappy one (that won't properly pull codes on our trucks) will show communication with the computer and let you know it's Not just a power issue.

[jbland83]

Chip was removed as previously stated. Just saying that if its hooked up it is getting power. All the fuses have been triple checked. Which relays or connections should I be looking at?