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Crusader 454 xli 1997 bog down (MAP sensor?)

Verdict

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Hi All,

I have a question on my 1997 Crusader 434XLI. I am having an issue with the STBD engine occasionally bogging down (2x per year) after a long run. Twice when heading on 40+ mile trips the boat has run great, however when i throttled down to an idle speed and then tried to bring it back up to cruising speed, the STBD engine would bog down at 2100 rpms to idle. (and could never get back up to cruise).

When i got to a dock, i have replaced the racors, (both engines and both clean). then on my trip home the boat would run great, and i couldnt replicate the issue if i tried.

Well the issue came back when running the boat on another 90+ mile trip. I ended up talking to the former owner and he said that the issue came up and his mechanic indicated that it was a MAP sensor issue. (not sure how they determined that but he did tell me that he replaced the fuel pump in the process of troubleshooting..ouch)

When i checked the MAP senor, the ground terminal was had a lot of rust and buildup on it. (see attached pictures) I ended up cleaning the terminals with emory cloth and some anti corrosive electrical spray. The issue has not come back since...knock on wood. My question is...does this make sense to be the issue? would cleaning up that terminal really be the solution to this issue? any help or commentary would be greatly appreciated! MAP 1.jpgMAP 2.jpgMAP 3.jpg
 
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Very possible....bad 'ground' on a sensor will cause the computer to read a voltage that doesn't represent reality....so it jumps to the wrong contour on the fuel delivery curve....only way to tell for sure is to hookup a scan tool to see what's going on.
 
Intermittent faults are always the pits. You may have nailed it from simple deduction. Knowing the history may have saved you a bunch of head scratching for sure. The previous mechanic probably just wiggled the connection and it cured the fault. When you run into a intermittent fault just do one thing at a time that way you have a good idea where to look next time. If you clean a bunch of connectors at the same time and the problem goes away you dont know which one was bad. I would just replace the map senser or have a replacement on hand if the problem returns just swap it out. use a small jewelers screwdriver and push the pins all the way in from the back side it could be the connector as well. put some dielectric grease on the connections to protect from moisture after you clean them good with electrical cleaner. pull the grounds apart and sand or wire brush them good including components that use the mount as a ground. All part of preventive maint.
 
Hi All,

I have a question on my 1997 Crusader 434XLI. I am having an issue with the STBD engine occasionally bogging down (2x per year) after a long run. Twice when heading on 40+ mile trips the boat has run great, however when i throttled down to an idle speed and then tried to bring it back up to cruising speed, the STBD engine would bog down at 2100 rpms to idle. (and could never get back up to cruise).

When i got to a dock, i have replaced the racors, (both engines and both clean). then on my trip home the boat would run great, and i couldnt replicate the issue if i tried.

Well the issue came back when running the boat on another 90+ mile trip. I ended up talking to the former owner and he said that the issue came up and his mechanic indicated that it was a MAP sensor issue. (not sure how they determined that but he did tell me that he replaced the fuel pump in the process of troubleshooting..ouch)

When i checked the MAP senor, the ground terminal was had a lot of rust and buildup on it. (see attached pictures) I ended up cleaning the terminals with emory cloth and some anti corrosive electrical spray. The issue has not come back since...knock on wood. My question is...does this make sense to be the issue? would cleaning up that terminal really be the solution to this issue? any help or commentary would be greatly appreciated! View attachment 14887View attachment 14888View attachment 14889

Knock Sensor?
 
The wiggle test will reveal alot of intermittent faults if they are wire/connector related and bending wires looking for weak spots. Sometimes a wire will corrode under the insulation and look normal until it kinks when you bend it..
 
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