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Discussion Starter #1
I have had a faulty fuel pump, the old bosch fuel pump didm't prime anymore. So I ordered an aftermarket fuel pump, changed it together with the fuel filter. Now the fuel pump primes, the bike starts, but as I wanted to take it for a ride, after I turned the throttle to the 3-4k RPM (I let the bike heat up on idle), the engine stalled. Then after I turned the ignition on and off it started again, but as soon as I get on throttle, the bike stalls. I assume, that the bike doesn't get enough fuel, as it stals when I turn the throttle up.

Bike is stock, has a corse eeprom (from Adam) and a hp corse exhaust (no cat). It's european standard 95 gasoline, that has been working now for last 6 years without any problems.

Do you have any, Ideas what I can check on the bike? Could it be the new pump?

Thanks for your help in advance.

BR,

Ziga
 

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It would be very nice to know what “the bike” is. That being said, you probably have a pinched or restricted lie to your fuel rail. Those lines are very sensitive to position under the tank...or you fuel connector isn’t completely made up.
 

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Discussion Starter #3
Sorry for the lack of informations. I have a Brutale 750S, 2005. I will check the hoses and give you a feedback. Thank you for your help.
 

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Or your new pump/filter cannot move enough fuel...... I will assume the filter is OEM and not the problem...what kind of pump?

That said, I think SS703 is on the right track.
 

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That pump should be fine.

I'd check supply lines from the pump plate to the injector rail.
 

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Discussion Starter #7
Hi guys, just to give you a short feedback. I dissattached the complete fuel tank and attached everything back on and the bike started and run flawlessly. Even in the revs, so I took it for a test run, and whe I was driving back home, at the last intersection it stalled/lost power again, after I changed from 1 to 2 gear on about 6-7k rpms. I stopped at a side of the road, wanted to start it again, but it didn't restart. So I turned the ignition off and back on, the pump primed and engine started again... My only option for the solution would be checking the electrical situation on the bottom of the fuel pump. Or am I wrong? Did anyone had the same issues?
 

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Well... since the problem only began after you removed and reinstalled the tank (the first time) I am going to say it has something to do with what you touched...

By the way...what model bike is it ??
 

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Discussion Starter #9
Well... since the problem only began after you removed and reinstalled the tank (the first time) I am going to say it has something to do with what you touched...

By the way...what model bike is it ??
The problem was even biger before, because the bike didn't even rev up, and stalled. So I reinstalled everything once again, to double checked it, but I can't say that this solved the problem, as the problem repeated... It is the Brutale 750S, 2005, with 26k km behind it.
 

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I'm wondering if there is a vacuum problem and you're losing pressure ?
 

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Discussion Starter #12
I'm wondering if there is a vacuum problem and you're losing pressure ?
Thanks for the help. I checked all of the fuel lines, and they look to be in a pretty good shape (pic in the attachment). Is there any way to test the vacuum? 🤔
 

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I don't know what Tim @cruiser was getting at by talking vacuum.

That line in your hand is under about 3 atmospheres of pressure when the system is up and running. Fuel degrades that material...and I cannot tell if it is an immersible material from the picture.

The line may "look fine" today, burt when it slips off the fuel pump outlet in a week, you will wish you had spent the dime to replace that line...it is a 3 year maintenance item.

I can't tell where you are on this planet, but I have the correct J30R10 spec hose here in my garage for $20/foot plus shipping.
 

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Reading Tim's comment in context, I believe he is wondering if your fuel tank cap is not venting properly and you are drawing a vacuum in your fuel tank.
 

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Reading Tim's comment in context, I believe he is wondering if your fuel tank cap is not venting properly and you are drawing a vacuum in your fuel tank.
Thanks Chuck - exactly, I was wondering if there was an actual seal/pressure issue overall.
 

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Fuel tank failure to vent in will not stop the pump from sending fuel to the injectors... the pump will pull a strong enough vacuum in the tank to collapse the metal ones...not sure what happens with the hard plastics.
 

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Discussion Starter #17
Guys, thanks for all your inputs. But there I have a question, if there is a vacuum problem, then the pump would run the whole time, as if I understand it right. The pump primes until the preasure is high enough then it stops. Or am I wrong? 🤔
 

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Discussion Starter #18
I don't know what Tim @cruiser was getting at by talking vacuum.

That line in your hand is under about 3 atmospheres of pressure when the system is up and running. Fuel degrades that material...and I cannot tell if it is an immersible material from the picture.

The line may "look fine" today, burt when it slips off the fuel pump outlet in a week, you will wish you had spent the dime to replace that line...it is a 3 year maintenance item.

I can't tell where you are on this planet, but I have the correct J30R10 spec hose here in my garage for $20/foot plus shipping.
I from Slovenia, a small country in Europe. 😊🇸🇮 I have already order new hoses, just to make sure that also this one are changed after 15 years. I'm also always changing the seals of the fuel pump assembly everytime I open up the fuel tank.

Then ony thing I still want/need to proof is the electrical connection to the pump and the low fuel sensor, to see if there is something wrong with it.
 

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Guys, thanks for all your inputs. But there I have a question, if there is a vacuum problem, then the pump would run the whole time, as if I understand it right. The pump primes until the preasure is high enough then it stops. Or am I wrong? 🤔
The pump primes for three seconds and stops on initial "switch on". Once the bike is running the fuel pump is in continuous run mode and pressure is maintained by a pressure regulator.
 

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Discussion Starter #20
Hi guys, a short status update on my Brutale 750S. As I parked the bike after the ride last weekend, I wanted to take it for another ride today. So I turned the ignition key on and the shock was there instantly. The fuel pump didn't prime at all... 😳😢 I turned the ignition off and on again, to give it a couple of tries, but it didn't prime. So my next step would be to completely dissasemble the fuel pump housing, to check the wires that led from the pump, to the connector. But there is a questions that pops out in my head, what could change after I parked it and turned the ignition off, and the bike wan't even moved slightly and after 7 days it doesn't start???
 
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