So, I've got an 89 F350 4x4 with an EFI 460. It was apparently a factory conversion to propane over 20 years ago.

A bit of background. Skip this part if you don't care
I bought it, not running with the timing set removed (previous owner was changing it and had his toolbox stolen with parts in it). So I changed the timing set, pillaged parts from the local yard and put it back together. Got it started, and it ran like crap. Further investigation showed a dead cylinder, (exhaust valve), so I swapped out the heads to a used set.
Got it running again (kind-of), but it wouldn't idle smooth, or rev up. It then backfired, and blew the mixer to pieces. I've since changed the mixer and it hasn't run since. I had a propane expert stop by as a favour and he messed with it for 3 days, but still no go. I'm now to the point where I'm sick of pro-pain, and was curious what it would take to switch back to EFI.

It's still got injectors in the intake, and the injector harness LOOKS complete. The fuel lines are cut and the tanks are out (2 propane tanks under the truck in stock locations.

I'm curious if anyone either knows how to get the EFI back up and running, or knows the common process for swapping to propane in the first place. I'm uncertain if there's any mods to the computer or harness at all to disable the injectors. There is virtually NO information online for this stuff since the love for propane (in the general public) seems to have died out before the invention of the internet.

Anyone out there have any experience with old conversions that knows the common practice? Or even people who have swapped EFI from scratch?

Thanks for any info. I kinda like the truck and don't want to part it out yet.

 

i have no help for the propane conversion, but have you considered trying to find a whole 460 from another truck and swapping everything in? then of course you would need to find a fuel tank, pumps, and run lines

 

The local yard just got an 89 460 F350 in with about 110,000 miles on it and a rebuild tag on the intake, so that would be tempting. I'm just not 100% certain as to exactly how much I need to grab and what may have been modified, but not removed from my truck. I don't have gobs of money to spend on parts I don't actually need, so I'm trying to make a shopping list of sorts. I do also have to locate tanks somehow, as all the yards here punch holes in them.

 

Major major thing to remember is that propane engines use very little timing.
Retard timing to 0 and it will run and rev and not backfire (as much)
Try to find a forklift mechanic to work on it with you. It will be much more benneficial to have a propane engine mechanic help you.

 

I reread and you said you had a propane expert work on it. I was thinking regular mechanic.
I'm curious how the mixer and throttle and ignition is setup. Any way you can post pics or email me some. UNTAMND@aol.com
Does the truck Have the computer still in it. What trans. Is it a c6 or overdrive auto or manual. Overdrive auto needs the ecu hooked up and functional along with tps and stuff, so you may be still firing the injectors and all you need to do is put pressure to the fuel rail and it's running.

 

The mixer (Impco 425) is mounted on 2 hoses that lead to the stock throttle body. The entire intake is all stock. Throttle simply opens the TB and lets the propane/air into the intake. As far as I can tell the ignition is all stock. It is a 5 speed as well, and yes the computer is still in it (drivers kickpanel?)

I wasn't sure if the injectors would still fire after 20+ years, if they were just left clicking away. I almost assumed they'd have to be disabled or else they would just lock up with no fuel to go through them.

It appears that the fuel lines were cut off at the rail (rather than disconnected) and removed. I don't see anything running down the frame other than LP lines. Looks like the wiring to the pumps and stuff was also hacked off. Looks like a horribly ghetto job that was done.


With how it was running, I did get it to idle poorly when I retarded it to about 10*. In all honesty I've almost given up on getting it to run nicely on propane, and hate the fact that I can't really work on it since I know very little about it. It's been insured and non-running for about 8 months now, so it's just gotten to the point that I want to get it running, or part it out. I'd prefer the EFI anyways since I don't like the lack of power, or the horrible economy, combined with no fuel gauge so I don't even know what my range is. And lack of fill stations just adds to the headache. It might be a nice setup for a carbed 4x4 or something, but it seems like a backwards step in economy, power, reliability and ease of service in an EFI vehicle.

I'm not positive what I need in the fuel system since it seems somewhat complex with the dual tank setup, but I guess it might be worth a shot in just replacing as much of it as I can and giving it a shot. Maybe with some fresher injectors.

Also have to find out how to safely remove all this propane stuff without bleeding it off all over the place haha

Oh, and if you want, I can take some pics of the mixer setup tomorrow evening before it gets dark and post em up for ya.

 

Well here is the fuel system a 1989 EFI 460 truck uses.






The fuel tank selector/reservoir:


The front fuel tank:



The green fuel pump relay:



Inertia Switch:



Selector switch on the dash:


/

 

Wow, awesome! Thanks for all that! Now I know what to look for and pull from that other truck. I'll gut all that stuff out of it and see where that puts me. It would be so nice to have this thing run like it should...

 

You might want to reload this Thread as I added more to the post above.

 

Noted, thanks I'll be loading up this thread when I go to the junkyard so I can collect it all. Might try to get some before they close tomorrow evening.

 

If you're searching for a rear gas tank try to get one from an efi bronco. It's like 38 gallons. And then if you don't want to mess with front tank for now you still have plenty of gas.
I'd still gather front tank parts though as well.

 

Thanks again. It's nice to know they'll fit. Too bad older ones won't, since I have a new tank in the back of my ol rusty 78 (Parts) Bronco.

But I'll grab everything minus the tanks themselves from the yard, and then hunt down tanks elsewhere. I'm sure this will be the fun part, since I really don't want to have to buy new. Cheap truck gets cheap parts

Oh, do you know if the pump/hanger assembly is specific to each tank? can I just grab the front pump/hanger from the yard, and have it work with whatever front tank I find, or should I just save my money and try to get pump/hanger/tank as a complete unit? Makes sense to me that different hangers and sending units would be used with different tanks, huh?

 

I do not know if you still have the Evaporative Emission System still on the truck but their is a vapor orifice rollover valve assemblies in the top of each tank. The vapor line is "T"ed at the front tank and runs up on the passenger side to the carbon canister (located in the engine compartment or along the frame rail) for storage until they are purged to the engine for burning.

 

You may also want to read this Thread:
https://www.ford-trucks.com/forums/4...lp-please.html

If you would like to see the wiring diagrams referred to in this post linked to above just email me your email address and I will email them to you.
My email address is at the bottom of each of my posts.
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Front tank pumps and assembly are all same. Rear tank is either the f-1,2,350 or fsuperduty or bronco. You need whichever one you're gonna use for a tank. The bronco and superduty ones are deeper.