1936 Evinrude 4178 carburetor issues. A little help needed…

Home Forum Ask A Member 1936 Evinrude 4178 carburetor issues. A little help needed…

Currently, there are 0 users and 1 guest visiting this topic.
Viewing 15 posts - 1 through 15 (of 22 total)
  • Avatar
    huntleybill

    US Member - 2 Years
    Replies: 259
    Topics: 101
    #152355

    I’ve had this 4178 sitting is the shop for a long time and decided to see what I can do with it. It has good spark and compression. I have cleaned the carb but can’t seem to get it to run right. I can get it to start and run for a few seconds when I squirt fuel into the carb. When I press down on the plunger, fuel squirts out the top of the carb from around the plunger shaft.

    Isn’t the plunger supposed to “pump” fuel into the engine? I don’t think it is supposed to gush out around the plunger shaft but what do I know? This is why I’m here asking! Also, I can get it to run a little longer if I cover the intake of the carb with my hand choking it almost completely.

    I have sprayed carb cleaner through ports and holes. I have blown out the carb with compressed air. The float bowl is filling up and it seems that the float needle and seat are working. It seems to me that fuel is just not getting from the bowl to the motor but I don’t know why.

    Can anyone help with this issue? What should the needle be set to initially?
    I am attaching pictures if that will help.

    Thank you for your help
    Bill

    Attachments:
    Buccaneer
    Buccaneer

    US Member - 1 Year
    Replies: 4068
    Topics: 980
    #152417

    Does the plunger use leather seals like the Johnson HD and TD motors, or
    a rubber seal of some kind. Sounds like the seal is bad, and / or you have
    a blockage on the discharge of the pump.
    I can’t find a manual or parts list for a light four this old.
    I haven’t seen Garry Spencer on this new web site, but perhaps he knows?

    Prepare to be boarded!

    Avatar
    huntleybill

    US Member - 2 Years
    Replies: 259
    Topics: 101
    #152507

    I see no seals or o-rings on the plunger at all. I was thinking the same thing as you but I also do not have a parts manual for this motor. I can blow compressed air through it so I am not convinced it is clogged but who knows?

    Tubs
    Tubs

    US Member - 1 Year
    Replies: 3148
    Topics: 172
    #152517

    Pump-O-Ring

    You're only as smart as the person you're talking to.

    Attachments:
    Avatar
    huntleybill

    US Member - 2 Years
    Replies: 259
    Topics: 101
    #152534

    Thanks Tubs, I will try that.

    Avatar
    huntleybill

    US Member - 2 Years
    Replies: 259
    Topics: 101
    #152703

    I tried the O-ring and it did nothing to help.

    I also put the baffles back on the carb intake (not shown in pictures). I then put masking tape around the baffles to block off air flow. I covered all the openings except the very front small hole. I could then get the motor to start and run (albeit a little rough). I could adjust the air/fuel mixture needle with NO EFFECT until it was closed. When closed the motor would stumble, slow, and die out.

    Any other advice?

    Avatar
    lyks2tinkr

    US Member - 2 Years
    Replies: 338
    Topics: 41
    #152717

    I have a 37 Handifour that is mechanically the same motor with the same carb.
    It sounds like from what your describing that the motor is running very lean and your having g to choke it off to get it to run at all.
    It is either sucking air through a bad gasket or there is a fuel restriction.
    My experience with the internals of these 4 cylinders is limited but getting better as I’m rebuilding mine.
    Wondering if a worn rotary seal between the cylinders could be the culprit.

    Tubs
    Tubs

    US Member - 1 Year
    Replies: 3148
    Topics: 172
    #152731

    Pump-2

    You're only as smart as the person you're talking to.

    Attachments:
    Avatar
    huntleybill

    US Member - 2 Years
    Replies: 259
    Topics: 101
    #152809

    This motor does not have that tubing on it. It would seem to me as well that it is starved for fuel but I see no check balls or anything that would substitute for a check ball. I’ll look again.

    Tubs
    Tubs

    US Member - 1 Year
    Replies: 3148
    Topics: 172
    #152843

    Pump-3

    You're only as smart as the person you're talking to.

    Attachments:
    Avatar
    huntleybill

    US Member - 2 Years
    Replies: 259
    Topics: 101
    #153205

    OK…so I found what I believe is the check valve at the bottom of the bowl. See pictures. I Let it soak in lacquer thinner for awhile, and blew it out. I then put the carb back together and attempted to run the motor. I have attached a youtube link so you can see it running. As long as I pump the primer, I can keep the motor running. As soon as I stop pumping, the motor quits. Notice when I pump, the fuel gushing out the top of the primer.

    BTW, adjusting the needle did nothing.

    Thoughts???

    • This reply was modified 1 year, 10 months ago by Avatarhuntleybill.
    Attachments:
    Tubs
    Tubs

    US Member - 1 Year
    Replies: 3148
    Topics: 172
    #153213

    o-ring

    o-ring-2

    https://www.ebay.com/itm/NEW-Buna-N-70-109-O-Ring-5-16-ID-x-1-2-OD-x-3-32-thick-Lot-of-50/292446854831?hash=item441730deaf:g:X5QAAOSwVupTqK2h:rk:3:pf:0

    You're only as smart as the person you're talking to.

    • This reply was modified 1 year, 10 months ago by TubsTubs.
    Attachments:
    Avatar
    huntleybill

    US Member - 2 Years
    Replies: 259
    Topics: 101
    #153224

    I’m not sure it was exactly that o-ring. I will order those and see if it makes any difference..
    I can see how that might help with the fuel gushing out the top but how would it help the motor run better?

    • This reply was modified 1 year, 10 months ago by Avatarhuntleybill.
    Avatar
    huntleybill

    US Member - 2 Years
    Replies: 259
    Topics: 101
    #153350

    OK…with the help of a 3D printer, I made that O-ring and installed it. I have a lot less gushing out the top but the motor still will not run without drastically choking it. I went through the carb again and find nothing clogged but not ever working with this type of carb before, I don’t know if I got everything either.

    Any other thoughts?

    Buccaneer
    Buccaneer

    US Member - 1 Year
    Replies: 4068
    Topics: 980
    #153365

    Only thought I have is that there’s about 20 members wishing that carb was
    on their work bench so they could look it over! I’ll be curious to know what
    turns out to be the problem!
    Evidently there’s no parts diagram that exists for the model?

    Prepare to be boarded!

Viewing 15 posts - 1 through 15 (of 22 total)
  • You must be logged in to reply to this topic.