1985 Evinrude 8 HP hard cold start?

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  • billw

    US Member - 2 Years
    Replies: 2071
    Topics: 66
    #233980

    Hard to believe but even this motor is 36 years old! I am working on this for a friend. I did the usual stuff, checked spark and compression (125/135) cleaned the carb and did a water pump and thermostat, spark plugs, gear oil pressure test and change, etc. I put it in a barrel and it took quite a few pulls to light off. Once it did, the low speed needle was not as responsive as I would have expected but I eventually found a place that seemed good. The motor ran strong and idled down pretty nicely. Once warm, it started very easy. Still, I felt there was no reason for it to have started hard, when cold. When I checked out the choke operation, I found that the plate would touch at the top of the carb opening but not at the bottom. There were also three pretty good size holes in the plate, which were factory. Intuition tells me it starts hard cold because of this poor fit and the big holes. It’s a wonder it started at all. I remember another club member telling me that his 8 Evinrude did the same thing. What gives? Was there ever a bulletin on this? The carb is NOT one that has the plastic top and rubber tube inside it. It is very conventional, except for a stamped steel bowl.

    Choke-fit-8-Evinrude

    Long live American manufacturing!

    • This topic was modified 3 years ago by billw.
    • This topic was modified 3 years ago by billw.
    • This topic was modified 3 years ago by billw.
    • This topic was modified 3 years ago by billw.

    crosbyman

    Canada Member - 2 Years
    Replies: 3587
    Topics: 326
    #233987

    is this a new problem ? plate fit and holes are needed to let some air pass to vaporize and carry the fuel inside the crankcase on the upstroke.

    jmho

    may as well focus on carb adjustments, cleaning, sparks ? etc….

    btw nothing wrong with being 36 years old….. my 9.5 is 55 this year & works fine

    Joining AOMCI has priviledges 🙂


    need2fish


    Replies: 281
    Topics: 15
    #233991

    It’s not unusual for the top or bottom of the butterfly to not touch the carb body.

    I’m not familiar with your motor, but some have an adjustment somewhere along the choke linkage, but you don’t want the closed position to be so tight the choke butterfly sticks in the throat, and you want it to have the thinnest profile when fully open.


    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #233992

    Will have to have a look at one of my carbs, don’t really remember… Again, although these carbs were more or less the same through the years, there were many minor little changes. I don’t recall any bulletins/updates on this issue though. And yeah, that choke shutter sure doesn’t fit very well, sometimes I see that the shutters are bent causing this issue. But, this is usually because someone was in there messing around with it or attempted to remove/install the choke shutter. But, this one looks untouched, the screw heads are still dimpled. OMC didn’t want techs in there messing with the choke/throttle butterflies only because the screws were more likely to fall out and get sucked through the engine after being removed/installed. It is important to note that the screw threads on the back side are also dimpled during assembly in an effort to keep the screws from falling out. So, if you attempt to remove the screws, you are likely to mess up the threads on the choke shaft as well…
    So, what to do here… I would agree that there are two many holes here…I guess OMC was trying to keep the engine from quickly stalling out once started with more of a solid choke butterfly, giving the owner a chance to push the choke in before it stalls out. Unfortunately, all the holes lead to hard starting cold. Decent 8hp carb bodies are surely hard to find, they are different from the 6hp versions. I’m wondering if you could try soldering one of the bottom holes shut, or perhaps a pop rivet. Screws/nuts should be avoided for all the reasons mentioned above. The other thing that makes these things hard to start cold is the damn recoil interlock that prevents/jams the recoil at higher throttle settings. For my money, the interlock is set too low, but there is no way of “adjusting it”.
    Will have a look at some carbs I have to see what there chokes look like…D
    PS- Don’t attempt to get one of these newer 6-8s to idle like the older 6hps, will never happen. I oftentimes end up retarding the throttle pick up to make sure the throttle plate is completely closed at the lowest RPM the thing will run at…Later models (86 and later) had that crazy carb with the throttle cracking screw and no set throttle pick up point, I’m guessing this was an attempt to deal with erratic idle adjustments that plagued the older models.


    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #233993

    OK, just had a look at my carb collection….Most of the 6-8hp carbs had just one hole in the bottom of the choke shutter… But, then found a carb that still had the tag on it for an 8hp, it had the three holes like yours…But, the choke shutter surely fit better in the carb throat…
    So, I would start by sealing off one of those bottom holes…


    billw

    US Member - 2 Years
    Replies: 2071
    Topics: 66
    #234018

    is this a new problem ? plate fit and holes are needed to let some air pass to vaporize and carry the fuel inside the crankcase on the upstroke.

    jmho

    may as well focus on carb adjustments, cleaning, sparks ? etc….

    btw nothing wrong with being 36 years old….. my 9.5 is 55 this year & works fine

    Compare the 8 to the fit of a six horse:

    6-hp-choke-fit

    Long live American manufacturing!


    billw

    US Member - 2 Years
    Replies: 2071
    Topics: 66
    #234022

    Let’s try the picture again: Six hp with a fit that I would expect.

    6-hp-choke-fit

    Edit: I entered this picture again because it didn’t seem to work, the first time. After entering this one, I saw that the first one had begun to work. Sorry.

    Long live American manufacturing!

    • This reply was modified 3 years ago by billw.
    • This reply was modified 3 years ago by billw.

    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #234045

    I agree, the choke shutter fit on that 8hp carb is poor…This will only add to starting difficulties created by all those holes. Unfortunately, choke shutter replacement/adjustment isn’t an option due to the reasons I mentioned….You can try the 8hp carb I have if it might help, the choke shutter fits much better than yours….


    Michael

    International Member - 1 Year (includes $3 online payment fee)
    Replies: 77
    Topics: 9
    #234238

    I would try using my hand as a choke and see it is started within a couple pulls. If that works, then your choke is the problem – letting in too much air and I agree with others, block up one or two holes


    billw

    US Member - 2 Years
    Replies: 2071
    Topics: 66
    #234246

    I agree. It sounds easy to block off a hole, until you really think about how you’d actually do it, without the potential failure and ingestion of whatever solution you were to come up with. I’d like to find some of that brass sheet stock and make a new plate altogether; but I need to realign my mind towards that task….

    Long live American manufacturing!

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