2002 - 496 Mag - will not rev over 1500 RPM
 

Hi All,
I need help. Three mechanics have thrown in the towel on this project.
I have a 2002 - 496 Mag non-HO. Engine was locked. Bought a Short block from boatnt on here. It was an extra for his Fountain.
Dressed the short block from the old motor. Also changed out the Cam Position Sensor/timing cover/pig tail/sprocket (per BUPs post on here).
After all was said and done, the engine ran well when not in the boat. However, once in the boat, it starts and idles without issue. During the sea trial, it will not go over 1500 RPM. When pulling the codes it give says it cannot read the CAM Position sensor but it is an inactive fault. Also, when the engine is started the Tach reads, but when you give it gas, the tach drops to 0.
I have uploaded the documentation on what was replaced and included my write up when the cam position sensor was replaced.

Any help would be greatly appreciated. I would compensate for the time spent diagnosing/fixing the issue. (BUP -- any help?)

thank you,
wmrath

https://cimg4.ibsrv.net/gimg/www.off...fe40fdf6f2.png
Parts list
https://cimg3.ibsrv.net/gimg/www.off...3b54c6d45f.png
Cam Position Sensor replacement doc pg1
https://cimg4.ibsrv.net/gimg/www.off...5e5fa0bdcd.png
Cam Position Sensor replacement doc pg2
https://cimg5.ibsrv.net/gimg/www.off...e6403b5606.png
Cam Position Sensor replacement doc pg3
https://cimg7.ibsrv.net/gimg/www.off...bcfe1c5cec.png
Cam Position Sensor replacement doc pg4

Bup was banned a while back....you can contact him directly @

Boats Unlimited at 817.658.7721

thank you

Other will obviously ask - What do you mean by "will not go over 1500"? engine stalls, cuts out and misses/stumbles, just will not build rpm??

I assume all the connections were good on your sensors and all the wiring harness grounds are clean and secure? Where did you source the sensors as there is a lot of garbage on Ebay and the likes

I believe it is in Gaurdian mode. It really will not rev over 1500 RPM but runs fine. It does start to sputter and run rough when we push it.

3 mechanics and no one scanned/ checked for or cleared codes?

Do the wire colors on the cam sensor match up to pic?

https://cimg3.ibsrv.net/gimg/www.off...e78e755ab6.jpg