prepurchase 98 F250 Bifuel, things to look for?

[DMCCOY]

Hello everyone, I have been searching for a few months for a ford f150 or f250 bifuel in the Tulsa OK area and may have found one. I was wondering what things are typically needing maintenance on CNG vehicles. I found a truck with 60K miles, 1998 model and would like to know what questions to ask about maintenance before I decide to purchase it. Is there certain parts that need replacing at intervals or tend to go out? Or what maintenance I should expect to have to perform on the vehicle after purchasing. Thanks, I look forward to the .90 cents a gallon fuel charge=)

If there is already information posted with this same questions please point me in the right direction. Thanks.

[maxman]

Re: prepurchase 98 F250 Bifuel, things to look for?

Check to verify that the CNG system is indeed working. If it is like the 2000-2002ish models, there is a switch on the dash beside the steering wheel. Be sure the indicator light on the switch is lit when the key is on but the the engine is off. Be sure the switch in in the ALT fuel mode. Watch the fuel tank levels when it is in the different fuel modes. Look at sticker on the radiator brace where a lot of the labels are. Look see when the tank expires. Also, take the cover off the tank and look for inspection stickers on the tank. While the cover is off tank, check that valve area to be sure it is not bumping anything, look for rust, and make sure the tank is securely fastened in.Under the truck, on the drivers side, on the inside of the frame should be a CNG fuel filter little cannister about 2-21/2 inches in diameter and 3 inches long. There is a fitting on the bottom of it to drain it. I would get a 1/8 in allen wrench and crack it just a little to see what comes out. There may be some dirt and water, but it should also vent natural gas.
Try to staart the truck and drive it off when it is cold. Feel for misses. One of the biggest complaints on these trucks is the fuel injectors leaking at the seals and the coil packs, although I don't know if a 98 usest the COP (coil on plugs pack.) Feel for misses. see how it runs at highway speeds on CNG.
With it stopped and the engine running, put your foot on the brake with it in gear and press the accelerator all the way down for about 7-10 seconds. The engine should speed up, but only to a certain speed. If the engine is able to speed up, say in the 3000 rpm range, the transmission might be slipping. If the engine doesn't seem to speed up very much, the transmission is probably good, but the engine isn't putting out the power it should. 60,000 miles isn't bad. I would expect the engine and trans to be in good shape.
The biggest problem with the CNG Fords is the compuvalve.
When I buy a new vehicle, I like to take it to get a safety and emission inspection done. That's about the cheapest way I know to get a vehicle run through a quick check. With CNG, you might find a Ford dealer who has certified CNG technicians and take it to that dealer to have them run a diagnostics. It will probably cost about $80 or so. The Compuvalve is the biggest culprit on the Ford CNG vehicles.

Good Luck
Max

[DMCCOY]

Re: prepurchase 98 F250 Bifuel, things to look for?

wow. I was expecting a little response with a few pointers but the information you provided seems to cover about everything. Thank you. After reading a few threads in this forum I did read about the compuvalve and the expiration date on the tanks, but I had no idea about the other tips. I will look for a certified CNG ford tech to do a prepurchase inspection and go from there. Thanks again for taking the time to provide all the advice and information.

[maxman]

Re: prepurchase 98 F250 Bifuel, things to look for?

I'm not the expert here. However, this is what the forum is for is to help each other. I wish I knew then what.....you know the rest.

Good Luck!

Max