Hey all, a friend of mine has a 2000 F-150 7700 LEV (propane) with a 5.4 auto. After work today she started it, it ran for a second then died, the guage cluster was dead and it woud crank but not fire. I checked all the related fuses, ecm, cluster etc. and it fired up fine after that. The only problem is it hesitates when on propane now.(quit while on gas). Would really appreciate any help on this one guys and gals. Thanks.

 

I have looked into the system you have for propane/gas.
It is so involved, that any attempt to relay worthwhile info is of questionable value here.
The dual fuel system is quite complicated for hardware and it's control.
Hesitation on propane only, takes experience with that system that few people have.
Basicly the gas injection is the same but propane has it's own regulator and supplies it's fuel directly to the intake, not using any gasoline related hardware except the PCM control and sensors to report what is going on.
Usually if there is a fault in the propane system that becomes a bad drivability problem, a sensor auto switches back to gasoline etc.
Sorry I can't be of specific help .

 

I have the same truck and same problem. will not start in propane mode and hesitates in gas mode. These are real complicated because of the dual system. I am taking mine in for service this weak and I expect the computer to be out on the propane module.

 

No guages and no start are pretty typical of PCM problems.

 

Ok, that was what I figured. But as for the Propane system hesitation, the truck runs smooth and drives really well on it but if you hammer on it at any time it will fall on its face then snap your neck back. This problem showed up right after the no start incident on gas. But, from what I can gather the propane systems have a piggyback ecu that ties into the truck's harness. The local propane guys and Ford refuse to touch this, they just say junk it and throw an aftermarket system on it as the only part we can pin this problem on is what would normally be the mixer in another system.

 

I have a guy here at the local ford dealer that has been sent to special training by ford to deal with these. we live next to a army base and they have a ton of these that ford has to service. I own a CNG E350, and after talking to him about the van I know he knows what he is talking about. I will let you know when I get it back.

 

Just recieved a diagnostic from my ford dealer. They said the #8 coil and new spark plugs will fix the ruffness of the engine when in gas mode. And for the propane mode they claim the compu valve ( computer for the propane) is out + the fuel injector seals need replacing. I talked to the manafacture in canada of the propane module (GFI) and he was surprised that the computer would be out. He says to check the meatering valve and see if the propane is shut off there.
Just a note, you should run 1 tank of gas per 3 tanks of propane to keep the fuel injectors clean, that is from ford and the propane guys at GFI in Canada.
Problem: ford wants $3100 for the computer (which is plug and play) and $2000 for the rest of the work. Any body know of a repair manual for this truck or any advise for doing the work mysef. I am not familiar with these coils on each plug instead of plug wires, And also if I change the fuel injector seals should I just change all the fuel injectors. Also the whole propane system has to be lifted off to get to the plugs which when put back on needs all new brass seals, 2 on each rod. So is there pressure that has to be released on the fuel injectors?

 

$2000 for a coil, plugs and injector seals? Thats about 1800 more than its worth... You can buy an OEM coil, plugs, and seals from Y2K, and do the work yourself in about 4 hours... As for the computer, $3100 is ridiculous... see if they can re-flash it, there aren't any moving parts inside, its all flash memory, no reason it would be burned up.

 

He was referring to the piggyback system that GFI Teleflex added to the truck for the propane mode. If it needed injector seals it would run crappy on gas and propane, not one or the other.

 

so are there seperate injectors and seals for the propane, remember it currently does not run on propane so I do not know how they would have tested it running on propane

 

Propane and gas run on the same injectors. Does the switch light up when you change it propane and turn the key back on? I'm going to guess it was probly the computer that went not the seals. Seals would cause a leak, fuel or vacum.

 

Yes it does light up, But I think the mechanic was refering to the seals being bad in the gas mode. Agian, do you think I should just replace the injectors if I am going to go to all the trouble to replace the seals, I was told that the entire propane system has to be lifted off to at least get to the plugs.
Worst case, does anyone know where to get a cheaper computer,ie. used, junk yard, mail order.

 

I just got the truck back and I am going to do the work myself. Here is a better understanding of what is going on, however I thinks some of the testing done by computers can just reveal the first thing wrong and it might not be it. He said the Injectors sleeve seals for the propane - they dry out
and can cause a vacum leak and cause the truck to run rough in both propane and gas mode. And it needs plugs and #8 coil. So it is these seals, not the injector seals that need replacing. I also wonder if it is leaking, that maybe the computer shut the propane off or the meaturing valve off. Or he is right and the computer is bad.

 

I'm not real familiar with this specific system, but a propane leak should trigger some sensors to shut the system off.

As far as the seals go, I imagine that the mechanic is referring to the propane seals, no reason to dry out though, they should be designed for a dry application, unlike fuel injector seals that are designed to be lubricated (if ever so slightly) by the gasoline (which does degrade rubber).

 

This is getting more confusing, I will have some time next week to start breaking into this engine and seeing what is going on. I do no that the popane system has to be removed to just get to the plugs. And then you have to replace these brass seals when you reinstall the propane system back on. Is it worth just replacing the fuel injectors to eliminate any problems there or would that be a waste of money. Also can you tell me off hand which is the #8 cylinder on that 5.4. I guess any good manual would be good for helping me replace these seals or injectors and coil, but any pointers or lessons learned or short cuts