Sucking/Hissing noise coming from or around fuel pump

Maxmili2297

Maxmili2297

new rider
Joined
Mar 17, 2023
Messages
4
Location
Québec
Hey guys, just finished removing the airbox to put a K&N pod filter. Everything went smooth until I listened to the engine when putting key on the ON position (no cranking yet).
There is the usual priming sound for a second or two, then there is a weird Hissing or sucking noise that doesnt seem to go away as long as the key is on ON.

Important to note that after putting all back together after the airbox removal, I forgot to replug the fuel pump electrical connector. I than proceeded to crank the engine multiple times to make it run (maybe a total of 30 sec.) to test my upgrades (I also did the fuel dongle and 02 sensor removal, changed the slip-on exhaust, all at once), without success. Today I managed to find the problem; the fuel pump connector I forgot to plug back on.

I have a video with that weird sound, as well as a video with the motorcycle running, with audibly no idle problem or else... I'm lost on what to do with this. It feels like i might have screwed the fuel pump while trying to crank it for about 30 sec yesterday, but again, if the fuel pump was not connected it would just not pump, right ? So I don't know how it could have damaged it... Might be a vacuum leak ? But I don't get how there could be a vacuum anyway without anything pumping..

I also tried letting the key on ON for a few minutes to see if the sound would go away, but it kept going.



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Last edited:
Throttle valve actuator. It's normal ( though mine sound more whirring than sucking). Plenty of post and videos on it.
 
Maxmili2297 said:
Hey guys, just finished removing th airbox to put a K&N pod filter. Everything went smooth until I listened to the engine when putting key on the ON position (no cranking yet).
There is the usual priming sound for a second or two, then there is a weird Hissing or sucking noise that doesnt seem to go away as long as the key is on ON.

Important to note that after putting all back together after the airbox removal, I forgot to replug the fuel pump electrical connector. I than proceeded to crank the engine multiple times to make it run (maybe a total of 30 sec.) to test my upgrades (I also did the fuel dongle and 02 sensor removal, changed the slip-on exhaust, all at once), without success. Today I managed to find the problem; the fuel pump connector I forgot to plug back on.

I have a video with that weird sound, as well as a video with the motorcycle running, with audibly no idle problem or else... I'm lost on what to do with this. It feels like i might have screwed the fuel pump while trying to crank it for about 30 sec yesterday, but again, if the fuel pump was not connected it just didnt pump, right ? So I don't know howe it could have damaged it... Might be a vacuum leak ? But I don't get how the could be a vacuum anyway without anything pumping..

I also tried letting the key on ON for a few minutes to see if the sound would go away, but it kept going.



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Click to expand...
Did you install Power Commander (or any other Piggyback ECU) with the airbox delete and the fuel dongle?
 
LuisLAN said:
Did you install Power Commander (or any other Piggyback ECU) with the airbox delete and the fuel dongle?
Click to expand...
I have not, since it was mentionned by other guys doing the same modifications, that it wasnt necessary, since I kept the catalytic converter. Tho it is specified that the ECU would need some time to adapt, which it did very quickly.

I'd also add that even tho it needed a tune or piggyback, i dont get why there would be such a suction sound (negative pressure leak), it doesnt make sense to me...
 
Satur9 said:
Throttle valve actuator. It's normal ( though mine sound more whirring than sucking). Plenty of post and videos on it.
Click to expand...
Thank you, I didnt find anything regarding this weird sound, but it might just be me not being able to seearch for the right onomatopoeia (sound). Even harder since i didnt know where it came from.

I'll try to find the similar posts you are referring to see if it matches with mine.
 
To anyone reading this, I found a bunch of information regarding the Servomotor driving the throttle body valve. Its a stepper motor, which in many cases is renown to make the same type of noise mine is doing. There is a report made by Texas Instrument on how to reduce such noise. All in all they are explaining why they are making such noise.

Anyway, case close for me, I'm going to sleep well tonight !
 
Maxmili2297 said:
Hey guys, just finished removing the airbox to put a K&N pod filter. Everything went smooth until I listened to the engine when putting key on the ON position (no cranking yet).
There is the usual priming sound for a second or two, then there is a weird Hissing or sucking noise that doesnt seem to go away as long as the key is on ON.

Important to note that after putting all back together after the airbox removal, I forgot to replug the fuel pump electrical connector. I than proceeded to crank the engine multiple times to make it run (maybe a total of 30 sec.) to test my upgrades (I also did the fuel dongle and 02 sensor removal, changed the slip-on exhaust, all at once), without success. Today I managed to find the problem; the fuel pump connector I forgot to plug back on.

I have a video with that weird sound, as well as a video with the motorcycle running, with audibly no idle problem or else... I'm lost on what to do with this. It feels like i might have screwed the fuel pump while trying to crank it for about 30 sec yesterday, but again, if the fuel pump was not connected it would just not pump, right ? So I don't know how it could have damaged it... Might be a vacuum leak ? But I don't get how there could be a vacuum anyway without anything pumping..

I also tried letting the key on ON for a few minutes to see if the sound would go away, but it kept going.



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For more detailed information, see our cookies page.
Click to expand...
I have the exact same noise for the first time after installing the O2 fuel dongle. Did you figure out how to stop the sound? Have you had any problems since?
 
Chriskdavis said:
I have the exact same noise for the first time after installing the O2 fuel dongle. Did you figure out how to stop the sound? Have you had any problems since?
Click to expand...
You don't stop it . It's normal. You just never noticed it before.
 
I thought the same when I posted this same thing months ago. Then I realized I was also working on my bike. So normally I would have pressed the starter before the fuel pump stopped priming which would hide the sound. And also my helmet would be on lessening the sound.
 
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