I thought I already had this issue fixed, but sure enough when I put the replacement igniter (used) on, it still has no vacuum to the carbs when trying to start.  So before I accuse this guy of selling a bad part, I would like some help/opinions.

I originally diagnosed it as the igniter because I bypassed it by hooking the ground from the solenoid to the ground of the igniter (using a paper clip in the port where the igniter WOULD be, it was off).  Bypassing the igniter got the solenoid to allow vacuum from the engine to the carbs. Note that I didn't see the diaphrams moving up and down, but I could feel a good vacuum by putting my finger on the tubes.

So my question is this. If bypassing the igniter gets the vacuum to work correctly (by telling the solenoid to open), then is there anything else that could be causing the problem? As far as I know, the igniter is the responsible part for telling the solenoid when to open... so if this isn't a bad part, I'm at wits end. As far as I can tell, the wiring diagram shows the only possible culprits are the signal generator, solenoid, and igniter. The bike runs on prime and fires fine, so it's not the signal generator (since it controls the coils), and I can get the solenoid to work by bypassing the igniter.

Note that this is not a California model, so there is not a 2nd air valve.

Thanks for your time!

Bypassing igniter control of solenoid:


Solenoid:


Vacuum tube to carb (1 of 2):

Solenoid could be bad. The ignitor is solid state so may not have enough current to pull in a defective solenoid. A paperclip can drive it with full power of the battery. Try replacing that solenoid.

I'll have to investigate more of what that part really does. Not really sure what it is controlling. I'll play with it tonight on Phenix.

Holy Sheet!!  Please oil/lube your chain!!!!!!

Craigs449: I'm rebuilding this bike. I bought it from a lady that let it sit for a year and half, so before I take it out, believe me, that'll be taken care of! lol.

Adidas:

Excellent point.  Especially since the diaphrams aren't going up and down when I bypass the igniter and give it a full 12V. That could definitely mean that there's not enough current able to go through the solenoid to open it up fully, which in turn would limit the vacuum, and also provide too much resistance to the low voltage signals from the igniter.

Then again, I really don't know how much vacuum I should be able to feel. But I do believe the diaphrams should be moving up and down when I try to start it.

I originally had problems locating this solenoid under GS500.... but luckily I just tried looking up the Suzuki part # and wallah! Off of different models, but it'll work. Here's to try number 2! 

 

Quote from: craigs449 on April 19, 2012, 06:17:54 PM
Holy Sheet!!  Please oil/lube your chain!!!!!!

care to show us where you are connecting that hose? Maybe to the wrong place?

From the picture you see, that hose connects to the white plastic piece in the background (on the front of the carb). Let me get this vacuum working properly, and then we'll see how the hose set up is.... but I'd bet my girlfriend on my set up being correct!

The petcock vacuum comes from the right carb - not from the plastic caps. The lines to the plastic caps are under control of the ICU for emissions crap-ola.

Follow the line from the right carb where it connects to the engine. The petcock vacuum line has nothing that can possibly shut it off. (The same connection on the left carb is capped off with a rubber nipple.)

Two things:
1. I hope your girlfriend doesn't know you're making such a wager. (post a pic!)  Listen to Adidas. There isn't much he doesn't know about your bike

2. There should be enough fuel in the carbs to start and run for several seconds. So the petcock doesn't even need to be open during starting.  The float bowls will very slowly dry up due to evaporation, but typically takes a few days to affect starting.

Adidas, thanks for the detailed pictures. I did have the vacuum lines hooked up correctly.  However, your post plus one from Big Rich on another post made me take another look at my petcock, and sure enough, it has something I thought it didn't have because of the parts diagram.... a vacuum line.  A vacuum line that runs straight to the line that has constant vacuum from the intake manifold.

Looks like a clogged or stuck petcock issue now. I'll be taking it apart today... now I just gotta hope that all my extra parts will sell! Haha.

On most old carbed bikes all the ignitor does is provide spark. The spark itself is provided by a transistor (aka the TCI - transistor controlled ignition) and the rpm based advance of the spark. There have been cases where the transistor has been bad, and it doesn't spark or sparks wrong or weak.
On the GS I have never heard of a Transistor going and I've never even heard of a advance curve IC going. I have yet to hear of a bad ignitor in fact.
Cool.
Buddha.

Thanks Buddha. For this 2005 GS500F non-CA model, the igniter controls the ground from the solenoid, switching it off and on. All this time I missed the vacuum line running to the petcock, and I thought the exit lines from the solenoid were the ones that pulled fuel... a rookie mistake. But I can't beat myself up too bad, it was my first carb I ever worked with. And I'd really like to blame the parts diagrams anyway for not showing the vacuum line to the petcock! Haha.

Hi mcg2000  i take my vacuem off the left carb directly to the petcock so if i do have a petcock problem i can go directly to it .Ialso installed a vacuem tank in the line .

Quote from: twinrat on April 23, 2012, 12:24:55 AM
Hi mcg2000  i take my vacuem off the left carb directly to the petcock so if i do have a petcock problem i can go directly to it .Ialso installed a vacuem tank in the line .

Yes - that is possible since there is a left carb vacuum line that is capped off. Using it only for the petcock would insure a stronger vacuum to the petcock.