Loosing RPM 5.7 EFI
 

Working on a 1997 boat with a freshly rebuilt 5.7 EFI and a bravo 3. I cant get the motor to get past 3000 RPMs and it just sounds like its down on power. When you gun it, it sounds good up to about 2100 RPMs, then sounds like it runs out of power and hangs at 2100 RPM and very slowly creeps up to 3000. The motor was completely rebuilt over the winter. After I first reinstalled the motor I made the mistake of not putting the computer in "service mode" for timing. The motor would backfire through the carb trying to get the boat on plane. So I timed the motor with the computer in service mode, and it made an improvement, but still would backfire through the carb getting on plane. I replaced the fuel filter, fuel pump, cap and rotor, and cleaned anti siphon valve. The motor no longer backfires, but its still not reaching the RPM it should. I hooked a tech mate up and had a warning for low fuel pressure, and low oil pressure voltage. After the a new fuel pump and fuel filter, I no longer have either of those codes. Now I just have a "general warning #1"

I'd start by finding out the actual fuel pressure, and by confirming that the firing order is correct. Assuming cap/rotor/wires/plugs were new when motor was rebuilt?

A fuel injected motor does not have a carburetor.

What exact motor do we have ? Merc serial # ? Any mods during rebuild ? Cam, cyl head change , etc, etc ?

What caused need of rebuild ?

What's your motor serial number?

Fuel pressure requires a special fitting that I have been unable to locate. I have been trying to come up with a homeade fitting. Wires are the only thing thats not new, and I have confirmed the firing order.

Sorry, i meant the TBI unit that looks like a carb. I will get the serial number from the boat today. Only mods during the rebuild was that the block was bored .030 over, and the rebuild was needed because the boat overheated badly last summer and blew a head gasket.

https://cimg2.ibsrv.net/gimg/www.off...405182d47e.jpg
Unfortunately I cant make out a serial number on the engine cover. Its a 1997 5.7 efi, bravo 3, mefi 3.

I took the boat out again today with the techmate scanner plugged in to monitor a few things. When I increase the throtte to make it on plane, I got up to 28 degrees timing advance, but then it dropped timing down to 20 and just stayed there even at full throttle trying to get on plane. I should be seeing a steady increase up to 30+ degrees correct?

Edit: While watching the timing go from 28 degrees down to 20, I could definitely hear the motor lose power, and through all that the throttle position was never decreased

Did you see if there was knock retard at this time?

No, the knock retard stayed at 0