GM IMPCO maint and service question

[mattamhop Member Find all posts View Profile Close mattamhop]

I have had my 2001 Express bi fuel van for two months now and it is running great. Now my question is what if any service requirements are there for the CNG system- I've heard about CX's needing filters. What do I need to do with this beast?

PS My van came without a spare tire, and with the tanks in the location of the spare in the non-cng version of the van I was left with carrying the spare around in the luggage space in behind the back seat. I have 7 kids so we really needed that space and needed a new solution. Turns out rear door tire mounts for chevy's of this vintage (newer) do not exist, so I had a bit of effort to find one made for another van that would work on a chevy. The result is this: Miller Manufacturing, makes a bolt on rack for newer Fords called their "Ford Heavy Duty" that only needed a tiny bit of tweeking to get it to fit very nicely. That with a tire cover and some stainless bolts and we are sitting pretty with the spare outside the rear driver side door. I would gladly post photos if anyone is interested. The rack cost just over $100 delivered.

[Highmarker Regulars Find all posts View Profile Close Highmarker]

Re: GM IMPCO maint and service question

I don't know if the Vans have the same Impco system as the Cavaliers. For the Cavalier, I know you are supposed to replace the High Pressure Regulator Filter every 60,000 miles. You are supposed to clean the Filler Filter when necessary (replace the o-ring when you clean this filter). Other than that, I can't think of any other service requirements for the CNG system. You can remove the Low Pressure Regulator Cover and clean the diaphram inside with a clean cloth with a little bit of alcohol.

[mattamhop Member Find all posts View Profile Close mattamhop]

Re: GM IMPCO maint and service question

Thanks Roy,
It is an IMPCO system. Where is and how do I get at the filler filter? Where do I get a new one? The O ring, is that the ring at the filler nozzle?
Mattamhop

[Highmarker Regulars Find all posts View Profile Close Highmarker]

Re: GM IMPCO maint and service question

If you remove the o-ring in the filler port, you can use snap-ring pliers to remove the snap-ring and then the conical shape metallic filter will come out. Clean the filter in some acetone or alcohol and then put it back and put the snap-ring back in place. You most likely will damage the o-ring getting it out, so you should replace it. The o-ring is a -110 size Buna-N o-ring.

[mattamhop Member Find all posts View Profile Close mattamhop]

Re: GM IMPCO maint and service question

Very cool, thanks Jared. Last question for a while, I took the van in for routine maint (oil change, etc) and to deal with a check engine soon" light. The mechs put their computer on it and found that it was misfiring like a bandit on gasoline but running fine on CNG. Got any insight into that? Also, where would I get a service manual for the CNG system? I wrote a letter to IMPCO right off when I got the van looking for a manual and got no response from them. Anywhere I could get my hands on some documentation for that system?