Hesitation, Missing ????

[banchigu]

Forgive my ignorace in advance.


I have a 40 HP mariner that runs really good. About a month ago my ignition switch went kaput on me and at the same time I began to get some hesitation or missing problems. I thought maybe it was because of the bad ignition switch. However I changed the switch and it works fine. However, it still hesitates at about 1/3 throttle once I push it to WOT it works fine I can hear it miss or hesitate a bit but for the most part once above 1/3 throttle it goes and the millage or speed has not suffered.

I did blow some Sea Foam though it and it got a lot better, could this be a fuel system problem?

This boat was given to me by my dad and I think it still has the original fuel filter, one that has a nut/screw assembly but I cannot seem to find the same one, would any in-line gas filter made for this engine work even if it is not held up right by the attachment screw.

I did tear the carbs down last winter in order to clean up build up because it had been sitting for over 2 years.

Or could this be an electrical problem?

A million thanks in advance.

 

[lostinnd]

Re: Hesitation, Missing ????

Hey, I have about the same problem, look for the 1983 115hp post from today, and I believe it may be caused by a bad stator or trigger, after you go through the fuel system and try to tune it out I would suggest looking into the electrical.
Good Luck,
Matt

 

[scrobo]

Re: Hesitation, Missing ????

I have a Merc 402 and I am having the same prob I think.

When I am at 1/2 throttle or so it seems to chug or miss a fire. then at wot it seems to make a "popcorn" noise from the unit itself. I was wondering if maybe there is a way to clean out the fuel delivery system without disassembling the carb?

I also have a hard time starting some times and someone suggested to get a compression test. Is this a possible cause of my problems? (Cracked block?)