Fishing with Rod Discussion Forum
Fishing in British Columbia => General Discussion => Topic started by: iblly on March 07, 2009, 09:31:37 AM
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I have a 1974 Evinrude 6 horse that I cannot get to idle wether in gear or in neutral. Runs perfect from 1/4 throttle to full throttle, anything less than about 1/4 throttle the revs will surge up and down then quit. Starts again no problem. Will run all day with the throttle open. Here is a list of things that have been done or checked, any ideas on things I may have overlooked.
- All fuel lines and fittings in motor and on tank checked for restrictions etc.(yes,tank vent is open)
- Fuel pump rebuilt.
- Carb cleaned and rebuilt.
- Points are clean and gap is set.
- Spark is consistent and strong.
- New plugs, gap set.
- Compression is 90 psi on both cylinders.
Any ideas ? Thanks, Bill.
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defective fuel pump???
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defective fuel pump???
pump rebuilt !
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try iboats.com for repair information in their forums
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float in carborator set at right hight.
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There may be water in the gas--try dumping in a couple cups of menthal hydrate into the gas--this may be a long shot but it is something to try before paying big bucks on a experimental repair job.
harley
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float in carborator set at right hight.
There may be water in the gas--try dumping in a couple cups of menthal hydrate into the gas--this may be a long shot but it is something to try before paying big bucks on a experimental repair job.
harley
Fresh fuelfloat in carborator set at right hight.
carb float set and measured for throw
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sell the motor and buy a 4-stroke!
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Thanks for replying with some possible solutions.
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Thanks for replying with some possible solutions.
Ive got the exact same motor but a 69. Great little motor. Im not a great mechanic though so good luck. Maybe the points need cleaning. Anytime I have a motor question I go to Iboats.com. Another great forum like this one :)
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Carb problem probably.
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I have a 1974 Evinrude 6 horse that I cannot get to idle wether in gear or in neutral. Runs perfect from 1/4 throttle to full throttle, anything less than about 1/4 throttle the revs will surge up and down then quit. Starts again no problem. Will run all day with the throttle open. Here is a list of things that have been done or checked, any ideas on things I may have overlooked.
- All fuel lines and fittings in motor and on tank checked for restrictions etc.(yes,tank vent is open)
- Fuel pump rebuilt.
- Carb cleaned and rebuilt.
- Points are clean and gap is set.
- Spark is consistent and strong.
- New plugs, gap set.
- Compression is 90 psi on both cylinders.
Any ideas ? Thanks, Bill.
Still trying to sort out - any new ideas ?
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Still trying to sort out - any new ideas ?
You can buy my slightly used and abused 2.5 Suzuki four stroke. It runs good.
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A little too small, thanks though !
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sounds exactly like what happens to my weedwhacker when I prime it too much....revs up then sputters out. if you think about it, the symptoms kind of point to it getting too much fuel all at once (rev up/ die shortly after), maybe it has to do with throttle? just a guess. good luck.
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I know these motors quite well. First off the compression sounds a bit low, generally they should be at about 120 psi. It really sounds like the idle circuit in the carb is plugged and that is why it won't idle. I would go through the carb again maybe you missed the idle circuit. I know there are carbs that I have taken apart more than once before I got it right. Also try adjusting your idle mixture. It definitely sounds fuel related whether it is the carb or an air leak somewhere. Keep posting and I will try and help you out.
Good luck
Rob.
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You can also try checking for vaccum leaks around the carb, on the engine side of course, these can cause idle issues and are tricky to troubleshoot.
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I know these motors quite well. First off the compression sounds a bit low, generally they should be at about 120 psi. It really sounds like the idle circuit in the carb is plugged and that is why it won't idle. I would go through the carb again maybe you missed the idle circuit. I know there are carbs that I have taken apart more than once before I got it right. Also try adjusting your idle mixture. It definitely sounds fuel related whether it is the carb or an air leak somewhere. Keep posting and I will try and help you out.
Good luck
Rob.
Rob, Thanks for the response. I know compression is a bit low, but I was told it's more important that they are equal ? As for the idle circuit, where in the carb is that ? As you are aware there's not a whole lot of parts in that carb. I don't know if I missed that cause I don't know what it is. As I said earlier it tends to rev up and down before it quits, (idle circuit cause that ?) but this is only at low rpm's. It runs smooth as silk with the throttle pinned. Cheers, Bill
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I believe that carb has adjustable low speed mixture, which is the pin with the knob at the top of the carb. I would remove that pin and make sure it is clean and not plugged. Basically go through the carb and clean out all the varnish and other deposits that accumulate over time. With regards to low compression, yes it is important that they be even, but it is also important that it have good compression, yours is borderline. I would try using sea foam to to a de carbon treatment to see if that brings the compression back up.
Have a great day
Rob.
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Rob, Entire carb was removed and cleaned. All passage ways blown through both directions with compressed air. Carb kit installed. Float height set and measured for proper throw ??????? Heard about Seafoam, tried to find some but apparently it's only sold in the states. Anything else ? Thanks, Bill
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You can buy Seafoam from Don Dickey Supplies in Richmond by the River Rock Casino. If all else fails then low compression may be your problem. It is running on both cylinders right? Sometimes that can show up as poor idle.
Good luck
Rob.
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healthy spark on both cylinders, points clean and set. don dickeys for seafoam, right on, i live 2 minutes away. i will give that a try. thanks !
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Rob, Entire carb was removed and cleaned. All passage ways blown through both directions with compressed air. Carb kit installed. Float height set and measured for proper throw ??????? Heard about Seafoam, tried to find some but apparently it's only sold in the states. Anything else ? Thanks, Bill
I would go back and clean the carb again and install another new carb kit. As suggested it sounds like a fuel delivery problem..... Most small engine problems are related to fuel delivery.
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water or could be dirty ; check for carbon, clean and try again...if all else fails buy a new one!
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Sounds like robj is steering you in the right direction. Get a manual and be shure the idle circuit is clear of slightest bit of varnish or debris. After that, richen the idle fuel mix and give it a try.
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sounds definitly like carb issue. most carbs have an idle circuit, the jet can be clogged up by gas turned into gel or a bit of dirt from dirty fuel plugging the port. try soaking the body overnight in acetone, then blow&blow&blow all the jets and holes in the carb body with a 100p.s.i. air gun. you'd be suprised just how stubborn a little obstruction can be! when you're confident you've removed all obstructions, set float hieght & re-assemble, making sure the float bowl gasket is sound, no leaks . while you've got the float out, put it in a glass of water and make sure it floats, no holes in it. if it still won't idle, you've got another issue. often these older outboards have bad coils, that is the insulation on the underbody of the coil has broken down allowing the high voltage spark to short to ground. so, instead of travelling down the high tension lead and firing the plug with full voltage, part of the charge is being grounded out through the hole in the coil insulation to the mounting plate. i've had two outboards with this identical problem. good luck.