I'm just wondering if the CNG to gas conversion was done sloppy. Over the years, I've seen grounding issues cause intermittent problems. I'd go over the grounds. Both ends of each ground. I've seen cables that looked good at the top but at the other end be corroded. This includes the regular heavy ground cable, the cable that goes from the fender to the - terminal as well as the ground straps from the firewall to the engine.

Does it only fail when the van is hot? Any codes in the computer?

 

No lights are lit, but I haven't checked. I kind of figured if there was a code the check engine light would be lit up. So far it has only done it when it's hot. As far as the conversion that was done there hasn't been any issues with the van until now. It's going to be much cooler tomorrow morning so I'm hoping to make it home from the tow lot.

 

I had a thought. (Really!) What year is this van? A failing brain box on an OBD I system will do this. Those go bad so rarely, they get forgotten. If your van is a 1995 or earlier, that may be the issue. You can check for codes by doing the key dance. Do NOT hit the starter, but turn the ignition to on, then off, then on, then off and then on and leave it on the third time. This works on OBD I and OBD II. Either your check engine light will start flashing or the codes will appear in the odometer.

 

It's a 96. I have a code reader. I can check for codes when I get it home.

 

Darn, that was when Chrysler went to OBD II. You may have a transitional unit being a government purchase. If you have the OBD I engine controller, it may be bad.

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If you have OBD II.you won't have that but you will have a crank or cam position sensor. When those fail, they usually won't set a code because they just quit sending a signal. The computer doesn't know it's supposed to be getting one so it doesn't set a code.

Either way, they can both cause problems under a heat soak condition.

 

Got the van out of the police impound lot this morning and got to a block from the house before it died. Temp was in the 70's rather than the 90's. I have a code reader in the van that I have used not that long ago and it worked. All I got out of it was error. The pump would not run when turning the ignition on. Pulled it on home and let it sit. Went up a little bit ago and she fired right up. Code reader still read error. The fuel pump is now running when the ignition is turned on so the issue appears to be the fuel pump not running and killing the engine. Does the ecu have any control over the fuel pump?

I need to put the crossways tank support on that I picked up at pick and pull as I guess that didn't get done during the conversion. Would be a good time to put a new pump in. Is there any way for the rollover fuel pump killer circuit to act up and cause this? I hate to put a fuel pump in if it's actually something that is causing it to shut off.

 

I'm afraid I'm not computer savvy. It could be the ecm, others will know more than me. However, just because the temperature is in the 70's, doesn't mean the underhood is. If you have a hair line crack in a circuit part, like a cam or crank sensor, when it gets hot, the crack can expand and open the circuit.

 

Yep. Computer controls the fuel pump. Next time it dies, need to see if you are missing spark as well.

 

Yeah, I got out the manual last night and saw that the ecu controls the ground to the asd relay which cuts everything. It seems more logical it would be the ecu rather than the fuel pump. The really hard part is I'm not sure I can get it to do it here running in the driveway and that means another tow bill to get it off the road and back home to check things. I think it would be possible to ground the pin on the asd relay to see if that's the issue.

 

Throw some tools in it, and go for a back-road cruise. Have the doghouse already removed... Drive till it dies, troubleshoot from there.