Propane Engine backfiring. Need help
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Propane Engine backfiring. Need help
Hello!
I have a 1979 Ford Custom pickup on Propane. Everytime I go up a hill or accelerate hard it backfires and ofcourse I loose all my power and speed. It's embarrasing only being able to do 20km/hr up a hill while backfiring constantly.
On the flats and on gentle acceleration it works great. Even idles smooth at a stop.
I first thought it was bad propane so I switched gas stations but that didn't help.
Any ideas on what I could check or what my problem might be?
Thanks in advance for any input.
I have a 1979 Ford Custom pickup on Propane. Everytime I go up a hill or accelerate hard it backfires and ofcourse I loose all my power and speed. It's embarrasing only being able to do 20km/hr up a hill while backfiring constantly.
On the flats and on gentle acceleration it works great. Even idles smooth at a stop.
I first thought it was bad propane so I switched gas stations but that didn't help.
Any ideas on what I could check or what my problem might be?
Thanks in advance for any input.
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From: Greenwood In. USA
No
Propane is higher octane, it requires more intial advance.
Backfire thru the carb is usally a lean mix. What system are you running? Dedicated or bi-fuel? Have you checked the filter? Have you checked the converter for heavy ends? Let me know.
BTW: Welcome to FTE
Propane is higher octane, it requires more intial advance.
Backfire thru the carb is usally a lean mix. What system are you running? Dedicated or bi-fuel? Have you checked the filter? Have you checked the converter for heavy ends? Let me know.
BTW: Welcome to FTE
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It's running on straight propane. No dual fuel.
It used to run just great. Then on day I was going up a hill and it started to backfire real bad. It was a really cold day (-30). I figured maybe that was it but now it's warmed up and it still does it.
I'll put a new filter in today.
I can feel the backfires on my feet so I think it's backfiring thru the exhaust for sure.
I don't know what you mean when you say heavy ends on the converter?
It used to run just great. Then on day I was going up a hill and it started to backfire real bad. It was a really cold day (-30). I figured maybe that was it but now it's warmed up and it still does it.
I'll put a new filter in today.
I can feel the backfires on my feet so I think it's backfiring thru the exhaust for sure.
I don't know what you mean when you say heavy ends on the converter?
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From: Greenwood In. USA
Propane when it heated gets refined a little further, any oils or even the odorant will get craked out and settle in the vaporiser and the hose to the carb. Pull the hose to carb off and inspect it, shut the tank valve off, run the system dry and pull the front cover carefully from the vaporiser. If you see something that looks like heavy oil or even grease thats heavy ends and it needs to be cleaned out.
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I pulled the hose that leads to the carb off and it looked pretty good. I don't know a lot about propane systems but there seems to be two cylindrical devices the propane goes to before the carb. A smaller one the propane enters that comes straight from the storage tanks then a larger one the propane enters just before it goes to the carb. It has a little spring loaded push button in the middle of it. Not sure what that is. I'm assuming that one is the vaporiser. Is that right? ....here's a couple of pics.
http://f1.pg.photos.yahoo.com/ph/dsa...&.dnm=vap1.jpg[/IMG]
Once I know for sure which one is the vaporizer, I'll inspect under the cover.
http://f1.pg.photos.yahoo.com/ph/dsa...&.dnm=vap1.jpg[/IMG]
Once I know for sure which one is the vaporizer, I'll inspect under the cover.
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From: Greenwood In. USA
The unit the hose goes into from the tank is call a vacumn Filter fuel lock. It filters the fuel and "locks off" when the engine is off. The name and model is Impco VFF30, the filter element is F1-10, the repair kit is RK-VFF30-2. Your second unit is your vaporiser, it is a Impce Model "E", the repair kit is RK-E-2. The little spring loaded button is a manual primer which allows you to prime the system on a cold start simlar to a gasoline accel pump.
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From: Greenwood In. USA
Also if your mixer/carb is sticking that would cause it to go lean and backfire further compounding the problem with the mixer. I will assume since the other equipment is IMPCO that you have a CA425 mixer. They are real prone to the air valve sticking. Making them hard to start and prone to backfire. Post a picture if you can
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My truck starts great and runs at idle fine. Just under load it backfires (thru the carb I think). It had done this before a couple years ago when I was going up a hill but then went away. So it's seems to be a problem that sort of comes and goes. Today when I ran the truck I was very gentle on the throttle and it seemed ok. I punched it once up a hill and after about 2 seconds it started to backfire. So I let up on the throttle. I then resumed light throttle and it backfired more. The same light throttle I used before and it didn't backfire. So know I'm thinking it might be fuel starvation. I've never changed the filter in the vacuum filter fuel lock before and I've probably put 40,000 miles on the truck with the propane. Maybe that's it? Not sure where I can pick up one of those repair kits but I'll have a look around.
So is it pretty common to change filters in the propane system? I always thought propane was a pretty clean fuel.
So is it pretty common to change filters in the propane system? I always thought propane was a pretty clean fuel.
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I just put in a new filter in the fuel filter vacuum lock. The old one looked pretty gross. The truck runs a bit better now but still backfires. It seems almost to backfire at a bit higher rpm now. So I think definitely the filter needed to be changed. Not sure what else to check now....maybe I'll open up that converter and see if it's dirty.
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From: Greenwood In. USA
Check the throttle body for leaks by spraying it with carb cleaner or wd 40. They sometimes leak around the shaft when they get a lot of miles on them. Your leaning out under load so its either fuel starvation or a vac leak. Make sure the vac fuel lock is hooked to a good manifold source one that dosent fall badly under load.
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