MerCruiser 470 / 170 hp - Gauge Help

[pierpark]

I bought a boat with a MerCruiser 470 in it, and I am in the process of getting all the gauges wired up.

My volts gauge is working, and the RPM's only work when it's "cranking". I'm pretty sure they worked the other day just fine, but I don't know what might have happened.

What I need:

Can someone post a picture or describe where to put the wire from the tach gauge on the engine?

A picture for the temperature gauge and oil pressure gauge wires (where does it go on the engine)...

All my gauges have power (no lights apparently), but most just don't "work". Someone wired this boat in the most jacked up way possible. Colors on wires at one end are different from the other end.... If it goes into a harness, you just can't tell what wire is what, so I'm hoping to get these answers and re-wire it myself.

Thanks a lot!

 

[pierpark]

Re: MerCruiser 470 / 170 hp - Gauge Help

I've located the oil pressure sensor....

I definitely need to know where the engine temperature connection is though.

Thanks again.

 

[fabrimacator21]

Re: MerCruiser 470 / 170 hp - Gauge Help

No clue on that motor but my omc/chevy 305 has the temp sensor right at where the water hoses connect to the intake manifold.

It should be fairly obvious what/where your water temp sensor is. It should have 2 wires coming off of it. Just look for something that is in your engine's water. My guess is it's on the intake manifold.


What year is this thing?

As for the tach... you shouldn't see any sort of rpms while cranking.... mine just pegs itselft at 0 until it fires.

How many wires do you have on your tach? Got a pic?

You should have power (hook up to any wire with 12v when the key is "ON") , ground (hook up to any ground), light (wire it into any of your gauges' "light" wires) and signal which should go to the negative side of the coil. Keep in mind that I'm going off my 305 chevy so that merc may be a little different. You may have to hook the signal wire up to the dizzy if you don't have a "points" style dizzy.

Make sure all those are hooked up right. If it still won't read then I'd suggest opening up your tach and looking for anything obvious I.E. loose/burnt connections.

If it still won't read it's time for a new tach. Sunpro tachs are only 35 bucks new at autozone. I run a 35 dollar sunpro tach and it works great.

 

[Bondo]

Re: MerCruiser 470 / 170 hp - Gauge Help

Can someone post a picture or describe where to put the wire from the tach gauge on the engine?

Ayuh,... There should be a shop manual, complete with wiring diagrams, up in the Adults Only section of this forum...

 

[ErieRon]

Re: MerCruiser 470 / 170 hp - Gauge Help

I bought a boat with a MerCruiser 470 in it, and I am in the process of getting all the gauges wired up.

My volts gauge is working, and the RPM's only work when it's "cranking". I'm pretty sure they worked the other day just fine, but I don't know what might have happened.

What I need:

Can someone post a picture or describe where to put the wire from the tach gauge on the engine?

A picture for the temperature gauge and oil pressure gauge wires (where does it go on the engine)...

All my gauges have power (no lights apparently), but most just don't "work". Someone wired this boat in the most jacked up way possible. Colors on wires at one end are different from the other end.... If it goes into a harness, you just can't tell what wire is what, so I'm hoping to get these answers and re-wire it myself.

Thanks a lot!

Pierpark;

Manual #3 is probably the one you need to download. Post your serial number, engine & drive so we can be sure. Here's the link: http://www.myotherdrive.com/dyn/pv/318.450722.23072009.53414.6a64fi/cover.pdf

There are two wire color codes in that era, so you really need to look at the manual in the wiring diagrams section and instrumentation section.

Typically, on that engine there is a gray wire that goes to the negative (-) side of the coil. It is pin (2) in the connector and terminates at the tach's "sender" terminal.

Temp sender is under the front of the exhaust manifold (see pic) , behind the dip stick tube. It usually has a tan wire on it which terminates at the temp gauge sender terminal It is pin (3) in the connector.

Hope this helps. Post your S.N.'s so everyone's on the same page.

 

[pierpark]

Re: MerCruiser 470 / 170 hp - Gauge Help

Serial number is A494755 guys...

I ran a wire directly from the negative side of the coil to the RPM gauge and now it works fine. So I'm going to clip off the bad wire and make a note with a piece of tape that it is the old wire. These things are ran so bad in here otherwise I'd just remove it, but whoever did this stuff before was an idiot.

I found the temp. sensor under the dip stick, as shown in the picture, so I appreciate it. I'm going to try to find that wire as well and see if I can get a reading.

A manual would be great... that's for sure.

 

[ErieRon]

Re: MerCruiser 470 / 170 hp - Gauge Help

Serial number is A494755 guys...

I ran a wire directly from the negative side of the coil to the RPM gauge and now it works fine. So I'm going to clip off the bad wire and make a note with a piece of tape that it is the old wire. These things are ran so bad in here otherwise I'd just remove it, but whoever did this stuff before was an idiot.

I found the temp. sensor under the dip stick, as shown in the picture, so I appreciate it. I'm going to try to find that wire as well and see if I can get a reading.

A manual would be great... that's for sure.

The manual I put in my previous post is a free, down-loadable factory service manual for your engine...knock yourself out. It will enlighten you eventually , it's a huge file..

Glad you're making progress.

Your serial number doesn't sound right. Look on the starboard side of the block, just aft of the fuel pump for a metal tag attached to the block, or right on the valve cover.

 

[stonyloam]

Re: MerCruiser 470 / 170 hp - Gauge Help

I definitely need to know where the engine temperature connection is though.

Thanks again.

Should be underneath the front of the exhaust manifold. see: http://www.mercruiserparts.com/Show...r=70&bdesc=EXHAUST+MANIFOLD+AND+EXHAUST+ELBOW #10. Welcome to the wonderful world of 470's.

 

[gettin'even]

Re: MerCruiser 470 / 170 hp - Gauge Help

Should be underneath the front of the exhaust manifold. see: http://www.mercruiserparts.com/Show...r=70&bdesc=EXHAUST+MANIFOLD+AND+EXHAUST+ELBOW #10. Welcome to the wonderful world of 470's.

Misery loves company............LOL!

 

[ErieRon]

Re: MerCruiser 470 / 170 hp - Gauge Help

I found the temp. sensor under the dip stick, as shown in the picture, so I appreciate it. I'm going to try to find that wire as well and see if I can get a reading.

A manual would be great... that's for sure.

Anyone even read the full post any more before replying ?

 

[pierpark]

Re: MerCruiser 470 / 170 hp - Gauge Help

I might have made a mistake in saying 470. On the top of the engine it shows "170" and shows the spark plug specs, serial number, etc. And that's what I put. I will look again if I made a mistake.

I'm having another problem. My fuel gauge wasn't working because the sender in the tank didn't have a ground wire running to it as well as the main wire.

When I connected the ground and turn the key, the needle jumps to half a tank. When I manually moved the float arm, it goes from half a tank, to full tank when I move the arm to the full position. When it's at "empty" position it shows half.

Any ideas on this?

Also, is there any way to test the temp. sender to see if it works, or if it's the gauge? The test light shows power to the wire on both ends when I have the key on, but when I start the engine and let it run for about 30 seconds, I'm still not seeing a reading. There are letters on the back of the gauges like S, B, L or I, and G.... Can someone give me the full meaning of these letters and where this temp gauge wire should be going, just to make sure?

Thanks a lot.

 

[ErieRon]

Re: MerCruiser 470 / 170 hp - Gauge Help

Pierpark;

Honestly, did you download the manual yet? It's all in there plain as day. If you PM me with your email address I'll send you the section on testing all of those gauges. But, do yourself a favor and download the full manual.

BTW; The 170 is the same as the 470 for the most part...just a newer version. Having said that, if your serial number started with an "OA" it is probably correct.

Lastly, for that engine you need manual #8

Here's the link: http://www.4shared.com/account/file/121929231/58a54283/MercruiserManual8.html

 

[pierpark]

Re: MerCruiser 470 / 170 hp - Gauge Help

I did download the manual. I even bought a multimeter to check the sender a few minutes ago.

The manual said to check it against 240/30 for empty and full. Well, I'm getting about 36ish and 216ish every time I check. I hooked it back up and when I turned the key, the fuel gauge jumps to half a tank from the E position, and as I rotate the arm, it will climb appropriately to the full position.

I'm downloading this other manual you linked me to now. I appreciate that.

 

[ErieRon]

Re: MerCruiser 470 / 170 hp - Gauge Help

I did download the manual. I even bought a multimeter to check the sender a few minutes ago.

The manual said to check it against 240/30 for empty and full. Well, I'm getting about 36ish and 216ish every time I check. I hooked it back up and when I turned the key, the fuel gauge jumps to half a tank from the E position, and as I rotate the arm, it will climb appropriately to the full position.

I'm downloading this other manual you linked me to now. I appreciate that.

Glad you got the manual and are using it. Manual #8 gives that spec as 30-300 ohm (+/-) 5 ohms...if I read it right.

Did you do the first check of the individual gauge where you jump it directly from the battery, and then jump the two terminals? And, is you battery fully charged? Since you bought a new multimeter (very good move BTW) check your battery's voltage.

If the gauge passes the test mentioned above, then it's the fuel capsule.

 

[pierpark]

Re: MerCruiser 470 / 170 hp - Gauge Help

Battery is new. Fully charged.

I jumped the gauge from S to G like it said and it shows a reading of "full", and it showed the reading of "empty" the other way, by removing jumper "S".

The sending unit reads around 36 / 217ish I think is what I said. Maybe the difference between 217 and 300 would be the reason why it reads halfway on EMPTY, and all the way full on full.

 

[pierpark]

Re: MerCruiser 470 / 170 hp - Gauge Help

Guys I'm showing the new manual #8 shows the same. 30 + 5ohms (what does the + 5 mean?) and 240 + 5 ohms. I'm reading around 36ish and 217ish.

Thanks for all the help. I have never done this stuff before so it's definitely a learning experience.

I managed to re-wire and fix all the gauge lights last night, get the tach working. Volts gauge works, tach works, but fuel gauge is being wacko. I have yet to test the oil pressure sender, but now that I have the multimeter I can do that. Temp gauge also does not work, but I am unsure on how to test that as of now. I will check the manual but I don't think it can be tested if its anything like the water temp.

 

[ErieRon]

Re: MerCruiser 470 / 170 hp - Gauge Help

That sounds like the problem to me. The manual was pretty clear that if it wasn't within that spec. it was time to replace it. I replaced mine a few years ago and it was no big deal. You could always pull it out and take it to a dealer and have them check it just to be sure.

 

[pierpark]

Re: MerCruiser 470 / 170 hp - Gauge Help

Don't ask me why, but I gave it a real good ground and sanded the cables AGAIN, and it works perfectly now... It's really time to replace all these things, but I was hoping to get it in the water before having to spend 150 on a net set of gauges and all that. If I can keep get and KEEP these things working the way they are, I should probably just wait it out until they stop before trying to replace. But I won't know what I'm going to do until I can see if the temp gauge and oil pressure gauges work. They are all getting power, but I haven't been able to test the temp or oil yet. I am going to peek at the manual again to see how to test them and try to go that route now.

Thanks again.

 

[ErieRon]

Re: MerCruiser 470 / 170 hp - Gauge Help

Don't ask me why, but I gave it a real good ground and sanded the cables AGAIN, and it works perfectly now...

Cool ! You will come to learn that good grounds and fully charged batteries are critical in the marine environment. A lot of problems are solved by simply doing what you did.

The manual is your friend...

Check what you can and take her for a spin. Let us know what happens.

Good luck.

 

[pierpark]

Re: MerCruiser 470 / 170 hp - Gauge Help

I think I have done this right, according to the manual.... regarding the Oil Pressure Sender.

I tried to put the positive connection on my ohms meter to the front of the sender terminal, and the negative to the back (by the bolt) to get a reading.... Absolutely nothing happened, so I removed the sending unit and tried again. Still nothing.

Does that mean I need to replace it if nothing was read from it? Or did I just do it wrong?