Propane questions

McCracken

McCracken

Logan Can't See This
Joined
Jul 9, 2005
Location
With your mom at a nice seafood dinner
Bits and pieces from another thread somewhere else...

Well, I got my hoses and everything ready to bolt in last night. Everything seemed to be going smooth until I couldn't get fuel to carb. I disconected the vaccum hose to the lock-off and sucked on it manually to try and see if I could get fuel flowing... and nothing. I then remembered when I got this set up there was a small dirt ball in the end of the fitting. I thought it was where it got dropped and dirt got in it. I tore it apart and low and behold there was some kind of dirt nest in it. It didn't look to be a mud dabber but it was something like that....

...It still wouldn't crank though once I hooked the line back up to the throttle plate. Seems the port I'm using doesn't have enough to actuate the lock-off. I called it quits after that...

...Well, I found my problem with the lock-off. I checked it again and I wasn't getting enough fuel. The amount of vaccum I had to pull was rediculous so I tore it apart again. This time I found that the bug in there clogged up another hole. I unplugged it and now the d*mn thing wouldn't lock fuel off

I tore it open for the last time and took the pin out that release the fuel. I ground the end down a little and put it back in. Now it locks fuel off and doesn't require an insane amount of vaccum. What was happening was the suction had to work through the dirt ball in order to pull the diaphragm down on the inside to actuate the lever to push the pin... clear as mud, right?

Anyway, now I'm stuck. I turn the key and crank the engine and hear the fuel entering the carb but nothing. Not a cough or nothing. I can even see the fuel coming out of the top of the carb. What am I missing? Is it another vaccum leak somewhere? I'd appreciate if someone had a picture of their setup on a 360.
 
I am confused... you say you hear "fuel entering the carb"? I assume you mean mixer? But fuel should be vapor at that point.... you do have a regulator/vaporizer that the liquid fuel line goes to? Then a 1" or so vapor line from there to the mixer (on top of the carb)? (Or, on some systems, vaporizer IS connected hard to the mixer with a 1" NPT nipple. I'm running 'pane on 2 motors now, never noticed much audible sound when the vacuum lock is released.

Can you post up model numbers of your lockoff, vaporizer, mixer? How about a pic of your configuration??

What do you mean that you can see fuel coming out the top of the carb? Are you seeing liquid propane? Condensed vapor?

edit: From your description, I got this bad picture in my head of you hooking liquid 'pane up to your gasoline carburator. If this is the case, shut everything down now. Burn centers aren't fun.
 
it's a AMC 360. I'm running a model E, VFF-30 and an Impco 425. pretty basic I think.

I had issues with fuel delivery but I think I got it solved. Once the liquid enters the vaporizer I can hear it pushing into the mixer. I can see, what I describe as, heat waves coming out of the top of the mixer. it looks like invisible waves. I advanced the timing and still nothing.
 
OK, sounds better...you had me scared for a minute there. :) Stupidity has no limits. Glad you aren't one of "those" people. :)

Will it fire on a shot of ether? Try leaving the vac line off the lockout, so you don't have fuel flow from the 'pane. (Don't think it'd be too rich to fire, but you never know.

I did have a problem when I first put the propane on my 350. Would crank but not start...kinda stumbled a few times like it was trying, but that was all. After checking the stuff that I had messed with, finally figured it out...module in the HEI had decided to take a dump. Replaced it, and fired right up.

Check the obvious (stuff you have messed with) but don't forget to think outside that box, too.
 
has it ever run on propane or is this the first time. Reason I ask when I swaped mine over it took me forever to get it to crank the first time. Even went so far as to call impco and make sure I had everything right. They told me to press the button on the regulator a couple time and see if that got it. Fired right up after that. Still don't know exactially what that did but it worked, I think it may have had a little air in the line that the pane would not push past but like I said not sure.


BTW not to hijac but what is the intended use for the button on the regulator?
 
66gasgrill said:
BTW not to hijac but what is the intended use for the button on the regulator?
Click to expand...

THe button is an "enrichener" a choke of sorts, allows extra fuel for cold start.

While it doesn't seem possible, it is very possible to FUEL FOUL the plugs on propane, they will look fine, might even spark when pulled out and connected to the wire and grounded.

I have had it happen time and again on forklifts, the regulator flooded the engine for one reason or another, repair/replace the regulator and still no start.

Change the plugs, it should start right up.

If you dare, just a puff of ether (starting fluid) could help a bit also.
I hate the stuff, only use it as a last resort (NEVER on an intercooled turbo diesel !!) and I keep the can well buried in my service van to keep it from becoming to easy to use. ( i have had the same can for 2 years, if that tells you anything )
 
66gasgrill said:
BTW not to hijac but what is the intended use for the button on the regulator?
Click to expand...


If you take the converter apart, you'll see that the button manually activates a lever which allows liquid propane into the "expansion area" for it to become gaseous.

Before it will be very effective though, you have to have liquid propane AT the regulator, which means manually activating the lockoff, be it with a vacuum source, or the electric.
 
I've used the button on top and shot ether down the hole. I can get it to run on ether but not propane. I don't think the plugs are fouled because it runs on ether.

edit: now i can't get it to run on ether. shit. i'll try the plug theory. anything else to try?
 
well, i tried the plug theory and it seemed to work. However, I didn't replace them but I cleaned them with a wire wheel and re-gapped them .30 (that's what i heard worked good). I turned the key and BINGO!! we have ignition. I let it run for 10 minutes and shut it off.

I tried again shortly thereafter and nothing. It's like it's back to the way it was. Does it need all new plugs even though I cleaned the ones I have. I even went as far as to pull one I cleaned and checked it again. It still looked good :confused:
 
Try going to a hotter plug, maybe a hotter coil as well.

Propane take more heat to ignite it, much like higher octane gas.

A weak coil won't be able to light a spark either, it's a physics thing, 10 years ago I could explain it pretty well, but I've been in too much of a veggitative state that last year.

I'm sure there is someone here who knows what I am refferancing and can explain it
 
I run Bosch Platinum plugs and an MSD Blaster 2 coil. I also run the MSD distrib and Accel 8.8 wires. Not trying to be smart but what would be hotter? I have no problem going to a different plug. I just a lot of money invested in the other to just give up on it. Would an upgraded ignition box be better?
 
try a regular plug with same gap, you might be surprised.

Platinum plugs need a weird environment to work properly, a hot running engine being one of them.

Too many times I have replaced spendy platinum plugs after a few hundred/thousand mile because the engine wasn't running hot enough to burn them clean. Yes, I have played around with this a bit, with out spending too much on the expensive plugs. There is a differance.

Propane engines don't burn hot enough for Platinum plugs.

Besides, when you hit the tips with a wire brush, you more than likely scraped away the platinum coating anyway ( thats all it is , a coating )
 
I run plugs for my engine, no variance. Stock coil, when I first installed the pane, I run points. I don't think that's where your issue is. If you are getting spark it should run.
Mine acted a lot like you describe when I first put it on. try advancing your timing. Advance it till it runs and keep advancing it till it sputters and then back it off. That's what I did, and have not touched it since. With propane, though it has a higher Octane, it has a slower burn, than gas. Hence the need for more advance.
 
upnover said:
With propane, though it has a higher Octane, it has a slower burn, than gas..
Click to expand...

Higher octane always = slower burn.. ;)

And I'll third the regular 'ol spark plugs. Platinum isn't that good of a conductor.
 
you may also try the hotter plug that was refered to earlier.

For example say you run a standard autolite 24 plug, up it to an autolite 25-26, same plug just a "hotter" heat range.
It works with most brands the last # is the heat index.

Oh if you want the whole physics and stuff check out
http://www.propanecarbs.com/questions.html pretty good read the FAQ's and the propane facts section are pretty good.
 
f'ing bullshit. I now officially pissed at propane. the damn thing ran for 10 minutes strong and I cut it off and nothing else.

well, i changed the plugs to Autolite 66s for extra heat. Still nothing. I even went as far as to change the ignition module ( i had a spare) and nope. This is getting really disheartening. All I want to do net weekend is wheel Tellico before it closes and I can't get my truck to fire.

I checked spark and I've got it. The ignition is brand new, the plugs are new, i smell propane and i see it too when I cut the engine. I can see it coming from out the top of the carb so I know I have fuel.

Can anyone help? Please. I'm dying over here.
 
did you ever turn the timing up more ? advance the dizzy until it runs.
 
ok, I'll try that but explain this to me. How could it have run before as strong as it did and not have the diz turned that much? I don't care to but it doesn't explain the previous result.

I'll go try it right now and see what happens....

edit: tried it both ways. I retarded it and advanced it and nothing.
 
orangecherokee said:
ok, I'll try that but explain this to me. How could it have run before as strong as it did and not have the diz turned that much? I don't care to but it doesn't explain the previous result.
I'll go try it right now and see what happens....
Click to expand...
just try it and see. my diz is turned up about 9 more degrees over stock. thats what it took for mine to run.
 
have you tried to lean or richen the mix at all ?

sounds like your mix isn't right. bet if you clean the plugs again it'll start. which lends to believe you are a bit fat in the mix.

Just because you have spark at the plug or when the plug is out, doesn't mean they will spark under pressure with fuel.

Especially if there is a means to ground other than the arc gap. (fouled)

A lean mix can foul just was well as a rich mix, if the mix isn't right and you run it for a bit, you can glaze the plugs either way ( real convienient right ? )

have you tried to partially block of the top of the carb ( like a choke) and crank that way ? takes two to play at that point, but it'll tell you if you are lean or fat ( if fat it still won't start, lean it should help richen the mix)
 
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