Engine bogs out under heavy acceleration

[legoman67]

1979 merc 255mie, when i rev it it bogs out(1500-2500rpms), and if i try to hold it when i rev it will stall... if i go slow on the trottle i can get it to rev up, and when i release the throttle it returns to idle. i checked the timing and its good, i also just finished rebuilding the carb.

any ideas?

 

[Alpheus]

Re: Engine bogs out under heavy acceleration

What kind of carb? Make sure your fuel pressure is good and double check your float level...

 

[legoman67]

Re: Engine bogs out under heavy acceleration

Rochester quadrajet

i just checked and im not getting a hell of a lot of fuel out the inlet to the carb, i wonder if my fuel pump is on the fritz.

 

[Alpheus]

Re: Engine bogs out under heavy acceleration

Thats is most likely your problem. Put a gauge on and check your pressure...

 

[Bondo]

Re: Engine bogs out under heavy acceleration

Ayuh,... Is there Crud in the filters,..?? the Tank,..??

 

[legoman67]

Re: Engine bogs out under heavy acceleration

brand new filters, clean gas from a jerry can... replaced the pump with a spare i had kicking around, still does the same

 

[OldNBold51]

Re: Engine bogs out under heavy acceleration

1979 merc 255mie, when i rev it it bogs out(1500-2500rpms), and if i try to hold it when i rev it will stall... if i go slow on the trottle i can get it to rev up, and when i release the throttle it returns to idle. i checked the timing and its good, i also just finished rebuilding the carb.

any ideas?

Is the accelerator pump working? When you hit the throttle fairly hard, there should be a visible stream of fuel jetting into the carb venturi's.

 

[legoman67]

Re: Engine bogs out under heavy acceleration

yes the accelerator pump is working, its brand new.

bump

 

[OldNBold51]

Re: Engine bogs out under heavy acceleration

Timing advance mechanism? If you've got fuel, spark, compression and assuming your exhaust is clear, that would be the thing I'd look at next is the timing advance... maybe rusted.

 

[legoman67]

Re: Engine bogs out under heavy acceleration

yeah, i was talking to another guy who suggested i look into the vacum advance as well, i have never touched one or adjusted one before, any tips or tricks?

 

[Boheefus]

Re: Engine bogs out under heavy acceleration

yeah, i was talking to another guy who suggested i look into the vacum advance as well, i have never touched one or adjusted one before, any tips or tricks?

vac advance is super easy. The hardest part can be finding a port ont he manifold to tie into.

 

[Bondo]

Re: Engine bogs out under heavy acceleration

yeah, i was talking to another guy who suggested i look into the vacum advance as well, i have never touched one or adjusted one before, any tips or tricks?

Ayuh,... There's No vacuum advance on boat motors,.. They use flyweights...
See if they move freely against their springs...