Wanting to install a fuel pump in a 25hp big twin, but no bosses on the bypass cover.

[todd281]

Hi, This is my first post, I recently came into a 1954 Evinrude big twin model 25916. I have read through the forum, and seen how to convert the double to a single fuel line by installing a fuel pump. My bypass covers however only have one " boss" [see the attach photo] I am wondering if I could drill that out and add a barbed nipple there,then use the freestanding type fuel pump. Or do I have to buy the other bypass cover with the boss placement for the attached fuel pump. Thanks in advance for any help.

 

[F_R]

Drill that hole through. Tap pipe threads in the hole. (1/8" NPT). Screw in 90 degree elbow hose barb nipple. Proceed with your pump installation.

 

[todd281]

wow that was quick! thanks for the advise. I will proceed with the pump project. and I am sure I will be posting again with more questions.

 

[Crosbyman]

don.t forget to plug the air nipple behing the carb. tye wrap a 1.5 inch piece of hose with a fat screw in it at one end. . plug it with some silicone

 

[geoffwga1]

Could he not just use that nipple to drive his pump,or is that not practical on that model,it's one I'm not familiar with.
G

 

[F_R]

Could he not just use that nipple to drive his pump,or is that not practical on that model,it's one I'm not familiar with.
G

It would be possible, but that is doing it the hard way.

 

[racerone]

You can not just use the nipple to drive the pump !------That is a one way air supply to the pressure tank.----Fuel pump do not work off that.-----It involves modifications to use that nipple to drive a newer pump.

 

[Crosbyman]

the harder way for 5.5hp with no bypass covers ....but I did mine and it runs perfect

https://www.youtube.com/watch?v=FtG4M7ye1N8


I did a QD and a FD ...with a square Mikuni and the other with a OMC pump on a plate over the pypass cover (found it to be the better way)


did my 5.5 with a round Brigss and Straton pump# 808656 ($20) single hose side connector and used the nipple

 

[todd281]

ok, thanks everyone, I removed the cover and completed this part of the project today [easy peasy] now on to all the rest, trying to find info on that engine is tough I do have some other questions but I will ask them in a new post.

 

[gm280]

If your addition questions are concerning the same engine, then post them here rather then starting a new post. That way everybody can keep all your engine question in one place to give you better answers...

 

[F_R]

--It involves modifications to use that nipple to drive a newer pump.

Exactly. That's why I said doing it that way is doing it the hard way. You have to tear the whole front end off the powerhead to do the modification to the air port.

 

[Crosbyman]

the book...

http://boatinfo.no/lib/johnson/manuals/1922-1964johnson.html#/0

 

[todd281]

ok I got the fuel pump installed, and thanks to Crosbyman posting the link to "The Book" I was able to manufacture a choke rod. The next hurdle, seems to be finding a fuel filter, or perhaps cleaning it . It is a "stone/ceramic" type that is inside the sediment fuel bowl. I have soaked it in acetone overnight but nothing seemed to come out of it. I also soaked it in carb cleaner with the same results. does anyone know where a new one could be had? or a part #. thanks again.

 

[racerone]

I have always cleaned them with laquer thinner.----When you set it an a flat surface with a gasket and pour fuel into it what happens ??

 

[Crosbyman]

try 100 lbs air pressure to blow it after the lacquer thinner ...carefull on the eyes

 

[todd281]

WOW.. now something else. The starting system on this motor was a 6 volt system, that the previous owner ran on 12. Needless to say the starter is shot it is a autolite model MAK 4033M . I ordered a new 12 volt starter and it arrived today. It was to be a replacement for a MDO 4002M starter that fit this motor. however it will not bolt to the starter bracket. So the question is ; did the starter bracket change when changed the system from 6 volts to 12? or did they use the same bracket and just change the starters? I don't know if I need to buy a different starter bracket , or send the new starter back and tell them it is not the right replacement for the MDO 4002M thanks

 

[nwcove]

you positive its the starter that is shot? they were pretty rugged and have been used with 12v.

 

[geoffwga1]

You can not just use the nipple to drive the pump !------That is a one way air supply to the pressure tank.----Fuel pump do not work off that.-----It involves modifications to use that nipple to drive a newer pump.

OK,it's jusy that I did it that way on my 5.5.As I said I'm not up on that model.

 

[nwcove]

OK,it's jusy that I did it that way on my 5.5.As I said I'm not up on that model.

geoff, the 5.5 doesnt have removable bypass covers, so what you did was the only option, it you were to convert a 7.5 or bigger of the two line motors, its just much easier to go with the bypass cover option.

 

[todd281]

Ok, now another problem , This motor was equipped with a 6 volt system . it had a autolite model MAK 4033M starter in it . the previous owner ran it on 12 volts , and cooked the starter. So I go online and find out that in 57ish Evinrude started putting a 12 volt system in . IT used a MDO 4002 M starter. I bought a starter that was a replacement for the MDO 4002 M and it arrived today. It is a slightly smaller starter than the 6 volt one, and will not bolt to the starter bracket. The question is, when Evinrude changed to the 12 volt system, did they change the bracket? I don't know if I need to buy a different bracket, or send this new starter back, and inform them that it is the wrong one. Has anybody done this change from 6 to 12 volts? thanks for all the help thus far. todd