Alarm Help/ Temp Gauge

[05StingRay]

So I bought my first boat this spring, 2005 Stingray with a 4.3L engine. Started out with a new gimbal bearing then a new water pressure sensor to quiet the alarm that would come on every couple minutes. Now we are experiencing a solid alarm at times, only trend I notice is that we are moving at a pretty steady clip when the alarm goes off. Noticed that the temp gauge does not appear to be moving, hover right over 120 on the gauge. Trying to keep the expenses to a minimum after the earlier repairs to keep my wife happy so any advice would be appreciated!

 

[alldodge]

Howdy

Do you have an engine serial number?

Guessing this is an EFI and may be a MPI motor. Constant alarms can come from
Lube oil low
Oil pressure low
water pressure
ECT engine coolant temp overheat
Over speed - ECM thinks the drive is in neutral

When you replaced the water pressure sensor did you check the grounding of the power steering cooler? Make sure its tight and there is no corrosion on the connector

 

[05StingRay]

Serial # is 0w063741, I didn't change the pressure sensor. Had a local shop do that but trying to save a few bucks if I can.

 

[Pete104]

Serial # is 0w063741, I didn't change the pressure sensor. Had a local shop do that but trying to save a few bucks if I can.

What made them go right to water pressure sensor? Any details from them as far a "diagnostic scan"?

 

[05StingRay]

Yes they did use a scanner and gave me the complete printout of the code and engine history

 

[alldodge]

The serial number list is for an MPI with 555 ECM.

Check the sensor connector and determine if the cooler is loose, as before need a good ground.

The sensor can also go off with weak water flow, which can be caused by the impeller. When was the impeller changed last?

Your seswater pump is the Gen 7 style and they have there own issues if the wear plate is not inspected for wear

 

[05StingRay]

Are you saying to check the power steering cooler? Will that set off the full alarm, just going off the earlier post of what would do it and I didn't see that listed. Not doubting just wanting to understand it all. As for the impeller, I have no idea when it was last changed. I am really thinking that could be the issue and I don't feel comfortable jumping in to that project.

 

[alldodge]

The water pressure sensor (item 16) is attached on the power steering cooler.
The water comes from the seawater pump, thru the PS cooler (item 14) and then goes to cool fuel module then the thermostat.
http://www.mercruiserparts.com/bam/subassembly/31501/11705/280

As for the impeller, it needs to be replaced every two years (IMO). some go three years. If the impeller is wearing out, it will not draw in the correct amount of water and the warning will sound off as it should.

Replacing the impeller (item 2) is not that hard, but not knowing when it was last changed that could very well be your issue
http://www.mercruiserparts.com/bam/subassembly/31501/11705/250

 

[05StingRay]

OK so I ordered a new temp sender, 806490T, went to change it this when I went to the lake and ran in to an issue. Looking to the back of the boat on the left side of the thermostat where I though should be the sender I saw the picture below. Shouldn't it be threaded on the end instead of just a push on connection?

 

[alldodge]

The sender is designed to use a eye terminal and can also be used with the push on connector as in your pic. When the push on connector is used, then nut a washer are not used.

That said, you have an alarm issue, this sensor goes to your temp gauge and the gauge has no connection to the ECM

 

[05StingRay]

I wanted to change this because the temp gauge didn't seem to be moving so I wanted to make sure it was working and see if it was an overheating alarm or try to help narrow it down a bit. Strange part is I pulled the push connector off of the original sender and then the temp gauge actually had a reading but the alarm did kick on once again. No overheating though.

 

[alldodge]

OK, sounds good.
Take the wire off the sender and touch it to ground, the meter should peg Hot