89 Mariner 45HP- won't go over 2K rpm in water

[matth121]

Hey Guys- haven't even laid eyes on this motor yet so can't give you a serial number but I'm hoping for a starting point.
it's an 89 Mariner 4 cylinder 2 stroke with oil injection- the owner tells me it has flat plugs(no ground strap to adjust gap) which i wasn't even aware was a thing until he told me and i checked, but that doesn't seem to be the problem anyways. The engine ran great for the 1st summer, then seemed to develop this issue- that being that while under load in the water- it won't go over 2000rpm. He can squeeze the primer bulb and it will pick up a bit(his words not mine, again, I won't see it until tomorrow.) that to me says he most likely needs a fuel pump- would anyone agree with that? more info- new tank, fuel line with primer bulb, fittings on tank and engine, filter.
Another thing that may be an issue- high speed jets on the carbs? I don't know enough to say for sure if this is actually a possibility since I haven't looked at the carb parts diagram- would need the serial to find the right parts list i'm guessing.
Really appreciate any help you guys can offer as to where to start with this- it's an hr drive from me and probably 30mins from anywhere you can buy anything so I'd like to get it in 2 trips if possible, lol, that's very optimistic i know.
Thanks,
Matt

 

[flyingscott]

I assume you are looking at buying this motor.

 

[matth121]

nope- sorry- fixing it for a friend

 

[jimmbo]

It's an 89, its first summer was a long time ago. Does it have a strong spark on each cylinder? By strong, I mean can it jump a 5/16 gap? Check for collapsed fuel lines. Did your friend use a fuel stabilizer and run the engine long enough to get the stabilizer into the carbs? Carbs might be gummed up

Surface gap plugs have been used in outboards for about 50 yrs.

 

[matth121]

thanks for the reply- i also suspect gummed up carb and most likely needing a fuel pump kit as well- going out to have a look and grab the serial and model from it to order parts. Odd about the plugs- never seen em before- my 83merc 18HP and 61 big twin 40HP both use standard plugs, but that's 2 out of 1000's i guess. Will try to get my hands on a gap tester as well. Thanks

 

[matth121]

So here's what I found- #1 coil is dead- no spark at all. Also, the fittings on his tank are loose(the screw in plastic one and the brass one that screws into it) so there's an air leak. I'm guessing once that's all corrected it should be better. I had no luck finding a sticker with any info related to the engine- the one thing I did find was a frostplug just behind the starter motor that has A744895 and a Mariner M stamped into it- That's it right? appreciate any help with the parts lookup, thanks for reading,
Matt

 

[matth121]

No Title

this is Canadian if that makes a difference- i hope it does because that SN doesnt seem to match with anything i see in the mariner lookup chart on this site

 

[hemi rt]

The plugs are rim fire (anti-fowling) and are not gap adjustable. The gap is set at the factory and should be replaced at least every 2 years, sooner if it gets a lot of use.

 

[matth121]

The plugs are rim fire (anti-fowling) and are not gap adjustable. The gap is set at the factory and should be replaced at least every 2 years, sooner if it gets a lot of use.

Thanks but this is totally nothing to do with my issue- It has brand new plugs- the issue is with #1 coil and an air leak in tank

 

[matth121]

I think I'm good- it needs sierra 18-5186 coil- gonna grab one and see if that helps. I'll hopefully remember to follow up and let you all know

 

[Silvertip]

Back to the squeezing the primer bulb helps bit! That is a classic indication of a bad/weak fuel pump.

 

[matth121]

Just to let everyone know- the coil and the air leak at the tank fittings was the issue- I had fixed those problems last week but wasn't able to test it until yesterday. Fuel pressure not an issue and after giving it a nice warm up cruise, it hit's 5500 on the tach at full throttle- seems great- thanks again and especially to jimmbo who's suggestion to check spark led me to find the problem- as opposed to my thoughts that the carb and fuel pump needed to be rebuilt.