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Discussion Starter #1
just got my jeep converted over to propane. forklift tank, vff 30, impco model e and impco 425 on a 258 i6. itll only start if I push the primer button on top of the model E. once started if you let it die, gotta prime it to start again. it wont idle either. messed with the timing and its not dialed in perfect but its pretty good. could it be a timing issue or maybe need to rebuild the model e or 425?
 

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Is your solenoid wired in correctly. I'd call Got Propane. They is awesome and i'm sure will figure out your problem quickly.
 

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Discussion Starter #5
Is your solenoid wired in correctly. I'd call Got Propane. They is awesome and i'm sure will figure out your problem quickly.
I don't have any wires to anything as far as the propane setup goes. it was running fine on an old hunk of shit leaky weber and all i did was take the carb off and put the propane stuff on.

thats pretty much all the propane set ups I've seen.
well shit. that will suck having to open the hood every time I have to start it. I thought propane was supposed to be good on cold starts. im in florida so its not really cold much.

Sounds like a vacuum leak. Sometimes hard start means it is not getting enough fuel.
that might be it. I have a really cheap 4bbl to 2bbl adapter to get the 425 on the intake and it seemed like it might leak. I hope that's it.
 

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check vacuum at the lock off (while cranking).. Next move to the converter and check fuel pressure (while cranking). Should be 1-2 psi. If not, then you may have an old crusty diaphragm or stuck plunger. Rebuild kits are cheap and no big deal to install.
 

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well shit. that will suck having to open the hood every time I have to start it. I thought propane was supposed to be good on cold starts. im in florida so its not really cold much.
False.. propane is in a liquid state when in the tank. It requires heat from your coolant or atmosphere to turn to a gas state. We have to pure hot water on the converters in the winter to get them to start.
 

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Is your solenoid wired in correctly. I'd call Got Propane. They is awesome and i'm sure will figure out your problem quickly.
Even if he had one, he is getting fuel past the lock-off so that is not the problem.

thats pretty much all the propane set ups I've seen.
guess you've only seen some hack stuff. :flipoff2:

Sounds like a vacuum leak. Sometimes hard start means it is not getting enough fuel.
Yes, quite possibly

check vacuum at the lock off (while cranking).. Next move to the converter and check fuel pressure (while cranking). Should be 1-2 psi. If not, then you may have an old crusty diaphragm or stuck plunger. Rebuild kits are cheap and no big deal to install.
He is getting fuel as far as the vaporizer, it is not likely a fuel issue. Given his posts, it is most likely worn out/ cracked components or a vacuum leak. If those are ruled out I would re-visit the timing. I set total timing on my propane setups and run them at mid to upper 30 ' s by 2500 rpm.
 

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False.. propane is in a liquid state when in the tank. It requires heat from your coolant or atmosphere to turn to a gas state. We have to pure hot water on the converters in the winter to get them to start.
How cold is it where you are? The boiling point of lpg is -42c
 

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Discussion Starter #10
I got this whole setup off a guys running truck. it was running when I went to his house to take it off. the only thing that wasn't is the 2bbl to 4bbl adapter. it is a cheap piece of shit but I couldn't find a decent one thatll fit. I bet that's the problem. if its not storming ill check when I get home. I have total timing set at 37 all in by 2500.
 

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2 things I found with mine that may or may not help but:

1st, when cranking don't operate the accelerator pedal. Just crank, since the fuel is drawn in by the engine vacuum, if you open the butterfly it kills the vacuum "signal" and wont have much luck getting it started.

2nd, I had similar issue you describe, and both times it ended up being a bad ignition module. Like not completely dead but guess it was a weak spark type scenario. 1st time was my stock ICM, then went to a MSD ignition box which lasted about a year then started doing it again.

May or may not help but those two things where my experiences with that issue. Everyone keep telling me it was a vacuum leak so I wasted a butt load of time chasing leaks that were none existant.
 

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Turn your idle up then spray the intake with brake kleen, if the idle goes up more then you have a vacuum leak. An O2 sensor and air/fuel gauge will help you tune it also.
 

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Another one for vacuum leak.I had the same issues when I put together my 4.3.Found the vacuum leak, and it started fine after that.
 

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Could the VFF30 be clogged? IE not getting vacuum, so no fuel.
Which vacuum line is hooked up to the VFF30?

Try bypassing it.

I put electric lockouts next to my tanks.
 

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guess you've only seen some hack stuff. :flipoff2:
x2

if my turbo 4cyl has been sitting over night or longer it takes about 8 seconds of cranking to start(no pushing the button), after that initial start up it will start up within 1-1.5 seconds. i pretty much never push the button unless i happen to be near it and its been sitting over night, its on the pass side so its rare.
 

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Discussion Starter #16
2nd, I had similar issue you describe, and both times it ended up being a bad ignition module. Like not completely dead but guess it was a weak spark type scenario. 1st time was my stock ICM, then went to a MSD ignition box which lasted about a year then started doing it again.

May or may not help but those two things where my experiences with that issue. Everyone keep telling me it was a vacuum leak so I wasted a butt load of time chasing leaks that were none existant.
it has a hei distributor on it. I do have to replace the module under the cap about once a year and did about 2 months ago. ill check it.
its a vacuum leak without a doubt. cranked it up and you can hear it. it wasn't like that last time I had it running but it is now. started storming so didn't get to work on it.
 

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It sounds like there may be more than one issue. It does sound like a vacuum leak in the intake system somewhere. The mixer you are running is also on the large side for that engine so the vacuum signal when starting would be weaker than a smaller one. We have a "start" valve that can be installed on the vaporizer so you can prime the engine with a toggle switch or connect it to the starter circuit so it opens whenever the starter is engaged. The mixer could also be old and have excessive wear in the housing causing hard starts and idle issues.

Here are general guidelines for setting timing on a propane engine.

Setting Timing for a Propane Engine

On most applications, the timing should be a total of 30 degrees(base and centrifugal) with all of it in by 2500 rpm. What we normally do is disconnect the vacuum advance, run the engine up to 2500 rpm, set the timing at 30, lock it down, then let it idle with the vacuum advance disconnected. See what your base timing is running. If it is low,4-10 degrees for example, you can alter the centrifugal to lower that number and increase the base, still keeping a total of 30 degrees. As you increase the base timing check to see if the engine spins and starts smoothly when hot. If you reach a point that the engine bucks or loads the starter, back off about 3-4 degrees and that is your base timing. Subtract that number from 30 degrees and that will be the advance you need to have. This will provide a good start, strong idle and proper advance curve. We have had some engines run as much as 20 degrees base timing but 14-16 degrees is normal. The vacuum advance should be connected to ported vacuum and have no more than 10 degrees. This helps fuel economy at light throttle positions.
__________________
Propane Systems: Buddy: 877-403-7827
Precision Sales and Service, Inc.;Birmingham, Alabama [email protected]

Contact me if you have questions.
 

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I'm going to go out on a limb here and ask if the tanks are laying down or upright. Depending on the tank the pickup tube could only be supplying vapor. Enough to start after a good purge but not supplying enough to run constantly.
 

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I'm going to go out on a limb here and ask if the tanks are laying down or upright. Depending on the tank the pickup tube could only be supplying vapor. Enough to start after a good purge but not supplying enough to run constantly.
True, upright should be fine (assuming fork lift type tank) but there is a proper way to lay the tanks down to submerge the pickup tube.
 

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tank locator pin down is what i came across when looking how to mount my tanks, i mounted mine standing up though and pin towards the rear

 
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