Ford 4.9/300 Propane Problems

Propane, Butane, LPG, GPL, C3H8, C4H10
LYNNMARINE
Posts: 7
Joined: Fri Feb 23, 2018 8:03 am

Re: Ford 4.9/300 Propane Problems

Post by LYNNMARINE » Sun Mar 04, 2018 4:22 pm

I got caught up with a few other things around the shop but I'll be putting in the Model E tomorrow and we'll see what happens.

I'll be sure to let you guys know. Thanks for the help so far.


LYNNMARINE
Posts: 7
Joined: Fri Feb 23, 2018 8:03 am

Re: Ford 4.9/300 Propane Problems

Post by LYNNMARINE » Mon Mar 05, 2018 11:18 am

So I swapped the Model E into the lift and I still have to push the primer button when going up hill or using hydraulics.

Should I start messing with the power valve while driving up hill to see if it clears up or does this sound like a misadjusted lever?

C3H8
Posts: 1001
Joined: Fri Sep 09, 2005 11:23 pm
Location: Winnipeg, Canada

Re: Ford 4.9/300 Propane Problems

Post by C3H8 » Mon Mar 05, 2018 2:23 pm

No. From here you need to return to basics and a uniform investigation.
- Starting from the tank you need to check out each component. Initially it sounds like you have a fuel restriction somewhere ahead of the converter/regulator. Check your tank valve and make sure it is functioning properly and that the tank is installed correctly. I presume you are using a standard forklift tank and it must be orientated correctly to send liquid to the converter.
- Next check the fuel filter. At the time your problem occurs quickly inspect the fuel line and filter for any signs of frosting or sweating. This would indicate a fuel restriction at that point the frost or sweating occurs.
- Next verify your converter is getting hot. It should be very warm to the touch. Many older forklifts had thermostat problems or the mechanics would not even bother with one but they are critical to proper converter operation. I am going to predict that your converter/regulators are OK since they both behaved the same.
- Inspect your vapour hose or fittings that connect the converter to the mixer. Vapour hoses rub against things and wear out causing vacuum leaks or they get old and crack.
- The next check is the 125 mixer. The proper opening of the converter relies on a proper functioning mixer. The mixer generates vacuum based on airflow and the vacuum is transferred through the vapour hose to draw fuel from the converter. A faulty mixer will not send adequate vacuum to the converter and the converter secondary will not open all the way. This is why pushing the primer helps. On a properly operating system the primer would not even be able to touch the secondary lever in the converter at anything above idle. It only requires the removal of 4 screws to check it out. Check that the screws are tight at the same time. Take the diaphragm assembly out and verify the parts are still attached and nothing is broken. Clean the diaphragm and gas valve and the inside of the mixer body. The gas valve is held to the diaphragm by 4 small screws. They may be loose or the gas valve metering bullet may be broken off and resting in the gas opening. Pushing the primer forces the bullet out of the opening.

Don't take short cuts now. Start at the tank and work towards the engine. The whole process should only take an hour or two. After that if you don't find anything it gets trickier.

storm
Posts: 565
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Ford 4.9/300 Propane Problems

Post by storm » Mon Mar 05, 2018 4:15 pm

Further to what C3H8 has said I would make sure the tank is within its required check date. In Australia they have 10 years between checks and all tank valves must be replaced at this time, I don't know how long for where you are or even if valve replacement is a legislated requirement but it is something worth looking at as well especially considering you purchased the forklift 2nd hand (the poor performance of the LPG system may be why it was being sold).
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

C3H8
Posts: 1001
Joined: Fri Sep 09, 2005 11:23 pm
Location: Winnipeg, Canada

Re: Ford 4.9/300 Propane Problems

Post by C3H8 » Tue Mar 06, 2018 5:43 am

A little add on to my previous recommendation. It sounds like the system is older and should have everything checked out. I do believe though that the problem will be found post regulator. Depressing the primer button should not affect the fuel mixtures off idle. The fact it does means the secondary valve has barely opened. This indicates a lack of vacuum reaching the regulator from the mixer. A prime source to check here is first the vapour line if it is equipped with that and then the mixer. Both pretty easy checks. Perhaps I should have stated this first. Either way I would still check out the complete system in the near future.

storm
Posts: 565
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Ford 4.9/300 Propane Problems

Post by storm » Wed Mar 07, 2018 4:37 am

Just so everyone knows I contacted C3H8 privately, something I wouldn't ordinarily do and don't encourage people doing, because I had some questions rolling around in my mind about something he posted. Now don't get me wrong C3H8 and Franz are the go to people here so if they make a suggestion it is because they have the actual experience on issues people post about but occasionally, and it really doesn't matter who it is, I will see something from a totally different angle thus the reason I contacted C3H8 before posting this was to see what he thought.

Now 1st things 1st, I totally agree with the idea of a complete system checkup on this setup. It is rather obvious that the system is "oldish" so a complete check is not only worthwhile to baseline the system but also probably a very good idea for safety reasons as well.

Now to what I asked C3H8 about. In his previous reply C3H8 said start at the tank, and please do this for the reasons as explained a few lines up, because there could be a restriction there. I don't see it this way because to me if the restriction was at the tank pressing the converter button wouldn't have any effect or it would be a minimal effect simply because the tank or parts from the tank through to but not including the converter would have stopped enough fuel from flowing through to make any real noticeable difference. I wouldn't discount the tank simply because I've seen, as I am sure C3H8 has, stranger things that simply don't follow a logical pattern happen but I think the issue on this particular system is from the converter though to the mixer.

Having said all that I think some pictures of the setup would be helpful at this point in time.

Lastly but by no means least, C3H8 you are a gentleman and so are Franz and Frank. I have learned so much from you, Franz, and Frank in the time I have been a member here and I thank you (all) for the free help you provide.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

Tom68
Posts: 9
Joined: Mon Jun 18, 2018 2:46 am
Location: Australia

Re: Ford 4.9/300 Propane Problems

Post by Tom68 » Sat Jul 07, 2018 5:19 am

Depressing the primer button at idle on my 300A equipped 327 that I'm happy with stalls the engine.

On my Commodore that's lean under load with Model N-L reg' depressing the button at idle also stalls the engine.

Reading posts in this thread I understand that shouldn't be the case, I always thought it was normal, is it ever acceptable ? Or is it an indisputable indication of a problem ?

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