1995 7.4 Mercruiser Dies after running for 15 minutes

[jritchie94]

Hello All,

I have an issue with my 1995 mercruiser 7.4 bravo that is driving me crazy trying to find a solution for. Long story short, it will run fine when you first get on the water until you are running on plane for about 10 to 15 minutes, then it will start sputtering, smoking from the exhaust, smells really badly of gas, and dies. Then won't start up until you sit and let it cool for 10 to 15 minutes. It will then start back up finally but not very smoothly.

I have replaced the entire thunderbolt 5 ignition system with a performance marine D.U.I system and that did not fix the issue, so I am leaning towards it being a fuel issue, but have no idea where to begin looking. I plan on removing the fuel/water separator to check for a high content of water in the fuel, add some seafoam to the fuel tank to possibly help take out any moisture. Could it be the fuel pump or the carburetor? Any thoughts or advice is greatly appreciated at this point!

 

[alldodge]

I am leaning towards it being a fuel issue

Agree, need carb rebuild

plan on removing the fuel/water separator to check for a high content of water in the fuel,

Agree, pour in clear container and look for anything other then clean gas

add some seafoam

Do not agree, snake oil, fix your problem first

Could it be the fuel pump or the carburetor?

Possibility but think its the carb

 

[Scott Danforth]

Hello All,


I have replaced the entire thunderbolt 5 ignition system with a performance marine D.U.I system and that did not fix the issue, so I am leaning towards it being a fuel issue,

90% of the issues are always fuel system related. the TB V system is leaps ahead of the DUI system as far as performance. so all you did was waste money vs diagnosing the problem

there is no "mechanic in a can" seafoam is snake oil"

pull your carb, soak your carb, chase every passage in your carb, rebuild your carb, go boating.

Inspect your tank anti-siphon valve and check your fuel vent too.