Any comments on a dual fuel 3500 I'm thinking about?

[strider3700]

I've been truck hunting for a few months looking for a crew cab to fit the growing family. Anyways today I ran across a 2000 chevy 3500 4x4 crew cab longbox with the 350 setup to run on gas and propane. It used to be a ministry of transportation truck so it's a gloriously ugly yellow and given it's size I'm sure it's visible from space. This also however means it was maintained religiously and there is a complete log book of every fuel up and mileage from the day it was purchased new.

It's only got 163,000 km, looks to be in decent shape bodywise, breaks are at 50% front 60% rear and the tires are maybe 70%. Anyways it's been at the lot for over a year and this being a small lot they haven't moved much in the last few months. The salesman said here's the price but we want it gone so try an offer. I'm thinking I could have 3000-5000 left over from my budget to put towards mods after all is said and done.

Does anyone have any info on what dual fuel trucks are like and what to watch for with them? I'm not too sure if I will go with the truck or not, It is ugly as sin and huge, I was really hoping for a crew cab short box but that is not a common setup in the older years that I can afford.

 

[dzzz]

Is there an advantage to you to run on propane?

 

[strider3700]

propane is 80 cents/liter gas is 1.12/liter at the moment. My understanding is propane loses about 10% in power and mileage vs gas. Even after the drop in mileage from using it it should still be a savings. I'm not sure if a conversion would be worth paying to have done but I don't have to worry about payback on the original install.

 

[redthies]

Most dual fuel set-ups are tuned to run on either fuel at any time. They are not very efficiant on either fuel because of that. Propane is cheaper, but can be hard to find if you are travelling. And range sucks. I would consider ripping out the propane system, sell it and use the cash to top up your gas tank. If you are determined to run the propane, set the engine up to run only propane, otherwise that 25 cents a liter is going to be burned up with inefficiancy.
I also was shopping for a cheaper crew shortbox. Ended up with a long box. No big deal if you don't live in the big smoke! I'm gonna guess you are north island... No parking issues up there!

 

[sjester]

Back in the mid-90s I was assigned a dual fuel chevrolet pickup with a 350. Drove it for two years. It was probably 25-30% less fuel efficient on propane than it was on gasoline (kind of like my wife's current flexfuel Suburban when it runs on E85). It ran fine on propane, although it did not like to tow at all that fuel. Most of our fleet was dual fuel at the time, some ran fine on both and others always had problems on propane at least. These were state vehicles and maintained the same. I think the difference was the initial install of the conversion, as trucks completed at one particularly contractor always seemed to do better.

I will say, contrary to the previous poster, the truck achieved fuel mileage on gasoline that was right in line with straight gasoline units in the fleet. Perhaps newer conversions have closed the gap in performance to 10% but that was not what I experienced.

 

[78Bronco]

was it a factory propane install? if so it will have better cylinder heads. My dad had a dual fuel ford aftermarket install and the old 360 gave up after a few years of hauling at nearly maxed gvw. it was natural gas/gasoline with a crappy recurve box to modify the timing when running on either fuel. I think the newer systems are better. Propane and nat gas are dry fuels and do not provide the necessary lubrication required of standard built heads.

 

[strider3700]

I don't think it was a factory install. The filler door for the propane doesn't look anywhere near as nice as most things from the factory. Definitely looks like an after thought. I'll pop the hood next time I'm there and see if I can tell anything more about the propane.

Another question, when I showed it to my wife this evening we noticed that the under carriage is plastered with under coating and it looks relatively new. Newer then 163,000km anyways. Everything but the muffler under there is coated, springs, fuel tanks, axles... I mean everything. Would this be done to hide something or is that just the way they apply this stuff?

 

[deserteagle56]

So is this 2000 truck with the 350 fuel injected? I'm just trying to figure out how they managed to run both fuels through the injection system. For many years I had a small-block 400 that was dual-fuel but it had a separate propane carburetor that sat atop the Holley 4-barrel gas carb. And I had no trouble with the system; my mileage and power seemed to be pretty much the same whether running on gas or propane. In seriously cold weather I had better luck starting on propane than I did on gas.

I know that Ford still makes fleet cars that can run on CNG or propane - but they can't run gasoline also because the injection system is set up for only the one. That's why I'm curious as to how your 2000 pickup (which should be injected) would accomplish dual-fuel.

 

[strider3700]

Google found me a bunch of info on how propane can be used on carbs, TBI and MPFI systems with MPFI being the most difficult and I'm assuming expensive to set up. I haven't looked under the hood yet and the place is closed today so I can't tell you for sure whats under the hood

 

[charlieaarons]

Liquid propane has only ~74% of the btus of gasoline per unit liquid volume so the price is virtually identical per btu, for you.
You could find a turbo 6.5L V8 cheap, transplant it, and keep the propane tank for power boosting?
A spark ignition heavy pickup of that sort won't get very inspiring fuel economy.

Charlie

 

[Bullseye240]

Liquid propane has only ~74% of the btus of gasoline per unit liquid volume so the price is virtually identical per btu, for you.
You could find a turbo 6.5L V8 cheap, transplant it, and keep the propane tank for power boosting?
A spark ignition heavy pickup of that sort won't get very inspiring fuel economy.

Charlie

Everything there is correct except for converting a gas truck to diesel being "cheap". Huge trouble converting gas to diesel or diesel to gas.

 

[strider3700]

Thanks for the info everyone. At this time I'm going to pass on it. close inspection of the box revealed tearing in a few spots that looks to me like it had a massive load put into it. Can't tell if the frame is OK because it's swimming in undercoating so too many unknowns. Throw in how ugly it is and I have no urge to spend money on it.