c5vettster
Member
- Joined
- Nov 9, 2014
- Threads
- 7
- Messages
- 48
Our scag mower developed a strange problem when taken out of storage this year. By all appearances it runs very rich. The engine has about 300 hours. It was fully serviced, carb was cleaned and valve clearance was adjusted. I took the airbox off and I can see fuel misting out of the carb. It would use a 1/4 gallon of fuel in about 15 min of running. The first thing I did was to check if both cylinders are running by taking the spark-plug lead off. The engine appears to run equally rough on either of the cylinders. That tells me that the ignition is fine. I can see black smog coming from the muffler. Right away I took the carb off and checked the needle seal by apply compressed air to the fuel inlet. The seal seems to hold air when the float is top position. Here is what I suspect.
1. Fuel pump is defective and pushes too much fuel into carb?
2. The mechanic didn't do the valve clearance right. The poor fellow was nearly 80 and unfortunately passed away after a bout of flu in Feb. However, he was always very competent in the past.
3. One of the head gaskets is blown?
I am leaning toward third option. For one it seems like the fuel is misting out of the carb rather than being sucked in. Doesn't indicate that there some positive pressure may be entering the intake manifold? This could also explain excessive pressure that causes fuel pump to increase the fuel pressure.
Or could the old fellow make a mistake in valve adjustment? I only just ordered the leak down test kit. Anything else I can do to narrow down the problem in the mean time?
1. Fuel pump is defective and pushes too much fuel into carb?
2. The mechanic didn't do the valve clearance right. The poor fellow was nearly 80 and unfortunately passed away after a bout of flu in Feb. However, he was always very competent in the past.
3. One of the head gaskets is blown?
I am leaning toward third option. For one it seems like the fuel is misting out of the carb rather than being sucked in. Doesn't indicate that there some positive pressure may be entering the intake manifold? This could also explain excessive pressure that causes fuel pump to increase the fuel pressure.
Or could the old fellow make a mistake in valve adjustment? I only just ordered the leak down test kit. Anything else I can do to narrow down the problem in the mean time?