1983 35HP bogging down

[Fishing in driveway]

Good afternoon everyone, I have a 1983 35HP Evinrude that boggs down and stalls after half throttle. It will not run without 3/4 manual choke. Otherwise it will run but stall when I put into gear. Primer bulb not staying firm. I’ve rebuilt the carburetor about 2 months ago, but have not run it since. The boat was sitting for about 3 years before I bought it. I’m an I/O guy and have rarely worked m on outboards. Thanks!!

 

[racerone]

Primer bulb does NOT stay firm once engine is cranked over or running.-----Having to use the choke indicates a fuel supply problem.

 

[Bosunsmate]

Is that primer bulb not staying firm with the engine off?
Have you tried manually priming bulb when running to act as a temporary fuel pump to see if that alleviates the issue

 

[Fishing in driveway]

It stays firm when the engine is off for about 15 minutes, which I’m assuming is normal. Yes I’ve tried priming while the engine is running, it helps a little bit. The only that seems to keep it going is putting the choke at 3/4. Thinking it might be the fuel pump

 

[racerone]

So does it keep running / run properly when you operate the manual pump ?

 

[Fishing in driveway]

It helps a little, not much

 

[oldboat1]

Easy stuff first. Set the idle mix needle 1 1/2 turns open from lightly closed, and see if it starts and runs. After warm up, adjust it for best running -- small adjustments.

As you seem to have issues at idle and half throttle, a compression check would be a good idea (screw in style tester with release button). Get an adjustable open air spark tester, and test with plugs removed.

Don't throttle up on muffs (fine tuning also difficult w/o back pressure.) A large plastic trash can can work, water about half way up the leg at all times.

 

[Fishing in driveway]

Did the compression test 125 both cylinders, replaced the fuel pump, started with 1 1/2 turns in low speed jet, and adjusted accordingly. All to no avail. Removed the carburetor once again and am waiting on ANOTHER rebuild kit. This motor is trying my patience. Motor misses hard without the choke 3/4 to full and will not go 1/2 throttle. Pumping the primer no longer helps. Did the spark test, all checks out. Ran the motor on one cylinder per cylinder. That checks out. Meaning the motor runs like it should on only one cylinder. About ready to call it quits in this one. Also, although not recommended, I did spray starting fluid into the intake, while the choke was open and it performed normally. I know it’s a fuel issue, don’t know where I’m going wrong? Thanks for all of the advice keep it coming

 

[racerone]

Fuel is metered by a high speed jet.-----Or called an " orifice plug " in the parts book.------It is found in the very bottom of the float bowl.----Did you have it out for cleaning , yes or no ?

 

[Fishing in driveway]

It’s soaking in Acetone as we speak. I’ve rebuilt many carburetors, I don’t think it’s the issue. I’ve already rebuilt this one, and soaked it overnight. I ordered another kit hoping there was a defect in the first one

 

[Crosbyman]

opinion..


choking basically serves to increase the vacum pull from the crankcase vacum directly on the fuel supply so
either :

- the fuel supply is restricted (carb cleaning is in order

..again ​

incl those small ones under the top dome plug !! incl high pressure air blow out of all orifices …. some may be internally crudded and require some poking. soaking is not enough

check inlet needle operation by doing a blow test on the fuel inlet air goes in upside no air goes in upside down

check needle seats for air leak check for any missing plugs/parts on the carb


- The fuel filter on the fuel pump is causing poor fuel flow… was it cleaned ????

- normal crankcase vacum is weak (bad seals) ?? carb base gasket missing ??

- fuel hose or tank pick up causing restrictions on fuel flow (have you tried feeding the carb directly bypassing the tank - the hose- the fuel pump/filter by connecting a fuel supply directly to the inlet on the carb


try a new tank (spare) and hose check all fittings for air leaks


vent open on the tank ?? check for plugged venting on the tank even if vent open

 

[racerone]

To be honest I do not believe in " defective " carburetor kits.----Something simple is being overlooked.-----Is the nozzle gasket in place ?