FI to propane

david7w5 · 11-08-2009, 08:55 PM

I have a 1998 gmc sonoma that has been heavily converted in to a rock crawling buggy. it has military dana 60 axles, turbo 400 trans, 205 transfer case, with the fi 4.3. Well I purchased it already started and i am almost finished with it but have alot of engine eletronic trouble. So after several gm machanic look at it i have decided to convert it to Propane. i have all the propane kit and have it on a v8 already my question is how to make the altanator charge and for the engine to crank with key. i believe its all controlled by computer? any help would be great or a web site to refer to.

t_mo89 · 11-10-2009, 05:10 PM

The ignition should have nothing to do with the computer. When you turn the key, the ignition touches 2 wires together that complete the circuit to send power to the starter which cranks the flywheel on the motor, starting it.
As for the alternator you would most likely use one from the v8 that you have and set it up the same way as you would normally.

david7w5 · 11-10-2009, 09:57 PM

I was thinking the starter wire was in the computer harness, I may be wrong I will have to check. on the alternator can you make it a single wire charging.

t_mo89 · 11-11-2009, 12:27 PM

It might be tied into the harness. vehicles that get their fuel from a carb and have a mechanical/vaccuum controlled tranny still start with a key. It might mean that you rewire the ignition wires to where they need to go on the starter and ground it properly. As far as the alternator, I don't think you can do it to a stock one due to how it is setup to re-charge the battery. However if you are able to get an aftermarket one that comes that way you can make brackets so that it will work.

Bilster · 11-11-2009, 02:31 PM

I agree. Purchase an aftermarket one-wire and you'll be good. Did you get your propane kit from GotPropane.com? They provide great service to the rock crawler crowd. Did you build your motor specifically for propane? There is a 10 percent power loss due to propane's BTU value in comparison to gasoline but you can make up that difference by raising the compression. Propane is about 110 octane.

david7w5 · 11-16-2009, 09:07 PM

I found a local alternator shop that is in the process of converting it to one wire for $35.00. I got the propane kit off a large forklift with an impco 425 mixer and model e evaporator from the salvage yard. the motor is stock for now but I would like to build one in the future. I have built plenty of old school v-8 with holleys . so am learning on newer things, I was told the 4.3 make plenty of power, is lighter, and is taking up less room

Bill Wheats · 11-16-2009, 09:46 PM

I know that in New Zealand all the 4.3 are sold stock to run on propane, if that is any help.

11-08-2009, 08:55 PM	#1
david7w5 Registered User Age: 37 Join Date: Apr 2009 Posts: 24 Location: User is: OffLine	FI to propane I have a 1998 gmc sonoma that has been heavily converted in to a rock crawling buggy. it has military dana 60 axles, turbo 400 trans, 205 transfer case, with the fi 4.3. Well I purchased it already started and i am almost finished with it but have alot of engine eletronic trouble. So after several gm machanic look at it i have decided to convert it to Propane. i have all the propane kit and have it on a v8 already my question is how to make the altanator charge and for the engine to crank with key. i believe its all controlled by computer? any help would be great or a web site to refer to.
	[Reply w/Quote]

11-10-2009, 05:10 PM	#2
t_mo89 Registered User Join Date: Feb 2009 Posts: 62 Location: User is: OffLine	Re: FI to propane The ignition should have nothing to do with the computer. When you turn the key, the ignition touches 2 wires together that complete the circuit to send power to the starter which cranks the flywheel on the motor, starting it. As for the alternator you would most likely use one from the v8 that you have and set it up the same way as you would normally.
	[Reply w/Quote]

11-10-2009, 09:57 PM	#3
david7w5 Registered User Age: 37 Join Date: Apr 2009 Posts: 24 Location: User is: OffLine	Re: FI to propane I was thinking the starter wire was in the computer harness, I may be wrong I will have to check. on the alternator can you make it a single wire charging.
	[Reply w/Quote]

11-11-2009, 12:27 PM	#4
t_mo89 Registered User Join Date: Feb 2009 Posts: 62 Location: User is: OffLine	Re: FI to propane It might be tied into the harness. vehicles that get their fuel from a carb and have a mechanical/vaccuum controlled tranny still start with a key. It might mean that you rewire the ignition wires to where they need to go on the starter and ground it properly. As far as the alternator, I don't think you can do it to a stock one due to how it is setup to re-charge the battery. However if you are able to get an aftermarket one that comes that way you can make brackets so that it will work.
	[Reply w/Quote]

11-11-2009, 02:31 PM	#5
Bilster Registered User Age: 50 Join Date: Nov 2008 Posts: 19 Location: User is: OffLine	Re: FI to propane I agree. Purchase an aftermarket one-wire and you'll be good. Did you get your propane kit from GotPropane.com? They provide great service to the rock crawler crowd. Did you build your motor specifically for propane? There is a 10 percent power loss due to propane's BTU value in comparison to gasoline but you can make up that difference by raising the compression. Propane is about 110 octane.
	[Reply w/Quote]

11-16-2009, 09:07 PM	#6
david7w5 Registered User Age: 37 Join Date: Apr 2009 Posts: 24 Location: User is: OffLine	Re: FI to propane I found a local alternator shop that is in the process of converting it to one wire for $35.00. I got the propane kit off a large forklift with an impco 425 mixer and model e evaporator from the salvage yard. the motor is stock for now but I would like to build one in the future. I have built plenty of old school v-8 with holleys . so am learning on newer things, I was told the 4.3 make plenty of power, is lighter, and is taking up less room
	[Reply w/Quote]

11-16-2009, 09:46 PM	#7
Bill Wheats Registered User Join Date: Apr 2008 Posts: 2,115 Location: Maine User is: OffLine	Re: FI to propane I know that in New Zealand all the 4.3 are sold stock to run on propane, if that is any help.
	[Reply w/Quote]