GL1500: Looses power above 60 mph


Information and questions on GL1500 Goldwings (1988-2000)
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ronjr123
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GL1500: Looses power above 60 mph

Postby ronjr123 » Thu Aug 28, 2014 10:27 pm



I bought my 2000 SE in March with 91,000 miles. I have since rode 6000 miles this year. It has ran flawlessly until two weeks ago. Running down the highway at 70mph with cruise on or off in about two miles it will start to lose speed and power. While it does this I can hear alot of air being introduced into the carbs if I twist the throttle I have to pull off the road and come to a stop. Let it idle for a minute or two, then it is just, fine. It never stalls. If I keep my speed at 55 or below it runs fine.

I changed the spark plugs this week and no change. I read somewhere that the gas cap should vent. I dont think mine does this too well as when opening it I here some pressure being released. I checked the vent hose and ran it without the hose and even with the cap loose and no change. Could it be the fuel filter? If so, why not all the time instead of just at highway speeds? Sub air filter? Vacuum leak?

I was planning an 800 mile round trip ride this weekend, but unless it is a quick fix tomorrow morning, it will have to scrub that.



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MikeB
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Re: GL1500: Looses power above 60 mph

Postby MikeB » Thu Aug 28, 2014 11:47 pm

A fuel filter problem is a probability but most likely it is the vacuum operated fuel shut off valve located under the filler door and forward of the fuel filler cap. When it does it again, down shift to 4th and open the throttle. It will probable suck fuel past the vacuum operated fuel shot off valve and accelerate nicely. If it does that, rebuild the valve. Cyclemax sells the rebuild kits.
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ronjr123
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Re: GL1500: Looses power above 60 mph

Postby ronjr123 » Fri Aug 29, 2014 12:14 am

Thanks Mike, I will put that in my checklist. When it does occur I do downshift but it doesn't do any good until I am at idle.

Another thought. Could one of my timing belts jumped a tooth?

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MikeB
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Re: GL1500: Looses power above 60 mph

Postby MikeB » Fri Aug 29, 2014 12:18 am

Then it just may well be a clogged fuel filter.

Timing belt jumping a tooth will cause consistent runability problems I would think, not intermittent problems. Have you been making any adjustments to the timing belts or adjusters? If not, I would not suspect them as the culprit.
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Re: GL1500: Looses power above 60 mph

Postby dingdong » Fri Aug 29, 2014 7:10 am

Try loosening the gas cap and go for a test ride to see if the problem goes away. They can get clogged up.
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MikeB
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Re: GL1500: Looses power above 60 mph

Postby MikeB » Fri Aug 29, 2014 9:41 am

ronjr123 wrote:...I read somewhere that the gas cap should vent. I dont think mine does this too well as when opening it I here some pressure being released. I checked the vent hose and ran it without the hose and even with the cap loose and no change....


If you hear pressure releasing when you remove the gas cap, the cap is doing its job. You have already tried riding with the cap off so that eliminates it as a problem I would think.

ronjr123 wrote:...Could it be the fuel filter? If so, why not all the time instead of just at highway speeds? ....


At higher speeds (higher fuel demand), there is increased fuel flow. If the fuel filter is partially clogged, it will not be able to keep up with the demand.
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HawkeyeGL1200
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Re: GL1500: Looses power above 60 mph

Postby HawkeyeGL1200 » Fri Aug 29, 2014 10:28 am

Definitely sounds like it is starving for fuel. You've received excellent advice.

In order, I'd check fuel tank, fuel cut off valve, fuel filter, fuel pump.
I am wrong as often as I am right concerning what is wrong with someone else' motorcycle without having seen the machine in person. Guessing with limited information, as to the source of the trouble, is sketchy at best.

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Re: GL1500: Looses power above 60 mph

Postby WingAdmin » Fri Aug 29, 2014 1:36 pm

I agree - it's fuel starvation. At high speeds, you're using enough gas that the float bowls in the carbs are being emptied faster than they can be filled. When you pull over, it gradually fills them back up again, so your bike comes back to life. All of the suggestions here are correct. Assuming you have tested riding with your gas cap loosened, and the problem is still occurring, if you haven't changed your fuel filter in a while (or ever), I would do that one first, as it's easy and cheap: How to replace your fuel filter

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Re: GL1500: Looses power above 60 mph

Postby ronjr123 » Fri Aug 29, 2014 2:09 pm

Thank you all for your suggestions and tips. I replaced the fuel filter using the method ststed here and went for ride. That has seemed to have solved it, or atleast temporarily. I went down the interstate for over 30 miles and it didn't skip a beat. Using cruise control at a steady speed and using the throttle myself up to 90 mph. Power there all through the band now.

when buying the filter stopped by the service department and talked to the service manager. He tends to believe it is the pump. He may still may be right, with a new filter there is less of a differential pressure acoss it and a weak pump that may be enough.

Anyone know of a way to test the output? There has to be a spec out there stating what it should flow and that would be measureable.

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Re: GL1500: Looses power above 60 mph

Postby HawkeyeGL1200 » Fri Aug 29, 2014 2:32 pm

ronjr123 wrote:Thank you all for your suggestions and tips. I replaced the fuel filter using the method ststed here and went for ride. That has seemed to have solved it, or atleast temporarily. I went down the interstate for over 30 miles and it didn't skip a beat. Using cruise control at a steady speed and using the throttle myself up to 90 mph. Power there all through the band now.

when buying the filter stopped by the service department and talked to the service manager. He tends to believe it is the pump. He may still may be right, with a new filter there is less of a differential pressure acoss it and a weak pump that may be enough.

Anyone know of a way to test the output? There has to be a spec out there stating what it should flow and that would be measureable.


I would ride it and see if the performance degrades over time. I'm pretty sure that filter took care of your trouble. I do not know what the pressure and flow output for your model motorcycle's fuel pump would be, but if you rode 90 MPH and have fuel and power to spare, I sincerely doubt your pump is faulty.

Ride and enjoy.
I am wrong as often as I am right concerning what is wrong with someone else' motorcycle without having seen the machine in person. Guessing with limited information, as to the source of the trouble, is sketchy at best.

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Re: GL1500: Looses power above 60 mph

Postby ct1500 » Fri Aug 29, 2014 2:37 pm

Wrap your lips around that old filter barb and blow through in same direction as fuel would have flowed.

If there is significant resistance that was probably the problem, if not then go to petcock and fuel pump for further testing.
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Re: GL1500: Looses power above 60 mph

Postby WingAdmin » Wed Sep 03, 2014 10:56 am

ronjr123 wrote:Anyone know of a way to test the output? There has to be a spec out there stating what it should flow and that would be measureable.


Yes. Disconnect the fuel pump from the fuel filter, and put the hose from the fuel pump into a graduated beaker or cylinder. Disconnect the light blue wire from the fuel pump terminal, and apply +12 volts to that terminal for 5 seconds.

Multiply the amount in the beaker by 12 to determine the fuel pump flow capacity per minute.

Fuel Pump Minimum Flow: 640 cc (21.6 oz)/minute

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ronjr123
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Re: GL1500: Looses power above 60 mph

Postby ronjr123 » Wed Sep 03, 2014 11:05 am

Man, what don't you know about these machines?

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Re: GL1500: Looses power above 60 mph

Postby WingAdmin » Wed Sep 03, 2014 12:14 pm

ronjr123 wrote:Man, what don't you know about these machines?


Not so much what I know, just I've done it before and can remember where to find the numbers required. :)

I actually did this to pump out the fuel tank when I was working on calibrating the float-based low-fuel sensor that Virgil and I installed. I'd fill the tank, test the levels, use the fuel pump to pump it back out into a gas can, open it up, make an adjustment, fill it back up, repeat...

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Davek80514
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Re: GL1500: Looses power above 60 mph

Postby Davek80514 » Wed Sep 03, 2014 1:28 pm

dingdong wrote:Try loosening the gas cap and go for a test ride to see if the problem goes away. They can get clogged up.


When I stop to get fuel and I loosen my gas cap I get a air rushing sound. Is this normal?
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MikeB
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Re: GL1500: Looses power above 60 mph

Postby MikeB » Wed Sep 03, 2014 1:42 pm

Yes, it is normal. Nothing to worry about.


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