Centauro run without a tank

[steven c]

 I have my 97 mostly back together except for body work, it's been off the road for many a year when I dragged it home. I have the new belts in, the injectors where sent out and cleaned and reinstalled, I know the bike ran when Ron parked it years ago. But it will not start. It will fire on starting fluid and when I pulled one of the injectors it fired off with the gas in the injector manifold. There is power to the injector when cranked and the injected clicks when voltage is applied. Fuel pump works fine after cleaning, new filter,. I did put the tank on to see if that would make a difference but still didn't fire. Working on FI is new to me so perhaps I'm missing something?
 Does the air box need to be on? There is a hose going from the box to a fitting with a plug on top of the frame.

[guzzisteve]

Sounds like you need some software to activate things while you sort.  You don't need an airbox, hose is for crank vent crap. The little hose to top of airbox WAS to go to pressure sensor, they run better if that is just in a dead air area not the airbox.
The fuel system has to be all routed and working, fuel tap, pump, pressure regulator, return line back into tank(or gas can). You can make a portable can to hang the bike for riding it & running it.

[steven c]

Okay. So is this the regulator on the right side of the tank?

[Wayne Orwig]

Okay. So is this the regulator on the right side of the tank?

Yes.
Leave that one barb vented to atmosphere.
Loosen the fuel line at the regulator and verify that you get a good amount of fuel when the key is turned on.
Can you hear/feel the injector clicking when you crank it over? Since you are getting spark the timing sensor should be good.
That fitting on the frame is atmosphere pressure sensor. The hose to it is not critical.

[steven c]

I guess it does need the tank to run! Sprayed some Carb cleaner into the pressure regulator and she fired right up. Brought back to life after 16 years.

[steven c]

 Hopefully my last questions (I doubt it) there are two vent hose that come up fromt the back of the transmission, small diameter, where to they connect I can't see any obvious places.

[steven c]

https://youtu.be/GBpBoWKGLJk

[bmc5733946]

Those are probably tank vent and tank inlet surround drain, look under tank about center in tunnel, should be two small nipples. Tank vent used to go to charcoal cannister for EVAP Emission control, most have been removed and hence tank then vented to air. A caution about the screws that hold the side panels to the tank, there are short ones and long ones, installed in the wrong hole the long ones can peirce the tank, not an easy fix.

Brian

[Chuck in Indiana]

https://youtu.be/GBpBoWKGLJk

Isn't that a glorious sound? 
bmc beat me to the hoses use.. and pay attention to the side panel screws.

[steven c]

Thanks for the screw info I haven’t heard that

[Wayne Orwig]

Hopefully my last questions (I doubt it) there are two vent hose that come up fromt the back of the transmission, small diameter, where to they connect I can't see any obvious places.

If you mean the hoses that go to the bottom of the oil pan, those go up to the spine, to drain it back to the sump. The spine is the oil vapor box.
The transmission only has one vent line on the back, I think.

[pehayes]

Of course you need the tank or some cobbled substitute.  In your old carb bike, gravity supplied and replenished fuel to the carb bowl.  With no tank, you could start and run for a moment or two until the bowl level dropped.  Hower, with fuel injection, the fuel pump continuously circulates fuel like the water in your fish aquarium.  The regulator allows for some of the hoses to develop an internal pressure.  Without that pressure there is no injection.  The 'injector' doesn't actually inject anything.  It is just an electrical binary valve which allows the pressurized fuel to pass through.  The computer tells the injector 'how long' in milliseconds to remain open during each cycle.  No fuel line pressure?  No run.  Fuel Injection isn't black magic (well, maybe inside the computer).  It is just sensors and switches.  Learn what each one does and how it impacts the running performance.

Patrick Hayes
Fremont CA

[rschrum]

Sound great! Nothing like that feeling when you get one fired after a long sleep.

[steven c]

Of course you need the tank or some cobbled substitute.  In your old carb bike, gravity supplied and replenished fuel to the carb bowl.  With no tank, you could start and run for a moment or two until the bowl level dropped.  Hower, with fuel injection, the fuel pump continuously circulates fuel like the water in your fish aquarium.  The regulator allows for some of the hoses to develop an internal pressure.  Without that pressure there is no injection.  The 'injector' doesn't actually inject anything.  It is just an electrical binary valve which allows the pressurized fuel to pass through.  The computer tells the injector 'how long' in milliseconds to remain open during each cycle.  No fuel line pressure?  No run.  Fuel Injection isn't black magic (well, maybe inside the computer).  It is just sensors and switches.  Learn what each one does and how it impacts the running performance.

Patrick Hayes
Fremont CA

with
 I used an off bike tank, sorry I just assumed people would get that. I was told by a couple of people it would run with a off the bike tank just have a catch tank for the return. Now I know.

[pehayes]

I suggested a '... cobbled substitute'.   Sounds like that is what you did.  Did it not run with your '... off bike tank...'?  The fuel flow would be constant into your catch tank as long as the engine was cranking.  What happened with the pump and fuel when you turned on the key?  What happened to the motor when you cranked it?  It should have run unless there is something I don't understand about your off bike tank.

Patrick Hayes
Fremont CA

[Kiwi_Roy]

All you ever need to know about the Guzzi Fuel injection

https://dpguzzi.com/efiman.pdf

But leave the vent open on the pressure regulator as Wayne says

[steven c]

 I have one of those tanks you designed for working on a bike with the tank off. Everything worked when key was on, pump primed, relays clicked, power to injectors fuel flowed out into the my catch gas can when crank, there was gas in the manifold, bike would run on starter fluid and when I pulled the injectors it fired from the gas sitting in the intake. So thats what I did. Put tank on, hooked up everything at first it didn't start , sprayed some carb cleaner in the regulator and it fired, reconnected the hose, bike fired right up.

[Howard R]

I used an off bike tank, sorry I just assumed people would get that. I was told by a couple of people it would run with a off the bike tank just have a catch tank for the return. Now I know.

The reason the bike wouldn't run without your tank on is because of the pressure regulator.  On this system, the pressure regulator is at the distal end of the fuel lines, and is also the return to the tank.  Without the pressure regulator, no fuel pressure would build up even though the pump had good flow into the catch tank.  When the injectors opened, there was not enough pressure to squirt anything out.  If you could have rigged up a pressure regulator, either taken the one off the tank or found something else to perform the same function on the end of the pipe in your catch tank the engine should have run.

Howard

[steven c]

 Next time I'll know!