Problems with my 75’ 25 Johnson

[john8504]

Well I was assuming the fly wheel torque is 45lbs but I can’t find any info if the electric start adds more. Also I got it running. I was getting no pulse from the motor to run the pump. Pulled both exhaust ports and found gasket very wet on the bottom of each. Replaced gaskets and waiting for sealant to dry to start it up this afternoon to see if I have a pulse again.

[john8504]

Does anyone know the likely hood of the lower crank seal causing a issue?

[Mumbles]

I think you might have answered your own question.

[john8504]

Hey there mumbles. Long time no see. On my 2nd pump and same results. Having a hard time spending 150 for a pump Locally. I guess I don’t have a choice

• This reply was modified 4 years ago by john8504.

[crosbyman]

no need to spend $150 for a pump…these work fine but find out why you have no pulse… no pump will work without a vacum pulse from the crankcase….. regardless of price !

https://www.amazon.ca/18-7350-Compatible-Johnson-Evinrude-Outboard/dp/B07W7RCH17/ref=sr_1_13?crid=263ZW3EXXS5IG&keywords=omc+fuel+pump+outboard&qid=1641907588&sprefix=omc+fuel+pump+outboard%2Caps%2C192&sr=8-13

check amazon of all models ..some just get rebuild kits but a fully assembled pump can be purchased for the same price.

some do not like chinese pumps.. up to you

http://www.leeroysramblings.com/Rebuilding_fuelpump.htm very tricky reading …not bad after youv’e done a few . 🙂

Joining AOMCI has priviledges 🙂

• This reply was modified 4 years ago by crosbyman.
• This reply was modified 4 years ago by crosbyman.

[john8504]

I have been through 2 of those pumps and neither worked.

[crosbyman]

I tried 3-4 of them last summer and was going nuts till I found oud I had misaligned the pump’s rear vacum port with the modified side cover drilled hole to get vacum pulses on my converted QD.

It is very unlikely you had 2 bad pump but sh… does happen

I would try to first run that engine with a small supply of fuel fed directly. into the carb. .. it all goes well you can start backtracking to fix the pump

fuel pumping requires vacum pulses from the crankcase to flex the pump diaphragm .

if you remove the pump and sparkplug and spin the FW with a drill can you feel pumping action in the motor’S vacum hole where the pump mounts ???

if you don’t……. I suspect that engine will not even run properly in the above “manual” fuel test because it won’t pull in the fuel either from the carb .

if you do feel good pumping yes then concentrate on the pump not doing its work to feed the carb properly

aside from my mindless alignment issue last summer I never really had any issues with these small pumps and I use mostly chinese versions

keep at it… patience brings joy !

Joining AOMCI has priviledges 🙂

[billw]

What tank are you using? A lot of the plastic tanks have plastic pick ups. These will distort and cause places for air to enter. Since it’s a lot easier for the pump to pull air than fuel, you lose fuel and think it’s a bad pump. Is that clear as mud? All that being said, air leaks have also happened to me on steel tanks. Recently I had a three gallon Mercury tank whose pick somehow was starting to unscrew itself, which caused a leak. The o-ring at the tank end quick-connect fitting is another place air can leak into the system. All this is why troubleshooting 101 states to try another known good tank and line, before zeroing in on the engine itself.

Long live American manufacturing!

[fleetwin]

billw wrote:

What tank are you using? A lot of the plastic tanks have plastic pick ups. These will distort and cause places for air to enter. Since it’s a lot easier for the pump to pull air than fuel, you lose fuel and think it’s a bad pump. Is that clear as mud? All that being said, air leaks have also happened to me on steel tanks. Recently I had a three gallon Mercury tank whose pick somehow was starting to unscrew itself, which caused a leak. The o-ring at the tank end quick-connect fitting is another place air can leak into the system. All this is why troubleshooting 101 states to try another known good tank and line, before zeroing in on the engine itself.

I would agree with Bill, am thinking the problem is much simpler than leaky exhaust gaskets. Every time i “get in too deep/happens to all of us”, I always back up and re examine “the basics”. Nine out of ten times, I find the simple problem/issue I somehow overllooked…D

[Steve Martin]

Occam’s razor

[Author]

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