Hard to start Husqvarna FC450

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12/15/2019 5:54 PM

What I have is a Husqvarna Fc450 Rockstar bike 2018 (or some say 2018.5) which is very close to the 2019 450SXF. It is a bear to start when cold. I ran the battery down today trying to get it started and had to put in my spare battery. When it starts it springs to life instantly. I did the easy things first. The valves are in spec, installed new spark plug, set TPS from .58 to .60 volts, changed inline fuel filter and dumped gas and put in fresh (should have been fresh anyway). I went back to stock muffler from FMF and did the idle reset with a fan blowing on it for 5-6 minutes like the dealer does with a new bike. It runs great when it starts with maybe a rough loping idle at worse. I hate to start throwing parts at it without asking for ideas first. Help!

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Take it to the limit, one more time!

12/15/2019 6:43 PM

Remap ECU from Twisted Development helps. I added the Vortex ECu.

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12/16/2019 3:50 AM

What is your starting procedure ?

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12/16/2019 4:12 AM

Is there a high idle knob on that bike?

Does it run better once its warmed up?

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12/16/2019 5:08 AM

erik_94COBRA wrote:

What is your starting procedure ?

Hit the starter button to prime the fuel pump, push up on the start button, hit the starter button once again to warm the battery and it used to would start on the third time spinning it over. This is the same I used with my 2017 KTM 450 SXF and it always started great. This one had got worse and it only has 41 hours on it.

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Take it to the limit, one more time!

12/16/2019 5:13 AM

kb228 wrote:

Is there a high idle knob on that bike?

Does it run better once its warmed up?

It has an idle adjustment knob and a start button which I think just cracks the throttle open slightly.

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Take it to the limit, one more time!

12/16/2019 6:05 AM

erik_94COBRA wrote:

What is your starting procedure ?

mx317 wrote:

Hit the starter button to prime the fuel pump, push up on the start button, hit the starter button once again to warm the battery and it used to would start on the third time spinning it over. This is the same I used with my 2017 KTM 450 SXF and it always started great. This one had got worse and it only has 41 hours on it.

Sounds like a good one. My '19 450SXF will usually start pretty easily once I've primed the fuel pump.

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12/16/2019 6:08 AM

CarlinoJoeVideo wrote:

Remap ECU from Twisted Development helps. I added the Vortex ECu.

I am really interested in the Vortex ECU, but it is a bit pricey.

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Take it to the limit, one more time!

12/16/2019 8:43 AM

CarlinoJoeVideo wrote:

Remap ECU from Twisted Development helps. I added the Vortex ECu.

mx317 wrote:

I am really interested in the Vortex ECU, but it is a bit pricey.

Vortex ECU with Twisted Development maps is hands down the best investment for these bikes, aside from suspension. Makes a huge difference.

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12/17/2019 7:31 PM

I had the same thing. In cold weather, just SoCal cold weather was a pain in the ass to start. I would also have to use the enrichener to start all day. I would stall and and had decel pop. All that is gone just a stock ECU remap. My bike runs great now.

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The older I get, the faster I was.

12/18/2019 5:07 AM

captmoto wrote:

I had the same thing. In cold weather, just SoCal cold weather was a pain in the ass to start. I would also have to use the enrichener to start all day. I would stall and and had decel pop. All that is gone just a stock ECU remap. My bike runs great now.

I may have to go that route or spring for a Vortex or Get unit.

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Take it to the limit, one more time!

12/20/2019 11:26 AM

This sounds crazy, but it's worked like this four times now. I can uncouple the fuel line where the inline filter is, snap it back together and it will start right up! I am thinking I may have an injector going bad.

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Take it to the limit, one more time!

12/20/2019 11:48 AM
Edited Date/Time: 12/20/2019 11:51 AM

mx317 wrote:

This sounds crazy, but it's worked like this four times now. I can uncouple the fuel line where the inline filter is, snap it back together and it will start right up! I am thinking I may have an injector going bad.

OK, now we have added a new wrinkle. That gives all the signs of fuel starvation due to the lack of proper venting to the fuel tank. When you break the fuel line apart, you have released a vacuum created by fuel flow. Look at the fuel tank cap. Also a weak fuel pump will not deliver fuel under any sort of vacuum created by the fuel cap being bad.

Paw Paw

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12/20/2019 11:52 AM

mx317 wrote:

This sounds crazy, but it's worked like this four times now. I can uncouple the fuel line where the inline filter is, snap it back together and it will start right up! I am thinking I may have an injector going bad.

Paw Paw 271 wrote:

OK, now we have added a new wrinkle. That gives all the signs of fuel starvation due to the lack of proper venting to the fuel tank. When you break the fuel line apart, you have released a vacuum created by fuel flow. Look at the fuel tank cap. Also a weak fuel pump will not deliver fuel under any sort of vacuum created by the fuel cap being bad.

Paw Paw

I'll try that, but it runs very well after it starts.

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Take it to the limit, one more time!

12/25/2019 8:55 AM

mx317 wrote:

This sounds crazy, but it's worked like this four times now. I can uncouple the fuel line where the inline filter is, snap it back together and it will start right up! I am thinking I may have an injector going bad.

Paw Paw 271 wrote:

OK, now we have added a new wrinkle. That gives all the signs of fuel starvation due to the lack of proper venting to the fuel tank. When you break the fuel line apart, you have released a vacuum created by fuel flow. Look at the fuel tank cap. Also a weak fuel pump will not deliver fuel under any sort of vacuum created by the fuel cap being bad.

Paw Paw

I may have found my problem. When I look down in the tank and hit the button turning on the fuel pump, it bubbles like crazy. I read somewhere the filters were cracking and doing this allowing a pressure drop.

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Take it to the limit, one more time!

12/25/2019 11:49 AM

replace the inline filter while your at it. i've seen them basically stop fc450's from running. the filter is so small it gets clogged easily(this isn't your issue i dont think, the clogged filter wont let the bikes rev out) but worth doing since it's small and cheap.

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12/25/2019 1:14 PM

soggy wrote:

replace the inline filter while your at it. i've seen them basically stop fc450's from running. the filter is so small it gets clogged easily(this isn't your issue i dont think, the clogged filter wont let the bikes rev out) but worth doing since it's small and cheap.

Thanks! Yes I did that in the beginning and tried another one just to be sure. You are correct, they will put a halt to your fun!

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Take it to the limit, one more time!

12/25/2019 1:17 PM

I just pulled the pump out and the filter is cracked at the seam. I'll pick up a new filter set and see how it goes. A lot of my fuel pressure was leaking from there I'm sure.

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Take it to the limit, one more time!

12/27/2019 3:27 AM

The filter fixed it. It was cracked and losing pressure. I found a filter online (Mahle KL 97) the same as original for $6.99.. KTM/Husky wants $70 for a filter set. If you look in your tank and the fuel is bubbling, then you have a cracked filter.

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Take it to the limit, one more time!

12/27/2019 3:35 PM

I might have the same problem with my 2019 450 SX-F. Recently became really hard to start. I’m guessing changing your cracked filter fixed your problem?

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12/27/2019 4:46 PM

ig_redfriedkid wrote:

I might have the same problem with my 2019 450 SX-F. Recently became really hard to start. I’m guessing changing your cracked filter fixed your problem?

Yes, that filter fixed it. Shine a light in your tank and hit the starter button and you will see bubbling like its boiling if your filter is cracked when you fuel pump kicks on. It causes a loss of pressure to the injector. The filter is a Mahle KL 97 and can be sourced on line for $6.99. I found the clamps for 6.75 for a pack of eight. Much better than the $70 KTM/Husky wants..

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Take it to the limit, one more time!