Discussion:
Propane fuel Trouble shooting/adjustment

I have just purchased a Toyota Mod. 40-5FG25 forklift that has propane fuel. I is a 4Y engine.
This was an "AS IS" out of a lease/rental fleet. It is 100% complete, less the tank and mount.
I did compression cold tests before purchased and it was 190# on all cylinders. Plugs were clean.

I brought it home and put a full tank of propane on a mount I made. Properly positioned with the locater holes down. Removed the tank hose and blow it out before installing a new tank connector.

Cranked over fine and tries to start but runs like it is out of fuel. Will keep firing and miss firing as long as I keep the starter engaged. Once I got it to run "rough" without the starter engaged and about half throttle but it was rough and would pop back into the intake occasionally. Evenually died but did run long enough for the coolant to warm up and I noted the frost on the propane "stuff" melted. Haven't been able to get it to run continiously since.

The only adjustment I have been changing is the large head screw on the side, towards the top of the throttle body. This is a IMPCO model 100 system and everything seems to be hooked up and the vacuum lines, etc. check out ok.

I just don't know anything about propane systems or trouble shooting.

It could be ignition but it has one of those distributors with the coil pack built in. I plan to check it out next to see what type of components it uses.

If anyone could provide me with some direction on trouble shooting and adjusting this propane system, or even a link to a reference manual on this. I would appreciate it.

Thanks
STEVE
  • Posted 8 Sep 2013 03:47
  • By OleSteve
  • joined 20 May'12 - 27 messages
  • Washington, United States
Showing items 21 - 30 of 30 results.
this is normal Steve, it requires vac on that hose to allow fuel to flow. no vac and no fuel is correct and what you wanted to see.
I would offer that the correct path would be to start at the beginning and confirm that #1 spark plug is firing when the crankshaft is just before tdc by looking in the distributor with the cap off and confirm the rotor location in relation to the mark on the crankshaft pulley. and then confirm or do a complete tune-up
  • Posted 9 Sep 2013 20:09
  • By edward_t
  • joined 5 Mar'08 - 2,334 messages
  • South Carolina, United States
"it's not rocket surgery"
Looks like the problem is in the vaporizer since I have tested the vacuum lock out assembly and it releases liquid over through the inter connecting line each time I crank the engine over.
However, when I remove the gas line from the vaporizer outlet, to the mixer (carb) throttle assembly, I get absolutly nothing now.
Originally, I was getting some flow because I it did fire and run a little. Now, I get nothing.

Might be time to order a rebuild kit.

I did find some operating description online with parts break down. Just in case the kit doesn't provide any.

Thanks

Steve
  • Posted 9 Sep 2013 07:48
  • By OleSteve
  • joined 20 May'12 - 27 messages
  • Washington, United States
Hi first you shouldn't be getting any frosting on components at all this usually points to either a leak of if its the vaporiser a cooling fault. First thing to check is that coolant is getting too and passing through the vaporiser if it isn't the vaporiser will frost over then freeze up if this is happening this will give the problem you have ive had water pump impellors fail that give this fault. I don't know if you can buy kits over there for the J type impco but if you do stip it there is a strip valve with a rubber seal in the middle these are prone to failure and you wont get it to start if it is they fail due to the body wearing where poppet that works on the hp diaphragm wears. My advice if you cant get a repair kit would be to fit an imcpo k type to it.
  • Posted 9 Sep 2013 04:51
  • By lifter01
  • joined 4 Jul'09 - 461 messages
  • West Yorkshire, United Kingdom
Steve with known fuel in the lines, take the large LPG hose going from regulator/vaporizer to mixer off the mixer. With fuel shut off or disconnected from tank, spin engine over. If fuel comes out then you have a vaporizer that needs replaced. The frost you are concerned of is evap of LPG. Check coolant level also. If unit has vaccum lockoff then check for LPG coming out of vacuum line on lockoff.
  • Posted 9 Sep 2013 04:28
  • By RCAV8TOR
  • joined 12 Nov'11 - 366 messages
  • Alabama, United States
What i used to do all day now takes me all day to do.
Thanks for that tip. I did try that and since the tank valve seems to have a leak thru, even when turned off, I think I still have pressure until I disconnect the tank coupling. Something I will deal with when I refill the next time.

Now, onto the LP gas fuel system.
From the quick research on Google, it seems the be made up with a converter, mixer and the carburetor.
If my problem is flooding, then where should I start? Hmmm!
I would assume the liquid fuel would be converted to gas through evaporation in the converter and that process would account for the frost I observed on that case, since the coolant temp wasn't yet high enough to assist in that process.
Not sure what the Mixer does??

As I search ebay, I see there are parts kits for the carboretor but nothing for the mixer or converter. I don't see any adjustments on either of the latter. The carburetor only has an Idle adjustment. Three is some kind of adjustment in the lower carburetor mount plate that looks like it not be "field serviceable" (seal wired).

I'm going to go back to google and search for other trouble shooting help.

Still hoping someone here will have some "Sage" advice?

Thanks
Steve
  • Posted 9 Sep 2013 01:41
  • By OleSteve
  • joined 20 May'12 - 27 messages
  • Washington, United States
Your statement about "frost on the propane stuff" makes me think that the J-model fuel regulator (what the coolant hoses run to) is leaking liquid propane into the intake. What you think is acting like it's out of fuel is in reality probably "over-fueling". I have always found that a simple way to test this is to shut off the supply valve on the propane cylinder and see if the engine begins to run better as the fuel in the hose is consumed.
If the condition is due to over fueling, the engine may seem to run "about right" just before it uses up all the fuel in the hose and dies.
  • Posted 8 Sep 2013 09:44
  • By L1ftmech
  • joined 25 Apr'12 - 394 messages
  • Tennessee, United States
I just checked and verified that the plug wires are correct.

Now, I have to verify that the last person to have the distributor out, put it in correctly.

Steve
  • Posted 8 Sep 2013 05:11
  • By OleSteve
  • joined 20 May'12 - 27 messages
  • Washington, United States
And yes the firing order is 1-3-4-2
  • Posted 8 Sep 2013 04:55
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
Have an email to post in your profile has to be as mine is as this site strips out readable addresses
  • Posted 8 Sep 2013 04:49
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
I just checked the distributor and the mount/adjusting bolt was loose.
Now I have reservation and think this problem is timing or in the ignition system. I tried varying the distributor within the adjustment range, but not positive results. Then I began to wonder about the plug wires and realized I don't know the firing order of this 4Y engine. Toyota 4 cylinders have had of 1342 or older Corona's were 1243.
I checked for the firing order on the engine but didn't see it on the manifold.

Since the distributor mount bolt was loose, I suspect the whole unit might have been removed and re-installed. Hmmm, could be of a tooth when re-installed. Another possibility.

Without a manual, I'm going to have to play around with this one.

Steve
  • Posted 8 Sep 2013 04:39
  • By OleSteve
  • joined 20 May'12 - 27 messages
  • Washington, United States

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