Injector test

[dxhall]

After working on the Centauro off and on for most of a year, I'm down to the fuel injection system.  I know that the pump is working and that I have pressure in the fuel lines.  Is there a simple way to tell whether the problem is non-functioning injectors?  The motor will run for a few seconds if I shoot gas into the throttle body throats, but won't stay running.

[fotoguzzi]

both injectors fail at the same time? unlikely.. does it have a FW sensor? if so does it have swarf all over it? just guessing/..

more details of your "After working on the Centauro " might help.

[rodekyll]

Do you have guzzidiag or VDSTS?  I believe that has an injector test.  If not, here's a test:

Ensure fuses and relays are good before proceeding.  Ensure 42# +/- 3# fuel line pressure.  Without knowing these are in specs and working anything else is meaningless.  Guzzidiag/VDSTS would help on these checks.  Simply changing out he fuses and relays isn't good enough.  You need to also be sure the contacts in the fuse and relay blocks are in good order and clean.

1) Probe the injector plug to ensure 12v+ at one terminal and ground at the other.  A test light is good for this.  It will light up when the injector is fired.  Put your hand or a stethoscope on the injector and fee/listen for the solenoid to click as you toggle the ignition. Guzzidiag/VDSTS would help because you can trigger the injectors from the software.  verifying the click will tell you if the injector solenoid is electrically and mechanically functional.  It does not tell you if it is plugged or restricted.  If you've validated the electrical part (probed the injectors with a test light and find juice for a couple of seconds when the ignition is toggled ) and get no click, rap on the injector with something hard. like a socket extension or screwdriver.  You might get lucky and unstick the solenoid.
 
2) If you get a click, and have confirmed fuel pressure in specs, pull the injectors and point them into a container.  Jumper the solenoid terminal with one side 12v+ and the other to ground.  This will open the solenoid and hold it.  Run fuel pump continuously by hotwiring it.  Guzzidiag/VDSTS would help here.  You should get ~100cc of spray in 30sec.  I get between 90cc and about 105cc.  For this test, exact measurements aren't important.  Check the shape of the spray.  It should be a uniform cone of fine mist.  If you see big droplets or if the spray doesn't shut off immediately and no drip when the kill button is used the injector is dirty.

If you notice a diagnostics software theme, it's for a reason.  Hope this helps. 

[dxhall]

This was a non-running bike that looked pretty nice.  Mechanically it turned out to have been badly neglected - brake pads down to metal, rotors ruined, other caliper pistons frozen, steering head bearings brinnelled, thick sludge in sump, fork tubes and seals nfg, etc.  I've fixed all that stuff, installed new belts and a Joe Caruso oil pump, and am now trying to get it to run.  As had been said on this forum, sometimes free is too much (it wasn't free).  I should open a home for neglected bikes.

[beetle]

What rk said. GuzziDiag is your friend.

[Wayne Orwig]

You aren't likely to have both injectors fail at once, as you imply, unless you have pumped some goo into the injectors.

You need to start with GuzziDiag and verify the TPS, etc. You need to verify that you have good fuel pressure at the injectors.

[dxhall]

I've ordered the harness for GuzziDiag and will build a pressure test rig this week.  I need to stop buying bikes like this.

[yogidozer]

Do you have guzzidiag or VDSTS?  I believe that has an injector test.  If not, here's a test:

Ensure fuses and relays are good before proceeding.  Ensure 42# +/- 3# fuel line pressure.  Without knowing these are in specs and working anything else is meaningless.  Guzzidiag/VDSTS would help on these checks.  Simply changing out he fuses and relays isn't good enough.  You need to also be sure the contacts in the fuse and relay blocks are in good order and clean.

1) Probe the injector plug to ensure 12v+ at one terminal and ground at the other.  A test light is good for this.  It will light up when the injector is fired.  Put your hand or a stethoscope on the injector and fee/listen for the solenoid to click as you toggle the ignition. Guzzidiag/VDSTS would help because you can trigger the injectors from the software.  verifying the click will tell you if the injector solenoid is electrically and mechanically functional.  It does not tell you if it is plugged or restricted.  If you've validated the electrical part (probed the injectors with a test light and find juice for a couple of seconds when the ignition is toggled ) and get no click, rap on the injector with something hard. like a socket extension or screwdriver.  You might get lucky and unstick the solenoid.
 
2) If you get a click, and have confirmed fuel pressure in specs, pull the injectors and point them into a container.  Jumper the solenoid terminal with one side 12v+ and the other to ground.  This will open the solenoid and hold it.  Run fuel pump continuously by hotwiring it.  Guzzidiag/VDSTS would help here.  You should get ~100cc of spray in 30sec.  I get between 90cc and about 105cc.  For this test, exact measurements aren't important.  Check the shape of the spray.  It should be a uniform cone of fine mist.  If you see big droplets or if the spray doesn't shut off immediately and no drip when the kill button is used the injector is dirty.

If you notice a diagnostics software theme, it's for a reason.  Hope this helps.

Wow! I don't need to do this test at this time, but what an awesome bit of knowledge!

[Chuck in Indiana]

I've ordered the harness for GuzziDiag and will build a pressure test rig this week.  I need to stop buying bikes like this.

Aww, c'mon. Guzzi Barn Finds are fun. 
Yes, it was my old friend Jim (aircraft restorer and homebuilder) that said, "Sometimes, free is too much." 

[antmanbee]

Check the cam or crank position sensor too. If it is bad there will be no opening of the injectors but you will still hear the fuel pump.

[Wayne Orwig]

Check the cam or crank position sensor too. If it is bad there will be no opening of the injectors but you will still hear the fuel pump.

It has spark, so those sensor should be fine.

[dsrdave]

I had a similar problem with my sport 1100 that uses the same FI system...  First an foremost use good basic trouble shooting  practice.  So not overlook basics.  I went through hell assuming a fully charged new battery was good...  you can purchase a noid light at harbor freight, plug it in and determine if you are getting injector pulse.  If so and fuel pressure is correct then I suspect plugged injectors.  That was my problem, the bike had sat unused for an extended period of time.  I was not able to clean them.  After replacing the injectors it fired right up.
Good luck, the centy is a GREAT bike!!!

[dxhall]

Where did you get the new injectors?  They're pretty pricey from the dealer.