Question about 2003 Harley Davidson FLSTFI Fat Boy

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05 fatboy fuel carb, problem, black foul on plugs black smoke when reved

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  • 38 Answers

Poor plug or poor timing advance

Posted on Jul 31, 2013


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Posted on Jan 02, 2017


SOURCE: my 2004 springer is running rough put new plugs in

Hi ,
Your bikes engine is running too rich !! , you will have to set the air-fuel mixture ratio.
Try to check the air filter it may be too dusty and kinda clogged thus not allowing air to go in.
If all is ok thn you may have to clean the carbs and reset the float in the carbs.

Knight.(YamahaSeca XJ 750 A 1981)

Posted on Mar 01, 2009

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SOURCE: location of the fuel filter

fuel filter is located in the fuel tank at the end of the fuel pump

Posted on Jul 10, 2009

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Why does vvti engine SMOKING HEAVILY 135000kms .1.6 verso. is this common?

if its black smoke then its a fuel problem too much fuel the car can`t burn it . could be fuel injector over fueling. if its white smoke then its burning coolant, there is a head gasket problem that is damaged in the cyl #3 area. it could also be a bad valve guide/valve seal, oil rings, compression rings. you don`t say what colour the smoke is.

Aug 17, 2014 | 2006 Toyota Corolla Verso

1 Answer

91 psortster 1200 runs ruff and fuel spitting out of carb. Black exhaust smoke.

Hi Anonymous, and the usual suspects are:
1. Spark plugs in bad condition or partially fouled.
2. Spark plug cables in bad condition or leaking.
3. Spark plug gap to close or to wide.
4. Faulty ignition coil, module and or sensor.
5. Battery nearly discharged.
6. Damaged wire or loose connections at battery terminals especially the ground cable at BOTH ends, ignition coil, or plug between ignition sensor and module.
7. Intermittent short circuit due to damaged wire insulation.
8. Water or dirt in fuel system, carburetor or filter.
9. Fuel tank vent system plugged or carburetor vent line closed off.
10. Carburetor controls misadjusted.
11. Damaged carburetor.
12. Loose or dirty ignition module connector at crankcase.
13. Faulty MAP, CKP, and or CMP sensors.
14. Incorrect valve timing.
15. Weak or broken valve springs.
16. Damage intake or exhaust vale.
good luck:

Jul 17, 2013 | Harley Davidson XL Sportster 883...

1 Answer

Trying to set air / fuel ratio 1977 sportster zenith will start run foul plugs black smoke.tried air screw in till die screw out 5 half turns.3 full turns cannt find sweet spot rebuilt zeni

Hi Anonymous, take a ride over to your local dealers service department, I'm sure they will be happy to offer advice and assistance concerning your issue. Have a nice day.

Mar 03, 2013 | Harley Davidson XL 1200 C Sportster Custom...

1 Answer


You need to look at the exhaust and the plug so you can figure out why it is fouling. It could be from being too rich fuel mixture from the carb or you could be burning oil which could mean your rings are shot.

Fuel will look black and you should smell raw gas smell. Oil will be blue smoke. I don;t see your model etc so can;t help with much more. Once you know what is fouling it then you can talk to a repair shop and see if it is worth fixing. If it is rings then the engine needs a rebuild. If it is fuel it could just need adjustment or the carb setup. Again not knowing where you are I don;t know if there are any small engine repair shops around you or lawn care companies etc to direct you towards. Just have a good idea of what a new mower is worth when you start asking around. If the repair estimate is too much just get a new one.

Sep 14, 2011 | Yard Machines Garden

1 Answer

Help with 76 ironhead 1000 fouls plugs when it get hot and it wont charge

Ok, you have two problems. Fouling plugs and charging system problems. Work with one problem at the time. I'd work on the plug fouling problem first. What is fouling the plugs? Is it oil or gasoline fouling the plugs. Take one of the fouled plugs out and smell of it. Is it gasoline or oil fouling the plugs? If its gasoline, you have a problem with the carburetor. In this case, I'd need to know what kind of carb is on the engine. Is it the original Keihin or has someone put an aftermarket carb on the engine? Do you know how to check the jet sizes in the carb? If it's oil fouling, is it due to valve guides or rings? Does the engine smoke from the tailpipes? What color is the smoke? Black or blue smoke is caused by a too rich fuel air mixture. White smoke is oil burring.

As for your charging system, the first thing to do it to polarize the generator by momentarily shorting the positive battery post with the armature of the generator. If the generator still does not charge, you need to check the brushes in the generator and the output of the generator.

Good Luck

Jun 13, 2011 | Harley Davidson XLH 1000 Sportster...

1 Answer

I bought a 92 fzr 600 ride it for a month no problem. But now it keeps popping the resistor in the spark plugs. 3 sets of plugs in the last 2 weeks. Last set lasted 2 days. All have been ngk.

NGK plugs dont stop, especially all at once, so there is another problem.
There are some resisters in the plug caps that can fail.
Are the plugs carbon fouling?(dry black) if so make sure the air filter is new, and oil is changed.
Does the enginge blow smoke or use oil?(wet black)oil fouled may mean rings.
Fuel fouled may mean the jettting is wrong or choke stuck open
Its the battery good(new) and charging ,put a multi meter across the terminals 12v stopped, 14v running approx.
it always helps to drain the carb bowls every few weeks
If exhaust is not standard, the jetting may be wrong.
does the fuel tap work correctly? only use the run or res positions never pri
A short in the kill switch or a worn ignition switch can cause a miss or backfire

May 28, 2011 | 1992 Yamaha FZR 600

1 Answer

Kawa zzr 1400

first try some Seafoam carb cleaner from Autozone 1/3 can to two gallons fuel. drive it around for about 10 miles see if it cleans up the carbs. if thats not it then i'd look into plugs and wires if seated properly, could also be fouled plugs.

Apr 06, 2010 | 2002 Suzuki GSX-R 600

1 Answer

My 2004 springer is running rough put new plugs in it let run 5 minutes plugs fouled out black smoke out pipes any suggetions?

Hi ,
Your bikes engine is running too rich !! , you will have to set the air-fuel mixture ratio.
Try to check the air filter it may be too dusty and kinda clogged thus not allowing air to go in.
If all is ok thn you may have to clean the carbs and reset the float in the carbs.

Knight.(YamahaSeca XJ 750 A 1981)

Feb 28, 2009 | 2008 Harley Davidson FLHX Street Glide

1 Answer

2005 fatboy starting problem

Start with the battery and make sure u have at least 12.5 volts and good cable connections
1. Are the plugs fouled ?
2.Fuel filter clogged ?
3.Check all the (vacuum) lines for tight connection
4. Sparg plug cables, coil
5.Ignition timing, sensors

Dec 01, 2008 | Harley Davidson Harley-Davidson Motorcycle...

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