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I'm having some difficulties with a carburetted mazda 121. Some might remember I had difficulties with the engine bucking and a suspicion of a vacuum leak - I had solved that temporarily by adjusting idle richness for highest RPM and backing out the throttle stop.
Recently the same problem reappeared and I decided to refurbish the carb - so carb off, cleaned the exterior, managed to unbind the second venturi linkages, etc.... finally carb back on the manifold and new rubber hoses for vacuum.
She started quite well, and with a bit of fiddling the idle was perfect and the engine revved great. Engine pulled 22inches of vacuum at idle and when it warmed up it drove great. Then I drove hard for a minute and worked well at high revs.
Problems reappeared when I slowed down again with the engine surging between tickover and 2000 rpm randomly when out of gear and even dying.
It seems that the fuel level in the carb was getting too high - way higher than the sight glass. I bent the float arm to keep it from getting too high and now I have a situation where the level fills very rapidly to the sight glass, and then keeps filling up slowly higher and higher - I'm betting this is the problem with the surging. Locally nobody sells carb kits or float needles! Other than trying out the float needles in a couple of old carbs I have lying around I'm stumped!
I checked the fuel return and it is not blocked - I even ran a new hose from the pump to a can but no change in things.
Can anyone help with some ideas?
N
PS: I don't know if this is relevant, but the previous owners completely butchered the vacuum and emissions control piping leaving nothing but the carb, a small aluminium canister and tubes to the pcv valve and distributor. The fuel cut solenoid is connected as is the float bowl vent solenoid (with no tube connected). Choke is manually operated.
Recently the same problem reappeared and I decided to refurbish the carb - so carb off, cleaned the exterior, managed to unbind the second venturi linkages, etc.... finally carb back on the manifold and new rubber hoses for vacuum.
She started quite well, and with a bit of fiddling the idle was perfect and the engine revved great. Engine pulled 22inches of vacuum at idle and when it warmed up it drove great. Then I drove hard for a minute and worked well at high revs.
Problems reappeared when I slowed down again with the engine surging between tickover and 2000 rpm randomly when out of gear and even dying.
It seems that the fuel level in the carb was getting too high - way higher than the sight glass. I bent the float arm to keep it from getting too high and now I have a situation where the level fills very rapidly to the sight glass, and then keeps filling up slowly higher and higher - I'm betting this is the problem with the surging. Locally nobody sells carb kits or float needles! Other than trying out the float needles in a couple of old carbs I have lying around I'm stumped!
I checked the fuel return and it is not blocked - I even ran a new hose from the pump to a can but no change in things.
Can anyone help with some ideas?
N
PS: I don't know if this is relevant, but the previous owners completely butchered the vacuum and emissions control piping leaving nothing but the carb, a small aluminium canister and tubes to the pcv valve and distributor. The fuel cut solenoid is connected as is the float bowl vent solenoid (with no tube connected). Choke is manually operated.
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