1983 70 HP Carb issue

[nmeadows]

I purchased a 1983 Evinrude 70 HP motor last year and have been trying to get it running in good condition. I have tried out the motor running on the water and it has bogged down as im applying throttle. I have pulled the carbs a few times to get them clean, rebuilt, and the floats set correctly. I have cleaned the jets and internals and have put the carbs back on and the motor seems to be running better now that the carbs have been properly cleaned and set. I did notice however that my top carb has gas sitting in the carb. The bottom two carbs do not have this. I have also put clean non ethanol fuel in yesterday to try to make sure that there is no water in the gas. The gas that is pooling in the carb is this whiteish color which makes me thing that somehow there is water finding its way into the system. I was looking up this issue and seems that cool weather can cause similar issues due to condensation. Is this the reason for the whiteish looking gas or maybe I have the float set wrong for that carb. If so why is only 1 carb having this and not the other two?

 

[Sea Rider]

Welcome to Iboats,

Did you cleaned well the needle's seat while soaking the upper carb in a cleaning solution or by squirting Carb Cleaner Spray through the seat. What's the needle tip cond, is it still sharp pointy, not rounded ? Is the float a hinged or fixed one ?

Happy Boating​

 

[Faztbullet]

The whitish fuel puddle is condensation and gas vapor..no big concern's. Is your sync and link correct and at least a 1/8 gap between roller and cam?

 

[nmeadows]

I think I might have fixed it. My fuel lines were leaking so after I fixed that and ran the motor on muffs this afternoon and it seems fine now. I did follow the manual to link and sync and my timing is at TDC as the carbs start to open. I have the idle set to around 850 RPM currently but will need to correctly set the idle once I am back on the water.

 

[ct1762@gmail.com]

what do you mean "TDC when the carbs start to open"? the carbs start opening with the first hash mark on the throttle cam, although on these to do it properly you really need a digital tach to get a consistent idle out of it and good throttle response. needs .010'' gap as fazt mentioned.

 

[nmeadows]

From what I understood from the manual is that you advance the throttle until the throttle roller starts to move along the cam. I did ensure that the roller lines up with the first mark on the cam when they meet. At that point the timing should be TDC. Thats what I have done on this motor. When I do set the idle there is around a 1/8th inch gap maybe a little more between the roller and throttle cam. I think that is the correct procedure unless I misunderstood the manual.

 

[nmeadows]

I did a little reading and I found 2 methods link and sync. One is to sync the throttle plates, Line up the roller with the mark on the cam, and then using a timing light to check timing and adjust by rotating the cam on the threaded connector. Then once on the water use the idle screw to set idle down to right RPM. The other method I saw was to set the idle first. So the process was sync the throttle plates, line up the roller with the mark on the cam, then while on the water set the motor idle and move the cam on the threaded connector to meet the roller with a .010'' gap between. Im not sure which is the correct method. One is setting the idle then the throttle cam and the other is to set the throttle cam then the idle.

 

[racerone]

You say you just bought this 37 year old motor.------Step # 1 is to determine why it might be bogging.-----You can do the mythical " sink and link " all day long and it won't help a motor in poor condition !!----Post you compression values , they should be 135 PSI or more to be called GOOD.

 

[nmeadows]

The compression is between 140 and 145 on all 3 cylinders. So far I swapped the spark plugs with Champion QL77JC4 and gapped to .04. I checked spark on all 3 cylinders with a tester set to 11 mm. I rebuilt the fuel pump and replaced all the old fuel hoses with brand new hoses, fuel filter, and primer bulb and made sure that my tank was as clean as possible. I ran sea foam through the engine to try to clean it. I have also rebuilt the carbs. I dont think I am missing anything to check.

 

[racerone]

It should run like a new one.

 

[nmeadows]

I hope so. But if the synchronization is off wouldn't that cause it to run poorly. I just want to make sure I am doing the sync part correctly since I have seen a few different ways to do it

 

[racerone]

Follow a factory manual.