Rpm gauge hook up on 318 F25 ?

[gordd]

http://www.youtube.com/watch?v=vs8XVPHUskc
http://www.youtube.com/watch?v=dOubTug4 ... e=youtu.be

So finnaly got boat started with water running thru system. Considering it sat for years runs well, only one small leak at exhaust manifold by water pump but overall happy with progress.

http://www.youtube.com/watch?v=1_HZfmhi8nw

Does anyone know where the Rpm tach is hooked up to on engine of F25 318 , coil ? celinoied or somewhere else . Its a yellow wire and was lose .. traced it to Rpm gauge which doesnt work for obvious reasons , but unsure where it hooks up?

[prowlersfish]

The tach wire goes to the - side of the coil ( dist side)

[gordd]

Ty prowlersfish . I wasnt sure and didnt want to hook it and and burn up something ..

[gordd]

It bit short for there but will add on.. I have wiring diagram but it doesnt show that one

[prowlersfish]

Make sure thats the tach feed wire , my book shows a gray wire at the coil . ( could be a different color at the tach )

You said you traced it to the tach ? Better doulble check it .

[The Dog House]

Congratulations on your progress! Considering not that long ago the engine wouldn't even run, having the engine running with water coming out the exhaust and the propeller spinning must really make you happy. Just don't spin the propeller for too long at a time since there isn't any water to cool the shaft packing when the boat is sitting on a trailer.

Regarding the tachometer wire, the tachometer should have three wires connected to it. The three wires are ignition (12V), ground, and signal. The OEM wiring scheme for Trojan was yellow for ignition, white for ground, and yellow for the tachometer signal. I don't know why they used yellow for both the ignition and signal wires, but they did. Hope that helps.

[The Dog House]

It looks like the wire coming out of my wiring harness for the tachometer is red and connected to the distributor side of the coil (see picture above). I can tell by the connector on the red wire that it is not OEM. A previous owner must have replaced the wire some time in the boat's history.

[prowlersfish]

I was showing gray for the tach signal at the coil and one diagram show the wire being red at the tach and yellow for the power wire at the tach '

Gray is the standard for most marine tachs merc and omc anyway But I have learned never trust the color on these older boats .Some times i believe if they run short they grab whats on the shelf On my diesels gray is the tach signal wire by that is not OEM Trojan wiring on them engines LOL .


Your photo shows the yellow going to the resistor

Got to love this old wiring stuff

[larryeddington]

Trojan 318 Engine Wiring Harness Color Code
Colores are SAE and BIA Standard Legend for harness Plug Female Side
Color Circuit

Purple Ignition
Light Blue Oil Pressure
White Starter
Grey Neg on Coil for Tach
Tan Water Temperature
Black Ground
Red Battery
Pink Aux fuel, buzzer etc

This came from a Chrysler tag connected to the engine wiring harness near the 8 prong plug connector. The tach signal wire goes to minus side of coil and is grey according to Chrysler, at least at the engine harness.

Hope this helps.

[gordd]

Congratulations on your progress! Considering not that long ago the engine wouldn't even run, having the engine running with water coming out the exhaust and the propeller spinning must really make you happy. Just don't spin the propeller for too long at a time since there isn't any water to cool the shaft packing when the boat is sitting on a trailer.

Regarding the tachometer wire, the tachometer should have three wires connected to it. The three wires are ignition (12V), ground, and signal. The OEM wiring scheme for Trojan was yellow for ignition, white for ground, and yellow for the tachometer signal. I don't know why they used yellow for both the ignition and signal wires, but they did. Hope that helps.

Ty TheDogHouse .. yes very happy with progress and big step forward .. Knowing engine runs and runs well I can move on with other projects that have been on back burner . I will take better picture of wiring in morning when get to boat and post it

Your photo shows the yellow going to the resistor

Got to love this old wiring stuff

Lo @ got to love this old wiring stuff prowlerwish . If you seen the mess behind the tach gauges oyy wayy .. will take pics and show you lol

This came from a Chrysler tag connected to the engine wiring harness near the 8 prong plug connector. The tach signal wire goes to minus side of coil and is grey according to Chrysler, at least at the engine harness.

Ty larry : I will take a look see if I have a tag . Think I will have to trace wire one at a time as over time different owners have been adding stuff and splicing into original set up or changing it ,after I take a power washer to engine and bilge compartment. Back end of engine by gear box , starter so on has growth everywhere . Have a feeling it was filled up with water at one point so time to clean that stuff up

[larryeddington]

Tag is most likely gone, is a cardboard tag, but was still on mine from factory.

[Commissionpoint]

Make sure thats the tach feed wire , my book shows a gray wire at the coil . ( could be a different color at the tach )

You said you traced it to the tach ? Better doulble check it .

+1

Make a new connection with the proper wire and pull the old one from the harness if you can.

[gordd]

+1

Make a new connection with the proper wire and pull the old one from the harness if you can.

I may just do that .. maybe even change few other wires .
Its the yellow wire sticking up with electrical tape on it for now

[gordd]

Tag is most likely gone, is a cardboard tag, but was still on mine from factory.

It is gone yes but your color codes look right for that motor

[The Dog House]

If you can determine continuity of the wire you may not need to run a new one. You'll probably have to use an extension wire with alligator clips to get the engine wire and tachometer wire close enough to use a multi-meter to determine continuity. If you can determine that the wire at the engine is the same wire that is connected to the tachometer, it may be as simple as connecting the yellow wire at your engine to the distributor side of the coil.