old merc question

brambo0311 · Post by **brambo0311** » Mon Sep 10, 2007 8:23 am

I have a 76 mercury 20 hp on my budget gregor bass boat. After about 15 seconds at full throttle it starts to sputter and die. If I run less then full it has no problem. I had all the electrical replaced a little over a year ago, could have bought a new motor for the price. Could this be a fuel delivery problem? I tried removing the gas cap and adjusting the carb all the quick fix stuff nothing helped. The electrical repair is out of warranty and it took them 3 times to get it right. They had wires rubbing the flyweel and grounding out. And I dont think they replaced everything like they charged me a grand for anyway. It is acting like a fuel problem but it starts 1st pull after it dies so I dont know.

Bill K · Post by **Bill K** » Mon Sep 10, 2007 8:54 am

Sounds like your carb needs a little cleaning. If you are some what mechanically inclined you should be able to pull it off and break it down (slowly and remember where everything went) clean the little holes, etc. blow out the jets, etc. (with low air pressure) and try running that after a good cleaning. Bill K

fishyd · Post by **fishyd** » Mon Sep 10, 2007 9:06 am

Check your priming bulb the smallest air leak will cause mystery problems.

brambo0311 · Post by **brambo0311** » Mon Sep 10, 2007 9:14 am

I will replace the tank, and all the line and bulb. But they are all less than a year old. The only problem is I cant get parts for this motor anymore they are no longer in production. I have turned my garage into a mini machine shop just for this motor. I dont see any leaks in the fuel lines in the motor, but they are off of a different motor and are longer, and snake around kinda funny. They have a odd sized conector and are no longer in production and no one has any new ones. But they have worked for years with no problems. I just want to make this thing work a little longer before I have to buy a new motor.

The Lone Angler · Post by **The Lone Angler** » Mon Sep 10, 2007 1:38 pm

Try replacing the fuel pump. Those probably have a rubber diaphram in them that can get worn/torn and still function at lower speeds. Try removing your fuel pump and connect the gas line directly from the tank to the intake for the carb. When you run the motor at WOT, squeeze the bulb continuously to keep the fuel pressure sufficient. If it runs fine doing that, replace the fuel pump. If it does the same thing, the fuel pump was not the problem.

Hope this helps,

Phil

brambo0311 · Post by **brambo0311** » Mon Sep 10, 2007 1:49 pm

No fuel pump is available for that beast. Its to old. And it only does it when its full throttle under load and takes about 15 seconds to start sputtering.

troutnut · Post by **troutnut** » Mon Sep 10, 2007 5:50 pm

for parts, contact the guy below. He has lots of old Merc parts. I would look at fuel bulb, carb float sticking

http://www.maxrules.com/fixmercindex.html

Whoopbass · Post by **Whoopbass** » Mon Sep 10, 2007 6:17 pm

Try www.iboats.com for motor help.
There's some knowledgable guys on there. Try searching for your problem first.

I'm going to say it's an electrical problem. It doesn't seem to be starved for fuel if it fires right up after it dies.

brambo0311 · Post by **brambo0311** » Mon Sep 10, 2007 6:24 pm

thanx guys i think i am just gunna get a new motor anyway. looks like the lower end is full of water to. I put 20hr a week on that thing for 10 years. I guess its time for a burial at sea.