85 LTD Issue


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Saskrider
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Motorcycle: 1985 GL1200 LTD, 1982 CB900C,1984 XL350R, 1977 CB750

85 LTD Issue

Postby Saskrider » Mon Aug 01, 2016 6:31 pm



Hey all,
I've been a long time owner/collector of many vintage Honda's which I ride regularly and daily, however I've recently taken the step up and become a Goldwing owner! I picked myself up a 1985 GL1200 LTD in great shape. The other day I ran into a small issue on it and I'm hoping one of you LTD/SEi guru's may be able to help me out. My issue takes about 1 hour of riding to develop and once it develops it can be replicated fairly consistently. Here's what's happening:

In situation where I'm riding on a flat stretch of road and the engine is running in such a way where the bike is not accelerating nor decelerating and it held at a perfect speed (particularly at 60-70kph, yes I'm Canadian) the engine will cut out very similar to if it it running out of fuel. If you accelerate it pulls fine, no problem under deceleration, however it will develop once you start to roll from a stop unless you keep the RPM's above 1500-2000 range. If the engine speed isn't dramatically increased and I ride the clutch it will cut out and cause a stall. No fuel system lights come on, nor are there any lights displayed on the ECU when it's occurring. Fuel filter doesn't seem to have any abnormal obstruction, fuel pressure remains constant at around 30psi while the problem occurs, spark plug burn looks good, compression is good, fresh fuel, air filter is clean, tested nearly every sensor on it as per the supplement manual and everything seems within spec. The problem doesn't seem to exist above 90 KPH just around town and sometimes just a little bit of hesitation after changing gears and accelerating. To me it doesn't seem like a spark or ignition issue because there is no backfire from unburned fuel on a missed stroke, it just acts like there's not enough fuel getting to it. Does anyone have any ideas on what I might be missing or where to go from here? In the mean time, waiting on a new fuel filter to eliminate it for sure...


Last edited by Saskrider on Mon Aug 01, 2016 8:36 pm, edited 1 time in total.

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virgilmobile
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Re: 85 LTD Issue

Postby virgilmobile » Mon Aug 01, 2016 7:16 pm

I'm gonna read this over a few times to get an analysis of your problem.
Be back in a few
For clarity...This problem does not occur at all until the bike is warmed up,the hour time?

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Saskrider
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Re: 85 LTD Issue

Postby Saskrider » Mon Aug 01, 2016 7:33 pm

No it starts up cold and runs great until about an hour into riding. Doesn't seem to be directly temperature related, happens at 4 bars or 6 bars on the coolant gauge, doesn't seem to matter. If it stalls it fires right back up, no loss of spark as would be expected with the common pulse generator issues and not at a consistent enough point of throttle to convince me it's a tps.

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Rednaxs60
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Re: 85 LTD Issue

Postby Rednaxs60 » Mon Aug 01, 2016 10:18 pm

There are only three things necessary to keep the bike going - air/spark/fuel. Air does not seem to be an issue. Fuel may be an issue. I take it you have done the pressure test as per the supplement to get the 30 PSI number. The next is the spark.

The wiring on these bikes have many takeoffs and one wire may service several items reducing spark to the items at the end of the run. Check the voltage at the coil from the kill switch. Coils like to be as close to battery voltage as possible. It has been mentioned that there can be up to a 2 volt drop at the coils themselves. I ran a new wire from an accessory fuse block I installed that is switched so it turns off by key or kill switch.

Have you checked the Ns sensor (crankshaft sensor)?

To check the TPS (don't think it is this) you can splice in some wire taps to the wires to do the checks. Did this on my LTD so I can keep an eye on the system.

The coils could be going bad, but not gone completely - you did mention that it happens when at operating temp. They are in a very challenging spot if you have to change them out.

Just a first go at possibilities.

Cheers
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

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virgilmobile
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Re: 85 LTD Issue

Postby virgilmobile » Tue Aug 02, 2016 7:23 am

OK...I'm about done...Keep in mind that I do not have one of these but I do have a solid understanding of the system functions....
First....this is a standard simple control system.
The bike is in a open loop mode or limp mode
Until the engine reaches a specific temperature and then all the sensors are read by the computer for "fine tuning"the fuel delivery.
This does not include the throttle position sensor.
2 things come to mind that you can easily monitor.
First is the power needed to operate the computer.It must stay above 12.5 volts.
Second applies to the sensors....Each sensor is supplied with a precisely regulated 5 volt supply from the computer.
This can be seen at the(any) sensor plug.
It should never vary more than 0.2 volts from 5 volt.
If it drops to even 4 volts,all the sensors will send the wrong signals to the computer.
I have seen this voltage change and the cause was a poor connection at the computer.Just a pull and plug back cured it.
Check each volt points when it's acting up.
Here some schematics that may help.
TPS power feed 5 volts on the (P) wire.do not unplug it while run testing.
12 volts minimum feeding the module on the white wire.
Do sub the relay and tend to the sub fuse.Its a old fuse and they tend to hairline crack.

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Saskrider
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Re: 85 LTD Issue

Postby Saskrider » Wed Aug 03, 2016 9:42 pm

Thanks for the replies, much appreciated! Coils look good, I've checked the voltages to the TPS and it looks good, I let it run for awhile in the garage (currently raining) and monitored it through different rpm ranges and saw a very minimal supply fluctuation, however upon further inspection I did find the tps was out of range at idle at .570 vdc instead of the .475-.495 the sup manuals says. I adjusted it to .480 vdc and reset the idle stop screw, synced the throttle bodies and reset the idle and it smoothed everything out real nice and the roll off idle seems much smoother and more responsive, also the extreme rich fuel smell is now gone at cold startup. Just waiting on the rain to stop here so i can take it for a spin and see if these adjustments make any difference at all.

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virgilmobile
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Re: 85 LTD Issue

Postby virgilmobile » Thu Aug 04, 2016 7:52 am

Good catch...keep us informed please.

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Re: 85 LTD Issue

Postby Saskrider » Fri Aug 05, 2016 4:17 pm

Was able to go for a ride yesterday evening although shorter than I would have liked I was still able to get some worthwhile feedback from the bike. The hesitation has dramatically decreased while cruising, had a couple little hiccups when held at exactly 73kph in 4th gear. After riding on rural roads steady at the 60-70 kph range that was giving me problems before for about 40 minutes, I ducked back into the city and the problem now developed really bad when getting going from a stop and after the shifts from 1st to 2nd and 2nd to 3rd. First will start to roll and usually once the clutch is fully engaged the bike will start to lurch just like it's out of fuel or you dropped the clutch at a very low rpm before it stalls. Every now and again if you are at idle and you 'blip' the throttle it will have a slight hesitation just off idle but not consistently. I'm going to start troubleshooting the vacuum system more in depth and see if anything turns up. Could it be a clutch issue? Once heated up has anyone ever had problems with a slave dropping the pressure too fast and dumping the clutch? That is almost what it feels like now. Tomorrow I will ride until the problem develops around town and then see if it affects that midrange speed as it did before.

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Re: 85 LTD Issue

Postby Rusty Bike » Sat Aug 06, 2016 10:50 am

Thanks for the replies, much appreciated! Coils look good, I've checked the voltages to the TPS and it looks good, I let it run for awhile in the garage (currently raining) and monitored it through different rpm ranges and saw a very minimal supply fluctuation, however upon further inspection I did find the tps was out of range at idle at .570 vdc instead of the .475-.495 the sup manuals says. I adjusted it to .480 vdc and reset the idle stop screw, synced the throttle bodies and reset the idle and it smoothed everything out real nice and the roll off idle seems much smoother and more responsive, also the extreme rich fuel smell is now gone at cold startup. Just waiting on the rain to stop here so i can take it for a spin and see if these adjustments make any difference at all.

I have an SEi, could we talk about this some more? Where is the TPS located and where do we check the voltages. Is this supply V or output V we are looking at. Where do we set this voltage. I do know my way around a tool box and have the OEM manuals but I don't know my way around this bike yet. Been working on mechanical issues so far. Thanks...Rusty

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virgilmobile
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Re: 85 LTD Issue

Postby virgilmobile » Sat Aug 06, 2016 11:23 am

I don't own one but I can help a bit.The TPS is the throttle position sensor.As I recall it has 3 wires attached.One is 5 volts from the module..one is common and the third is the feedback to the module.At a idle,the feedback voltage is specified and adjusted by rotating the TPS unit where it mounts.As soon as the throttle is opened,that voltage should increase.This increase in voltage increases the time the injectors stay open.
TPS units have been known to be erratic.The voltage must be smooth in its changes.I do recommend using a analog volt meter to watch it.The feed voltage must also be stable at 5 volts DC plus or minus 0.25 volts max deviation.

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Saskrider
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Re: 85 LTD Issue

Postby Saskrider » Sat Aug 06, 2016 11:44 am

The TPS is smooth throughout the range, but I may have had a breakthrough last night and again this morning to get me headed in the right direction. Last night I was able to get the bike to replicate the symptoms so I came back to the house, ripped the false tank off and checked the pb's, the crank sensor and ohmed the coils. Everything was good on the meter, so I replaced plugs (had dpr7's so I replaced with dpr8's for a little cooler heat range) and went for a ride. At first it ran like it had, then got better, then went back to running like junk. Went back to the house and put a spark gap tester on it and #4 was fairly irratic, so I figured I had found my problem. This morning I tried to replicate the irratic spark but has so far been unable to. But heres what I need everyone's brains for; if I have the bike idleing, I can unplug the spark plug leads one at a time and it will continue to run on 3 cylinders. Until I get to #3 and 4. If I unplug #4 it will drop to 3 cylinders and then drop to 2, and then hit on 3 fairly irratically with no real pattern. If I unplug #3 it will drop to 2 cylinders with no change. Voltage on the spark unit transistors is as follows at idle:
White-> green = 9.6
Yellow-> green= 11.3
Bl/w-> green = 12.1
Battery voltage =13

Readings are the same on both transistors. I believe I've narrowed it down to an ignition issue.

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Re: 85 LTD Issue

Postby Saskrider » Wed Aug 24, 2016 9:29 pm

UPDATE: Over the last week or so I have been around in circles with this bike. I've been making progress but in need of some opinions again! So far I've found: cam sensor gaps out of adjustment, loose right hand timing belt, replaced both coils (one was weak) and new plugs wires and caps, reset & checked tps, pb sensors, air valve & intake temp sensor. The bike is now running 3 times better, however now I am left with one single problem. The bike will get into a state where just off idle it will develop a hesitation/miss. This hesitation becomes repeatable if you 'blip' the throttle very minimally at idle in neutral and will eventually just die and start right back up after, or if you hold the bike in any gear at 2500 RPM for a short period of time and roll into the throttle very slowly (most noticeable in 1st, 2nd and 3rd gear but can be felt in 4th and OD as well). This will continue under the same circumstances for a period of time and then disappear, and the recur with no pattern or warning. I have a video of the problem at idle and doing my best to upload it so you can see exactly what I'm talking about. Any ideas in the mean time?

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virgilmobile
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Re: 85 LTD Issue

Postby virgilmobile » Wed Aug 24, 2016 10:03 pm

Have you done a fuel pressure test?
I don't remember the number however if the fuel pump is worn a bit,it may be maxed out on delivery.You might have a momentary drop in pressure resulting in a bit of fuel delivery loss.
I'd suggest testing the fuel pump pressure and flow rate to see if it's up to snuff.
I also have read that if the pump is OK, increasing the fuel rail pressure a few pounds (5psi) may be enough to overcome a bit of lag.
There's a adjustment on the pressure regulator..it's the part that restricts fuel bleeding back to the tank.

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Saskrider
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Re: 85 LTD Issue

Postby Saskrider » Thu Aug 25, 2016 12:20 am

Thanks virgilmobile. I forgot to mention I have checked the fuel pump and flow rate (out of the filter) and I get a little more than what the sup manual specs and the rail pressure is within spec as well. I had taped a gauge to the handlebars when I was having more severe issues earlier and it never showed much of a change under those conditions, however like you say it could be just enough to throw everything off. I will try increasing the pressure slightly tomorrow and see what results I get. The hesitation comes at a very small ammount of throttle off idle so I'm not 100% it's a delivery issue but it's worth a shot!

Here's a link to the video of the bike at idle. keep an eye on the throttle inputs for an idea of where the hesitation occurs. Idle is set a little high.



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Re: 85 LTD Issue

Postby tbeiler » Thu Aug 25, 2016 8:36 pm

Hey Saskrider, have you cleaned and synchronized the throttle valves. Clymer manual pages 172 and 173, show how to clean throttle valves and then synchronize them.
From the manual, "when the fuel injection throttle valves are properly synchronized the engine will warm up faster and there will be an improvement in throttle response, performance and mileage."
Procedure is much like carburetor synchronization.
I just did the synchro to my carbed 86, and the throttle response is definitely improved, but will also be doing the throttle valve cleaning and synchro on my 85 LTD, which is this winters project. It might just cure that little blip I heard in the video.

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Re: 85 LTD Issue

Postby Saskrider » Fri Aug 26, 2016 9:11 pm

Hi tbeiler,
I've reset the sync after every adjustment I have made, they were off to start with and I was able to get them very close by 'cleaning' the throttle plates with carb clean while running. The sync has stayed the same throughout. Yesterday I took it out (fairly warm outside) and the problem developed faster than it has yet and smelled extremely rich. While idling on the driveway at temperature I noticed a lot of moisture being expelled out the right hand exhaust pipe. I have yet to check the coolant temp sensor so that is next on my list as well checking all connections throughout the bike and on to injectors after that. Something is causing it to run rich, noticeable at idle it does have a little bit of a stutter that sound more of incomplete combustion more than a miss.

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Re: 85 LTD Issue

Postby Saskrider » Mon Sep 19, 2016 9:00 pm

Hey guys,
Been awhile since I've given an update but I have been gaining ground on my LTD. My problems were getting consistently worse until I was able to replicate the problem consistently at a certain throttle input. This led me to take the chance to replace the TPS (which had already been modded to an aftermarket unit) even though my meter reading weren't showing any problems, so a quick run to the local auto parts store and $60 and about 10 minutes later I figured I had my problems solved, was even able to take it on a 160km trouble-free cruise! A couple days later I threw the wife on the back and we headed out on some back roads for some further tests and I've now got the exact opposite problem I had before. Initially I had a low speed/low end hesitation/stumble. Now I'm getting a symptom very similar to running out of gas only once I'm up around 95-110 kph. It's completely random, I've tried but cannot MAKE the stutter happen, it just happens on it own, no relation to engine load, road conditions (bumps etc), uphill/downhill or anything. It's defiantly not as severe as the low end problem was, just enough to feel the tranny backlash slap. Plug burn looks almost perfect, coils/caps/plugs are brand new and have great spark, stator charges ~14.2V, so I'm now to the point where I'm thinking it could be an injector issue OR an issue with the computer firing the injectors. I've gone through the whole harness and turned up nothing for bad connections etc. Any Ideas? I am waiting on a new fuel filter (the current one seems clean and haven't had any sediment come out of it yet while cleaning), coolant temp sensor tests fine, any ideas about a gear shift sensor possibly? I do have trouble finding neutral on a consistent basis.




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