1985 gl1200LTD


Information and questions on GL1200 Goldwings (1984-1987)
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rmc10
Posts: 7
Joined: Sun Oct 26, 2014 7:45 pm
Location: attalla alabama
Motorcycle: 1986 gl1200a1984 gl1200i

1985 gl1200LTD

Postby rmc10 » Mon Jun 01, 2015 7:19 pm



I have a 1985 gl1200LTD that boggs down when trying to take off on hill. Sometimes on startup it has smell like it is running rich. I have changed out about everything but ns sensor, and wiring harness. Has anyone with a gl1200L had this problem.



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virgilmobile
Posts: 7660
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: 1985 gl1200LTD

Postby virgilmobile » Mon Jun 01, 2015 8:19 pm

I do not own one nor ever seen one....however I have diagnosed problems with the fuel injected systems before..
You did mention that you changed out about everything....Have you actually tested any of the components for specs.?
A couple of things come to remember..The fuel injection computer control will run the bike even if there is a problem with one of the "fine tuning" sensors..It's kinda like a limp home mode..
The major things to actually put a meter on...
Fuel pressure...it must be within specs..
Throttle body control...This is like a volume control...A ground,steady 5 volts and the center varies with the throttle...very smoothly.
the 2 vacuum sensors...Same procedure...as the vacuum changes,so does the output voltage...You can simulate a vacuum and verify both have the same output with the same vacuum...These parts are used by the computer to effectively sync the left and right sides...Should one be bad,that cylinder may get more fuel than needed to run properly.
One last thing..actually two...Voltage...Verify the module is properly powered...measure at the module for volts using the module harness wires...not the battery or frame for a meter ground...Many problems can be associated with just corroded connections...The module also provides a well regulated 5 volt power to most of the sensors...don't miss this one...Just a little drop and the bike will not run well at all.
Iffin I had to guess, The 5 volt power should be well within the range of 4.8 to 5.2...steady too.
One fellow finally found his vacuum sensors had only 3.85 volts feeding them....The problem was narrowed to the plug connection at the module...
All this is assuming that the compression is above 145 psi with less than 5 psi difference...the air cleaner is clean and the exhaust isn't plugged or rusted shut.
You can pull all 4 plugs and look at how each cylinder is firing too...plugs tell a lot about a engine.

rmc10
Posts: 7
Joined: Sun Oct 26, 2014 7:45 pm
Location: attalla alabama
Motorcycle: 1986 gl1200a1984 gl1200i

Re: 1985 gl1200LTD

Postby rmc10 » Mon Jun 01, 2015 8:56 pm

Thanks for reply. I haven't metered anything for voltage yet, but I guess I should have started there. I will start checking the things you mentioned tomorrow. I've checked the fuel pressure and it was within spec. I connected another ECU unit in no change. Checked for air leaks, changed injectors,fuel pump,fuel pressure gauge no change. I will reply back as soon I check item you mentioned . Again thanks for the reply.

User avatar
virgilmobile
Posts: 7660
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: 1985 gl1200LTD

Postby virgilmobile » Mon Jun 01, 2015 9:29 pm

Fuel pressure gauge.?There is a fuel pressure regulator on the return line....With out looking at the book,I think it is adjustable...
The fuel pump is capable of developing more pressure that the injectors need..this regulator bleeds the excess to keep the pressure in tolerance.I think there is also a "rest pressure. Something like 23 psi with the key off...
Probably the easiest to do is locate the 2 vacuum sensor leads and throttle leads at the module (including the ground wire)... use a digital volt meter for accurate readings of the feed voltage and a analog meter for the varying voltage...If your DVM does not have a bar scale indicator as well as numbers...It's hard to watch for stable moving readings on a digital meter...The volts move up and down very smooth.They should never jump around...They may also not go completely from zero to 5 volts...You might see 2.8 to 4.4 volts change as a sensor operates....
This is why voltage readings are critical...just a change of 1 volt can dramatically affect the injector open pulse duration.

rmc10
Posts: 7
Joined: Sun Oct 26, 2014 7:45 pm
Location: attalla alabama
Motorcycle: 1986 gl1200a1984 gl1200i

Re: 1985 gl1200LTD

Postby rmc10 » Tue Jun 02, 2015 9:09 pm

Today I did compression test,and I had 135 to 137 on all cyclinders. I tried putting wd-40 in cyclinder and then checked cyclinder but not much improvement. also checked throttle sensor and it was within specs. I found a small secondary leak and fixed that. I think I may have found the problem but I'm going to be out of town for the next week so it will be later next week before I know for sure. I think the throttle valve is out of synchronization. I did some adj on one side and it seemed to pick up like it should. So thanks again for all the feedback, it got me started in right direction. Next thing to sync throttle valves then test ride.




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