1987 Evinrude 8 bogging down

[saltchuckmatt]

Another question for you. My 1987 Evinrude 8hp (e8rcud) is having some issues. That model is the one with a primer not a choke. Starts fine with one pull on the primer, idles good, rips around at high speed but when I start to slow down it bogs out and then dies and wont restart. When I pull the plugs they are all wet (flooding condition).

Compression is around 120 lbs +/- a pound or two, both coils jump a 1/2 inch when I check for spark, water telltale pees strong.

Only thing I can think of is float sticking or something...but only on the high end? or does the primer have a check valve?

Any help would be muchly appreciated.

Thanks,
Matt

 

[oldboat1]

Haven't looked at a diagram, but your primer probably has a red lever on the side -- should be parallel with the primer body for running.

 

[racerone]

No red lever on that 8 HP primer !

 

[saltchuckmatt]

No red lever on that 8 HP primer !

Yes, red lever on the bigger engines. Anyone have a guess. Strange scenario.

 

[racerone]

Step # 1 would be to have a look inside the carburetor.----Also inspect fuel pump diaphragm.

 

[oldboat1]

Well, checked a diagram and your motor has (if original carb) a low speed mix needle on top (in front). That's an air/fuel mix adjustment. It sounds like it may be too rich (too much fuel, too little air). The initial setting is likely 1 to 1 1/2 turns (c.clockwise) from lightly closed (clockwise). I would start there and see if the motor fires up for you. Let it warm up, and adjust leaner (clockwise) about 1/8 turn at a time until it gives you a light backfire (lean sneeze) or quits. Then open about 1/4 turn and start it again -- should be fairly close.

If you have a service manual (!!!), check the book setting for the '87 (could be a different initial setting). No danger, btw, as the motor will not run if too much air in the mix.

 

[saltchuckmatt]

Step # 1 would be to have a look inside the carburetor.----Also inspect fuel pump diaphragm.

Well, that's my guess (Carb) but I don't think its the fuel pump. Don't really think it would foul out with a fuel pump issue. Fuel pump on that year is the big one. If it is the carb than why does it start so good (1 to 2 pulls) and top out great? Something weird I guess.

 

[racerone]

???-------But the primer puts fuel into the motor.----This fuel bypasses the metering circuits that are inside the carburetor !----Blunt statement on my part.----Do not guess and assume when trouble shooting.----Learn how things work and repair as needed.

 

[saltchuckmatt]

Well, checked a diagram and your motor has (if original carb) a low speed mix needle on top (in front). That's an air/fuel mix adjustment. It sounds like it may be too rich (too much fuel, too little air). The initial setting is likely 1 to 1 1/2 turns (c.clockwise) from lightly closed (clockwise). I would start there and see if the motor fires up for you. Let it warm up, and adjust leaner (clockwise) about 1/8 turn at a time until it gives you a light backfire (lean sneeze) or quits. Then open about 1/4 turn and start it again -- should be fairly close.

If you have a service manual (!!!), check the book setting for the '87 (could be a different initial setting). No danger, btw, as the motor will not run if too much air in the mix.

Carb and motor are all original and I looked at the breakdown too (just now) and if I just looked at that I would say it has an adjustable low end jet but if you look at the engine the air box covers everything. I'm going to pull the airbox but I would guess that carb has fixed jets.

If a carb makes an engine to rich and has fixed jets what causes that? To me its the float bowl or float pin. Correct me if I'm wrong.

Thanks

 

[saltchuckmatt]

???-------But the primer puts fuel into the motor.----This fuel bypasses the metering circuits that are inside the carburetor !----Blunt statement on my part.----Do not guess and assume when trouble shooting.----Learn how things work and repair as needed.

I guess I shouldn't have said carb....fuel related. And I understand the primer shoots directly into the intake. Still don't see how the fuel pump would be the problem unless its making the primer malfunction. Maybe I should temporally disconnect the primer and see if that cleans it up.

Oldboat thinks it has a adjustable low end jet, what do you think?

 

[racerone]

Well the parts book clearly shows a low speed mixture screw.-----But how can you guess that it has all fixed jets.

 

[saltchuckmatt]

Well the parts book clearly shows a low speed mixture screw.-----But how can you guess that it has all fixed jets.

Because I'm staring at the motor and if it is than OMC gave you a low speed adjustable jet that you have no access to, that doesn't make sense to me. I believe there is a screw there but you tighten it all the way down. I could be wrong, maybe its an adjustable jet that you can't really get to unless the air box is off...we shall see....