RPMs under load vs. Neutral

[Eddie Ray]

What would cause the rpms to max out at 3000 under load , and climb easily to 5000 in neutral .
Volvo aq125a 270OB 21 ft trophy. The rpms should around 4800 at wot. Goes to 3000,plenty of throttle left. But rpms and speed will not go any higher?
Thanks for any ideas
Eddie

 

[Bondo]

Re: RPMs under load vs. Neutral

What would cause the rpms to max out at 3000 under load , and climb easily to 5000 in neutral .
Volvo aq125a 270OB 21 ft trophy. The rpms should around 4800 at wot. Goes to 3000,plenty of throttle left. But rpms and speed will not go any higher?
Thanks for any ideas
Eddie

Ayuh,... Revin' it to the moon in neutral is irrelevant, 'n not at all Useful....

It's probably starvin' for fuel under load(when it's using the MOST fuel)....

Sooo,.... Check out yer Fuel System, tank vent to carb...

 

[Don S]

Re: RPMs under load vs. Neutral

Testing for max rpm without a load is a useless test. You can remove 2 of your 4 spark plugs and get enough rpm to destroy the engine.
Here is a list of items that can cause low WOT (wide open throttle) rpm.

http://forums.iboats.com/showthread.php?t=295070

You have lost 2000 rpm, so you know it's not the prop. Prop change will only give you 100 to 150 rpm per inch of pitch.

 

[Eddie Ray]

Re: RPMs under load vs. Neutral

Ayuh,... Revin' it to the moon in neutral is irrelevant, 'n not at all Useful....

It's probably starvin' for fuel under load(when it's using the MOST fuel)....

Sooo,.... Check out yer Fuel System, tank vent to carb...

Tried to rev it slowly ,to not do any damage. Just wanted to see if it would go beyond the 3000 mark with out a load on it. People kept telling me it was the linkage to the throttle? I didn't agree and wanted to be sure. I also think it is a fuel delivery problem. I think it needs a fuel pump? I will check the vent? Can I just disconnect it and blow on it to see if there is a clog in the line? Checked,and the fuel in the filter is very clean,but she is old and something could be clogging the vent?
Thank you very much for your help.if you think of any thing else I should look for ,please let me know.thanks again
Eddie

 

[Eddie Ray]

Re: RPMs under load vs. Neutral

Don,thank you. This site is a life saver to many ,many boaters. I have all ready gone to the link you gave and will check the list.
Thanks for the help.
Eddie

 

[Maclin]

Re: RPMs under load vs. Neutral

Eddie,

Pick one or the other of these threads to update everyone on...here is the "other" one I am referencing...:

http://forums.iboats.com/showthread.php?t=512827


I am not all that familiar with the actual distributor, but it may not be advancing like it should, rusty weights or springs or other problem. The timing check should show that.