F250 Powerstroke Natural Gas Conversion Project Pt. 5

Click here for Part 1, here for Part 2, here for Part 3, and here for Part 4

I suppose it’s not necessary to leave the wiring until last, but I have chosen to do so. The wiring process is very simple if you’re only installing the kit. The kit comes with two crimp-type wire connectors, a switch, and a length of red wire. One of the two wires on the conversion kit solenoid is a ground wire and the unit is meant to be grounded via one of the bolts that mounts the kit to the bed. The other one is the positive voltage to energize the solenoid.

Find a source of engine-on-only power somewhere, either under the dash or under the hood. Just turn the key on to the run position, and ground your test light. Poke around at electrical connections until you find one that’s lights up the test light. Turn off the key and check the connection again. If there’s no voltage present, you’ve found your power source. I chose to connect to a solenoid under the hood.

I’m a little bit hyper about my wiring connections because there’s no problem more maddening to find than an intermittent ground or something like that. For that reason I don’t like crimp connectors and I loathe Scotchloks. I’m a big fan of solder and heat shrink tubing wherever I can use it, especially when the connection might be exposed to the weather. I also like ground connections to be made under the hood, at least. I’ve seen some body grounds get pretty unreliable as the vehicle ages and rusts, especially grounds toward the rear of the vehicle. But the body grounding under the hood is usually pretty decent. So I chose to solder and heat shrink all my connections at the conversion kit in the bed, and ground my circuit to an existing body ground on the firewall of the truck. I elected to use the crimp connectors under the dash, and to connect the wire to the fittings under the hood.

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F250 Powerstroke Natural Gas Conversion Project Pt. 4

Click here for Part 1, here for Part 2, and here for Part 3

Now that the bed mounted conversion kit is installed and the hot water and vapor lines are all run, it’s time to install the high pressure stainless steel tubing that brings the gas from the tank to the conversion kit.

Swagelok compression fitting

In some ways this is the most difficult part of the conversion because of the high pressure compression fittings. They are expensive, and it’s possible to install them incorrectly and ruin the little self swaging crush-sealing ferrules. If you ruin the ferrule it can be replaced, but it’s not something you can run down to Autozone and pick up. It has to come from a company that deals with high pressure fittings. I’m in a small town in the upper Midwest, and my nearest retail outlet for these fittings is over 500 miles away. So if you goof one up, and you didn’t purchase extras (always a good idea) then your project is on hold until you get more ferrules. It’s best to order some extras when you buy your fittings.

There are three U.S. based companies that I know of who manufacture these fittings: Swagelok, Duolok, and Parker. There are also several foreign companies, mostly Chinese. Due mostly to the way I went about acquiring my fittings, I’ve got a mixture of brands. Some of mine are Swagelok, some of mine are of Chinese manufacture with no discernible markings telling me who the manufacturer is, and one is by a Chinese company called Li Feng Lok. Continue reading

F250 Powerstroke Natural Gas Conversion Project Pt. 3

Click here to read Part 1 and here to read part 2.

Keep in mind you don’t have to make the type of rack for your tanks that I have made if you don’t want to.  You could go with slightly smaller tanks and mount them under the truck along the frame rail, or you could mount them to the bed floor. I did mine this way because I wanted lots of fuel capacity and lots of attention. You should be able to get 16-20 gasoline gallon equivalent (gge) worth of storage under most full sized pickups, and about 10 gge if you simply mounted a short, fat tank across the front of the bed like a toolbox. 10 gge doesn’t sound like much, but keep in mind that you’re burning both natural gas and diesel. You’ll get between 40-50 mpg out of each gallon of diesel and about 25 mpg out of each gge of natural gas. So if you get a good, full fill on a 10 gge tank, that’s about 250 miles of driving before the gas runs out and the engine begins running on diesel only again.

Having fabricated my rack to hold my CNG tank, I drilled 13 holes all over my bed rail and floor in order to secure the rack and the tank into the bed of the pickup with grade 8 bolts.  I also spot welded three of the six pieces of sheetmetal to the rack.  The next time I do this, I’m going to get thinner sheetmetal.  I really went overboard on this part. It’s hard to cut with a disc-type cutter and it adds a lot of unnecessary weight.

Fortunately I’ve got an DHC 2000 (formerly the Henrob 2000, formerly the Cobra) torch which welds like a TIG and cuts like a plasma cutter. It does make nice, straight cuts once you learn how to use it.  Yes, it really works. Watch the videos on the website. I like TIG welding with this better than I like TIG welding with a TIG welder because I don’t have any tungstens to stick in the weld puddle that I then have to stop, re-dress, and sharpen.  So, yes, you should get one. But no, it’s not necessary to have one to convert your pickup to CNG.

My first attempt at cutting looked like I used an angry beaver to cut the metal.  After some fiddling and some adjustments to the regulator I got a slightly more respectable result. Continue reading

F250 Powerstroke Natural Gas Conversion Project Pt. 2

Click here to read Part 1

The selection and mounting of CNG cylinders, or tanks, are among the most critical aspects of any CNG conversion. The array of options can be dizzying to a novice, and improper placement can significantly reduce the usefulness of a vehicle. Not only that, but improper tank installation can be dangerous. In this piece we will discuss the types of tanks and some mounting locations. I will also describe the planned installation on our F250 Powerstroke conversion.

There are four types of CNG cylinders: Types I, II, III, and IV. They are all going to be about the same size for a given gas volume. The main difference is composition and weight.

Type I tanks are made of steel. They are similar in construction to the cylinders used for welding gasses. They are the generally the cheapest option, but they are also the heaviest. A 10.9 gge (gasoline gallon equivalent) cylinder may come in a variety of lengths and diameters, but they’re all going to weigh about 320-350 lbs. Continue reading