Re: Fuel System Vent?
Posted by Mike On 2011/6/26 20:38:20
Attached are pics of the cap...unless it's really well engineered and it doesn't seal against that seemingly cardboardish gasket that tight, i'm guessing it's not.
After ironing out some other issues, there's one that i've noticed i've had since the motor swap and i think it's causing a different issue.
After the car has been running a bit in the driveway (maybe 10-15 min?) or after taking off about 1-2 miles down the road from a cold startup, or from a warm startup, the car has 0 psi fuel pressure at the carb.
Today i took the glass bowl filter off, all the lines and put a new rubber line from the tank, to a round plain new cannister pass through style filter, to the fuel gauge and into the carb.
Tested and the same symptoms. At first i thought maybe i was running into the dreaded vaporlock, but then i did the cold test today and the car wasn't even all the way warmed up, or the choke all the way open and it did it again. You can let it sit and go start it and get 3 1/2 - 4 psi instantly.
When it loses pressure, i believe the car is WAY leaning out. It knocks and pings, especially at part throttle cruising when it would seem the vacuum advance is in. I have it retarded almost all the way and the vacuum advance disconnected and it can still knock some, and has just no real power.
I have a new fuel pump, new carb, all new lines, all heat shields in place and then some, and moved the new rubber line WAY out of the way of any heat source. I started to consider maybe the tank was building a vacuum and after running a bit idling or even sooner when driving, it was keeping the pump from keeping the carb full.
Strangely, the car still runs, just without power and kind of out of breath around 50mph. I'm sure the timing is contributing.
I'm banking on trying it without the gas cap tomorrow, and hoping that's it. Also thinking maybe what Kevin said about debris clogging the pickup and when the car shuts off, it floating away. Again, strangely, the car doesn't stall or anything. When i had the glass bowl on, i did noticed once, right after shutoff, it was only half full, and it's usually full all the time.
At least i got the rough idle solved with the manifold and carb swap....is anyone running a bathtub and a 4 bbl? Solving this and setting the right timing should solve the running out of breath at higher rpms.
Edit: also strangely, I've run this cap since i got it a few years back, it was on it when it came to me. I used to run this car with the 288 like crazy down the highway. Maybe it did vent some somehow or i never had it tight? Hard to imagine it never worked when i got 2 solid summers of mostly highway driving out of it.
Attach file:
(143.29 KB)
(136.17 KB)
After ironing out some other issues, there's one that i've noticed i've had since the motor swap and i think it's causing a different issue.
After the car has been running a bit in the driveway (maybe 10-15 min?) or after taking off about 1-2 miles down the road from a cold startup, or from a warm startup, the car has 0 psi fuel pressure at the carb.
Today i took the glass bowl filter off, all the lines and put a new rubber line from the tank, to a round plain new cannister pass through style filter, to the fuel gauge and into the carb.
Tested and the same symptoms. At first i thought maybe i was running into the dreaded vaporlock, but then i did the cold test today and the car wasn't even all the way warmed up, or the choke all the way open and it did it again. You can let it sit and go start it and get 3 1/2 - 4 psi instantly.
When it loses pressure, i believe the car is WAY leaning out. It knocks and pings, especially at part throttle cruising when it would seem the vacuum advance is in. I have it retarded almost all the way and the vacuum advance disconnected and it can still knock some, and has just no real power.
I have a new fuel pump, new carb, all new lines, all heat shields in place and then some, and moved the new rubber line WAY out of the way of any heat source. I started to consider maybe the tank was building a vacuum and after running a bit idling or even sooner when driving, it was keeping the pump from keeping the carb full.
Strangely, the car still runs, just without power and kind of out of breath around 50mph. I'm sure the timing is contributing.
I'm banking on trying it without the gas cap tomorrow, and hoping that's it. Also thinking maybe what Kevin said about debris clogging the pickup and when the car shuts off, it floating away. Again, strangely, the car doesn't stall or anything. When i had the glass bowl on, i did noticed once, right after shutoff, it was only half full, and it's usually full all the time.
At least i got the rough idle solved with the manifold and carb swap....is anyone running a bathtub and a 4 bbl? Solving this and setting the right timing should solve the running out of breath at higher rpms.
Edit: also strangely, I've run this cap since i got it a few years back, it was on it when it came to me. I used to run this car with the 288 like crazy down the highway. Maybe it did vent some somehow or i never had it tight? Hard to imagine it never worked when i got 2 solid summers of mostly highway driving out of it.
Attach file:
(143.29 KB)
(136.17 KB)
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