Jump to content
Sign in to follow this  
tizfun

Motor Problems (NF)

Recommended Posts

Hey all, My 20 yesr old nephew bought his first boat and took me out today for a days fishing on Simcoe... Boat started fine and when he went to hit the throttle,it bogs right down... It's an older 70 hp Merc... Can't figure whats wrong and we took the cowl off and everything looks fine... He said to me that he replaced the seals of the carb earlier in the week as they were leaking..

 

Can anyone give us an idea of whats happening ?? He's in Trent Univerity and on a very limited budget for repairs...

 

 

thanks in advance,

 

Tiz

Share this post


Link to post
Share on other sites

Look for other air leaks in the fuel system..cracked hoses etc.

It sounds to me like there is enough vacuum to keep fuel flowing at idle, but when the throttle is opened air is leaking into the system somewhere and the flow of fuel is interrupted.

Share this post


Link to post
Share on other sites

I have a 1987 90 H.P. Merc which is basically the same engine. The 70,80, and 90 all use the same base, with just some minor modifications.

When I first got it back in 2001, it did the same thing, but only on occasion. some times it picked right up and took off, other times it bogged.. In the end, it turned out to be the ignition module. This is a roughly 3" by 6" metal block filled with black epoxy, mounted to the engine in the vertical position, and has all the wires going out to the coils and such. It is very simple to replace yourself (which I did), but unfortunately, it costs about $470.00 from a Merc dealer.

Thankfully, mine has worked great since.

 

Hard to tell if this is your problem, but I believe a Merc Mechanic can diagnose this.

 

good luck!

Share this post


Link to post
Share on other sites

Did he check the floats and level of them while he had the carbs apart.Also might have disturbed the syncronization of the carbs when having them off and replacing them.

 

Kerry

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×