1985 V4 90 Hp tach question

[Billythepokerkid]

First outboard, I just need to know what kind of tach I need to buy for this motor or if I can just use whatever. That's it, thanks!

 

[emdsapmgr]

Re: 1985 V4 90 Hp tach question

You'll need a marine type tach. These tachs count the pulses from the charging system on the engine. They work in most all marine applications. The instuctions will have you set the pointer on the back of the tach to the 6 setting for your OMC engine. Teleflex makes numerous cost-competitive tachs available a most marine dealerships.

 

[SparkieBoat]

Re: 1985 V4 90 Hp tach question

any marine outboard tach will do..set it to 6P. you probably have a tach connector on the bottom rear of your controls, just below the key switch, it usually has a rubber cap over it that you just pull off. here is a link to the harness.
http://www.iboats.com/J-E-Outboard-...arine/dm/view_id.72638?cm_mmc=Google+Shopping
If you want to save $$ on the harness you can make your own and just connect inside the controls, the gray wire is your tach sensor wire, red is 12V and black is ground. you can use the 12v and ground from your other gauges (if you have them) or from any source close by, you mainly need the gray wire to tach.

 

[Billythepokerkid]

Re: 1985 V4 90 Hp tach question

In this wiring harness is there also a connection for any other gauge like temp?

 

[emdsapmgr]

Re: 1985 V4 90 Hp tach question

Your engine has no sensor(s) to drive a temp gauge. The overheat warning system on that engine works off two switches, one in each head. Once one/both of the heads heat up to 212 degrees, the switch/sender adevices sets the horn off in the control box. These switches only perform on/off functions. You will need to invest in a temp gauge and compatible sender, then install it on the powerhead yourself.

 

[Billythepokerkid]

Re: 1985 V4 90 Hp tach question

I think the horns have been disconnected on my engine, that's why I was looking into a temp gauge.

 

[emdsapmgr]

Re: 1985 V4 90 Hp tach question

You may want to get the original overheat warning system fixed. It's actually a simple system. It has a temp switch each head. Since that engine has two thermostats, one in each head, the factory overheat system will warn if one head (or the other) is overheating. If you put an aftermarket temp sensor and gauge on the engine, it will only detect the temps on that single point/location. (usually on one head.) How about the other head? You won't know if it is overheating unless you put a second sensor and a switch to toggle the gauge from one head to the other. With this type setup you always run the risk of not noticing an overheat on one side of the powerhead.

 

[Billythepokerkid]

Re: 1985 V4 90 Hp tach question

I hear ya. I am looking at the wiring diagram and trying to find out if I can fix the factory system, the previous owner removed the VRO so it appears he just simply cut the power to the horn.