FUEL PUMP


Information and questions on GL1500 Goldwings (1988-2000)
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john pasterjak
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FUEL PUMP

Postby john pasterjak » Mon Dec 12, 2011 1:38 pm



Recently, after working on my carbs I was running the bike to make final adjustments ,the engine just quit for no apparent reason.
Attempts to re-start were futile. It appears that no fuel is getting to the carbs. I can squirt some starting fluid into the carbs and the bike fires right up indicating ignition. I've checked all the fuses and relays and all check OK. I pulled the pump and it runs fine when connected to 12 volt source.
Im looking for any help I can get.
I would like to provide the following information to anyone having a problem of stalling on quick acceleration or quick throttle opening.
My bike was recently purchased from a Bike Shop. They claimed it ran fine but it didn't. They took it back and said they would overhaul the carbs.
When I got the Bike back there was little or no improvement. The claimed the Bike ran fine and I claimed it didn't. It would stall if I quickly advanced the throttle. All this led a confrontation with the Shop which I wont go into at this time. I finally decided to overhaul the carbs myself.Here is what I found; The acceleration pump mounts on the side of one of the carbs and is fed fuel from the float chamber. Behind the pump is a small O-Ring where the pump makes contact with the carb. THE O-RING WAS MISSING RESULTING IN A METEL TO METAL CONTACT. This resulted in poor fuel flow to the pump and no fuel available for quick throttle movement. After repairs with a new O-Ring the bike ran much better until this new problem occurred. I hope this information helps anyone having a stalling problem upon acceleration.



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virgilmobile
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Re: FUEL PUMP

Postby virgilmobile » Mon Dec 12, 2011 2:20 pm

You and I both are going through a 1500 of this vintage and problems.
Before you delve into an electrical problem,this info MIGHT help.
1.Open up the gas cap and listen....turn on the key and listen for the pump.
2.The fuel pump appears to "cycle" for about 2 seconds when the key is first turned on and then won't run again until the engine is cranking over.
3.If the pump does not "cycle"there IS an electrical problem.
4. After the fuel filter,just in front of the gas cap,there is a vacuum operated fuel cutoff valve.Mine was leaking gas.Your's may not be operating as well.Either a bad valve or the vacuum line is off.It trapes from the left side of the valve down to a "T" connector next to the right intake manifold.
5.If the pump cycles,the cutoff valve can be "temporally" bypassed to get it going.I've posted a electric valve replacement for it.A new one(if you can find one is near $150).

6. if the pump refuses to run at all,I look into the schematic for test points....let me know.

One last question...Is your shifting lever sloppy like mine?...viewtopic.php?f=6&t=9365

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virgilmobile
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Re: FUEL PUMP

Postby virgilmobile » Mon Dec 12, 2011 2:42 pm

Here's a little more info I just dug up.


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Re: FUEL PUMP

Postby virgilmobile » Mon Dec 12, 2011 3:01 pm

Here's the best wiring I can find.

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Re: FUEL PUMP

Postby virgilmobile » Mon Dec 12, 2011 3:31 pm

This is odd...Looking at the schematic,I see that the fuel pump relay is "energized" directly from the coil....This would lead me to believe that the relay is not just a simple coil and contact type but a pulse detecting circuit that energizes the relay..hmmmmm..something special about this thing. :?: :?: :?:

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WingAdmin
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Re: FUEL PUMP

Postby WingAdmin » Mon Dec 12, 2011 6:01 pm

virgilmobile wrote:This is odd...Looking at the schematic,I see that the fuel pump relay is "energized" directly from the coil....This would lead me to believe that the relay is not just a simple coil and contact type but a pulse detecting circuit that energizes the relay..hmmmmm..something special about this thing. :?: :?: :?:


I'm looking at the same schematic. The relay coil is energized across the yellow/blue and the green wires. This means that the "carburetor control unit" (CCU) must supply +12v to both the relay and the ignition coil at the same time, on the black/white wire. The other side of the ignition coil (the yellow/blue) is then run to the ECM - and this is most likely where this wire is pulsed to ground, causing the coils to create spark.

The +12V from the CCU also powers the fuel pump itself, but only after it has been enabled by the fuel pump relay. This is a cheap and easy way to allow the ECU to enable the fuel pump without having the ECU have to handle the current of the fuel pump. Later GL1500's do away with the fuel pump relay altogether and power the fuel pump directly from the ECU.

What confuses me is that the coil of the fuel pump relay is supplied with the same pulsed power as the ignition coil. It's possible that Honda engineers didn't want to create another discrete "relay enable line" on the ECU/CCU, and that the pulsed power going to the coil is frequent enough to keep the fuel pump relay pulled in?

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virgilmobile
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Re: FUEL PUMP

Postby virgilmobile » Mon Dec 12, 2011 8:10 pm

I think the fuel relay is more than just a relay.It must have a circuit in it that responds to the ignition pulses and keeps the relay energized.

new82
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Re: FUEL PUMP

Postby new82 » Mon Dec 12, 2011 10:36 pm

WingAdmin wrote:
virgilmobile wrote:This is odd...Looking at the schematic,I see that the fuel pump relay is "energized" directly from the coil....This would lead me to believe that the relay is not just a simple coil and contact type but a pulse detecting circuit that energizes the relay..hmmmmm..something special about this thing. :?: :?: :?:


I'm looking at the same schematic. The relay coil is energized across the yellow/blue and the green wires. This means that the "carburetor control unit" (CCU) must supply +12v to both the relay and the ignition coil at the same time, on the black/white wire. The other side of the ignition coil (the yellow/blue) is then run to the ECM - and this is most likely where this wire is pulsed to ground, causing the coils to create spark.

The +12V from the CCU also powers the fuel pump itself, but only after it has been enabled by the fuel pump relay. This is a cheap and easy way to allow the ECU to enable the fuel pump without having the ECU have to handle the current of the fuel pump. Later GL1500's do away with the fuel pump relay altogether and power the fuel pump directly from the ECU.

What confuses me is that the coil of the fuel pump relay is supplied with the same pulsed power as the ignition coil. It's possible that Honda engineers didn't want to create another discrete "relay enable line" on the ECU/CCU, and that the pulsed power going to the coil is frequent enough to keep the fuel pump relay pulled in?


Hi Virgil. I don't know enough to know whether this applies to a carb'd 1500 fuel system, but the FP Relay on my 93 nissan pickup quit working after about 5 hours idling on I 59 heading to Picayune before Gustav. Both hot leads of the Relay are always on with the ignition, but the ground on the switch goes thru the ECU which I guess quit working (maybe the ECU overheated?) Anyway after swapping relays, pulling fuel pump & other unnecessary stuff, I ended up jumping relay ground so that it's always on with ignition & It's worked fine for 4 years or so .

I'm thinking maybe tying the relay to the coil pulse is to help regulate fuel pressure by tying it to engine rpm. Just a thought

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virgilmobile
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Re: FUEL PUMP

Postby virgilmobile » Tue Dec 13, 2011 8:54 am

I just can't imagine a chattering relay directly proportional to a coil firing would be a good thing for a relay,it's contacts or the pump.Especially considering the relay is tied directly across the ignition coil primary.There's somewhere near a 300 volt spike on that line.That pulse,like it's use for the tachometer,would have to trigger a circuit that operates the relay.
Pump pressure is usually regulated by a spring loaded valve or it's mechanical design.

Sorry..I do tend to rattle with random thoughts...

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virgilmobile
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Re: FUEL PUMP

Postby virgilmobile » Tue Dec 13, 2011 10:54 am

The schematic I got from here is a euro manual and the schematic for the fuel control may be different from the USA model.???
I've dug for a few hours and can't find anything else to look at. :cry:
The only info is that there is a fuel cutoff relay in the back of the bike,but I have no definite information of it's wiring,type of relay .....
Can anyone help on a fuel system schematic that may apply to the 1988 gl1500?????

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virgilmobile
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Re: FUEL PUMP

Postby virgilmobile » Tue Dec 13, 2011 11:10 am

Just found this post...http://www.goldwingfacts.com/forums/forum1/113317.html
It references that the fuel cutoff relay is operated by the ECU.

john pasterjak
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Re: FUEL PUMP

Postby john pasterjak » Tue Dec 13, 2011 6:16 pm

PROBLEM SOLVED. Thanks to the responses I received I was able to back track what I had done after I overhauled the carbs and the engine was running.
In preparing to synchronize the carbs I had disconnected the vacuum line at the right hand intake manifold,connected a vacuum gauge, and left the vacuum line hanging. This line provides vacuum to the fuel shutoff valve. With it disconnected there was no vacuum to operate the valve, thus no fuel flow.Once I reconnected the vacuum line she fired right up. (LESSON LEARNED)
Thanks to all of you who responded with your comments and suggestions. Without your help I could still be looking for the problem.

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Re: FUEL PUMP

Postby WingAdmin » Tue Dec 13, 2011 8:13 pm

I actually love it when a problem is self-inflicted - it reinforces my opinion of the reliability and longevity of these bikes. :)

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virgilmobile
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Re: FUEL PUMP

Postby virgilmobile » Wed Dec 14, 2011 8:16 am

Whew,I was getting worried there for 3 seconds that I had erroneous information that I passed on.
Or did I ??? Is the euro manual different than the USA version in some features or something critical?

Last question for John...Does your shifting lever feel a bit loose? My inquiring mind wants to know If it's a very common problem to the design or just a few bikes.

The shaft that the shift lever mounts to on mine will deflect almost 1/8" before it snugs up in the trans.It should be near 0.

john pasterjak
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Re: FUEL PUMP

Postby john pasterjak » Wed Dec 14, 2011 6:38 pm

The electrical schematic I have from a HAYNES owners work shop manual shows the fuel pump being fed directly from the ECU.
On the subject of the shift lever shaft, my bike supposedly has less than 20K miles and I have the slightest play. I have no signs of oil leakage
in this area so this may not be a problem.
JOHN

john pasterjak
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Re: FUEL PUMP

Postby john pasterjak » Wed Dec 14, 2011 6:44 pm

To WingAdmin. I agree as to the reliability of the Honda. Recently, while talking to a bike mechanic who was working on a Harley, he said the Honda was the most reliable bike he ever worked on.

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virgilmobile
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Re: FUEL PUMP

Postby virgilmobile » Wed Dec 14, 2011 7:40 pm

Can you scan and post the fuel pump schematic?Or is that a No No
I,m interested if the wiring is different from the euro version as this applies to my bike as well

Also about your shifter.Great it doesn't leak.I've been hearing about sloppy shifters and leaking on bikes with around 50 k miles.Just like mine.




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