Fuel pump activation on kickstart motorcycle

All questions about MS2/Microsquirt/Microsquirt module. See also MS2/Extra manuals

Moderators: jsmcortina, muythaibxr

Post Reply
sweet_baby_james
Helpful MS/Extra'er
Posts: 56
Joined: Wed Oct 22, 2014 9:53 am

Fuel pump activation on kickstart motorcycle

Post by sweet_baby_james »

I have a microsquirt setup on my ‘85 Yamaha RZ350, which is a kickstart motorcycle. When I kick the bike over to start up and the RPMs are synced the fuel pump comes on as expected. However, they are only a few rotations of the crank with each kick before the fuel pump shuts off again and fuel pressure drops. I would like a set up where the fuel pump is running continuously without having to kick the bike over, so that when the RPMs sync (plugs fire and injectors open) there is already fuel pressure in the rail. The only way I can see to accomplish this is to install a manual toggle switch to send 12v direct to the fuel pump to run it, bypassing the microsquirt control of the fuel pump. Once the engine is running I could then turn off the toggle switch and the fuel pump should continue to run through microsquirt control.

Does anyone have any other ideas of how I could accomplish this?

Thanks

James
EFI and Turbo Yamaha RZ350
Microsquirt with MSExtra 3.3.2
ChevelleFan
Master MS/Extra'er
Posts: 786
Joined: Sun May 02, 2004 5:55 pm
Location: Cleveland, Ohio
Contact:

Re: Fuel pump activation on kickstart motorcycle

Post by ChevelleFan »

You just need to run an extra wire to same point on the fuel pump relay that the microsquirt is connected to, and run a switch to ground to manually turn on the pump.

-Dave
'70 Chevelle ZZ383/700r4/3.73 MS3X, 36-1, LS Coils, Holley Stealthram -- success story
'92 Saturn 1.9 DOHC/5sp, MS3, Champcar racer success story
'79 Malibu DartSHP400/80mm/PG/3.55, MS3X/36-1/LS Coils -- success story
Porsche 944 S2 3.0 -- MS3X/36-1/LS Coils, 1:44s Mid-Ohio, Pro Course
jsmcortina
Site Admin
Posts: 39587
Joined: Mon May 03, 2004 1:34 am
Location: Birmingham, UK
Contact:

Re: Fuel pump activation on kickstart motorcycle

Post by jsmcortina »

sweet_baby_james wrote: and fuel pressure drops.
Something is perhaps a problem here. With normal OEM setups there is a non-return valve in the pump and pressure is retained for weeks.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
sweet_baby_james
Helpful MS/Extra'er
Posts: 56
Joined: Wed Oct 22, 2014 9:53 am

Re: Fuel pump activation on kickstart motorcycle

Post by sweet_baby_james »

So maybe a small check valve is needed on the rail side of the fuel pressure regulator?

James
EFI and Turbo Yamaha RZ350
Microsquirt with MSExtra 3.3.2
jamies
Master MS/Extra'er
Posts: 523
Joined: Tue Apr 07, 2009 12:22 am

Re: Fuel pump activation on kickstart motorcycle

Post by jamies »

usually a check valve at the pump outlet is all thats needed (or pretty much anywhere between the pump outlet and rail)
hybrid
Super MS/Extra'er
Posts: 1275
Joined: Thu Apr 07, 2005 11:23 pm
Location: Sydney, Australia
Contact:

Re: Fuel pump activation on kickstart motorcycle

Post by hybrid »

jsmcortina wrote:
sweet_baby_james wrote: and fuel pressure drops.
Something is perhaps a problem here. With normal OEM setups there is a non-return valve in the pump and pressure is retained for weeks.

James
Was just about to reply before I saw this.
Yes there should be plenty of fuel pressure after priming that this should not be an issue.
An in-line non-return valve sounds like it's required.

Edit: it's either that, or the regulator is bad.
Do not load someone elses tune and expect it to work for you!
Image
sweet_baby_james
Helpful MS/Extra'er
Posts: 56
Joined: Wed Oct 22, 2014 9:53 am

Re: Fuel pump activation on kickstart motorcycle

Post by sweet_baby_james »

How long should a fuel pressure regulator be expected to hold pressure in the system?
EFI and Turbo Yamaha RZ350
Microsquirt with MSExtra 3.3.2
jsmcortina
Site Admin
Posts: 39587
Joined: Mon May 03, 2004 1:34 am
Location: Birmingham, UK
Contact:

Re: Fuel pump activation on kickstart motorcycle

Post by jsmcortina »

sweet_baby_james wrote:How long should a fuel pressure regulator be expected to hold pressure in the system?
I've undone hoses on a car that had been on a scrapyard for months and got sprayed by fuel.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
hybrid
Super MS/Extra'er
Posts: 1275
Joined: Thu Apr 07, 2005 11:23 pm
Location: Sydney, Australia
Contact:

Re: Fuel pump activation on kickstart motorcycle

Post by hybrid »

Oh, by the way;
When I first injected my RZ500 I had a lot of trouble replicating the choke on a 2stroke.
I really wanted the priming pulse to be triple the default maximum.

For a while, I was turning the key on/off/on a few times before I would attempt the first kick so it would fire.
Do not load someone elses tune and expect it to work for you!
Image
Post Reply