fuel soaked exhaust pipe on start up

TCap

TCap

Member
Sometimes when I go to start her up, the carb shoots (not dribble) fuel out the back and all over the exhaust pipe. This is a big concern since I've had to shut her down when the fuel starts to smoke. I try to clean the pipe as much as possible but I still see smoke on start ups after.

Anyone else have this issue?
 
Do some checking on your valves. you may have a stuck open intake valve or a broken valve. A compression check will tell you. Timing ok?
 
I think timing is good, I've set it and it sounds good at idle. I've done compression check, all cylinders came in between 58-60. I've check valves recently but can always check again.
 
Clem Clement said:
... or a broken valve. A compression check will tell you...
Click to expand...
Not always. I had a broken valve last year & the compression check showed normal on that cylinder. The (exhaust) valve was broken below the keeper, and therefore it stayed closed all the time, makingthe compression reading normal or slightly above what the other 3 were.
 
You are getting compressed air into the intake somehow. With the switch off, The fuel sut off and prefererably the battery off, have a helper hand crank over the engine. Put your gloved hand over the carb intake and see if you can find a position the blows air. Maybe you could use the starter after running the carb empty. Be safe here!
 
had a helper crank engine over by hand while I checked valves. All valves seemed to move fine, but I could only see 4 total. Did the carb intake check, put hand over intake while my brother cranked by hand. Felt some air push out intake and stopped on that spot. Checked valves but not sure what I'm looking for. Feeling really lost right now.
 
I think the most likely cause is over choking the engine on start up. Only hold the choke closed for two compression strokes and excess gas will no splash back out of the carb. While cranking the engine over with the starter you can hear the compression strokes if you listen closely.
 
I've never had that problem. It just seems that if a valve was sticking that it would cause loss of compression on that cylinder and you would get a dead miss.
 
Try swapping out your carb with a known good one and see if it runs ok. If so you have a carburetor problem that needs fixing.
 
Another question that may shed some light on this issue. I'm still having problems with the number 2 and 3 spark plugs running very lean...still white porcelain and number 1 and 4 running a little on the rich side. Now with that said, the car sounds really good. I'm thinking, would an intermitten stuck valve cause both issues? If so, would it be more likely to come from exhaust valve or intake valve sticking? I was only able to see the intake valves when I checked, they seemed to be opening and closing fine. I think MMO may be the way to go and then if needed pull the valve cover off and check the valves.
 
Not sure if this is your problem but I've had the float valve inside the carburetor stick open, flooding the carburetor and causing fuel to pour out the back and onto the exhaust. Normally, a few taps on the outside of the carb jiggles the valve closed, however I did need to replace the valve about 6 months ago. Easy to do.
Mike
 
I think you are just over choking the engine. So when the engine doesn't start and kicks backward slightly when stopping, it forces excess fuel out of the carburetor and onto the exhaust pipe. Nothing to worry about. Try choking it less when you start it.
 
In common , i would more likely have a look onto the carb.
You might cross-check with a proven one, as mentioned earlier.

I had a comparable prob there.
The GAV was loose in the carb .
By turning the GAV to the left , i screwed the complete GAV out of the carb :cool:
Its to be seen from outside
Have a look on the carb while letting someone turn the GAV....

Good luck
Christoph
 
so I decided to just start the car as is no mmo added yet. Car starts with no gas shooting out the carb (lightly choking). after 3 mins of running smoke is coming off the inside lower part of the exhaust pipe right before the bend. Not sure what is causing this. I shut it down when it starts to smoke. This has happened two days in a row. I'v cleaned the pipe both times and don't see anything that would burn...no clue
 
TCap said:
so I decided to just start the car as is no mmo added yet. Car starts with no gas shooting out the carb (lightly choking). after 3 mins of running smoke is coming off the inside lower part of the exhaust pipe right before the bend. Not sure what is causing this. I shut it down when it starts to smoke. This has happened two days in a row. I'v cleaned the pipe both times and don't see anything that would burn...no clue
Click to expand...

Do you open the right side of the hood and watch everything as it warms up?
 
Had this issue yesterday with my dads a. The carb float was not making contact with the needle. The bowl would fill up and than puke out excess gas. We have two extra carbs and swapped out the float with one that was shaped better. Problem eliminated.
 
Tcap,
Could it just be some old cooked on oil or something that won't just wipe off. Maybe if you run it longer maybe it will burn off. Lay under the car while it's smokin' to find the origin of the smoke. Does your car run with GUSTO? If not, you may have a partially plugged exhaust, causing the pipe to get hotter than normal & puff off some smoke. Bill W.
 
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