Home › Forum › Ask A Member › 1958 envinrude 35 HP big twin running rough
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November 20, 2018 at 8:24 pm #154121
My 1958 Evinrude 35 HP big twin has been running rough. It has a new coil, new plug wires, cleaned fuel filter, new carb kit with jets and float and fresh unleaded fuel with correct oil mixture and marine Sta-Bil additive. It was running great after recent new carb kit installed.
It is running rough on idle and it will not go to full throttle without sputtering and eventually quitting running. .
I’ve included pictures of the two plugs.
Tell me what you think my issue might be. Thanks for the great help this site provides.
Picture of the boat we built as well. She’s too beautiful not to grace the lake!
November 21, 2018 at 9:03 am #154278Did you replace only one coil? What about the points and condensers?
November 21, 2018 at 10:40 am #154311Yes both coils, plugs, plug wires, points and condenser all replaced and new.
Thanks!
Steven
November 21, 2018 at 12:13 pm #154345Have you checked compression?
DaveNovember 21, 2018 at 1:10 pm #154363Did you rest the timing and did you use the proper ignition timing tool or did you use feelers gauges?
Richard
http://www.richardsoutboardtools.com
classicomctools@gmail.comNovember 21, 2018 at 2:18 pm #154431After reading your post again, since you had it running great at first, I’d first check your points adjustment again and if that doesn’t fix it, go back into the carb and look for any small fleck of dirt, and spray carb cleaner through all passages again with needle valves removed. With new gas lines, I’d be suspicious of small rubber fragments shaved loose when pushing gas lines onto mating nipples. This can happen downstream of the filter. That bit me twice this summer.
DaveNovember 21, 2018 at 2:22 pm #154434If you are using ethanol-blended unleaded your carburetor may be worth a look. You state that you put a new kit in your carburetor. Did that kit include a float? I know even the new OEM kits still have a cork float in them. They are a lighter color and are supposed to be coated with an ethanol resistant coating but I have not tested this. I only run ethanol-free gasoline in my outboards. If you did not replace the float and it still has the shellac coating, the ethanol will dissolve the coating and it will end up in the bottom of your carburetor’s float bowl in little gummy bits and block fuel flow. It takes a little time for this to happen, but if the carburetor is not run dry each time and the float is floating in fuel all the time, it will happen. Marine Sta-Bil has the ethanol additive in it too, but I’m not convinced that will save a shellac coated cork float from the effects of the ethanol. I’m not sure what the Sta-Bil does chemically, but it does not magically make the alcohol disappear.
-BenOldJohnnyRude on YouTube
November 21, 2018 at 3:29 pm #154464Until proven otherwise, I suspect it is ingesting water into a cylinder.
November 21, 2018 at 8:55 pm #154514I was thinking along the same lines as Frank.
However, first, start with the basics.
What is the compression, cold and dry?
Does the spark jump a 1/4″ gap on an adjustable inline spark tester?
Most Big Twins of your Vintage should fall in the 90 to 110 psi range. If so, and you have a bright blue spark that jumps a 1/4″ gap, I would look at your exhaust gasket, head gasket, etc… for water intrusion.
November 22, 2018 at 7:10 am #154575Did you use a Sierra carb kit along with Sierra points? Both are terrible, and could cause your symptoms. i made the mistake of trying Sierra points a few yrs. ago, mainly because I can by them dirt cheap. I found them to be of terrible quality, and went right back to OEM. Same goes for the carb kit, that does not come with a new float from Sierra.
Is your motor running a single line hose with a fuel pump? If so, and if you are using an aftermarket fuel line and bulb from Wal mart, or whatever, that will eventually be an issue. The inner barrier liner in those aftermarket fuel line will eventually come loose and clog the line shut. I’ve had to replace a truck load of those things. The motor will start and run for a short distance, then slow down and eventually stall out. Just a few things you may want to consider. Hope this may be of help. -
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