Just thought I'd share....

[Chemdawg]

I thought I'd share my contraption here, since it might be of interest to other boaters here. I purchased an 87 arrow glass carisma 175 this last summer, and started working on fixing it up. The motor is complete, and I had rewired the electrical, but decided to redo some parts of it over the winter. I had a major catastrophe happen when I first got it. The 3.0L mercruiser overheated due to no water coming from the outdrive. Due to the overheating, it blew a head gasket. I was very fortunate that It didn't do any other damage. I now have the motor running great again, and decided to prevent this from happening again. Also, a bit more background. The mechanical fuel pump was bad, so I capped it off, and replaced it with a holley blue pump and fuel regulator. Now. With this being said, there are certain laws that must be met when using an electrical fuel pump.

So this is what I did.

I have a 6X6 metal hoffman box with a sealed door on the top so I can close it off and seal it. This is mounted in one of the compartments at the rear of the boat. Inside this there are two 12v Allen Bradley relays with multiple contacts on each. I also purchased from jegs performance an adjustable coolant temp switch, and an adjustable oil pressure switch. I also purchased a cole hersee engine alarm system.

Now when you turn the key on to the acc position, the fuel pump won't run. When you start the engine, the fuel pump will run, and the oil pressure switch will close causing the pump to latch and stay on.

Now here is the cool part. When the engine is running, if there is an issue with the oil pressure, and it drops below the preset value, it will break the relay contact which will not only shut off the fuel pump, but break the ignition and shut off the motor, and the alarm will sound, and on the dash, there is a bi color LED that will turn red warning you that there is a oil pressure problem. If the motor shuts off because of a temp issue, the same situation will happen, but the LED will turn green telling you it's a temp problem. I have BOTH sensors set at a level below the VERY bad point, so that if the motor over heats, it's not like an idiot light that comes on when it's already screwed. IT will come on when the motor gets to a point where it's too hot, but not hot enough to cause damage.

I know this might sound like overkill, but I don't want to keep rebuilding the engine for things that can be prevented. And since I already had several of the components, it was done at a pretty cheap price.

Just thought I'd share.

Pat

 

[Bondo]

Re: Just thought I'd share....

I thought I'd share my contraption here, since it might be of interest to other boaters here. I purchased an 87 arrow glass carisma 175 this last summer, and started working on fixing it up. The motor is complete, and I had rewired the electrical, but decided to redo some parts of it over the winter. I had a major catastrophe happen when I first got it. The 3.0L mercruiser overheated due to no water coming from the outdrive. Due to the overheating, it blew a head gasket. I was very fortunate that It didn't do any other damage. I now have the motor running great again, and decided to prevent this from happening again. Also, a bit more background. The mechanical fuel pump was bad, so I capped it off, and replaced it with a holley blue pump and fuel regulator. Now. With this being said, there are certain laws that must be met when using an electrical fuel pump.

So this is what I did.

I have a 6X6 metal hoffman box with a sealed door on the top so I can close it off and seal it. This is mounted in one of the compartments at the rear of the boat. Inside this there are two 12v Allen Bradley relays with multiple contacts on each. I also purchased from jegs performance an adjustable coolant temp switch, and an adjustable oil pressure switch. I also purchased a cole hersee engine alarm system.

Now when you turn the key on to the acc position, the fuel pump won't run. When you start the engine, the fuel pump will run, and the oil pressure switch will close causing the pump to latch and stay on.

Now here is the cool part. When the engine is running, if there is an issue with the oil pressure, and it drops below the preset value, it will break the relay contact which will not only shut off the fuel pump, but break the ignition and shut off the motor, and the alarm will sound, and on the dash, there is a bi color LED that will turn red warning you that there is a oil pressure problem. If the motor shuts off because of a temp issue, the same situation will happen, but the LED will turn green telling you it's a temp problem. I have BOTH sensors set at a level below the VERY bad point, so that if the motor over heats, it's not like an idiot light that comes on when it's already screwed. IT will come on when the motor gets to a point where it's too hot, but not hot enough to cause damage.

I know this might sound like overkill, but I don't want to keep rebuilding the engine for things that can be prevented. And since I already had several of the components, it was done at a pretty cheap price.

Just thought I'd share.

Pat

Ayuh,.... Come on Pat,.... This is iboats,.... without Pictures, it never happened,.... :laugh:

 

[Chemdawg]

Re: Just thought I'd share....

Here are the photos of this project. Been kinda busy lately, so no time to download them. But here they are.

 

[achris]

Re: Just thought I'd share....

....Now here is the cool part. When the engine is running, if there is an issue with the oil pressure, and it drops below the preset value, it will break the relay contact which will not only shut off the fuel pump, but break the ignition and shut off the motor, and the alarm will sound, and on the dash, there is a bi color LED that will turn red warning you that there is a oil pressure problem. If the motor shuts off because of a temp issue, the same situation will happen, but the LED will turn green telling you it's a temp problem. I have BOTH sensors set at a level below the VERY bad point, so that if the motor over heats, it's not like an idiot light that comes on when it's already screwed. IT will come on when the motor gets to a point where it's too hot, but not hot enough to cause damage.

Nice idea, but that part worries me.... A lot!!!

Have the alarm sound and the LED do its thing, but DO NOT kill the engine. Invariably these things happen at the worst possible moment, like crossing a sandbar with a 6 foot wave up your .... If my engine got hot right at that point, I'd definitely be wanting to keep it running.... Just think of the consequences of an engine quitting (and unable to be restarted because the alarm has disabled the ignition)... Doesn't bare thinking about.... :scared:

Chris.......

 

[Grandad]

Re: Just thought I'd share....

Hi Chemdawg. I've always thought about a need for a warning system for our I/O's for temp and oil pressure. I know I don't stare at my gauges while boating. I do agree with achris that this should be a warning only, perhaps a real loud annoying one that can't be ignored, but it should not kill the engine. Times such as when docking or maneuvering past another vessel in a tight place, is not a time to be entirely without motive power.

On another point, as a former electrical equipment approvals inspector, I am a little concerned with your attempt to seal your general purpose relays in a non-hazardous location enclosure. There are basically 3 ways that electrical equipment is made safe in a location where flammable vapours may be present.
One is to switch electrical energy that is low enough that it cannot produce a spark sufficient to cause ignition. Such levels are found in what is termed "intrinsically safe" circuits.
The second way is to contain arcing and sparking devices within an enclosure rated for the hazardous environment. Such enclosures are typically made of heavy cast metal that has machined mating surfaces sufficiently wide to actually cool a flame if an arc inside causes vapours within the enclosure to ignite. The enclosure has no gaskets, but has sufficient strength to withstand the pressure of an explosion while releasing flames sufficiently cooled to avoid igniting surrounding vapours such as in your bilge.
The third way is to switch relatively heavy currents without causing a spark using specially built components, such as solid state relays approved (such as by UL or CSA) for such hazardous locations.

What most people fail to recognize is that enclosures used in hazardous locations are not designed to seal out vapours. They are designed to stop flame spread from an internal explosion. The enclosure you have selected is designed to seal out moisture, not fuel vapours and it certainly will not contain an explosion. I suggest you consider substituting your general purpose relays with solid state relays such as a quick search brought me to here www.automationdirect.com/static/specs/ssclass8relays.pdf
You'll need to scroll down to find the appropriate hazardous location relay. Such relays may be expensive. As an alternative, you could locate the relays outside of any area where hazardous vapours can accumulate. Sorry to rain on your parade, but I thought you should be aware. - Grandad

 

[tazrig]

Re: Just thought I'd share....

Nice idea, but that part worries me.... A lot!!!

Have the alarm sound and the LED do its thing, but DO NOT kill the engine. Invariably these things happen at the worst possible moment, like crossing a sandbar with a 6 foot wave up your .... If my engine got hot right at that point, I'd definitely be wanting to keep it running.... Just think of the consequences of an engine quitting (and unable to be restarted because the alarm has disabled the ignition)... Doesn't bare thinking about.... :scared:

Chris.......

+1^^^ Even the new mercs with all their granny like safeguards will only drop the motor into idle but not kill it.

 

[bruceb58]

Re: Just thought I'd share....

Nice idea, but that part worries me.... A lot!!!

Have the alarm sound and the LED do its thing, but DO NOT kill the engine. Invariably these things happen at the worst possible moment, like crossing a sandbar with a 6 foot wave up your .... If my engine got hot right at that point, I'd definitely be wanting to keep it running.... Just think of the consequences of an engine quitting (and unable to be restarted because the alarm has disabled the ignition)... Doesn't bare thinking about.... :scared:

Chris.......

Totally agree. If that was the best way to do it, the OEMs would be doing it and they don't.

 

[Chemdawg]

Re: Just thought I'd share....

Here in Wisconsin, I only fish and boat on the inland lakes like long lake, etc... I agree, that it could happen at the worse possible time. I'm going to modify the system so that the shutdown feature can be disabled. However, I also don't want to rebuild my motor because of something like a bad thermostat, or an oil pump that went bad. Just seems like something that can be totally preventable.

And I would like to think that the reason the OEM's don't do it is cause the idiot light is a perfect way to make money. By the time an idiot light comes on, it's almost too late. You can figure on repairing.

But I do think that the feedback given here is something I need to think about, and I will take into consideration. I like the ideas.

Thanks to all.