Fuel leak on carb, Please help me diag
03-28-10, 06:08 PM
#1
Fuel leak on carb, Please help me diag
Coming from the drivers side of the carb. Puddles onto the plastic tray above the exh.
Car is a 79
Please list all places where fuel could leak, so that I may have miore knowledge for diag and fix.
Thank you
Car is a 79
Please list all places where fuel could leak, so that I may have miore knowledge for diag and fix.
Thank you
03-29-10, 06:24 AM
#5
Probably the accelerator pump, as noted above. A new pump diaphragm comes with the GP Sorensen carb rebuild kit for the Nikki. Autozone has the GP Sorensen kit, usually in stock, for $27.99.
Rebuilding the carb is a whole lot less expensive than "upgrading" the carb, especially since it's hard to find an all around better carburetor for the FB than a Nikki (a Holley, Delorto, etc will run you several hundred bucks and your gas mileage will probably drop significantly, sometimes into the low teens).
Here's the Autozone link:
http://www.autozone.com/autozone/cat...&parentId=49-0
Rebuilding the carb is a whole lot less expensive than "upgrading" the carb, especially since it's hard to find an all around better carburetor for the FB than a Nikki (a Holley, Delorto, etc will run you several hundred bucks and your gas mileage will probably drop significantly, sometimes into the low teens).
Here's the Autozone link:
http://www.autozone.com/autozone/cat...&parentId=49-0
03-29-10, 06:45 AM
#6
Lives on the Forum
Sterling has a nice bit of information on rebuilding the stock carbs. You can also look around his site if you are considering upgrading the carb (Sterling makes great carbs!).
www.sterlingmetalworks.com
.
www.sterlingmetalworks.com
.
03-29-10, 07:24 PM
#7
Sterling and his website have already helped me very much in understanding my nikki carb and its/my problems.
I believe my carb to have some sticky linkage and a ventilation problem.
I get whooshing sounds (breaking vacuum) from both the oil cap and the gas cap.
She was flooding after I shut her down.
Also puddles in the plastic tray.
I overnighted a GP Sorenson kit and am ready to tackle the problem.
I believe my carb to have some sticky linkage and a ventilation problem.
I get whooshing sounds (breaking vacuum) from both the oil cap and the gas cap.
She was flooding after I shut her down.
Also puddles in the plastic tray.
I overnighted a GP Sorenson kit and am ready to tackle the problem.
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03-29-10, 07:49 PM
#8
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03-31-10, 01:54 AM
#9
https://www.rx7club.com/showthread.p...ht=ventilation
Seems like my problems.
Posting up here for my own reference
Seems like my problems.
Posting up here for my own reference
03-31-10, 02:35 AM
#10
Depends on what other mods have been made.
In the stock carb, the bowl vent solenoid opens the bowl vent to the carb throat while the engine is on. When engine is off, it closes the carb throat vent and directs venting to the charcoal canister instead.
"bad things"
Carbs operate based on air pressure differentials - - if you change the potential difference in air pressure between two areas of the carb, you change its behavior.
If the bowl isn't vented properly when the engine is running, the carb can't operate properly because there's no atmospheric reference pressure inside the bowls to properly drive fuel feed rates... pressure fluctuates as fuel is added and removed, which can cause surging, flooding, all kinds of unpredictable behavior.
If the bowl is not vented when the engine is shut down, vapor pressure from the fuel's natural evaporation (accelerated by the heat from the engine) builds up air pressure within the bowls, forcing fuel out thru the jets and flooding fuel into the engine while it is stopped. The problem here is twofold:
1) flooding a stopped engine makes it very hard to restart
2) excess fuel in the combustion chambers washes the residual oil off of the side plates, which increases oil-ring wear on startup (something Mazda identified as a problem early in the 7's life - - it's mentioned in the engine rebuild evaluation docs)
The idea behind the charcoal canister is to trap bowl and tank fuel vapors after shutdown (for emissions purposes), and then let them be sucked thru the engine when its running, so they can be burned up.
In the stock carb, the bowl vent solenoid opens the bowl vent to the carb throat while the engine is on. When engine is off, it closes the carb throat vent and directs venting to the charcoal canister instead.
"bad things"
Carbs operate based on air pressure differentials - - if you change the potential difference in air pressure between two areas of the carb, you change its behavior.
If the bowl isn't vented properly when the engine is running, the carb can't operate properly because there's no atmospheric reference pressure inside the bowls to properly drive fuel feed rates... pressure fluctuates as fuel is added and removed, which can cause surging, flooding, all kinds of unpredictable behavior.
If the bowl is not vented when the engine is shut down, vapor pressure from the fuel's natural evaporation (accelerated by the heat from the engine) builds up air pressure within the bowls, forcing fuel out thru the jets and flooding fuel into the engine while it is stopped. The problem here is twofold:
1) flooding a stopped engine makes it very hard to restart
2) excess fuel in the combustion chambers washes the residual oil off of the side plates, which increases oil-ring wear on startup (something Mazda identified as a problem early in the 7's life - - it's mentioned in the engine rebuild evaluation docs)
The idea behind the charcoal canister is to trap bowl and tank fuel vapors after shutdown (for emissions purposes), and then let them be sucked thru the engine when its running, so they can be burned up.
03-31-10, 02:53 AM
#11
Your bowl is empty because the vent isn't opening and your gasoline is boiling out. It won't start because the boiled gasoline drained through your throttle plates into your engine and flooded it. Double check you bowl vent. Your plugs could be fouled from this as well. FYI boiled gasoline doesn't burn very well.
If you can run the car for a bit after it de-floods, let it warm up to operating temperature. Turn it off, pop the hood, remove the carb ha and watch for boiling vapors. OR you can just pop the hood and listen for a coffee pot noise.
If you can run the car for a bit after it de-floods, let it warm up to operating temperature. Turn it off, pop the hood, remove the carb ha and watch for boiling vapors. OR you can just pop the hood and listen for a coffee pot noise.
And another good tank vent thread
https://www.rx7club.com/showthread.p...ight=tank+vent
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