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1991 Evinrude 70HP Problems

racerone said:
In Canada try----evinrudeparts.ca----See if they can help.
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Thank you! I checked them out and they have the part listed as "Call Us" so I emailed them and will give them a call when they open up.

As far as the new hole for the tell tail, where is the best location for it? And could I put a pressure gauge in the old outlet on the side to monitor it in the future? And if so what would the pressure range be?
 
The latest water pump kit has the instructions for drilling.----And yes the instructions say that you can use the old port for a pressure gauge.
 
I'll let Racer answer that for you. But you can call Tim's Outboard in Hackensack MN, they will direct you....or provide you that part. 218 682 2331, Teresa, Mike, or Dan....55 years family business....best I have ever found.
 
So I've moved the tell tail to the top and it is working as it should, no steam, only water on both test tank and muffs.

The timer base is now moving freely and the motor will idle and rev up.

I now have discovered a new problem, the top cylinder isn't firing. With the motor running, at multiple throttle positions, I pulled the plug on the top spark plug with no change to how the motor was running. The carb seems to be spitting out fuel, there is spark and compression is still 125. I don't think that the cylinder is getting fuel, if I take the plug out and turn it over a few times I'm not smelling anything and nothing on a paper towel.
 
Also, if I spray starter fluid in the top carb the motor will rev up more. When I spray it into either other carb the motor will bog down.
I've tried swapping spark plugs and the wires and the top cylinder is still the culprit
 
What does the insulation look like inside the cowling?
Congratulations Racer for your 20,000 posts I don't think anyone here will ever last that long.
 
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So upper carb must be blocked up, unless something else got sucked in there. I have found all kind of crap in the reeds over the years. After you clean it, you need to address the rest of your fuel system or contamination could continue. It all depends on what you find. Be sure to re sync. carb so it opens at exact time as the others. When you remove these carbs there is so much play in the mounting studs....if careful, you can sync. by just bolting in the exact location.....but whose to say it was right before you worked on it....may have been way off.
 
Can I take the carb off and if a visual inspection doesn't show anything in the reeds, try to turn it over a few seconds (fuel line disconnected) and see if the reeds move at all? Just so I know if that's the issue before stripping everything down?
 
Redrobinyum3 said:
Can I take the carb off and if a visual inspection doesn't show anything in the reeds, try to turn it over a few seconds (fuel line disconnected) and see if the reeds move at all? Just so I know if that's the issue before stripping everything down?
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If the carb is spitting fuel back at you, it would indicate that crankcase pressurization on the downstroke of the piston is pushing the air/fuel mixture past the reeds instead of containing the air/fuel charge so it can reach the combustion chamber for the next power stroke. If the carbs haven't been off in a few years, it's probably better to pull them off anyways so you can dismantle them and clean up everything to inspect all the components. At which time you'll be able to inspect the reeds as well. I learned about how vitally important carburetor function is on two-stroke engines when going through the ensuing saga of repairing my '64 Evinrude 9.5 Sportwin. This forum was a great help for getting it running right! :cool:
 
CarMech1969 said:
If the carb is spitting fuel back at you, it would indicate that crankcase pressurization on the downstroke of the piston is pushing the air/fuel mixture past the reeds instead of containing the air/fuel charge so it can reach the combustion chamber for the next power stroke. If the carbs haven't been off in a few years, it's probably better to pull them off anyways so you can dismantle them and clean up everything to inspect all the components. At which time you'll be able to inspect the reeds as well. I learned about how vitally important carburetor function is on two-stroke engines when going through the ensuing saga of repairing my '64 Evinrude 9.5 Sportwin. This forum was a great help for getting it running right! :cool:
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What would cause the piston to push the mixture past the reeds?
 
If the reed valve is broken ( rare ) or say a seagull feather is holding a reed valve open it will change the way your 2 stroke works !!---You have to do the trouble shooting !----I can not see / hear / or touch your motor.
 
Right. Reeds rarely break and of one is stuck open with some debris, it will certainly create noticable distinction of associated cylinder and carb. If you post a video link we can study the action with air box removed...we can hear and see but not touch......kinda like a stripper at the club, but being JW, I don't do that anymore.
 
timguy said:
Right. Reeds rarely break and of one is stuck open with some debris, it will certainly create noticable distinction of associated cylinder and carb. If you post a video link we can study the action with air box removed...we can hear and see but not touch......kinda like a stripper at the club, but being JW, I don't do that anymore.
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I'll see what I can do about a video.
I will pull the carb off, hopefully tonight, and take a look at whats going on. I also forgot to mention that I put my hand over the top carb and there was suction, and no change in the rpm. Would that along with the fact that the motor rev'd up when I sprayed starter fluid in the top carb mean that it is more likely a carb issue?
 
I pulled the carb and the reeds were good.
I swapped the top and bottom carbs and did all the test that I did before: Pull the plugs while idling, sprayed starter fluid into the carb, ect...
The top cylinder (now with the bottom carb supplying it)was receiving fuel while the bottom cylinder was dry (now with the top carb supplying)
I would say with a good level of confidence that I have a carb issue (the one originally on the top).
I installed a new float, seat and float valve and it didn't have an affect.
I disconnected the link from the problem carb and would move the lever on just the problem carb while the motor was idling and the motor would start to run rough.
 
The carburetors are very simple and it should be easy to figure out.----Nozzle gasket is in place I hope.------And stop running the motor as no fuel going into one cylinder also means no OIL going in !
 
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