GL1200 Dies under load


Information and questions on GL1200 Goldwings (1984-1987)
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trenaud
Posts: 10
Joined: Thu May 21, 2015 1:07 pm
Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

GL1200 Dies under load

Postby trenaud » Mon Aug 08, 2016 11:09 am



Hi Folks,
My 1987 Aspy has suddenly developed an engine power problem. I've had it less than a year and the only problems so far were all electrical (charging system). I have not done the timing belts yet, that's supposed to be next, but I don't think that's related. I have no garage at the moment and it's summer in Phoenix so I'm hoping for a quick, cheap, obvious solution (switch was off stupid).
Here it is:
After sitting for a couple of weeks it was uncharacteristically difficult to start, but once going it warmed up and idled normally. I topped off the tank nearby and when I got back on the street and accelerated, it acted like I just hit the kill switch. When I backed off the throttle it ran fine as usual. I can drive it (I don't) and it runs okay, and will even gain RPMs if I go easy on the throttle, but as I throttle up it starts to run like crap as if it's choking out then dies. If I keep the throttle open it will come back to life, kind of, run like crap for a few seconds and dies again, small backfires out the exhaust, smell of gas. If I back off it's back to normal and delivers appropriate power. It feels vacuum related, like no spark under load.
I haven 't had much time to check things. I did check flow to and from the fuel filter, engine off. I was going to blame the fuel pump but the gas smell seems to indicate air or fire as the culprit rather than fuel. The problem came on suddenly
Vacuum advance messing with the timing? Sun baking a fuel line causing vapor lock? Weak fuel pump? Weak coil(s) / pulse generators? Some kind of system I didn't learn about in shop class? Any advice would be appreciated!



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virgilmobile
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Re: GL1200 Dies under load

Postby virgilmobile » Mon Aug 08, 2016 3:26 pm

Backfire and smell of gas....Unburnt fuel....Spark problem??...Forget about the vacuum possibility...
Look for low voltage feeding the ignition system....Possibly bad continuity through the kill switch.
What's the battery volts when running??...The ignition system doesn't like to operate well below 10.5 volts.
Measure the volts at the black/white wire at the ignition module

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ct1500
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Re: GL1200 Dies under load

Postby ct1500 » Mon Aug 08, 2016 3:29 pm

You have a fuel delivery issue, check pump, lines, filter and petcock if equipped. If it was getting too much fuel it would run a bit better when throttle opened. ;)
Last edited by ct1500 on Mon Aug 08, 2016 6:23 pm, edited 1 time in total.
This is what I do
Local and need repair help with your 1500, Valkyrie or ST please PM

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trenaud
Posts: 10
Joined: Thu May 21, 2015 1:07 pm
Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

Re: GL1200 Dies under load

Postby trenaud » Mon Aug 08, 2016 6:23 pm

I definitely hadn't ruled out low ignition system voltage but figured it would run like crap at all loads.
This bike has an EC harness modification that's driven me nuts in the past before I knew it was there. I had a shorted cell that would blow the EC charging fuse and leave me stranded with a dead battery 100 miles out in the desert. I've since replaced the battery and hooked up a cheap DVM across the battery and velcro'd it onto the faring for piece of mind.
I'm getting 13.6 at idle to about 14.8 cruising, between the Batt+ and the frame. From what I gather, the EC harness supplies power to the coils directly from the battery, through a 10A fuse, when a relay is energized from a switched source up near the Reg/Rect.
I won't be able to get the seat and 'tank' off until the weekend. But I can measure the voltage at this fuse tonight. That should get me close to what potential the coils are seeing. Could be this relay has developed some carbon on the contacts and the voltage is different than what I'm seeing at Batt+. The behavior is similar to whan the battery would die, only now it runs again when I get off the throttle like there was never a problem.

I did give it a light sponge bath since the last ride and thought water may have leaked past the centerline split in the false tank, but I'd think after 5 days in 110 degrees that wouldn't be an issue anymore.

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trenaud
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Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

Re: GL1200 Dies under load

Postby trenaud » Mon Aug 08, 2016 7:31 pm

[img]
vacuum%20line.jpg
[/img]
Stopped off at home for lunch and decided to check to see if I had an obviously disconnected vacuum line to think about back at work.
I don't know if this is related, but I'm sure it does't seem right. The vacuum hose in the picture seemed very loose at the end I couldn't see. I wiggled it off the carb and sure enough the whole hose dropped into my hand. The other (upper) end was not connected to anything and was plugged solid with dirt right up to the end. It obviously hasn't been hooked up to anything recently. I checked the other side, same thing. I don't know if this affected my problem. But I cleaned the dirt out anyway. I'm assuming it's not factory-installed dirt, and this isn't an auxillary dirt intake. I've seen references to an auxillary air intake, but still it seems to me that vacuum lines are supposed to connect to something. On both ends. Right?
Where are these lines supposed to go?
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Rusty Bike
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Re: GL1200 Dies under load

Postby Rusty Bike » Mon Aug 08, 2016 8:44 pm

auxiliary dirt intake... :lol: We have bugs around these parts that will pack dirt in a hole. They load up my electrical outlets in the basement with light brown dirt. No doubt the hoses are not correct and may be causing problems. Anyhoo, your problem sounds like a plugged up air cleaner to me. Maybe a critter did some construction work in you air box??

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virgilmobile
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84 GL 1200 I

Re: GL1200 Dies under load

Postby virgilmobile » Mon Aug 08, 2016 9:52 pm

The relay...easy to check...look at the volts feeding the ignition module..The 10 amp fuse should be from the battery and give battery volt readings..not necessarly what voltage the ignition is getting...
The mod was intended specifically to improve power to the ignition system...any failure in the mod,eg bad relay,can cause a poor spark.
Measure the volts at the ignition module between the black/white power wire and the green ground.....Do not use the frame or battery post as your meter ground please...(We) want to verify that the ignition module is actually being provided with the proper volts...Grounds do get bad and can upset the computer...
If all this check OK..watch the carb slides for proper movement. ...All stuck down?

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landisr
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1994 GL1500A

Re: GL1200 Dies under load

Postby landisr » Tue Aug 09, 2016 10:25 am

Two questions:

1) Sorry, but I have to ask... did you by chance accidentally fill up with diesel?

2) What part of Phoenix? I'm in Gilbert.

Ron in AZ
Beam me up, Scotty. There's no intelligent life down here.

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trenaud
Posts: 10
Joined: Thu May 21, 2015 1:07 pm
Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

Re: GL1200 Dies under load

Postby trenaud » Tue Aug 09, 2016 10:57 am

I'm in Avondale until I find a house. Just moved back after 5 years in Alaska.
Definitely not diesel, but that's an easy mistake to make. I remember hitting the 91 Octane button.
That would also make it run like crap all the time. At half throttle and below it runs great. I'm going to follow up with virgilmobile's suggestion regarding the voltage to the coils, although the EC harness is supposed to eliminate that as a possibility unless the extra relay has bad contacts. If I'm pulling the seat and tank it won't be until the weekend, and I'll replace the fuel filter & check the air filter then. Too hot to touch. I'm still thinking no or bad vacuum signal to the ECM. The vacuum lines on this model are as crazy as the electrical system and I've already found 2 plugged with dirt that go nowhere and AZ is tough on rubber.
I guess one way to test the theory would be to see if there's still a problem in 4th and 5th gear, where timing advance is handled differently.

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virgilmobile
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Previously owned
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83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: GL1200 Dies under load

Postby virgilmobile » Tue Aug 09, 2016 11:28 am

I'm going to very politely tell you to forget about the vacuum advance being the problem.
Vacuum advance doesn't come into play until the engine hits 1700 rpm and then it just starts to change the timing.The vacuum line comes from before the throttle plate so there is NO vacuum at a idle.
The vacuum line does have a "T" connection with a test port that should have a plug in it.
My suggestion is to first check for proper volts before you get sidetracked to other areas.
A process of elimination.
Spark,fuel,comperssion... Obviously one is OK.

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leakyroof58
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Re: GL1200 Dies under load

Postby leakyroof58 » Sat Aug 13, 2016 4:51 pm

No spark under load.....had a truck like this once. Ford F-150.
Same symptoms, but then I didn't demand a lot of acceleration
from it (usually). Then one day I tried to pass someone....choke,
cough, same as you describe. Pulled the plugs - they hadn't been
out in a long while - gap was at least 1/8" !!!! No wonder. New plugs
cured all.
Also had an old '85 chev, same symptoms. Turns out the cat converter
fell apart and was blocking the exhaust from getting out the tailpipe.
Maybe one of your mufflers fell apart internally ????

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trenaud
Posts: 10
Joined: Thu May 21, 2015 1:07 pm
Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

Re: GL1200 Dies under load

Postby trenaud » Mon Aug 15, 2016 10:02 am

I'm going to follow Virgil's path as soon as I get the chance to pull the seat and the shelter. He hasn't led me wrong yet. The way that EC harness works there may be a voltage drop between the battery and what shows up at the PGs due do a bad relay. Enough spark to run, not enough to fire a heavy gas mixture. Same effect as too big a gap, could be easy fix.
Could be a litter of feral kittens in the air box.
It's frustrating that the only time I have is when it's dark or 110 degrees - no garage :(
...when my 30 year old bike doesn't run right, none of my friends have garages either.

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twocams
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Re: GL1200 Dies under load

Postby twocams » Mon Aug 15, 2016 10:31 am

I just had a new shop built. Have a 12,000 btu AC coming for it . If not enough cooling I buy another.
So bring your bike up to Oregon...I share my shop.


twocams

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trenaud
Posts: 10
Joined: Thu May 21, 2015 1:07 pm
Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

Re: GL1200 Dies under load

Postby trenaud » Mon Aug 15, 2016 11:25 am

I appreciate that! Im, if I could ride out to Oregon I probably wouldn't need it :)
At this point I wish I had a back yard.

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trenaud
Posts: 10
Joined: Thu May 21, 2015 1:07 pm
Location: phoenix, az
Motorcycle: 1987 GL1200A Aspencade
previous:
1979 CB750K Ltd
1978 CB750K
1975 400F Super Sport
1976 XL100
1975 XR75

Re: GL1200 Dies under load

Postby trenaud » Tue Aug 30, 2016 12:45 pm

I'm grateful to everyone who helped me think through this, wanted to let you all know what the answer was. Fuel, Air, Compression, Fire. Of the 4 Virgil was right thinking weak spark, but the voltage at the Ignition Module was okay but I did improve the ground connection.
Even though I'd only lightly washed it before our trip it seems when one of those flipping spark plug drain holes gets plugged, capillary action draws water right into the boot, which itself is soaking in a deep puddle. This whole mess stays wet. For days. Even in the desert. It gives a path to ground, not a good one, but it weakens the spark enough prevent ignition when I'd really crank the throttle.
Either that or acceleration made the water slosh just to that right spot ...I don't believe that one.

So, I could have fixed the thing with a guitar string and salvaged a long-planned weekend ride...
I missed the experience of 3 days of this on a fully loaded wing with the wife on the back.

Again, thanks to all you guys! It helps to have someone to think with.
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