2002 gl 1800 won't idle


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Slik-Rick
Posts: 1
Joined: Thu Feb 04, 2016 8:33 pm
Location: Madison Florida
Motorcycle: 2002 GL 1800

2002 gl 1800 won't idle

Post by Slik-Rick »



Working on my neighbors 02 gl 1800 his mpg went way down it won't idle has black soot on the new ngk spark plugs & it recently had a new knock sensor installed. As long as I twist the throttle at what would be just above idle it runs good & revs up quick & sounds strong just won't idle & burning a lot more fuel. Looking for ideas & the best place to start. Thanks in advance!


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virgilmobile
Posts: 9102
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
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83 GL1100 standard
84 GL 1200 I

Re: 2002 gl 1800 won't idle

Post by virgilmobile »

I know almost nothing about this bike....However because no one else has jumped in I'll speculate.
If this is multi port fuel injected,there's obviously a method to control the duration that the fuel injectors stay open.In default mode or when first started,the bike,just like a car guesses on the amount of fuel needed (called open loop or limp mode) and runs it a bit rich..Kinda like a choke adds more fuel.
It sounds like the computer may be in this mode..a cold start.
Once it starts,the computer "reads" the sensor inputs to trim the fuel properly.Adjusting for air temp,coolant temp,cylinder vacuum,etc.
I can only guess at this point but I would tend to suspect just a few things.
First...does the computer generate any error codes?
If not then a test procedure would be needed to check a few things like...
Throttle position sensor,vacuum sensors and hoses,temperature sensor,ambient air sensor,fuel pressure,O2 sensors.
I hope this may lead you somewhere.
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virgilmobile
Posts: 9102
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: 2002 gl 1800 won't idle

Post by virgilmobile »

By the way,I know that if a sensor is simply unplugged it can force the computer into limp home mode.Did that on my car.It ran but was horrible.
When the vacuum line came off the vacuum sensor on my Benz,it dropped to 10 mpg too
peppilepew
Posts: 495
Joined: Wed Jun 08, 2011 4:35 pm
Location: Hampton, New Hampshire
Motorcycle: 1985 GL1200 (Sold)
2000 Gl1500 Se (Sold)
2012 GL1800 Level 3 (Sold)

Re: 2002 gl 1800 won't idle

Post by peppilepew »

Virgil is correct

A poor running condition must be diagnosed in a linear fashion. The first step is to check the air cleaner. Has it been replaced? Check the ECM for codes. Rich running can be caused by a multitude of sensors. I would focus on the Intake Air Temp (IAT), Oxygen sensor (O2), Coolant Temp (ECT), Baro sensor and Manifold Air Pressure (MAP). Without some way the scan the ECM you are running completely blind here. Parts changing is expensive.

This guy on youtube did a great job explaining the process. You just need a piece of wire to do the same. Codes are needed to repair this condition.



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