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davesoutboard, Marine Mechanic
Category: Boat
Satisfied Customers: 1579
Experience:  marina owner for 20+years, certified Evinrude tech
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I have a 70 hp Evinrude. Engine will start and run with choke

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I have a 70 hp Evinrude. Engine will start and run with choke up. Once it is put in idle sometimes it dies out. If it doesn't when I give it power it either dies out or will run for about 20 seconds and then die out. What could be causing this? I have checked fuel filters. It gets fuel but doesn't act right with a load put on it. When I am able to give it power and go... it runs really well. Then all the sudden it startes loosing power and dies...?????
Submitted: 8 years ago.
Category: Boat
Expert:  davesoutboard replied 8 years ago.
What year or model is the 70? Also the lever you are raising is not a choke that is a fast idle. If it is a older model just raise it up and leave it there until it is running. The choke is on the ignition switch. Once I know the year I can tell you if it actually a choke or if it is a primer. Once it dies what do you do to get it started again? If you have to squeeze the fuel bulb then it sounds like your problem is the fuel pump.
Customer: replied 8 years ago.
It is a 1977 Evinrude 70 hp. Sorry, your idle. It runs if I have the fast idle up just fine. I slow it and sometimes it fizzles out. If I manage to get it going I slowly push the throttle and sometimes it will run great then with in 20 seconds it fizzles out gain. To get it restarted I have to turn the fast idle up somtimes. Once it's warm I still have to start it in the fast idle up sometimes.
Expert:  davesoutboard replied 8 years ago.
OK what it sounds like is the high speed jets are plugged up in one or more of the carbs. While it is dieing if you bump the choke in I bet it will pickup for a short time. Carbs will have to be removed and at a minimum high speed jets cleaned. If you want to do it yourself let me know and I will give you a hand. I would bet this is the problem, but have you replaced the plugs? QL77JC4 or QL78YC or has there been a compression test done lately?
Customer: replied 8 years ago.
The plugs look new. Unsure of the last compression test. The previous owner took good care of it. I have read others having a similiar problem. I would like to try and clean the high speed jets. I have never done this before but i figure I will only learn if I do it. Is it difficult? This seems to be a common issue. If I rev it by pulling the throttle at the motoe it revs fine most of the time. Other times it sounds like it's drowning and starts to die. I have learned if I put it back into nuetral to will recover but suffer when I give it power. Then it will get to speed and boat will level off then in about 20 seconds die out. Still think high speed jets? And what do I need to get started. Hook me up with that and I can accept...thanks.
Expert:  davesoutboard replied 8 years ago.

If you ever tried hitting the choke while it was dieing that would tell us for sure.

Hi speed jets are not hard. Top two carbs are easy once the airsilencer is removed (lots of screws). You should have direct access to the carbs. You can check the top carbs without removing them. Take the plug out of the bottom of the bowls. 7/16 wrench. You should have fuel drain out. Be sure and disconnect fuel line so it does not continue. Once the plug is out you will need a very small straight screwdriver to go into the hole that is left. They make a special tool for this, but I have done it with a small screwdriver (might need to grind it down to fit). Unscrew the jet that is in the hole and inspect. You can run a small wire thru it. I am usually able to blow them out with a compressor. Be sure and do all three. You will probably have to remove the bottom carb to get at the drain. If you find one or more plugged that was the problem. Reassemble and be sure to use locktite on the small fine threaded bolts on the air silencer, you do not want them to fall out and be sucked into the engine. I would then add some quality fuel additive to prevent it from happening again. Alot of the time this is all you need to do. If they are plugged real bad and either no fuel comes out of the carb when the drain is pulled or you get dirt out. I would suggest pulling the carbs and having them cleaned and rebuilt.

Customer: replied 8 years ago.
I took out the carb plugs already and clean fuel drained from all three. I'll try to clean the jets. So to remove the jest you have to take the plug out from under the barrel where the fuel drains and the screw for the jets accessed through the same hole?

And where is the choke located? When you refer to the silencer is that a piece that fits on the outside of the carbs? Because when I take the cover off you can see all three barrels and just below the air intake is the plug I removed and fuel drained.
Expert:  davesoutboard replied 8 years ago.

Yes that is the hole the one right below the airintake take the plug out and the jet is about 1.5" inside that hole. The jet will unscrew right out the same threads that the plug uses.


The choke is the outermost moveable plate in the throat of the carbs. All three of them are linked together on the starboard side and controlled by the solenoid.

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