1988 johnson gt150 wiring questions?

[wwcj101]

i recently bought a 88 venture tournament edition bass boat with a gt 150 on it. the tach voltmeter and fuel gauge were all inop. i read a few things, i talked to sammy sausage and ernest eeg. they all pointed me at the voltage reg. i checked the voltage with my engine running it was staying right around 14. and it also looked brand new.
so i get to looking at wiring under column and behind gauges. i find that the ground wires to all of them is getting 12v in run. i disconnect that lead from the ground bus and hook up a known good grnd. now the voltmeter works the tach drops to zero with the key on and the fuel gauge was doing some crazy jumping. i find the sig wire is tied directly to the ignition (hot in run) wire. i disconnected it. i think that i will be able to trace the correct sig wire because i can see them on the other end.
my question is what color is the tach sig wire under the dash when it comes out of the harness? or am i going about this all the wrong way? any tips suggestions or input will be greatly appreciated.

 

[etex driller]

Re: 1988 johnson gt150 wiring questions?

It will be a grey wire going to signal on back of tach also make sure tach is set on 6 p position

 

[ezeke]

Re: 1988 johnson gt150 wiring questions?

The gray wire come through the harness but is not connected to the ignition, ever. If voltage reaches your gray wire it will cook your rectifier instantly.

Careful with the fuel gauge - remember that the sender is a variable resistor sitting in the middle of your gasoline.

 

[wwcj101]

Re: 1988 johnson gt150 wiring questions?

ok thanks, when the sun gets behind the trees ill crawl back under there. the wires coming from the tank,? can the neg wire go straight to -batt. or should it go back to gauge also?

 

[ezeke]

Re: 1988 johnson gt150 wiring questions?

Teleflex wiring for the sender is typical: http://www.downloadingfiles.co.uk/teleflexfiles/gauges/Fuel Systems.pdf

If the sender is the old kind with a cork float, the float will degrade in ethanol.

 

[wwcj101]

Re: 1988 johnson gt150 wiring questions?

mercy. i ran the test for the fuel gauge and sending unit. its the sending unit. but heres whats messed up, when i flip the nav lights switch the fuel gauge jumps past full like during the test. i dont understand why. i almost want to rewire the whole thing or at least cut the wires off where the come out of harness and redo the gauges and switches. the only gray wire i found coming out of the harness went somewhere else(i think to 12v). how will i know if the rectifier is blown? the wire they had hooked to the tach was purple. looked like it didnt come out of harness. i am totally confused and irritated. are there any diagrams on the internet? i guess tomorrow i will disconnect the gray wire from the connection block on the engine and check resistance between it and the gray wire under dash prob should have done that today but just thought of it. sorry for the essay.

 

[ezeke]

Re: 1988 johnson gt150 wiring questions?

The purple wire on the tach is for positive voltage and should run to the 'A' accessories post on the ignition switch.

The gray wire should run from the terminal block on the engine to the remote and then to the tachometer 'S' connector.

You should have a water-cooled rectifier which is difficult to test. You can test the rectifier output by putting a voltmeter on the battery terminals and seeing if the voltage changes when the engine is running aroun 1000+ RPM.

The standard side mount remote control came pre-wired for the tach with a three wire plug located below the ignition key.

See: http://www.maxrules.com/graphics/omc_pics/REMCONTBOX.jpg

 

[wwcj101]

Re: 1988 johnson gt150 wiring questions?

man i appreciate that. i want to go look at it right now. but it will have to wait till tomorrow after work. thanks again.

 

[wwcj101]

Re: 1988 johnson gt150 wiring questions?

i found out what the problem was that was confusing me. the boat has 3 batts. 2 of them are in parallel. the other one was in series to the other 2. the ignition feed came from the cranking batt which was one of the parallel at 12v. there was a hot at all times feed at the console that ran the bilge and lights it was 12v except it came off the batt that was in series. all was ok except the neg of the ignition and neg of the others were tied in the same spot. but that was the only place they were hooked together. my new trolling motor is a 12v i cant think of anything else that would be 24v so i think im going to hook them up on a 12v only system.