28 HP Evinrude 1988 backfires & stalls in idle

[Royce Brown]

I have a 1988 Evinrude 28HP E28ESLCCR that runs really well aside from the fact that it will backfire & stall out when left in full idle.

I've played with what I believe is the low speed carb adjustment screw on the front by a full turn each direction, in 1/4 turn increments, same behavior throughout. My dad suspects it's a fuel pump issue because it has stalled out occasionally with more open throttle, only to find the primer bulb soft. A few pumps and it seems to pressurize itself. He thinks the fuel pump is the cause of fuel pressure loss and I can't disagree. I have no issue replacing the fuel pump & I have a full OEM service manual.

Also note this motor has had zero maintenance on it since birth aside from changing plugs each year, my dad ran it 6-8 times a year and it never failed to start/run consistently. If I were to guess this motor has maybe 250 hours on it, somewhere in that range.

Any suggestions? Run some kind of seafoam additive through it?


Cheers, Royce

 

[jakedaawg]

Fuel pump doubtful, primer bulb should NOT remain hard while running.

backfires in 2 strokes are more likely "lean sneezes". Not rich enough in one cylinder or a slight seal leak in crankcase most often.

Careful link and synch then more in depth diagnostic needed if it persists.

does it do it even after warmed up?

 

[racerone]

Sounds like the carburetor is opening too early.-----Move the stop screw on the rod towards the carburetor 1/8" and test run

 

[Royce Brown]

It does still stall out when warm. It does appear that the throttle plate is not quite aligned properly with the carb throttle assembly, need to adjust the linkage a bit and hopefully that solves my problem.