1970 merc 800 big trouble

[macstang99]

ive got a 70 merc 800. i started out having trouble with the throttle not working right. im the process of fixing that , i started the boat up several times, and it ran just like it normally did. so about 2 weeks ago i turned it on twice to see if i had fixed the throttle problem it ran fine, but when i went to fire it up a third time, it would only stay running with the key turned all the way, as soon as you let go, it turns off. the throttle is also screwed up and the boat only goes about 10mph. so i got out the phone book and called around and only found one place that would work on that old of a motor, and it is 2 hours from my house. they have had it for a week now and just got to it today. they called me and told me they are stumped as to what it might be. any ideas????

 

[Deep_Blue]

Re: 1970 merc 800 big trouble

What do you mean by "Throttle Problem"? There are so many things that could be. And let me get this right. You say "it would only stay running with the key turned all the way" do you mean in the starting position? So if the starter is still spinning the engine, how do you know it "stays running"? What do you mean by that as well? Sounds to me that it’s probably either your throttle is set way to low or you have an electrical wiring problem.
Secondly, your boat only goes 10 mph? Wow, with an 800 your engine should be able to go faster then that at slightly greater than an idle. What are the symptoms? Does it bog out, sputter or just reaches an rpm and doesn’t go any further?

help us out so we can help you out.

 

[macstang99]

Re: 1970 merc 800 big trouble

the problem with the throttle is when you put it in the forward gear, you have to put it all the way to the 9 o'clock position before you even start moving, and it only gets up to about 10 and just stays at that speed. with the cover off you could manually move the throttle lever on the motor and the speed would pick up. i adjusted the cables and still no luck. i took apart the controller and everything looked fine, the cam was in the right spot and the two grooves were not worn down. the problem with it starting is you do have to hold it on the start position for it to run, but it runs very rough like that. hope this helps, thanks