Henry D

I enjoy your reports back in the early 80’s John and Frances and I fished together a lot out of Braddocks Bay I’m still at it though on a smaller scale your mention of them brought back great memories Tight Lines

Yes it does I looked at the charts you sent you nailed it

I sent a email to marineengine.com they responded with no results on that serial number too

I’ll check it out thanks

Not knowing the history of this boat I wouldn’t be surprised if it’s not a 80 hp (that’s the decal on the cowling) Mercury also made 75 hp motors on this 3 cylinder platform best I can tell its of a 1982 vintage although the serial number has a 75 in it and I don’t get an exact match up when searching on the serial # online As far as the ignition issue I described in my last post you’re correct I believe Mercury calls the control module the coils are wired to a Switch Box those wires all look okay I did check them for rust and broken insulation etc.I checked the grounds for continuity the anomaly I saw in the spark test tool on the Top cylinder is quite different from the middle and bottom cylinders and the fact I didn’t move the issue swapping coils makes me think the switch box is faulty I haven’t looked to see how much they are but I’m sure they’re not cheap I hate just throwing parts at a problem not fully understanding the root cause Im slowly learning the ins and outs of this motor I really appreciate your knowledge as well as the other guys and your willingness to help me out Thanks

Hi guys I hooked up a in-line spark tool & set up my phone on a tripod so I could video in a dark garage The Top Cylinder looked very different (weaker in my opinion) than the middle and bottom I then swapped the coils between the top and middle and repeated the test this did NOT move the weaker signal to the middle cylinder So at this point I would think I have an issue with the ignition control module i tried to attach the videos but was unsuccessful so would I be on the right track replacing the module the coils are wired to or is there something else I can check at this point Also if you have recommendations as to where your buying parts please send them along The other issue I’ve run into is looking up this motor by its serial number it is Canadian built I’ll attach a photo of the serial number

The disconnect fitting is the up to date I have not gotten into the fuel pump as of yet I wasn’t aware of a filter inside the pump itself I can’t imagine replacing the diaphragm in the pump can be too bad is the filter cleanable or replaceable I guess I’ll have to familiarize myself with the pumps inter workings Is there a way to check fuel pressure and what should it be or am I better off just rebuilding the pump So my list grows I’ll give playing with the throttle and choke a try next time out check spark across all 3 cylinders and if the issue persists I’ll take a look at the pump Thanks for the help gentlemen I’ll keep you up to date

I just finished replacing the fuel lines from the quick connect to fuel pump and out to all 3 carbs i have replaced the ignition wires (plug wires) checked the resistance of all 3 coils & through the plug wires everything is even across the 3 coils I have to get an inline spark tester would be able to use it in the driveway I really appreciate the help I’ll keep you posted

Hi all am currently replacing fuel lines and clamps they were secured with Ty wraps and some were not exactly what I would call tight i should clarify the fuel that I find in the well on the back of the boat is not from a fuel line leaking, even when I run the boat out of fuel by disconnecting the fuel line after towing home at highway speed that’s when I find the fuel Is it possible that I have a float in one of the carbs sticking and that cylinder is flooded also resulting in the lack of performance? Mercury lists WOT at 4750 to 5250 for this motor from the info I’ve been able to find the prop on it is a 13 3/4 x 15 pitch so based on seeing 5100 rpm the one time it ran what would your thoughts be I really appreciate all your input

I have a new to me 17 1/2’ center console power is a Mercury 80hp 3 cylinder 2 stroke Motor starts right up every time idles at 800 RPM Trolls pretty well when you accelerate to get up on plane everything goes well to about 3300 RPM then the motor seems to bog down and that has been repeatable with the exception of once it actually planed out and reached 5100 RPM I have run it off a remote fuel tank Primer Bulb an fuel line to motor is new compression is between 110 and 115 across the 3 cylinders i emptied the fuel tank and have been using only non ethanol fuel treated with SeaFoam since I purchased it fuel filter replaced twice plugs replaced ignition wires replaced I also have observed fuel in the well in front of the motor after I tow the boat home even though I disconnected the fuel line and let the motor run itself out of fuel before I put it on the trailer So I’m looking for next step recommendations carb rebuild & cleaning ? timing ? Stator ? I appreciate the experience and knowledge of the community and look forward to your recommendations thanks Henry