Re: 1977 115HP Merc horrible gas consumption
Here's more details for you guys. First of all, I live and boat in Colorado at between 5,000 - 6,000' elevation. The .070 are the jets I've been running successfully in the motor for the past 10+ years. Several weeks ago I traveled to S. Dakota to a lake that is 1,500' and changed the jets to .072. As far as general performance, both jets worked well at each elevation.
The "slight" surging at a medium speed cruse started after the mechanic rebuilt the carbs last fall and the surging was/is present at both elevations. As I said, it does not affect the overall performance, but I notice it, just as you guys get to know your engines. The greatest difference to me is the fuel consumption.
The whole carb thing started when the motor suddenly was not able to get the boat to a plane. I was able to accelerate only up to 7-10 MPH. As it turned out, the carb rebuild was due to a cracked and leaky float in one of the carbs. Unfortunately, the mechanic did a lot of other things before he got to the carbs. During the first round he (1) Replaced plugs that I had replaced the year before and mine were the correct plugs and looked fine to me. (2) Replaced all the fuel lines and checked for leaks, there were none. (3) Checked and cleaned dist cap and brush. (4) Checked in the tank and said "sounds good in the tank, good accel." After a lake trip, there was not change and he rebuilt the the carbs. So, back to the lake and it seemed to run OK except for the slight surging and increased gas consumption.
Regarding the suggestions by Faztbullet, and thanks BTW, not sure if my skills are up to checking all those possibilities, but I know that the mechanic did replace the fuel line and bulb. The size of those ?? Is checking the float level in those carbs a difficult task for a novice? I do have the Seloc vol lll for reference. I've got a call in to my buddy to find out what year his Mariner is. I know it's newer than my Merc which is a 1977, but his is not real new. And yes, we basically went the same distances. And just to sum up, the surging is "slight" but noticeable to me. Let me know if you have more questions, I'm serious about getting this old girl right. Thanks!
I notice the motor surging at a mid range cruse. Wide open or at a troll it runs fine and starts good as well. The surging and poor gas consumption happened with both the .072 and the .070 jets so that's not the problem. What do you think is my problem and how can I fix it? Thanks!
