48 IDF, Fuel puking into the bores
#1
48 IDF, Fuel puking into the bores
Carb is a 48 IDF. Boost prepped.
I have a full rebuild kit on the way and will thoroughly go thru it soon but have been pondering an issue with it.
After the car is turned off fuel is steadily flowing into the bores. It seems to do this until the float bowl is almost dry. It is almost like a vacuum is being created and sucking the fuel right out of the bowl.
I have swapped out the needle and seat for a new one. I have adjusted the float level 10+ times. Fuel is regulated with a very accurate gauge.
Anyone have any thoughts?
-billy
I have a full rebuild kit on the way and will thoroughly go thru it soon but have been pondering an issue with it.
After the car is turned off fuel is steadily flowing into the bores. It seems to do this until the float bowl is almost dry. It is almost like a vacuum is being created and sucking the fuel right out of the bowl.
I have swapped out the needle and seat for a new one. I have adjusted the float level 10+ times. Fuel is regulated with a very accurate gauge.
Anyone have any thoughts?
-billy
#7
Eats, Sleeps, Dreams Rotary
iTrader: (1)
Ha, it happens to the best. I have seen some veteran technicians at my work chase their tails around an electrical problem on a car, spending a day on the a car trying to diagnose when it was just a blown fuse. It's easy to get caught up and forget to check the basics first.
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#8
gross polluter
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Did the fuel cap take care of it? My Weber DCO had a similar issue, turned out I needed a larger idle jet. The idle air mixture screws had to be backed out too far and this allowed fuel to leak past so when I put in the larger idle jets and turned in the idle mixture screws the leaking stopped.
#9
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Did the fuel cap take care of it? My Weber DCO had a similar issue, turned out I needed a larger idle jet. The idle air mixture screws had to be backed out too far and this allowed fuel to leak past so when I put in the larger idle jets and turned in the idle mixture screws the leaking stopped.
thats a fun one....
#10
Nope. Still have the problem. I removed the cap so no pressure can build up.
Been reading a bit and have adjusted to carb with the mixture screws 1 turn out. Idle speed 1/2 in from first touch of the lever. Air bleeds fully seated.
Once the car has run a few minutes and is warm I turn it off and the fuel spills onto the butterfly from the progression hole in the front bore only.
3PSI +/- .1 on the gauge ( ) and float level is set.
I am stumped again.
-billy
Been reading a bit and have adjusted to carb with the mixture screws 1 turn out. Idle speed 1/2 in from first touch of the lever. Air bleeds fully seated.
Once the car has run a few minutes and is warm I turn it off and the fuel spills onto the butterfly from the progression hole in the front bore only.
3PSI +/- .1 on the gauge ( ) and float level is set.
I am stumped again.
-billy
#11
Eats, Sleeps, Dreams Rotary
iTrader: (1)
Nope. Still have the problem. I removed the cap so no pressure can build up.
Been reading a bit and have adjusted to carb with the mixture screws 1 turn out. Idle speed 1/2 in from first touch of the lever. Air bleeds fully seated.
Once the car has run a few minutes and is warm I turn it off and the fuel spills onto the butterfly from the progression hole in the front bore only.
3PSI +/- .1 on the gauge ( ) and float level is set.
I am stumped again.
-billy
Been reading a bit and have adjusted to carb with the mixture screws 1 turn out. Idle speed 1/2 in from first touch of the lever. Air bleeds fully seated.
Once the car has run a few minutes and is warm I turn it off and the fuel spills onto the butterfly from the progression hole in the front bore only.
3PSI +/- .1 on the gauge ( ) and float level is set.
I am stumped again.
-billy
#13
Banned. I got OWNED!!!
#16
Holly pump.
Mallory Regulator. (has return)
Pressure gauge can tell the difference in 3 PSI and 3.1 PSI
Float level has been set. That was my first thought so I messed with it for a while.
As soon as the fuel pump is turned off the pressure drops to zero.
While running everything is fine. If turned off before the engine is warm everything is fine. It only happens once the engine is at operating temp.
-billy
Mallory Regulator. (has return)
Pressure gauge can tell the difference in 3 PSI and 3.1 PSI
Float level has been set. That was my first thought so I messed with it for a while.
As soon as the fuel pump is turned off the pressure drops to zero.
While running everything is fine. If turned off before the engine is warm everything is fine. It only happens once the engine is at operating temp.
-billy
#17
gross polluter
iTrader: (2)
It's not a fuel pressure problem, I run my Weber with no regulator and deadheaded, using a pump that does about 7psi. Float problem would make it dribble all the time, not just after turning it off.... What does the fuel spray look like when running? Should be a very fine mist you can barely see.
Screw the idle mixture adjust screws all the way in and see if that problem persists. Some Weber carbs the screw should be out no more than 3/4 of a full turn.
Yeah it was, that sucked. I had that problem for years before I figured it out!
Screw the idle mixture adjust screws all the way in and see if that problem persists. Some Weber carbs the screw should be out no more than 3/4 of a full turn.
Yeah it was, that sucked. I had that problem for years before I figured it out!
#18
Eats, Sleeps, Dreams Rotary
iTrader: (1)
^ How would idle mixture screws cause a fuel dripping when the engine is off?
Man, I am stumped now too. Did you figure it out yet? The thing that has me stumped is that it only does it when the engine is off and at operating temps. The only thing I can think of and this is a shot in the dark is maybe your fuel lines up to the carb are getting too hot causing the fuel to boil and when you turn off the engine it drips out . Like I said... a shot in the dark. Let me know what you find, I'm very curious now.
Ps. how long does the dripping go on before it stops?
Man, I am stumped now too. Did you figure it out yet? The thing that has me stumped is that it only does it when the engine is off and at operating temps. The only thing I can think of and this is a shot in the dark is maybe your fuel lines up to the carb are getting too hot causing the fuel to boil and when you turn off the engine it drips out . Like I said... a shot in the dark. Let me know what you find, I'm very curious now.
Ps. how long does the dripping go on before it stops?
#19
Going by your sig this is in an RX3? I've seen this once before in an Rx3 with an IDA. As soon as the engine was turned off fuel would slowly gravity/siphon feed into the bowl flooding the engine. This would only happen when the tank was half full or above. There was no pressure build up at all. Pump and reg were Holley blue.
#20
Seems to go on until the float bowl is about dry.
Should have it back on this weekend. Will let you know what I find out.
-billy
#21
Well.....I completely rebuild the carb. new need/seat, new idle mixture screws and all new gaskets and o-rings.
Set the float level at 15mm (so I know it is low).
Same thing.... I even pulled the top off as soon as I shut it down to see if it was the needle/seat letting the fuel in.....nope. With the top of the carb off, float bowl with fuel in it.... it leaks out the progression holes.
So that has to eliminate the float level, pressure buildup in the gas tank and overflowing the carb......
-billy
Set the float level at 15mm (so I know it is low).
Same thing.... I even pulled the top off as soon as I shut it down to see if it was the needle/seat letting the fuel in.....nope. With the top of the carb off, float bowl with fuel in it.... it leaks out the progression holes.
So that has to eliminate the float level, pressure buildup in the gas tank and overflowing the carb......
-billy
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