help with 1984 Mercury 115

[beake77]

Hoping for some help. I have an 84 Merc 115 6 cyl that the Mercury guy of almost 30 years can not figure out. Last summer it got a new stator, since then, it has been under powered and has not been able to get up past 2800-3000 rpm when in the water in gear. It starts to rev up, right when you put it in the water, and then bogs down. It has good compression, spark, no fuel line problems and the tech replaced the small fuel return hose that runs vertically. I put the update kit in the fuel pump. It bogs down further when you tap the choke, so i assume it is getting too much fuel rather than not enough. has a new rectifier and i drained the fuel tank and started with fresh fuel, no improvement. Any advice would be greatly appreciated. mike

 

[jimmbo]

Re: help with 1984 Mercury 115

I had a 1984 115 and I don't ever recall it having a small or any kind of return fuel line. Every so often mine would act like that, I noticed fuel was spitting out the airbleed on the top of the carb fuel bowl. It turned out the floats would occasionally stick and the carb would flood. If your motor is an 84, it does not have a choke, it does have a fuel enrichment system that drains some fuel from the top carb into one or two of the lower cylinders transfer ports to enrich the mixture. Maybe that is what appears to be the 'return fuel line', or you are refering to the oil recirc lines. Careful adjustment to spark timing/carb sync can make a huge difference on that engine.

Oh yeah. Welcome to the board

 

[redjmp]

Re: help with 1984 Mercury 115

OK you need to check for good spark on each cylinder and timing.
Pull your plugs and see if they all look the same or are any wet or fouled?
Make sure that your pointer is set to exactly TDC and then do a link and sync...
http://forums.iboats.com/showthread.php?t=128495
You will also need to build or buy a DVA and a spark gap tester...
http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=ESP640&source=froogle&kw=ESP640
http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=LIS50850
Then use the testing procedure here:
http://www.cdielectronics.com/downloads/Mercury_DVA.pdf
http://issuu.com/cdielectronics/doc...t.xml&backgroundColor=000000&showFlipBtn=true

page 83 and 84

 

[beake77]

Re: help with 1984 Mercury 115

Thank you both for the help. Couple questions. Is spark, spark? Meaning, if I am idling in the water and I pull wires and find each one is contributing or it makes a difference that I pulled the wire, does that mean that they are firing ok? Does it need to be a certain strength? You said "good spark." Just making sure because i have read quite a few posts and have seen that referenced.
On the return line, that is what the tech said he replaced. he may have called it somethine else; but he said it moved excess fuel back to the plenum. Thank you

 

[redjmp]

Re: help with 1984 Mercury 115

Good spark is the ability to jump a 7/16" gap on the spark tester.

 

[Faztbullet]

Re: help with 1984 Mercury 115

You could have a bad switch box thats not flipping to the high speed side( internal rectifier) or that stator is miss wired(red/blue pairing is off)

 

[beake77]

Re: help with 1984 Mercury 115

turns out I had replaced one switchbox instead of both, first problem. Second problem- bad stator. Previous hsop had told me they put a new one in last fall, the had put in a trigger and told me the worn thing. Found a new shop that did a great job, could have really stuck it to me and did not. No more ouboards for me, sold boat- bought IO

 

[emoney]

Re: help with 1984 Mercury 115

Lol about the "no more outboards", we all have our comfort zone, eh? Good luck with your new boat, btw.

This thread is a good indicator of the fact that sometimes it's better to NOT tell a mechanic what's "been done before" or what "you think it is". Sounds like he believed the stator story too, even though he probably should've checked it for himself. Now, by no means am I condoning letting someone just start replacing things that've already been replaced, but sometimes we cloud other's thinking which in all things mechanical, can sure get in the way of a successful repair.

 

[Chris1956]

Re: help with 1984 Mercury 115

OK Beake77, Now you have gone over to the dark side, buying an I/O. The good news is that the guys who live in the I/O forum are real experts, and will be able to help you.

I hope you are mechanically inclined because the normal maintenance items plus the stuff that mysteriously breaks on an I/O is long.....JMHO

 

[beake77]

Re: help with 1984 Mercury 115

OK Beake77, Now you have gone over to the dark side, buying an I/O. The good news is that the guys who live in the I/O forum are real experts, and will be able to help you.

I hope you are mechanically inclined because the normal maintenance items plus the stuff that mysteriously breaks on an I/O is long.....JMHO

Funny you say that. Last weekend, i blew a headgasket on my 3.0 liter mercruiser. the boating gods frown down on me being on water. the only saving grace is that I can look at this GM 3.o liter and be able to point at something and tell you exactly how it fist into the cycle of life on the engine and waht it does...

 

[Chris1956]

Re: help with 1984 Mercury 115

Beake77, It is not your fault. I have 8 or 9 years experience with a 4.3LX Mercruiser (std and popular powerplant). Obviously I boat in salt water, but the maintenance items (both planned and unplanned) were more than I expected. The outdrive is a bit more fragile than an OB gearcase, likely due to the second set of gears. Stuff on the motor breaks that lasts on an OB. Not sure why...
Regular maint items: Impellers, anodes, Exhaust manifolds, risers, hoses, belts, gear oil, U-Joints, bellows. Other stuff that breaks: Circulating pump, thermostats, alternators, starters, oil pressure sensor, oil pan leaks, power steering hoses, Driveshaft yokes. Not sure why this stuff breaks, but it does. I would also find rusted bits of metal in the bilge from time to time...not sure what they were. My neighbor had a power steering cooler rot out and leak. All the PS fluid leaked out and the boat was unsteerable.

 

[Charlie61]

Re: help with 1984 Mercury 115

Hey jimmbo sorry to but in but I have a 1983 115 inline 6 with a enrichment vale and it was leaking gas from the top pin which was playing h--- with my idol so I got a new one but there is no ajustment it looks like it is a solid vale or choke need a real replacement can you help thank charlie

I had a 1984 115 and I don't ever recall it having a small or any kind of return fuel line. Every so often mine would act like that, I noticed fuel was spitting out the airbleed on the top of the carb fuel bowl. It turned out the floats would occasionally stick and the carb would flood. If your motor is an 84, it does not have a choke, it does have a fuel enrichment system that drains some fuel from the top carb into one or two of the lower cylinders transfer ports to enrich the mixture. Maybe that is what appears to be the 'return fuel line', or you are refering to the oil recirc lines. Careful adjustment to spark timing/carb sync can make a huge difference on that engine.

Oh yeah. Welcome to the board