1980 Mercury 150 questions

[sillverchevy]

"Hi,
I have a few questions r

"Hi,
I have a few questions regarding my 1980 merc 150. Powerhead was rebuilt 3 years ago, with minimal use (as per previous owner). Beginning of season I replaced power packs, starter, impeller, lower unit oil, thermostat, and had carbs rebuilt. Engine ran and continues to run good, with the exception of:
1) Carbs leak gas -Mechanic addressed this 2 weeks after carb rebuild, stating it had to do with the ethanol in the fuel expanding the seat. He attempted to correct, but engine continues to leak considerably. What could be causing the leaks? Looks to be coming from the middle carb, but I'm not sure.
2) Engine clunks when in reverse. This does not happen when I initially put into gear, rather 2-3 seconds after being in reverse, I hear a clunk'clunk, that does not appear to affect performance. Any ideas
Is this a decent motor- or was this model merc flawed in someway. Just trying to learn a little about this engine. Sorry for the long post, thanks for all your help."

 

[Chris1956]

"Ronald, That model was prett

"Ronald, That model was pretty successful. They were made with minor differences until the late 90s.

On the carb gas leak. Tilt the motor up a bit, open the throttle plate and pump the primer bulb. You should see gas run out of the air intakes, and know what carb it is. The carb will need to be removed, the inlet needle replaced and the float height set.

One thing to check first. if the gas comes out of the lowest carb, remove the pulse line on the fuel pump and see if gas comes out of the fuel pump. If it does, rebuild the fuel pump. If the gas comes out of the middle carb, you will need to remove the fuel pump from the block to see if it is leaking."