Vac lines help / Hahn stage 1

[Jimingle10]

just finished install of hahn stage 1, and having strange issues which i believe are vaccum related.

Bike idles terrible, sounds like its running on 3 cylinders (but its not). Fuel pressure guage jumps crazily, from 35psi - 60psi and the idle almost correspsonds to the jump in fuel pressure. It sounds terrible.

Could someone post a diagram or try to explain how all the vac lines should be hooked up? BOV/FMU/MAP etc

The kit included a little black box which was soldered to 2 ECU wires that is supposed to prevent MAP sensor from triggering FI light from what I am told.

I am using NO check valves.

Please help, I want to bring it to the tuner this morning but would like to fix this issue first!

 

[Jimingle10]

also on the turbo itself there is a vac line fitting and almost right next to it on the wastegate is a vac line fitting, have those 2 connected together. Is this correct?

 

[POWERHOUSE]

just finished install of hahn stage 1, and having strange issues which i believe are vaccum related.

Bike idles terrible, sounds like its running on 3 cylinders (but its not). Fuel pressure guage jumps crazily, from 35psi - 60psi and the idle almost correspsonds to the jump in fuel pressure. It sounds terrible.

Could someone post a diagram or try to explain how all the vac lines should be hooked up? BOV/FMU/MAP etc

The kit included a little black box which was soldered to 2 ECU wires that is supposed to prevent MAP sensor from triggering FI light from what I am told.

I am using NO check valves.

Please help, I want to bring it to the tuner this morning but would like to fix this issue first!

If you have your FMU connected directly to the plenum, you would not need a check valve. If your FMU is connected to any of the signal hoses, you will need a check valve in the line to the FMU, with the black side of the check valve facing the FMU. Set your idling fuel pressure to 42-43 lbs. If you have a BOV, it MUST be connected to a signal hose, that is, a hose that sees vacuum. A map sensor can be connected to either a signal hose, or directly to the plenum. Turn your bleed screw on the FMU out approximately one turn, and make sure your tuner monitors the fuel pressure rate of gain while on the dyno . . .

 

[Jimingle10]

thanks powerhouse, my issue i guess is that I cannot get a stable fuel pressure reading, the needle is almost a blur as it bounces so fast between 35-60psi. What is the SIMPLEST way to hook the vac lines up? I have vac lines galore with like 4 t-fittings....alot of stuff ended up getting capped. Its a rats nest and any picture/diagram on best way to configure this would be great.

From Plenum - To FMU - got that
From all 4 TB's, I run lines to boost gauge and BOV and MAP sensor? Is that it?

No check valve needed on map sensor?

 

[Jimingle10]

also, on the FMU, there is the large bleeder valve on top, but what is the tiny brass knob with a vac line on it?

 

[Jimingle10]

Well I think vac lines are all good, starting to think fuel is the issue. If I turn bleeder valve down to 30psi everything stabilizes. As soon as I turn it a little higher the pressure surges out of control, the fuel line even starts jumping/pulsing cause of the pressure fluctuation. Is it possible the petcock on 2000 hayabusa is too small? My busa had stock external fuel pump prior to this, unlike most newer busas
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[POWERHOUSE]

Well I think vac lines are all good, starting to think fuel is the issue. If I turn bleeder valve down to 30psi everything stabilizes. As soon as I turn it a little higher the pressure surges out of control, the fuel line even starts jumping/pulsing cause of the pressure fluctuation. Is it possible the petcock on 2000 hayabusa is too small? My busa had stock external fuel pump prior to this, unlike most newer busas
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The large hex-head screw in the middle of the FMU with the lock nut is not a bleeder valve - it is the adjustment for your base pressure - the fuel pressure when the bike is idling, and it should be at 42-43 lbs. The small brass adjustment screw that sticks out at a right angle from the unit is the bleed screw - it adjusts the "rate of gain" - it should be at 1 turn out, but that may change when the bike is dynoed, if your tuner does the right thing and looks at fuel pressures while the bike is being tuned. The petcock is not too small . . .

 

[Jimingle10]

i have some other issues than...i cannot get the pressure to stabilize. Ill take a video and upload to youtube to show what its doing

 

[Jimingle10]

What would cause fuel pressure to pulsate rapidly? I don't see any leaks or pinched hoses. I'm stumped
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[2wicked]

Shims in the FMU are wrinkled or cracked and causing your fuel pressure to jump around,

Richard

 

[Jimingle10]

Fmu lines were backwards, doh! Powerhouse, on hahn stage 1 kit, does the internal wastegate need to see vac? Right above where filter goes there is a vac connection off turbo, I have that connected to the wastegate about 3 inches away, is this correct?
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[POWERHOUSE]

Fmu lines were backwards, doh! Powerhouse, on hahn stage 1 kit, does the internal wastegate need to see vac? Right above where filter goes there is a vac connection off turbo, I have that connected to the wastegate about 3 inches away, is this correct?
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Yes, that is correct. It is not, however, a vacuum connection . . . a wastegate does not need to see vacuum at all, only boost pressure. A BOV is the only component that needs to see vacuum . . .

 

[Jimingle10]

sorry didnt know what else to call it, looks like a vac connection lol. There was no specific instructions on that, i just wanted to be sure they were hooked up properly. Thanks

 

[65Cobra]

Shims in the FMU are wrinkled or cracked and causing your fuel pressure to jump around,

Richard

Just an fyi... any BEGI FMU manufactured since the beginning of the year no longer has shims. The unit has been completely redesigned. Prior units with shims can be sent to BEGI for an upgrade ($90) as it will require machining.