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No vacuum twin commander 674

#1

C

Charleytuna

Back story on John deer. Part of fuel cap disintegreted into tank. Black gunk. Cleaned tank. Replaced fuel filter and line. Cleaned carb twice. No fuel out of pump. Replaced pump. Still weak erratic flow. Will run if l hold choke closed with finger. Vacuum gauge shows alternating positive and negative pressure. Pulled head with breather. Reed valve looked fine. Scratching my head now. Is there another reed valve in other cylinder. Should I check that breather in middle. When choked engine sounds smooth. Thanks


#2

Hammermechanicman

Hammermechanicman

Did you pull the pickup tube out of the tank and made sure it is clear?


#3

C

Charleytuna

Its clear. Will siphon with line down low. ABS clicks also.


#4

R

Rivets

Positive and negative pressure is what the pump needs to work properly. Sounds to me like you have a lean running condition, which means time to clean and rebuild the carb.


#5

C

Charleytuna

Oh ! So the vacuum is not really a vacuum. I thought the needle should stay on the neg. side. Time to clean carb better then better again. I got same vacuum reading on dipstick, breather and pulse pump hose.


#6

R

Rivets

The positive and negative pressure is the pumping action. I suspect the you should look closely at the float level. Post engine numbers and I’ll try to find a manual for your engine.


#7

C

Charleytuna

Got a manual. Its time for a closer look at carb. Thanks alto.


#8

Mower King

Mower King

Oh ! So the vacuum is not really a vacuum. I thought the needle should stay on the neg. side. Time to clean carb better then better again. I got same vacuum reading on dipstick, breather and pulse pump hose.
Putting a vacuum gauge on a mower engine gives you NADA!
Make sure you have a good full stream of gas to the carb, not just a trickle of gas. Running good / smooth with the choke on, is a carb problem.....as long as you have enough gas in the carb to begin with!


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