Propane Problem w/460. Engine Dies under load..
 

Hi Folks,

Hoping someone can help.
Running a 1995 Ford F-250 3/4 ton 4x4 on dual fuel.
Gasoline via fuel injection, and propane.
Engine runs excellent on the gasoline, and runs well on the propane, but when under load and have to give lots of gas for big hill or passing, the engine will die out as if no fuel. When it dies however, you smell alot of propane.
Try to restart on the propane, and will not start. Switch it to gas, and it will start, then can switch right back to propane, and will run.
It's like it's flooding itself out on propane. I checked the air filter, and it was clogged righht up. Replaced and went for a spin, and it ran excellent under full throttle without dying. I thought I solved the problem, and figured it was just that the engine couldn't breathe.
Later in the day, it started doing the same thing again.
Next morning when engine cold, ran it with no probs again.
It's when it warms up/gets hot, the problem happens continually.
Anyone run across this before?
PS: Just did tune up and brand new plugs, wires, rotor, cap, timing is bang on, and scoped. Runs perfect on the gas. Alo like I mentioned, it runs perfect on propane also, it's just when you need to goose the throttle for big hills, or to pass on highway.
Hopefully someone can help me with this puzzle.
Thanks in advance for any and all help!
Cheers!

Give me some info on the lp equipment on the truck and I will try to help.
Have you changed the filter in the LP fuelock?
Also is the tank valve fully opened and backseated?
And finaly dumb question what is your fuel level?

Regards

Reply to 460 Propane System
 

Hi Gasman,

Thank you for the reply.
Ok, system is a Vielle with dual throttle body for lp delivery to engine as is a fuel injected engine.
Propane tank is full or next to it.
I have not changed filter in the lp fuel lock, but did replace the totally clogged Vortox canister type air filter.
Tank valve is fully opened.
I thought I cured the problem when I replaced the air filter, as I took it out for test spin directly afterwards, and there were no problems.
However, once the engine heated to proper operating temp, it began to die again. When it's cold, there are no problems whatsoever.
hmm...... I thought the prob would be more persistant when engine cold, as I thought the evaporator worked off of the coolant temp, so more heat, better evap.
Reading Haynes manual informed me of a sensor/relay that advances the timing when the engine is cold, so I tried advancing the timing some figuring it may be as simple as that, but problem still persists.
I'm stumped. I had a fellow look at it before, but it wasn't running the best on gasoline at the time, and he needed running perfect on gas before he could carry on with lp prob. There was a shorting plug wire, plus the wrong plugs were installed before as they were the v-groove, and burn too hot.
Replaced plugs with proper motorcraft plugs, wires, dist. cap and rotor, and running great on gas. He had checked to see if coolant was getting into the evaporator, but no.
Also, the prob is getting worse as it dies more often now, not just under very wide throttle. Even will die now between shift changes when the rpm's go up to 2800 plus.
If you have any ideas, I would be VERY grateful to hear anything you may have to offer.
Regards.

Well I am not real versed in Vialle systems but here goes. Locate the lp filter lockoff and either bypass it or remove the filter. Test drive it, if the problem is fixed cool, If not you will probably need to rebuild the vaporizer/regulator.

Gasman and all others,

I <think> I fixed the problem.
I had to do alot of deducing, but figured since there were no problems when engine cold, and that there is a relay that advances timing when cold, I tried advancing the timing. Did it just a hair, and there was a small improvement in performance on gasoline, but nothing with the propane. Advanced a little further, and noticeable positive change in gasoline performance, and small + change with the lp. I also turned in what I am calling the output valve. (round metal knob on the hose coming from evaporator to supply throttle bodies.
When checking it, I noticed that it was backed off (opened) as far as it could go, so I figured that maybe it was letting out too much propane gas.
I screwed it in until the engine speed slowed, and then backed off a turn, then tightened up, and was rewarded with a HUGE improvement! It has not died on me once since doing so, and is running fantastic!
So...the ignition timing was retarded wayyyyy too much, (whoever worked on it had last had tightened the idle position screw too far causing to idle too fast, and they must have backed off the timing to compensate for the fast idle.) and also that valve was open way too much also.

Now the whole thing makes perfect sense!
Once the engine got hot I had the propane problems, because the evaporator works on engine coolant heat to evaporize the lp, and hotter the engine got, the more vapor is created.
So, with that valve too far open, it was simply getting way too much propane gas when demanding some flow.
Well....I'm slowly learning this alternative fuel mechanology!
I had absolutely no clue about these sytems until a couple of weeks ago when I purchased my truck with the exising dual fuel system.

I would not however have bought the truck if it did not have it, as gasoline is way too expensive, especially with that big thirsty 460 cu. in. engine!

I also wanted to let everyone in on something I found out about today.
In my town, (Prince George, BC) I've been paying 65.9 cents per litre of propane. It's the same price eveywhere I've been in town, but a customer of mine told me about a place in town where it's only 45 cents/litre.
I went there today, and it's actually down to 43.5 cents/litre.
$30 there gives me what it costs $45 everywhere else.
Almost 70 litres instead of 46!!
For local folks, it's the Super Save on Victoria, and the one by the BCR site.
For anyone else in any other city, If there are Super Save gas stations near you, check and see if they are the same.
I'm not trying to plug the business, but with fuel costs what they are these days , I thought I'd let everyone know about the huge price difference.
I also hope that the problems I encountered and hopefuilly remedied will help someone else with the same problem/s.
Cheers!

Hard cold start/ propane only. Just bought a F350 with a 460 on propane. I think there has to be a leak in the system and i'm wondering how to pressure test it? I can't otherwise see why it won't start. I'm going to go try putting propane straight to the tank with a cheater hose and see if she goes then. If that's the case and it is leaking somewhere, where would be the first place to look? At the physical switch for tank A to tank B like the old 7.3L diesels?

Help!

Hi Tribol!

If there's a leak anywhere in the system, besides the bad smell, you will see ice all over the area that is leaking.

So on cold start...are you cranking forever then starts, or do you crank awhile...no start...then try over and over agian until it fires?

You can try turning the key on and leaving a few seconds before cranking.
Sort of like how you would cold start a diesel. That may help.

I'm assuming your truck is pretty much the same as mine..just a little bigger, and you have a 460 that runs electronic fuel injection for gasoline operation.

There <could> be a problem with the box..<can't remember the number of it> which shuts down the electronic fuel injection and turns on the propane. The valve could be sticking, and after juice is there for a bit, it works properly, and then it starts.
Probably <not> the problem, but definately a maybe.

Another thing too is....check the connections on the two hoses going to your throttle bodies. There will be a main hose coming from the mixer/evaporator which then runs into the bottom of the diverter, and then two large hoses come from there to your throttle bodies.

Alot of the time those clamps come loose either on the throttle bodies, or the diverter, or on the bottom of the diverter where your main lp line connects.

Another problem which can be a biggy, but you can fix with some silicone, is that a backfire could have happened, and it blows out the diverter.

That's what I'm calling it...can't think of the actual name right now.

They're built to blow out either on top or bottom in case of a backfire so you don't end up with an explosion.

If you look at the top of it first, see if the square piece of plastic looks like it has come loose. Normally should just look like a square impression in the plastic. Sometimes it's just a square impression, other times it's the square, with an "X" in the center of it.

Alot of the time you will see that someone has siliconed it back in place as it has happened before. I have personally seen jar lids in place of the plastic!

If it looks good, look underneath it and see if it has blown out there.
The main line from your mixer goes right into the middle of it.

It's very easy to remove the assembly to inspect it.
If it has blown out, just silicone it back in place, and make sure it has dried completely before reinstalling it.

To actually replace the unit, you're looking at hundreds of dollars, so do the silicone thing, or gasket maker type stuff.
Do not gob it on so much that if a backfire happens, it will not blow the piece out as it is meant to, or you could have another Hiroshima happen in your own neighborhood! Haha! Not quite that bad...but major engine damage, and possible personal injury.

If you do have a backfire issue, you must remedy that or you will keep having those problems.

If you do not have an arrestor installed in your distributor, I suggest you get one as it can save you some issues, and they're quite inexpensive.

You probably know this...but never, ever step on the gas when starting a propane powered engine.

Please look through and try these things, and also please let us know if this helped, and what the problem was.

Cheers!

i had this same problem with my 95 f350, turns out the problem was with the right(looking into the engine compartment) snorkel coming from the air cleaner, there is a tight bend just before the injector housing, this bend had softened and when the engine was under load and pulling air, the bend would pinch choking the engine of air. to remedy the problem i just put a hose clamp around the hose in the bend to maintain the hose form and it solved my lingering problem