Power loss


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kane67
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Motorcycle: Honda GL1500-88

Power loss

Post by kane67 » Thu May 03, 2018 8:48 am



Well, got my ”power loss in heavy rain” back from last summer...

-88 wing. Carbs done 2016. Idle jets updated to 55.
Vacuum tubes replaced.

Something strange is still on with nice sunny day... speed lower than 80kmh it runs perfect, above 120kmh also.
But when speed is somewhere 80-100,it feels slowly loosing power, may have few hickups if I give more throttle. Feels powerless with light cruising throttle. If accelerate strong it runs ok but short after getting back to cruising speed... can feel it again.

Ok, what I’ve tested;
- add coil +12v relay supply modification
- replaced air and fuel filter (Honda filters)
- bypassed petcock
- removed right fan and sprayed water overall to find bad plug wire etc
- fuel pump test 150ml per 5 sec
- pilots open 2 1/2 to 3 1/4
- add fuel cleaning additive
- fuel cap

None seem to effect, what happens around 3000rpm?
Slides are not stuck, accelator pump squirts great.

What could I test next?


Last edited by kane67 on Thu May 03, 2018 10:05 am, edited 1 time in total.

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Erdeniz Umman
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Motorcycle: 2000 GL1500SE

Re: Power loss

Post by Erdeniz Umman » Thu May 03, 2018 9:17 am

You may want to watch this video to understand the system.
I suspect you have a bad, bent or collapsed vacuum line.



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kane67
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Re: Power loss

Post by kane67 » Thu May 03, 2018 11:40 am

Yes, I have this video ;)

Need to check sub airfilter and airjet valve 2&3 as they will supply air to carbs.
Of course other vacuum tubes also, but first white ones carb / fuel ratio related.

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kane67
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Re: Power loss

Post by kane67 » Sun May 06, 2018 12:37 am

I checked vacuum tubes (all tubes 2 year old)
- orange, if I remove service plug idle decrease and goes bad so that line is ok
- white, ajv2 & 3 all tubes open to carbs, subairfilter excellent condition
- blue/ red keeps vacuum (aicv)
- green looks ok
- pink looks ok
- yellow looks ok

For testing, I bypassed fuel cut relay, no change.

At the moment wing runs perfect below 80kmh, higher speeds it feels powerless like hitting a heavy wind. But if I give throttle it accelerates.
I ordered new fuel pump & strainer (Airtex e8371)

-kane

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Erdeniz Umman
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Re: Power loss

Post by Erdeniz Umman » Sun May 06, 2018 6:51 am

Kane, one more thing to check is the fuel tank cap. Its vent hole should provide enough atmospheric pressure, otherwise vacuum will occur in the tank, preventing adequate fuel flow.

You could try loosening the fuel cap and check if there is a difference in power.

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kane67
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Re: Power loss

Post by kane67 » Sun May 06, 2018 12:42 pm

Yes, I think I have done that but I could re-test that also.

Interesting is... today I took fuel pump out just to see if tank is ok and clean inside.
It was clean. When I put it back, I noticed that ground connector looks a bit bad and needs polishing. Thought pump assy is also grounded to tank by its bolts and nuts and tank is grounded...
Suprise... now it runs 90% trouble free. I drove over 60 miles test, different speeds.
Runs very nice but still when speed is up 110-120kmh, it feels there’s not enough fuel.
If I speed up slower it runs 120kmh...

I will test fuel cap, anyways it takes couple of weeks to get new fuel pump.

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kane67
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Re: Power loss

Post by kane67 » Mon May 07, 2018 11:24 pm

No change when cap open.
Btw, is there any reason to modify power supply for new pump or I just keep it oem?

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Erdeniz Umman
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Re: Power loss

Post by Erdeniz Umman » Tue May 08, 2018 3:28 am

The earlier models (88-89) have a fuel pump relay, but then this relay is not used on later models and ECU directly controls the fuel pump by a transistor internally.

This transistor has a amp rating for the oem fuel pump as you may guess, and if you will use a higher amp rated pump it may toast this transistor.

However your bike is a 88 model and you shouldn't have any problem if the oem fuel pump relay and the new fuel pump have correct amp ratings, and connections.
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kane67
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Re: Power loss

Post by kane67 » Tue May 08, 2018 7:44 am

Ok, good info... thanks!!

New pump will be Airtex e8371. I don’t know where to find oem rating, new pump amps may be estimated by 13.5V and resistance...

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AZgl1800
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Re: Power loss

Post by AZgl1800 » Tue May 08, 2018 9:34 pm

kane67 wrote:
Tue May 08, 2018 7:44 am
Ok, good info... thanks!!

New pump will be Airtex e8371. I don’t know where to find oem rating, new pump amps may be estimated by 13.5V and resistance...
The AirTex has too high a rate of flow, I advise against using that, read the 2nd post.

http://www.goldwingfacts.com/forums/2-g ... e8371.html

and here:
http://www.goldwingfacts.com/forums/2-g ... mod-3.html
~John

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kane67
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Re: Power loss

Post by kane67 » Tue May 08, 2018 11:28 pm

Wow... thanks for telling that!!

I was able to cancel my order. Found a ready kit on Ebay (Carter P72190 with tube and brass angle) so I order that.

I don’t know if it’s this one... pic looked similar...
viewtopic.php?f=9&t=42187


:D kane

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AZgl1800
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Re: Power loss

Post by AZgl1800 » Wed May 09, 2018 12:46 am

kane67 wrote:
Tue May 08, 2018 11:28 pm
Wow... thanks for telling that!!

I was able to cancel my order. Found a ready kit on Ebay (Carter P72190 with tube and brass angle) so I order that.

I don’t know if it’s this one... pic looked similar...
viewtopic.php?f=9&t=42187

:D kane
grab it, that is the same pump I used in my '98

this proved to be an AirTex: http://www.goldwingfacts.com/forums/4010530-post1.html

This is my thread, alas, Photobucket trashed all of the pictures. http://www.goldwingfacts.com/forums/10- ... ost1613038

Here is a thread that provides a lot of aftermarket numbers:

http://www.goldwingfacts.com/forums/4382617-post3.html
~John

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kane67
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Re: Power loss

Post by kane67 » Wed May 09, 2018 11:12 am

Got it :D
Shipment via customs takes about 14 days to get it here, but it’s on the way.

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kane67
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Re: Power loss

Post by kane67 » Wed May 23, 2018 12:04 pm

Update

Pump kit arrived yesterday, today was installation.

Test drive succesfull!! It runs nice to 140-150kmh without any signs of missing fuel.

Second thing is that when it rains next time, is my ”power loss in heavy rain” problem disappeared...

We’ll see...

:D kane

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AZgl1800
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Re: Power loss

Post by AZgl1800 » Wed May 23, 2018 6:04 pm

good,
maybe all is well now.
~John

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kane67
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Re: Power loss

Post by kane67 » Mon Jun 11, 2018 11:48 pm

Update II

Last week we had very very windy weather, went for a ride.
Found out that when riding against hard wind, it does the same... not enough fuel.
Drove back the same highway wind behind, no problems at all. :shock:

So, I figured it must be float level too low (I have checked it 2 years ago, 8mm / 1988 model).
I have original main jet #155 and updated #55 idle jet. I have always wondered a bit whitish spark plugs.
Well, yesterday I took carbs out, adjusted float to ~ 7.4mm (7.5mm from 89/90 =>)
Mix screws are 3 1/8 open like book says, synchronized the carbs.

Went for a test drive, medium wind, pulls strong in speeds 110-150kmh. No signs missing fuel at all.

Maybe... maybe I finally found the reason. Next I want to face heavy rain to see how it runs...

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kane67
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Re: Power loss

Post by kane67 » Fri Jun 22, 2018 5:53 am

kane67 wrote:
Mon Jun 11, 2018 11:48 pm
Maybe... maybe I finally found the reason. Next I want to face heavy rain to see how it runs...
Well, no... it was not only this.

But... :D one question here in forum a couple days ago made me think, ventilation for carbs.

Damn, I placed a tube from vent pipe to down under bike 2 years ago.

Took it off, I was just driving in heavy wind & rain for an hour and quess what... bike runs perfect without any trouble!!! Oh boy... live and learn by my own mistakes :lol:



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