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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10620
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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Need Tan in boat motors..... now that I fixed the leak and

Customer Question

Need Tan in boat motors.....Hey now that I fixed the leak and redid the carbs.... The motor is running rough .... How do I adjust the fuel mixture. The carbs or the idle for that matter?
Submitted: 5 months ago.
Category: Boat
Expert:  Tan replied 5 months ago.

Hello. The idle jets screws initial setting in turn all the way in till they touch bottom then turn CCW 4 turns. Then put the boat in the water and fine tune the idle jets to achieve best idle. You can fine tune on the hose.

Customer: replied 5 months ago.
Using a barrel right now.... What I need to know are where the idle jets are? There are two brass screws on the upper part of the carb and I unscrews those this morning then put them back.... They have a little hole in the screw..... Is the bottom one the idle jet? Do I need to acutually mess with the jets or just the screw?
Customer: replied 5 months ago.
I unscrewed ... Bah bad grammar .....
Expert:  Tan replied 5 months ago.

Here is the idle jet screw. The ones with holes are fixed jets no adjusting. The red arrow is the idle jet.

http://i.imgur.com/5JZ4856.jpg?1

Customer: replied 5 months ago.
Ok..... Mine have no screws ..... I just see the two fixed ones and the high speed jet on the bottom of the float bowl
Expert:  Tan replied 5 months ago.

The parts diagram shows that you have them # ***** Are these original carbs to this engine? http://www.marineengine.com/parts/evinrude-johnson-parts-diagrams/JOHNSON/51133.gif

Can you take a pic of the front of the carbs?

Customer: replied 5 months ago.
I sure can give me a sec
Expert:  Tan replied 5 months ago.

Ok

Customer: replied 5 months ago.
Here you go .
Expert:  Tan replied 5 months ago.

Ok your engine is older than 96 I went back a couple of years and they were fixed jets in 94. So we need to verify the jet sizes are in the correct locations.

The smaller jet needs to be in top hole larger bottom hole. When you had the carbs off did you make sure the small tubes were clear?

Customer: replied 5 months ago.
Well if the engine was running well before the leak and now that the leak is fixed.... Why would the engine be running rough? Also the motor tag on it says 95 but the model number comes up 96..... So not sure what the heck is going on with that..... You said small tubes..... You mean the brass ones in the carb that stick up.... There are two of them
Expert:  Tan replied 5 months ago.

Yes the brass tubes.

Running an engine in a barrel isn't the best conditions as you will be getting allot of exhaust fumes which will make engine run poorly.

Customer: replied 5 months ago.
Well was using rabbit ears also and it ran fine unti I fixed the leak and now it is running rough ..... With a cough every 20 seconds or so.....
Customer: replied 5 months ago.
Def has added more smoke to the exhaust since I fixed the leak
Expert:  Tan replied 5 months ago.

Coughing is a lean fuel condition. This is the engine sucking air or not getting enough fuel.

Did you make sure the tubes were clear. The tubes are fuel supply for idle and off idle. These are 3 stage carburetors. Low speed intermediate and finally high speed. With poor idle the tubes can be clogged or you are sucking air. The side ports on these carbs are critical about the screws being over tightened and squishing the gasket out allowing air in.

Are the side covers to tight?

The engine smoking allot can be a fuel restriction or air leak on the fuel side of the vro pump.

Customer: replied 5 months ago.
The vro was disconnected and I just premix the fuel.... The side plates could be over tightened but everything was running fun until I fixed the leak..... Readjusted the carb floats etc.... So what I have to do is take off the carbs again? Look at the brass tubes? See if the are clean? Should I use a piece of wire to clean them out?
Expert:  Tan replied 5 months ago.

Yes they have to be clean. When you reassembled are you sure all the gaskets were in place. These rubber o-ring gaskets are a pain to keep in place sometimes. I use oil on the gaskets to keep them in place for assembly.

Customer: replied 5 months ago.
if the were off they would leak
Expert:  Tan replied 5 months ago.

These will not leak fuel that is the suction side so you won't see fuel anyway. It can suck air and cause throttle up problems. This port is idle and off idle transition ports.

Customer: replied 5 months ago.
I'm just not sure.... The engine comes close to dying after awhile.... The barrel water gets really hot and I have this brown sludge floating on the water and sticking to the waters edge around the barrel and lower unit
Customer: replied 5 months ago.
I sprayed carb cleaner into the carbs
Customer: replied 5 months ago.
Maybe I should just put it on the water and run it but I don't want it dying in idle.... Plus not dying to take all those carbs off again.... That's seems what I do .... A lot of the times
Expert:  Tan replied 5 months ago.

Thats to much fuel or the engine isn't running on all cylinders. Check that you have spark on all cylinders. We may not have a carb issue anymore but an ignition issue. This would explain rough running and all the fuel in the water.

Customer: replied 5 months ago.
Ok it seems like the starboard side is running and pushing air out of the carbs while the port side is not really pushing air out and that is the side the leak was on
Customer: replied 5 months ago.
fixing the leak flooded the spark plugs? Should I take them out? I think we are getting somewhere now
Expert:  Tan replied 5 months ago.

Absolutely could have fouled spark plugs. We still need to check spark on all cylinders just to be sure.

Customer: replied 5 months ago.
Ok going to go check them and clean them
Expert:  Tan replied 5 months ago.

OK

Customer: replied 5 months ago.
Best way to check for spark? Also should I clean inside where the spark plug was? And what would be the best way to do that? Air hose?
Expert:  Tan replied 5 months ago.

You need a spark gap tester or a timing light. The gap tester is the best way set at a 7/16" gap. Air is fine to clear spark plug hole.

http://www.nationaltoolwarehouse.com/Ignition-Spark-Tester-with-Adjustable-Gap-P41027.aspx?utm_source=criteo&utm_medium=retargeting&utm_campaign=120x240%09

Customer: replied 5 months ago.
Started backfiring then smoking .... Like in fire on the top of engine
Expert:  Tan replied 5 months ago.

Ok that the rectifier/regulator # ***** gone bad. Pull the top cover # ***** off the back of the engine is the rec/reg burned?

http://www.marineengine.com/parts/evinrude-johnson-parts-diagrams/JOHNSON/49680.gif

That will affect the optical sensor causing poor running engine also.

Customer: replied 5 months ago.
What you think? Should I run it with it out and see if it smokes?
Expert:  Tan replied 5 months ago.

Is it cooked on the top side? It probably won't run very well as the optical sensor is powered by the rec/reg.

Customer: replied 5 months ago.
Looks ok at the top..... What I am worried about is that the motor sucked in fuel while in the barrel and it somehow is causing the over heating and smoking
Customer: replied 5 months ago.
Or maybe all the work I have put into it has been a waste and this motor is just garbage
Expert:  Tan replied 5 months ago.

It's very possible that why running in a barrel is not a good thing. On the water is the best test. Believe me I had to work at a marina where they didn't want us to go to the water. Finally after so many come backs they let us test boats at the water and the come backs went away. Just that the engine can't breath or cool correctly in a barrel.

Customer: replied 5 months ago.
do I go run it in the water after it has overheated and smoked like that?
Customer: replied 5 months ago.
I mean all of this has happened since I fixed the seal on the throttle assembley..... Just unreal
Expert:  Tan replied 5 months ago.

I would just to see how it runs. Did you check the spark on all the cylinders?

We don't know that what you did has anything to do with the issue now. You might put it in the water and it runs fine as long as you have spark on all cylinders.

Customer: replied 5 months ago.
Ok will give it a shot and see if it runs on the water .... But if it smoke even with rabbit ears how do I clean it.... This is pretty frustrating
Expert:  Tan replied 5 months ago.

Smoking is caused by the VRO pump cycling to fast due to an air leak or fuel starvation.

Now if the smoke is from over heating you have to replace the water pump in the lower unit. These engines don't run very well on the hose and do get hot.

Customer: replied 5 months ago.
I am going to run it in the water..... Also give it fresh fuel...... Water pump might be an issue will look at it..... Just so many things ..... Thanks for your time..... Want to run it on the water before I close the question
Expert:  Tan replied 5 months ago.

Ok that's fine. I'll be here. When you are on the water if engine acts up check for spark on all cylinders with a timing light. Push the choke. Does engine run better?

Squeeze the primer bulb. Does engine run better?

These are all checks that will reveal something if there is an issue with engine running poorly.

Your welcome....

Thank you.....Tan

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