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MerCruiser 5.0 (Carb Engine) will not turn after small fire, what is this part?

R

Robertse

New member

MerCruiser 5.0 will not start/turn due at minor quick fire. While the exhaust manifolds off the engine (for service), I started the engine and port (left) and rear side part of the engine caught on fire for a few seconds. I put the fire out quickly with a fire extinguisher. Now the engine will not turn at all (nothing at all), so I believe there is an electrical problem, the part in the photo was had prior rush and got damage further in the fire, but I don’t know what the part is called, to order a replacement. The starter motor works fine, as I connected direct power to it and it works as normal. The engine had good compression prior to the mini fire. Any help will be appreciated, what is the part called, and what else should I check. Thanks in advance.​

 

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  • Mercruise Port Side Part1.pdf
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not a clear pic butmost likely the oil pressure sender and the pressure switch for the electric fuel pump. Also looks like it was a v6 before the v8
 
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Hi All Dodge, I have replaced the Merc90 Fuse and the same problem is occurring. I also replace a small 20amp fuse behind the distributor. I connected power directory to the starter motor and it worked, but it will not work via the ignition key. I am not sure what the problem is. Any help will be appreciated
 
Need a voltmeter to find out where power is being lost.

I really need the motor serial number

Look for the slave relay


Slave Relay 89-96054T.jpg


The top post will have larger red/purple and yellow/red wires. The red/pur comes from the 50 amp breaker and the yel/red goes to the starter solenoid

Cross the top post and see if starter engages.
If it does not engage then there is a bad 50 amp breaker or needs reset, or a bad red/pur wire coming from the starter

If it does engage starter then need to test the relay.
The smaller bottom to post will have a smaller Yel/red wire and a black wire. Use a jumper wire and jump from the top Red/pur down to the smaller yel/red. This should energize the relay and starter will engage

If it does not engage then relay needs replaced

If it does engage then with a voltmeter measure voltage on the Red/pur wire and there should be 12V

Next check for 12V on the yel/red wire when key is turned to start. You should get 12V

If 12V is there check the neutral safety switch on the throttle. Turn key to start and hold key in position, now move the throttle a slight bit FWD/REV
 
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