Have a buddy with a 40 efi, installed heads cam and tuner. Dont know if the tuner was ever tuned exactly right. But right now it's only turning 4250 rpms trimmed in the sweet spot, where stock us used to turn at least 4600. 11.5 mercy, should be able to be on the limiter all day with it. Leakdown test good, compression good. Everything. Wngine runs and sounds good. Just won't go pass 4250 rpms with a load. Will hit limiter out the water.

1.Thinking either fuel pump is not giving it enough fuel.
2.Throttle position senor is off not allowing it to open full throttle
3.Or computer is not allowing it go pass these rpms.
I'm lost here, any help would be greatly appreciated.

Was the stock 40 pulling those higher rpms with the same prop. U could easily be over propped. The tps is very unlikely unless its not hooked up. Throttle cable not opening tbody all the way is possible. Check ur compression just to make sure it where u intended, this will tell u if the cam is indexed in the right spot. Aside from that its time to invest in oxygen sensors to see where the ecu is tuned to.

Yes he is saying the stock 40 was higher in roms with the same prop. Compression test was 180 on both cylinders. But yes think its time to invest in a good afr meter, cause it's running great so just running out of fuel I think. Trying to get him to trade the tuner out for a hard tuned ecm