3.0l bogging down only under load!

[chaspat]

I recently purchased a 1991 Rinker with the 3l and alpha 1 outdrive. I serviced the lower end, tuned engine, cap rotors plugs..... It'll rev fine, but boggs down under load. It'll cruise at about 10 mph, but any attempt to increase throttle, engine pops and then dies soon thereafter. I should also mention there is no vibration from the drive unit. Any ideas?

 

[Mowens]

Make sure on your firing order. Verify sparl at each plug. Most likely you have a plug wire cross over.

 

[chaspat]

I'll check on that tonight, I wouldn't suspect it would still rev fine in neutral though?

 

[Scott06]

I'll check on that tonight, I wouldn't suspect it would still rev fine in neutral though?

There is no load on the engine in neutral so it really doesnt mean anything reving up in neutral. Likely you have a fuel supply issue related to clogged fuell filter (which is in bottom of fuel pump on a 3.0), or have clogged carb passages and a carb rebuild is in order. WHen you open the throttle under load and it needs fuel it is lean and you get a lean sneeze and stumble.

You verified the igniton timing is ok?

 

[Scott Danforth]

I'll check on that tonight, I wouldn't suspect it would still rev fine in neutral though?

the engine will rev in neutral running on only 2 cylinders. that means nothing.

as Scott stated, when an engine is under load, it needs fuel. my guess your carb is plugged or your anti-siphon valve is stuck.

 

[chaspat]

Good to know, I already suspected fuel, I cleaned the system after the last shakedown, found the water fuel separator hadn't been changed in perhaps a decade. I am rebuilding the carb this week, so I think I am on the right track. Just new to boating, not mechanical work, thanks for the thoughts. I should have the carb rebuilt and be ready to give it another shakedown this weekend. I saved this one from the scrapheap, had the 3.l and alpha one, and the floors were solid! Almost everything else has been replaced in a few short weeks. Looking good! 1991 Rinker 181.

 

[1focus]

Two things I've experienced caused the exact issue. #1, bad plug wire. Revs like usual in neutral. Under load didn't even miss, just bogged down. #2 Plug gap got closed. Same as above. The normal "revs" had me looking at fuel filters, vapor locks, you name it, everything ignition. Start with the things easiest to check first, you might get lucky.

 

[Grub54891]

This one ran good the season before. Customers 3.0. Didn't understand why it didn't now. This is what I found. When I cleaned out the gunk, the bowl had a hole in the bottom also. How it didn't leak I don't know! New carb cured it. He said he uses ethonal exclusively. Don't be this guy.....

 

[chaspat]

This one ran good the season before. Customers 3.0. Didn't understand why it didn't now. This is what I found. When I cleaned out the gunk, the bowl had a hole in the bottom also. How it didn't leak I don't know! New carb cured it. He said he uses ethonal exclusively. Don't be this guy.....

I suspect the carb may be the most likely culprit as I did put new plugs, wires, cap and rotor. Thanks for all the input, I will be sure to update this weekend once I finish with the carb and get it out on the water again!