Excessive Fuel Consumption 87 GL1200

3326 Views 22 Replies 17 Participants Last post by Bike...and Dennis, Aug 7, 2009

yamtz750

Discussion Starter · Jun 15, 2009

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I'm working on a 1987 GL1200 Aspencade. The owner reports that the engine consumes about 6 gallons of gas to travel about 50 miles. Even idling, fuel consumption is ridiculous. Surprisingly, the exhaust is normal like. There's no black smoking indicative of overly rich air-fuel mixture.

The carbs have been thoroughly cleaned. All components inside carbs are confirmed OEM correct. Float heights and fuel service levels are at factory specs. Synchronization spot-on with Carbtune Pro gauges. Colortune indicates lean air-fuel mixtures on all cylinders (white combustion).

New air filter element, no air intake obstructions. No evidence of fuel in crankcase oil, in airbox, or leaking. Cylinder compression within service limits.

The appearance of the spark plugs indicate a dry, sooty black powder on one plug. Normal coloration on the other plugs. The plugs are new NGK DPR8EA9's gapped at 0.032"

I've swapped out the CDI/ECM with a new unit with same results. New timing belts installed. Belt timing re-checked- ok. Problems present prior to, and after new belt installation.

Tires and tire pressures in good condition and adjusted. Brakes are not dragging.

Any opinion on the causes, solutions, or tests to perform would be welcomed.

Respectfully,

Ohio Goldwinger

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1 - 20 of 23 Posts

terry_208

· #2 · Jun 15, 2009

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WELCOME to the forum! I can't help with the problem. Someone should be a long to help in a few minutes. One comment, please understand I don't wand to sound critical but I believe that '87s were 1200s. Eleven hundreds were in early 80s ('80-82?).

sandiegobrass

· #3 · Jun 15, 2009

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5 gallons in an hour is a leak... can't burn that much...

If you can't see it on the floor, The only thing that I can think of is that one of the cylinders is pumping grossly rich (like a main jet has fallen out) and the bike is really running on 3 cylinders..

(or reading GS's answer about leaking it at the fuel pump.. that sounds good too)

GSMacLean

· #4 · Jun 15, 2009

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I don't know if there is emissions crap on that bike, but is it possible it's sucking unburned fuel directly into the exhaust? That's the only reason I can think of for it to not show up as ridiculously rich on the plugs. That, or there is a pinhole leak AFTER the fuel pump, so that it is vaporizing the fuel into the air when the bike is running, leaving no evidence of a leak.

Those are my only guesses.

Perhaps the previous owner installed afterburners in the tailpipes?

yamtz750

Discussion Starter · #5 · Jun 15, 2009

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Right... my bad. It's a GL1200.

Good idea, GS. I wish I had access to an oxy sensor.

There's no evidence of any leaking; no fuel stains, no wet spots, no dripping. Have a blue arc at all spark plugs, however the arc is minute.

SETHAN12

· #6 · Jun 15, 2009

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Welcome from the state of Pennsylvania!

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SETHAN12

· #7 · Jun 15, 2009

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Welcome from the state of Pennsylvania!

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rcmatt007

· #8 · Jun 15, 2009

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my guess is it is those afterburners they put on the 87's.... 0-60 in about 2 seconds

gotta be some sort of leak, but wow you gotta smell that

wda-83wing

· #9 · Jun 15, 2009

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if no leak in the tank---got to be pumping it out some where. 6 gallon in 50 miles ---whewwwww

ChasW

· #10 · Jun 15, 2009

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Is it possible someone is stealing it?

William_86

· #11 · Jun 15, 2009

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how about using another fuel pump

zimmerleemark

· #12 · Jun 16, 2009

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ChasW wrote:

Is it possible someone is stealing it?

that would be my guess. way to much for a leak not to be noticed somewhere

mark:waving:

got any kids with mimibikes or go carts?:cheeky1:

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GSMacLean

· #13 · Jun 16, 2009

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Hey, have you checked the oil? It's possible it could be leaking into the crankcase, in which case you're going to have some very thin oil.

yamtz750

Discussion Starter · #14 · Jun 16, 2009

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Oil level is ok. Oil is thick as usual with no odor of gasoline.

Dang after-burners buggering up a otherwise very nice GL.

I appreciate all the thoughts. Please keep them coming.

Mike Toon

· #15 · Jun 16, 2009

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To be getting 8.3 mpg it has to run like crap, bring tears to your eyes and be down on power.

951Indy

· #16 · Jun 16, 2009

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Have you personally verified this rate of consumption? I'd top it off, ride it for 30 miles, and refill....something smells fishy. Sounds like a locking gas cap could possibly bring his MPG into the low 40s!

muaymendez1

· #17 · Jun 16, 2009

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You may be dumping raw fuel into one of the cyls as said before. On hot pipes you may not even notice any smoke. I parked my bike for a week with the petcock on and the crankcase was full of fuel. I also had alot drain out of the mufflers when started.
I corrected that problem but didnt realized the fuel in cranckase for over 3 days of riding. I just found it ierd that I had less fuel than I remember parking it with,
Check your oil, removed the intake runners and look for any fuel sitting on the valves.

chris in va

· #18 · Jun 16, 2009

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One of my float levels was off and caused a very rich condition and misfire, but even then the bike got about 35mpg on winding back roads in VA.

"The carbs have been thoroughly cleaned. All components inside carbs are confirmed OEM correct"

But see, in my mind that doesn't mean anything. It can be 'OEM correct' but the bike is 22 years old and those original parts may be junk. Mine certainly were. At least on the 83, there are over 70 rubber pieces to replace when doing an overhaul.

Jsalpha2

· #19 · Jun 16, 2009

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There has to be an explanation.
Reminds me of the guy who took his Wing to the shop to get a new water pump. After getting the bike back he noticed he was getting 70MPG. He was so happy until he found out that the mechanic had wanted to test ride the bike, noticed it was on E, and added a gallon or so.

yamtz750

Discussion Starter · #20 · Aug 4, 2009

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UPDATE:

Turns out that one of the ignition coils was defective, spark plugs possibly not arcing under compression.

The coil primary and secondary winding resistance metered within service limits. Continuity through HT leads, and caps all spec'd out.

My ColorTune indicated a white (lean) combustion with the bad coil cylinders. Could not tune the A/F mix back to optimum.

Installed used coils and the fuel economy returned to normal. Engine runs well.

Thanks to all who replied with ideas and suggestions.

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