FuelOil Mixture Ratio

"Hi guys, I have a 2002 25hp m

"Hi guys, I have a 2002 25hp mercury, and I am a little confused about the fuel/oil ratio, I borrowed a seloc book that covers upto 2001 and it says the ratio is 50:1, but I was also told by a few boating people that the mixture on all modern engines is 100:1, can anybody tell me the correct ratio, as I am running it at 50:1 and I keep getting fouled plugs, more the top spark plug than the bottom spark plug.

cheers

James"

"James, the new ones "do n

"James, the new ones "do not" run on 100:1 using modern marine 2 cycle oil (TCW3).

There is an AMSOIL (synthetic) on the market that they claim you can run at 100:1 but unless they were providing a written gurantee to cover any engine damage I wouldn't.

OMC produced a series of engines a number of years back that originally called for 100:1, but they later issued a bulletin changing that to 50:1.

Even the modern varible rate oil injection pumps run no less than 80:1 (and vary through the operating range of the engine).

Any chance these "boating people" own a dealership and are trying to sell you a new engine????? "

"Hi Graham, no not a dealer, j

"Hi Graham, no not a dealer, just local boaters on the loch where I go fishing, I found out that the signal to no1 coil is intermitant(spelling?), went out today, very under powered and sounded like a car running on 3 spark plugs, so I changed the spark plugs and it was the same,( the spark plug was wet so I presume its getting fuel) so I came home and checked the HT leads, then I swapped coils with each other, no change, so there is no signal to no1 coil, can I assume its either the switch box or the trigger,
going to do some reading just now to find out if there is a way to test these parts, if not then I will take it to the local outboard mechanic.

cheers

James"

what is the fuel/oil ratio for

what is the fuel/oil ratio for a mercury 2.2

"James, you did the troublesho

"James, you did the troubleshooting exactly right. No spark on "ONE" plug, swap coils. If that doesn't fix it, then it's most likely your switchbox.

Not cheap from Merc, but I would check out Ebay - they often come up for sale (unless you are in a real rush)...

Dennis - 2.2 Mercs built in the mid/late 80's use a mix of 50:1..."

"Hi Graham, thanks for that, a

"Hi Graham, thanks for that, after seening the prices for the switchbox, I think the ebay option seems reasonable, not in any rush, and I can always use the 4hp back up engine when my fingers are itching for fishing.

cheers

James"

"Hi guys, a little update for

"Hi guys, a little update for you all, I went out last night in the dark and checked no1 cylinder for a spark, yes there is a spark there, but looks very weak compared to no2 cylinder, and if I swapped the coils, the weak spark stayed at no1 cylinder, while I was searching and reading, I found that a spark plug will spark out of the cylinder, but when in the cylinder the pressures are so great it wont spark, and further reading led to the switchbox probably at fault.

Thanks to all of you helped, and to Graham, cheers buddy,

James"

"Hi guys, This is getting to b

"Hi guys, This is getting to be some story, went out today to do a compression check and to check there was actual fuel getting to the cylinder, ( simply because there is a spark at the no1 cylinder), well compression was great, and the was no fuel, Mmmmm so I got my colour tune, ( a little spark plug with a glass veiwing window, that way you see the colour of the flame and you can tune the engine, blue flame is good, yellow flame is bad),so put it in the engine, started it up and I had plenty of spark and the ocasional flame, so it looks like its not getting the correct fuel.

Before I strip the carb down and give it a clean, could this be as simple as faulty reeds or even a faulty reed to no1 cylinder.

cheers

James"

"James, you can kill two birds

"James, you can kill two birds with one stone here. It's probably well worth taking the carb off, stripping it down and giving it a good cleaning.

And on your model, the reed block (and reeds of course) are directly behind the carb (just hiding behind the plate where the carb mounts - so easy to pull and inspect with the carb off..."

"Hi guys, cheers Graham, thats

"Hi guys, cheers Graham, thats what I ended up doing, after reading the book and found I had to take the carb off to get to the reads, so checked the reads all clean and all moved with a little tiny bit of pressure (ie gently touched with a finger), stripped and cleaned the carb, apart from a tiny bit of corrosion on the securing screw for the spindle for the float spring, the carb was very clean, so put it all back together and fired up the engine, except for the mixture setting there was no change, I noticed the spark plugs where looking a little fouled so I put in short nose evinrude spark plugs and found the the engine ran better with an occasional popping similiar to a backfire, after it popped it would run on one cylinder then it would pick up as if the two cylinders where firing, then it would pop again,,,,,,,when I cleaned and put in the origional spark plugs it would only run on cylinder no2

I am going to read the book again and do a proper synch and link, and if there is no change,,,its time the professionals looked at it,,,,


cheers

James"