low power until 2400 rpm then just takes off

[Sashap]

weird situation. very hard to get rpms up but as soon as it hits 2400 rpm every time it then rockets off.
But, can't get past 4100 rpm. Overall, I don't care if it doesn't go over 4100, but I would like the bottom hole shot.
I have a new fancy 4 blade 15 pitch prop to fix hole shot (this worked until a day ago). Nothing much changed in the engine etc. The carb? The accelerator pump is working (I can see spray). It's weird that the power really kicks in at exactly 2400 each and every time. I am able to finesse it sometimes to go up semi-smoothly, but if I give it full throttle from the start, then is usually bogs until 2400. Would the carb be so precise? Almost sounds like a timing thing.

 

[TurtleTamer]

It does sound like timing. 2400 is right around the time your full timing should come in. It may be failing to advance until at the top of the RPM curve and then it brings it in. That is, IIRC and you have a 2000 or so 3.0. If so, you can easily check this with a timing light.

 

[GA_Boater]

8.2's are picky like that.

 

[Sashap]

It’s est ignition. 1992 engine. How do I fix it?

 

[GA_Boater]

It’s est ignition. 1992 engine. How do I fix it?

Are you going to ID what motor? 2 guesses so far - 3.0 and 8.2.

 

[Sashap]

Sorry. 3.0 .

 

[Scott Danforth]

check the timing advance. could need a new module.

 

[Maclin]

Is it still in base timing mode?

 

[Sashap]

Yes, that is driving me crazy. Both modules are the same. I tried but couldn’t get it to change. That’s why my max rpm is low too.

 

[TurtleTamer]

You'll have to go back to basics on it. Put it in base timing mode and check your base timing. Take it out and verify ~12*BTDC, ~24*BTDC by your 2400rpm (don't do that for long on the muffs). If none of this occurs you most likely have a bad module. Based on the symptom, that'd be my only guess as to what's wrong.

 

[Rick Stephens]

You'll have to go back to basics on it. Put it in base timing mode and check your base timing. Take it out and verify ~12*BTDC, ~24*BTDC by your 2400rpm (don't do that for long on the muffs). If none of this occurs you most likely have a bad module. Based on the symptom, that'd be my only guess as to what's wrong.

Exactly. Easiest if you have an electronic advance timing light. Almost impossible to do without.... I guess you could put tape on the balancer to check it. But a snap to determine if you are in the neighborhood with with a decent light.

 

[Sashap]

To all pros out there. Nobody mentioned that there are two types of est ignition modules for the 3.0. Same part number but different breed. The one ending in a stamped number 369 is automotive only with a timing curve that does not advance until 2400 rpm and then maxed out around 4000 rpm. The one stamped with a 399 is used for marine and some high performance uses with the correct curve.
Runs perfect now. Plus the automotive one has no base mode.

 

[zellerj]

Sashap,
Could you explain why this issue suddenly manifested itself? You said in the first post the nothing much changed in the engine, and the new prop worked fine up until a few days ago? Did you change out the ignition module to the automotive type?

 

[achris]

To all pros out there. Nobody mentioned that there are two types of est ignition modules for the 3.0. Same part number but different breed. The one ending in a stamped number 369 is automotive only with a timing curve that does not advance until 2400 rpm and then maxed out around 4000 rpm. The one stamped with a 399 is used for marine and some high performance uses with the correct curve.
Runs perfect now. Plus the automotive one has no base mode.

And this is why us 'pros' try to avoid using non genuine parts. Too many people out there trying to second guess the manufacturer.

'nough said.

Chris. ....