Putting together a microsquirt for my 83 BMW airhead bike, have most parts ID'd and ready to assemble this fall.
One challenge yet to yeild a reasonable answer is the efi fuel pump and the lower levels of fuel delivery required on this application compared to larger traditional automotive "More is Better" type product available.
Testing maximum flow today proved a pump capable of 60 LPH or 14 GPH would meet those theoretical maximum needs. Hence a pretty small unit. Additionally, I wish to locate an "inline" style of exterior pump below the tank and not get into tank modifications.
I have not been able to identify any product in that range that is affordable yet, however had a thought about driving the pump with PWM to tone down a larger unit to the flow range I need.
Any one tried this, any obvious reasons not to go that route?
As you all know on a motorbike amperage is not in unlimited supply, as well excess return fuel at an elevated pressure level is just creating heat from the wasted power consumption (see fuel spilling over the regulator "relief" type return port).
Any comments, feedback welcomed.
Sincerely,
Lorne in Abbotsford, Canada.
PWM for Fuel Pump reduction
Forum rules
Forum rules
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
Forum rules
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
-
pommie02
Re: PWM for Fuel Pump reduction
bike fuel pumps.....
i have been playing with mine for a while now, i think i have it done now.
from a personal view, i found i had to have a good strong fuel supply. pingel sell adapters that will fit in to tanks.
the next problem is returning the fuel...it has to go somewhere. having spent hundreds on a paintjob and then drilling my fuel tank.
i have used a msd 225 it has a good flow and only draws 5 amps, i think you could probably find a smaller pump. but i dont know if you could keep a constant pressure.
trial and error is my way, usually costing money
i have been playing with mine for a while now, i think i have it done now.
from a personal view, i found i had to have a good strong fuel supply. pingel sell adapters that will fit in to tanks.
the next problem is returning the fuel...it has to go somewhere. having spent hundreds on a paintjob and then drilling my fuel tank.
i have used a msd 225 it has a good flow and only draws 5 amps, i think you could probably find a smaller pump. but i dont know if you could keep a constant pressure.
trial and error is my way, usually costing money
Re: PWM for Fuel Pump reduction
Seems a general rule of thumb puts amperage and flow potential into a simple relationship, yours must be in the 30-40gph range? I will only be looking for a third of that and hence this perhaps complex secondary project on top of an already challenging one. Further searching on the net today revealed several systems that automakers are using PWM to fully control a fuel pump, with no pressure regulator being used.
I have ample amperage available (have upgraded to a 900 watt charging system from the traditional BMW Bosch 280W problematic overheating one that came on the bike. However, I'm building two sets of kit, and my brother bike doesn't have excess current to spare.
I'll keep searching for info I guess, thanks for your feedback.
Lorne
I have ample amperage available (have upgraded to a 900 watt charging system from the traditional BMW Bosch 280W problematic overheating one that came on the bike. However, I'm building two sets of kit, and my brother bike doesn't have excess current to spare.
I'll keep searching for info I guess, thanks for your feedback.
Lorne
Re: PWM for Fuel Pump reduction
I had a Ford Econoline van, the Fuel Pressure Regulator failed. Went waaaay rich, couldn't drive it. Until I could get a new FPR, I wired a headlight in series with the fuel pump. A light bulb is almost like a current regulator - if you give it less voltage, the filament cools off, the resistance goes down, the current stays about the same. Fuel pressure came down from 80-90 PSI to about 40 PSI, fuel pump ran slow and quiet, van ran fine. I drove it like this for a few days till I had a chance to install the new FPR.
I've been thinking about putting uS in my lawnmower - stupid Briggs never has enough spark, needs choke until it's fully warmed up or it quits whenever it needs a shot of power. It has very little electrical power to spare - I think the alternator is only good for about 1.5 amps at best. So I was thinking of doing something similar for fuel for it - use an electronic PWM current regulator, set the current to get the desired fuel pressure, run with no return. May need to have some method of bleeding the air out, if my wife ever lets the tank run dry.
My opinion based on my experience with the Ford van is it should work. Your mileage may vary.
HAROLD
I've been thinking about putting uS in my lawnmower - stupid Briggs never has enough spark, needs choke until it's fully warmed up or it quits whenever it needs a shot of power. It has very little electrical power to spare - I think the alternator is only good for about 1.5 amps at best. So I was thinking of doing something similar for fuel for it - use an electronic PWM current regulator, set the current to get the desired fuel pressure, run with no return. May need to have some method of bleeding the air out, if my wife ever lets the tank run dry.
My opinion based on my experience with the Ford van is it should work. Your mileage may vary.
HAROLD
Re: PWM for Fuel Pump reduction
Here's a question regarding the Microsquirt then - over and above the normal provision for injection, ignition and all the other features inherent to the unit, is there any way to:
a) provide an additional PWM signal in the 1-2 amp range for a fuel pump circuit as discussed?
b) provide a varying resistance value that might be substituted into a simple PWM circuit in place of its reostat, and that could be tailored to basically provide higher values to satisfy the varying fuel demands of a turboed unit?
c) or, barring the above might a fuel pressure sender signal be tailored to influence the PWM signal in one of the simple buildable units such that a constant fuel pressure is always maintained (hence the dead end circuit that conserved power and doesn't heat your fuel)
And, not to give up too easily if none of those are at present attainable, perhaps just a linkage off the throttle to operate the reostat within the PWM unit, and by choosing linkage/ pivot points shape the signal advantagously for a generally ball park pressure (dead ended and flow looking after itself).
a) provide an additional PWM signal in the 1-2 amp range for a fuel pump circuit as discussed?
b) provide a varying resistance value that might be substituted into a simple PWM circuit in place of its reostat, and that could be tailored to basically provide higher values to satisfy the varying fuel demands of a turboed unit?
c) or, barring the above might a fuel pressure sender signal be tailored to influence the PWM signal in one of the simple buildable units such that a constant fuel pressure is always maintained (hence the dead end circuit that conserved power and doesn't heat your fuel)
And, not to give up too easily if none of those are at present attainable, perhaps just a linkage off the throttle to operate the reostat within the PWM unit, and by choosing linkage/ pivot points shape the signal advantagously for a generally ball park pressure (dead ended and flow looking after itself).