85 120 - 5 pin connector - what does it do?

[tal]

There's a little 5 pin round water tight connector that runs into the main wiring harness bulkhead at the cowl right around the area where the fuel line comes in.

In that plug there is a light blue/white that seems to be making a bad connection. Is it possible, that any of these wires in the round plug could cause the engine to cut out/idle funny if there isn't a good connection? Reason being, when engine is turned a certain way it would affect the way the motor runs.

It's not the big red plug, but it looks like this:
I think some of them go to power tilt/trim?


^^
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[tashasdaddy]

Re: 85 120 - 5 pin connector - what does it do?

sounds like the trim and tilt harness. red power, green up/down, blue up/down, black and white is for tilt guage.

 

[tal]

Re: 85 120 - 5 pin connector - what does it do?

Ok, that's what I was thinking.

Odd though, when I turn the motor to the right it seems to change the way the engine will run. It's not pinching the fuel line so I checked electrical and that's what I found. I don't suppose it's possible this would change idle characteristics if it wasn't plugged in all the way?

I had it around 800rpms, bumping rough almost like a miss, turned the engine so I could see down the carbs and it idled up to about 1200-1400rpms and stayed there nice and smooth. I then shut it down, found the plug, started back up and moved around the engine and nothing changed. It stayed idling smooth. All of this is on the muffs of course.

Is there anything you can think of that will change the idle/running characteristics of the motor when it's turned? I seemed to recall it doing it on the lake the last time I had it out too. Running underway it would hesitate or try to cut out when turned back and forth.

 

[tashasdaddy]

Re: 85 120 - 5 pin connector - what does it do?

excess stress on main wiring harness,

 

[tal]

Re: 85 120 - 5 pin connector - what does it do?

Makes sense, but harness isn't tight and has enough slack to move back and forth.

 

[mhg]

Re: 85 120 - 5 pin connector - what does it do?

could be the throttle cable is being pulled when you turn the engine
pull the cowling off and watch the cables as you move the steering from lock to lock
also check the main harness for, the big red plug, may be a bad wire in that area and the wires in there can affect the idle.
Mike

 

[tal]

Re: 85 120 - 5 pin connector - what does it do?

I'm certain the throttle cables are not pulling. I will check the big red tomorrow and post back.

 

[Haffiman]

Re: 85 120 - 5 pin connector - what does it do?

The only things that may change the idling the way you described are:
A dropped cylinder all of a sudden starts working again.
(Check ignition connections, do a comp test)
Timing gets advanced from cables (throttle cable/wire harness) pulling on the throttle lever.
(check for cable tension and routing)

 

[tal]

Re: 85 120 - 5 pin connector - what does it do?

I didn't get a chance to check the red plug yesterday but I'll try to today. What exactly would a bad wire look like here? Missing insulation or bent pin not making contact? I'll also check all my ignition connections up top too. FYI, it has a brand new powerpack and I cleaned all the ground tabs on the coils over the weekend.

The last time I did a compression I thought I had 125psi across the board, but I checked this sunday and it was:
135 125
135 125

 

[tal]

Re: 85 120 - 5 pin connector - what does it do?

I unplugged the big red plug and visually inspected the pins and wires going into each end. All of them look to be in good condition.

I did not check any of the other connections up top yet, but I'm sure they're all making good contact and I recently replaced the powerpack so everything is tight. I will re-check this stuff when I get a chance again.

When I first started to work on this motor I found a red wire behind the tilt/trim box mounted on the block. I didn't like the way it looked with the inline connector so I removed it and soldered it together, coated with liquid tape, and wrapped with regular electric tape. I wonder if this wire is causing an issue? For some reason my manual doesn't list the 85 120 with tilt/trim, only without, so I'm sort of left scratching my head in the electrical area.

 

[tal]

Re: 85 120 - 5 pin connector - what does it do?

Figured I'd throw in an update. I cranked up the motor last night, in a make shift tank this time, so I can hear what's going on better. I could not get the motor to do what it was doing before by steering left & right and wiggling on wires. I think I might have a coil dropping off intermittently, but one thing I did last weekend was unbolt them and wire wheel all the ground tabs because some looked a little corroded.

The only bad thing about running it in the old trough I have is I can't trim the motor all the way down. I noticed with the engine tilted up and steering side to side the rpm would change a little but judging by the increase in smoke, it is doing this because fuel level in the carb is changing with the engine tilted up. This I'm not really worried about because the engine will never be tilted that high unless I'm in really shallow water.

So for now I don't have an idle issue, it's running perfectly smooth even when I turn the steering. Not sure what I did to make it stop though. Perhaps I can get some lake time in this weekend and see what happens.

 

[reelfishin]

Re: 85 120 - 5 pin connector - what does it do?

All of those V4 motors in that era could have had power tilt/trim. The power unit just bolts in place, it could have been original or simply added by someone along the way.
The power tilt/trim unit is the same from the three cylinder to the 6 cylinder motors.
Since they power tilt/trim on these motors is separate, it really can't affect the idle, unless you have a short in one of the wires which is creating a substantial draw on the charging system, but even at that the change would be most likely too minor to hear.
To have a 400 rpm change just by turning the steering, it would have to be pretty obvious. Did the engine miss as if dropping a cylinder before it revved up?
Keep in mind also that the exhaust note will often sound different as the motor turns, it may well have been just a matter of the exhaust sounding louder to you while in the boat?
(When I run my one boat on the muffs, it's parked between a hedge row and the garage, the motor is super quite while in the boat, but if I turn the steering toward the left, the exhaust gets louder since it's now bouncing off the garage wall).

 

[tal]

Re: 85 120 - 5 pin connector - what does it do?

Thanks for the info. I can't get the rpms to drop again by turning the steering. I want to lake test it to see if it happens while underway.

I'm sure it was actually changing the rpms because I was watched the tach race up when I turned the outboard. Again, this was on the hose with it tilted all the way down in running position. I cleaned the coil grounding tabs, wiggled around on wires and it hasn't done it since, so maybe I got lucky with a cylinder dropping off with a coil. I have done the timing light test in the past and it was getting spark on all cylinders even while running rough. I've read a weak coil could still cause this condition. Maybe once the coil reaches a certain temp the rough idle will come back? I'll continue to diagnose if it happens again.

One thing I'm certain of is it is not the carburetors. I've been through them 5 times now after putting in new kits and everything is spot on. Wires run through idle/intermediate jets, float is set, high speed jet is clean, pickup tubes clean, etc. If I get some lake time this weekend I'll post back my status. Thanks for the thoughts.