TKS issues

[alexvelarde]

Please help!

I have a Mercruiser 5.0L (serial # 0W622338)

TKS is making a hissing noise and does not stop when engine warms up. I changed it but problem continues. I let the engine idle for 15 minutes. The temp reached 175 in about 7 minutes. I don't know what to do next.

Thank you so much for your help!

 

[Bt Doctur]

did you check for 12v at the plug

 

[alexvelarde]

I checked before I changed the TKS. I had no voltage. What do I do if I have no voltage?

 

[Bt Doctur]

On the motor is 20A fuse. Locate it and check it .Manual does not show where,just says there is one

 

[alexvelarde]

the 20A fuse is good

 

[Bt Doctur]

1. The TKS carburetor casting allows starting fuel to be drawn from the float bowl and
mixed with air in a chamber. This enriched mixture is drawn into the engine through an
opening in the carburetor body below the throttle plate.
2. The TKS module mounted to the carburetor. When 12V DC is applied, the TKS module
will warm internally, causing a plunger to extend from the module and close the
enrichment fuel air passage in the TKS carburetor.
3. On 3.0L engines, an oil pressure switchprovides a ground (-) path for the TKS module.
Positive (+) voltage is continuously supplied through a 20 amp fuse directly from the
engine circuit breaker.
4. On V-6 and V-8 engines an existing oil pressure switch provides 12V positive (+)
voltage to the TKS module. Ground for the TKS module is continuously supplied.

The voltage starts at the 20A fuse and a groubnd is supplied by the oil switch.If no 12v, start tracing it back

 

[Bt Doctur]

TESTING THE 3.0L OIL PRESSURE SWITCH
1. Disconnect oil pressure switch connector from harness.
9526
a
b
c
Oil pressure switch, 3.0L, typical. Shown disconnected for clarity.
a - Oil pressure switch
b - Connector
c - Oil pressure sender
2. Connect a continuity meter to the indicated oil pressure switch connector terminals.
Ensure good electrical connection is made.
3. With engine not running, the meter should indicate no continuity between terminal A
and terminal B, and full continuity between terminal B and terminal C.
9815
a b c
d
3.0L TKS Oil pressure switch connector terminals
a - Terminal A - Normally open
b - Terminal B - Common
c - Terminal C - Normally closed
d - Connector retainer tab
4. With the engine running and engine oil pressure above 27 kPa (4 psi) meter should
indicate full continuity between terminal A and terminal B , and no continuity between
terminal B and terminal C

 

[Bt Doctur]

Says power starts at the starter solenoid, goes thru the fuse and to the module

 

[Fun Times]

Also just in case, try testing the diode following the steps inside the bulletin, http://ww2.justanswer.com/uploads/ROCKETBOAT/2008-12-09_042450_TKS.pdf

 

[alexvelarde]

BT Doctur, do you have a pic of TESTING THE 3.0L OIL PRESSURE SWITCH

I have a V8 Mercruiser 5.0L (serial # 0W622338)

I'm trying to figure out where the switch is and how to test it. Thank you!

 

[Bt Doctur]

Oil Pressure Switch Replacement
1. Locate the oil pressure switch.
a. On the 3.0L, the switch is located on the port side of the block, on a fitting with the
oil pressure sending unit.
b. On the 4.3L, the oil pressure switch is located on the port side of the block, near
the rear of the engine.
c. On the 5.0L and 5.7L, the oil pressure switch is located near the port side of the
block, towards the rear.
2. Disconnect the connector from oil pressure switch.
3. Remove the oil pressure switch with a wrench on the hex part of the base.
4. Insert a new oil pressure switch and turn until hand tight.
5. Torque with a wrench on the hex part of the base.

 

[alexvelarde]

Thank you so much BT Doctur!

I tested the TKS Diode and I think it is broken so I ordered a new one.

Should I still test the Oil Pressure Switch? And am I able to if the Diode is not working?

 

[Fun Times]

You could ohms check the oil switch to see/test it's working condition.
With the diode possibly not working correctly then it does play a part of the 12v system to the TKS so you may get a false 12v readings at least up at the TKS Module.

 

[alexvelarde]

Hey guys! I got the boat fixed. It was the TKS diode. Originally when I first read the "Troubleshooting TKS diode" I thought the diode was the TKS heater module, so I changed that part instead of the TKS diode.

Somehow reading the manual's wiring diagram I found out the difference between the diode and the TKS module. Obviously a rookie mistake, but I learned something new and I solved the problem.

Thank you for all your feedback and help!!!. I saved a lot of money and learned some new things in the process.