Crank Shaft Position sensor seating Indmar/Chevy Vortec 350

[scbeerabrge]

Boat decided not to start a couple weekends ago. It has an Indmar 340hp 350. Traced it to the CSPs. Had to replace it 4 years ago. Last time popped in new one and all was good. This time the new one(OEM GM) didn't fix it off the bat. Figured out if you push a little up and back towards the bow the boat will fire. Same with the old one because it was tested. So I have the opposite issue of everyone else that has to put in spacers due to the relcutor wheel getting a bit loose.
Any ideas on how to resolve other than gradually sanding the new ones housing down about .020 inch or so at a bit of an angle?
Also any ideas on what might cause this to happen?
Boat has 540 hours and has not been abused. Some water sports where I break 3000 RPM occasionally. Other than that she's babied.

 

[dubs283]

The reluctor wheel doesn't just come loose. It's held in place by the balancer

The only way it can come unseated is if the balancer has moved on the crank

Is there damage on the old sensor face?

 

[alldodge]

Might not be the sensor, might be bad connection, moving it causes it to make connection again

 

[scbeerabrge]

The reluctor wheel doesn't just come loose. It's held in place by the balancer

The only way it can come unseated is if the balancer has moved on the crank

Is there damage on the old sensor face?

No damage to the old one. Even the original replaced in 2019 didn't have any damage. My issue seems to be it's about .020 to far from the reluctor.
When I apply a bit of pressure upwards and back boat fires. With a clear head this morning I'm going to check the seating and if it's off. I don't see how. It's hard plastic against steel. One other question is I bought OE GM sensor for $70 vs an "Indmar" sensor for $200. FWIW I talked with Indmar about this and the CSPs came installed from the factory. I don't see how/why GM would install something slightly different. Also, aside from this starting issue what are the longterm issues with the balancer being .020 out of balance? Meaning if I end up modifying this sensor to work consistently am I looking at throwing the timing chain etc.?

Might not be the sensor, might be bad connection, moving it causes it to make connection again

99% I can rule out. We did testing on the connections for 5v and also were able to get it to work by pulling the sensor and running a magnetic wrench across it.

Thank You for the replys,
SCBB

 

[alldodge]

GM sensor is good

 

[dubs283]

Oem cps ought to seat proper in an oem timing cover.

Has the timing cover ever been replaced?

 

[scbeerabrge]

Oem cps ought to seat proper in an oem timing cover.

Has the timing cover ever been replaced?

Timing cover has never been replaced. I manipulated the cps again last night and took the boat out for a 30 min. +run all over the RPM range. Runs fantastic. But when I got back to the dock she would not refire after shut down. Not sure what to think at this point. You may be correct that the timing cover shifted. Not sure what would cause that. Also, not sure what the short term implications are if I take it out a bit this weekend aside it's a PITA to re fire.

 

[alldodge]

IMO, The issue is not the CPS, it's something else, just coincidence

 

[dubs283]

IMO, The issue is not the CPS, it's something else, just coincidence

Maybe inspect other 5 volt connections/components that share the circuit with the cps?