Simple Little Things

[Mojo^]

It always seems like the simplest things bite me in the rear-end. I'm looking so deep for answers that I miss the ones that are staring me in the face. For over a week I have been trying to troubleshoot a sputtering problem on my 25 hp. Johnson 2-stroke. Without going into excruciating details I'll just make it short and simple. This evening I noticed a short sentence deep within the Johnson Maintenance Manual in the section covering fuel pump functional test. "Fuel tank must not be more than 30 in. (76 cm) below fuel pump". The words practically jumped off the page and hit me in the face. I've been running the motor on a home built test stand with the fuel tank sitting on the ground which must be a good 42 inches below the fuel pump. :facepalm: I just came in from running the motor in a tank but this time sat the fuel tank atop a few Coke crates on a chair bringing it about 10 inches below the fuel pump. Problem gone, no more sputtering. Hopefully this will help someone who may be struggling with a similar situation. Just remember, the fuel tank should not be more than 30 inches below the fuel pump.

 

[highcountry]

Re: Simple Little Things

Thanks for the info. I have done the same in the past and feel better now.

 

[DamianJP]

Re: Simple Little Things

Wow good find, the small stuff get past sometimes huh.
How many motors do you think this tank distance can effect? Is your fuel integrated in the carb(s) or is it on the side of crankcase?

Ive been waking up a motor on a stand and gonna tune it up soon, a 1976 55HP Evinrude and will definitely keep this in mind.

Again good job finding it and sharing your oversight with us.


DamianJP

 

[Mojo^]

Re: Simple Little Things

Wow good find, the small stuff get past sometimes huh.
How many motors do you think this tank distance can effect? Is your fuel integrated in the carb(s) or is it on the side of crankcase? DamianJP

My fuel pump is on the side of the crankcase. I don't know how many models may be effected and I suppose it would largely depend on the strength of the fuel pump. The more I think about it, I guess a good rule of thumb would be to ensure that the fuel tank is located similar to how it would be on-board the boat.

 

[boobie]

Re: Simple Little Things

I've got a saying I've used for years, "it's the little things that always get you". This goes for any part of an outboard.

 

[DamianJP]

Re: Simple Little Things

I was working on a motor for a gentlemen, alittle 5HP merc 4 stroke. Very hard start and ran like crap. Cleaned carb and checked timing and resistances checks. Checked coils for cracks and in general. Then it hit me ,check the gap of plugs. They were both off alot, like he or someone just bought plugs and stuffed em in there. He said "Wow it never started , ran or sounded so good" since I bought it. I couldn't take his money it was such a small fix.


DamianJP