98 Mercruiser 7.4 driving me nuts

[IamMe]

Ok we replacing this engine with a rebuild. Hasn't run correctly since I did this. We are getting no codes. Timing is set at 8 degrees btdc and vacuume, compression and leak down tests are fine. The engine runs smooth but will not get above 2800 RPM unless I work the throttle back and fourth then it will slowly climb. I can get it up on plane but must constantly work the throttle back and fourth or I fall back down. If it was carbed if say top end is only working on accelerator pump. I am thinking map sensor but decided to see if anyone else had an idea.

 

[alldodge]

Ya know it sure helps to know what your working on. Being a 98 and the carb comment I'm guessing its fuel injected, might be a MEFI 1 or 3, but a serial number could help.

Have you checked for codes?

I would start with checking fuel pressure

 

[IamMe]

Different block. Ill see if I can read the serial number I believe it is mefi3

 

[Bondo]

Ayuh,.... Is the fuel system up to snuff, feedin' the motor what it needs,..??

Any crud in the tank or fuel filter,..??

 

[achris]

TBI or MPI?
You have checked you have the firing order correct?

Chris.......

 

[IamMe]

Firing order has been checked 3 times that was my first though. When I checked when we put the motor in and its first trip out fuel pressure was fine. If I can ill stick it back in the water and test fuel,pressure under load again.