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Author Topic: EFI: Lean then Rich  (Read 2138 times)

Mance

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EFI: Lean then Rich
« on: September 23, 2010, 07:36:44 PM »
Hi Fellas,

I'm a new RE owner, and this is my first post.  I'm glad to be a part of the club, and I love the bike.

I have a 2009 Military (C5 / UCE / EFI).  The bike has approximately 4300 miles on it, and I've only had a few minor problems: bad battery (twice), replaced chain at 4000 miles, and now I'm having a performance issue.

The bike misfires and backfires.   Sometimes it is REALLY bad.  I worried that I wouldn't make it to my house 2 miles away a couple of days ago.  Sometimes it doesn't happen at all.  I took an hour ride yesterday, wound out the bike and it performed perfectly.  Today it is working perfectly.

Related Notes:

1) The exhaust pipe has heavy bluing.  (Maybe the engine is running lean?)
2) I can't see a substantial difference with temperature, but the problems only started this summer, and the weather in Texas is always warm.
3) In the past couple of days, when bike has worked well, there is a strong smell of gasoline.  That is new and unusual.  Smells like it is running rich.

Here are the possibilities I can think of:

1) One of the sensors used for EFI is going bad.
2) There is a vacuum leak either in air intake or with the exhaust that gets seeled up when the engine heats up.
3) The bike just takes a while to warm up, and it is going to misfire / backfire until it does.  But that isn't normal for EFI?  Correct?  And this didn't start until around 3000 miles.

Any ideas?  What could make the system suddenly go from running lean to running rich?  Or could the symptoms be caused by something else?

Thanks

Mance

singhg5

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Re: EFI: Lean then Rich
« Reply #1 on: September 23, 2010, 08:20:05 PM »
Hi Fellas,

I'm a new RE owner, and this is my first post.  I'm glad to be a part of the club, and I love the bike.  I have a 2009 Military (C5 / UCE / EFI).  The bike has approximately 4300 miles on it, and I've only had a few minor problems: bad battery (twice), replaced chain at 4000 miles, and now I'm having a performance issue.

The bike misfires and backfires.   Sometimes it is REALLY bad.  I worried that I wouldn't make it to my house 2 miles away a couple of days ago.  Sometimes it doesn't happen at all.  
Mance:

Welcome.  The engine can backfire and misfire due to many reasons, as you have pointed out - including problems with spark, fuel/air supply, or compression.
 
Start by checking the simplest things.  Spark plug - is it worn out or ok ? Put a new spark plug and see if it improves.  The intermittent occurance suggests that there may be a loose electric connection.  Is the spark plug cable connected firmly into the spark plug and to ignition coil ?  Look for any air leaks in intake manifold.  A dirty or clogged fuel injector may also contribute to misfire or backfire.  

The bike runs lean by default.  I guess that if any EFI sensor was bad, the Malfunction Indicator Light would come on.  
« Last Edit: September 23, 2010, 08:44:52 PM by singhg5 »
1970's Jawa /  Yezdi
2006 Honda Nighthawk
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Mance

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Re: EFI: Lean then Rich
« Reply #2 on: September 23, 2010, 08:51:39 PM »
Thanks for the note.

Yes, I forgot to mention that I changed the spark plug.  Replaced with stock equivalent.  I don't have any experience looking at plugs to tell if the bike is running lean or rich, so I can't say much about how the old plug looked.

I wondered about the fuel intejector.   At its worst, it felt like the fuel line was clogged somewhere.  Almost impossible to keep the bike running.  However, a storm had just passed through, and the temp dropped 20 degrees.  No idea how / if that affects EFI on this bike.

The spark plug cable is connected firmly at the plug, but I haven't checked it at the coil.  Will do.

I'm not a mechanic, but I want to learn how to maintain this bike on my own.  Outside of visually inspecting the air intake, is there something else I should do to check for air leaks?

Mance

Mance

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Re: EFI: Lean then Rich
« Reply #3 on: September 24, 2010, 03:05:09 AM »
Whoa!! Major problem.  The reason I started the bike smells like it is burning very rich is that the fuel tank is actually leaking gas!  Near the rear bolts on the left side where there is a welded seam, gas is oozing from the tank.

I assume that something from the tank actually broke lose and made it into the gas line a few days back when the engine was running at its worst.  The performance of the engine has been great for the past two days.

I guess this calls for a trip to the dealer in the morning.

Mance

prof_stack

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Re: EFI: Lean then Rich
« Reply #4 on: September 24, 2010, 03:55:48 AM »
Whoa!! Major problem.  The reason I started the bike smells like it is burning very rich is that the fuel tank is actually leaking gas!  Near the rear bolts on the left side where there is a welded seam, gas is oozing from the tank.

I assume that something from the tank actually broke lose and made it into the gas line a few days back when the engine was running at its worst.  The performance of the engine has been great for the past two days.

I guess this calls for a trip to the dealer in the morning.
Mance

Yes, it does.  Let us know how it goes.
A Royal Enfield owner's cup is always half full.

singhg5

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Re: EFI: Lean then Rich
« Reply #5 on: September 24, 2010, 04:01:58 AM »
Thanks for the note.

Yes, I forgot to mention that I changed the spark plug.  Replaced with stock equivalent.  I don't have any experience looking at plugs to tell if the bike is running lean or rich, so I can't say much about how the old plug looked.

The electrode of too rich spark plug will turn black due to unburnt carbon deposits and too lean spark plug electrode will be whitish.

You found the leak from the tank.  Sure it is time to see the dealer.  
1970's Jawa /  Yezdi
2006 Honda Nighthawk
2009 Royal Enfield Black G5

Mance

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Re: EFI: Lean then Rich
« Reply #6 on: September 24, 2010, 04:44:10 AM »
Will do.  After doing a little more research, it looks like a few others have had problems with rust inside the tank leading to pinhole leaks.  But most of those are on older bikes. 

Rust would probably explain the sporadic misfires and poor performance of the engine, but this bike is less than a year old, so I am surprised.  I don't always keep the tank full, but I ride it daily and fill up frequently.

If it turns out to be rust in the tank (and it sure looks like a pinhole leak at the welding seam), then we can add another possible cause to the standard list of misfire / backfire / performance problems.

Mance

singhg5

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Re: EFI: Lean then Rich
« Reply #7 on: September 24, 2010, 02:49:10 PM »
Thanks for the note.
I don't have any experience looking at plugs to tell if the bike is running lean or rich, so I can't say much about how the old plug looked.

Here is a reference picture of what a spark plug looks like under different conditions -
1970's Jawa /  Yezdi
2006 Honda Nighthawk
2009 Royal Enfield Black G5

Mance

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Re: EFI: Lean then Rich
« Reply #8 on: September 24, 2010, 02:59:58 PM »
Wow.  That is a great reference.  Thanks.  It will get printed and put on the garage wall.

I took the bike to the dealer today.  He doesn't believe there is rust in the tank, but rather believes that the joint where the tank gets bolted to the chassis just isn't holding up from the vibrations.  After the tank is replaced, he plans to put some kind of dampener around the bolt.

Regarding the sporadic performance, he has heard some people speculate that the catalytic converter isn't getting hot enough on short trips.  As a result, gunk builds up and causes problems.  After I ran the bike hard for 30 minutes earlier this week, the symptoms did go away.   On average, I ride the bike only 5 minutes at a time, and the engine never really gets that hot.  So maybe it is the CC.

More to come.

Mance

Vince

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Re: EFI: Lean then Rich
« Reply #9 on: September 24, 2010, 03:42:08 PM »
     Riding the bike 5 minutes at a time is the cause of most of your issues, including the battery. It takes about 1/2 hour of normal running to recharge a normal battery from one normal starting attempt. Your riding habits run the battery down. The ignition system runs off the battery. The charging system charges the battery. Low battery=weak ignition/injection=poor running="defective battery". Even with F.I. you will not get proper burn/combustion until the engine is warm.
     You should change your riding habits. Ride more and longer.

WillW

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Re: EFI: Lean then Rich
« Reply #10 on: September 24, 2010, 04:05:12 PM »
"Ride more and longer"

music to my ears.......   :D
2010 Royal Enfield Electra (G5) DL

2004 Kawasaki W650
~ the best british bike they never made ~

1 Thump

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Re: EFI: Lean then Rich
« Reply #11 on: September 24, 2010, 04:42:00 PM »
     
     You should change your riding habits. Ride more and longer.

I like that .

1Blackwolf1

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Re: EFI: Lean then Rich
« Reply #12 on: September 24, 2010, 06:39:38 PM »
  Should also install a battery tender to keep it charged up if you can't ride it for long distances.  Cost is generally less than 30 bucks and will eliminate lots of problems.
Will Morrison
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2000 Victory V92SC
1976 Suzuki GT185 Rebuilder Special..AKA (Junkyard Dog)
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The garage is full.

prof_stack

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Re: EFI: Lean then Rich
« Reply #13 on: September 27, 2010, 04:47:14 AM »
  Should also install a battery tender to keep it charged up if you can't ride it for long distances.  Cost is generally less than 30 bucks and will eliminate lots of problems.
+1 

The Battery Tender will pay for itself after one year.  I think all new Enfields come with a connector installed.  Mine did and it is on the bike in the garage all the time.
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Geirskogul

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Re: EFI: Lean then Rich
« Reply #14 on: September 27, 2010, 08:27:26 AM »
No, the connector is a dealer special.  Mine didn't have one.
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