1986 johnson gt 150 speedometer hookup

[rsheffield]

I am new to this site and have a question maybe someone can help me with. A couple of months ago I purchased a 1986 Skeeter Starfire 175 with a 1986 Johnson gt 150 on it from my uncle, who bought it new in 1986. after a few times out the speedometer stopped working. when I raised the motor the plastic fitting that plugs into the lower unit had come off. I pushed it back in and ran it again. It worked for a second and quit again. when I got it home I applied low pressure air in the tube that runs to the speedometer and the needle on my speedometer worked. Can someone tell me where I can locate a schematic online of this lower unit, or give me some advice on how to fix it ? I also applied air to the lower unit side, but it seems to either be clogged or it has a check valve in it somewhere. thanks

 

[mak747]

Re: 1986 johnson gt 150 speedometer hookup

I too have an 86 Johnson GT150 and am not sure what tube that plugs into the lower unit you are referring to. I think that it must be some kind of after market spedo connection. My speedometer tube is connected to a pickup tube which is attached to the transom. Since my sonar unit includes a GPS I now use it to monitor my speed, which is a lot more accurate than the in dash one.

 

[ezeke]

Re: 1986 johnson gt 150 speedometer hookup

Some gearcases have that built in. It's just a duct that allows water pressure from forward movement to compress the air in the hose connected to the fitting. Blow out the duct and it should work.

If you cannot get it to function, you can mount a universal pitot tube and use that:

http://www.iboats.com/Pitot-Tube-Te...4296561--**********.876550459--view_id.169185

 

[rsheffield]

Re: 1986 johnson gt 150 speedometer hookup

Thanks for the advice. I will try again to blow air through the hole in the lower unit and see if I can get it unclogged. I tried once but it didn't seem to work..

 

[emdsapmgr]

Re: 1986 johnson gt 150 speedometer hookup

The lower units that have a speedo feed tend to clog up with debris. There is a small hole on the leading edge of the lower unit gets crud packed into it and it is not unusual to get plugged. Anything you run over with the boat seems to wind up in this hole. You can use a tiny drill bit and work it into the hole with your fingers. Make sure you use one smaller than the hole and do it by hand. With a delicate touch, you can unclog the pickup hole. An optional transom-mounted pitot speedo pickup tends to clog less frequently. It depends on how much room you have to mount it on your boat-many bass boats have multiple transducers which may limit where you can mount it.

 

[rtnmi]

Re: 1986 johnson gt 150 speedometer hookup

Can you send pic to ad5vj@ad5vj.com

Of where the tube plugs in that came out. The one you had to plug back into the "L".

Mine came out also from somewhere but the plastic "L" came out with the tube still attached to the "L".

It is just laying in the engine compartment with rhe tube from the speedometer gauge connected to it.

I can't figure out where the little plastic "L" plugs into.

Thanks Bob

 

[emdsapmgr]

Re: 1986 johnson gt 150 speedometer hookup

Looking at the factory exploded parts diagram for an 86 V6, I don't see the speedo fitting either. You can look one year earlier on the 85 parts list. The item you are looking for is item 1a. Thats on the gearcase parts list for an 85 V6 found on the factory website: epc.brp.com