'83 140 fuel starvation top end

[V153]

Okay guys: Motor started displaying a classic symptom of a bad fuel pump couple weeks ago. ie. Squeezing the primer bulb helps. But you have to squeeze VERY hard to make any difference?

So anyway we rebuilt the pump. No difference. Carbs were rebuilt and all fuel lines replaced with Anti-ethanol Sierra hose a couple months ago. All connections clamped. Fresh fuel, clean water seperator.

Fwiw I don't believe air's leaking in anywhere along the fuel intake path. Well 'sides the tank cap vent(s)?

I'm 99% sure it's a fuel delivery problem, but could it be a vaccuum leak? Only does it at high rpm. She'll come outa the hole'n haul a** but as soon as you hit bout 5K rpm: Blaaaaaaah. Back off the throttle and in a second or two it catches up.

If you nudge her onto plane and gently apply throttle you can get her going a lil faster. But soon as you push it a lil too far: Blaaaaah

 

[Bosunsmate]

Re: '83 140 fuel starvation top end

Did you replace the fuel pump to crankcase gasket?

 

[boobie]

Re: '83 140 fuel starvation top end

Are you running the mtr on a built in tank or a portable ??

 

[V153]

Re: '83 140 fuel starvation top end

Portable

 

[emdsapmgr]

Re: '83 140 fuel starvation top end

Agree, it does sound like fuel starvation. What size is the fuel tank hose- 5/16" or 3/8"? Is the fuel hose bulb new? If you replaced the hoses under the cowling with bulk hose, any chance that one is kinked where it bends sharply? I see at least one fuel hose under the cowling is recommended as a factory special, due to the heated/bend in it..326597 which supercedes to 333407.

 

[V153]

Re: '83 140 fuel starvation top end

3/8" hose. No kinks, primer bulb less than a year old.

Asked a buddy whose been in the business for 40+ yrs what he thought it might be. He said without hesitation, "Chunk of crud in the high speed jet(s)."

Got to thinking wouldn't that cause you to lose just a cylinder, or two mebbe? I'm baffled.

Find it hard to believe a piece of crud could find it's way through the seperator, then the see-thru inline filter in front of the motor, and then the filter screen on the pump? But I guess anything's possible, so looks like we'll be tearing down'n inspecting the carbs. Again. Dunno what else to do?

 

[emdsapmgr]

Re: '83 140 fuel starvation top end

I understand that the fuel hoses were just replaced. If there had been original 1983 hoses on the engine before that-it could be the problem. The older hoses are not ethanol complaint. I've seen those old hoses break down into tiny black bits, flow down the fuel system and lodge in the jets. Good call to check them. You can pull the high speeds out usually without removing the carbs, if you want to visually check a couple of main jets.