K75S Excessive fuelling, won't start

[Liverpool Brick]

Hi Everyone,
1991 K75S.
I've taken my tank off, removed pump, electrics etc, resealed the hole it had and reffitted it. Problem I now have is wild excessive fuelling when cranking but won't fire up. It tried to fire a couple of times and burbled a bit but now I have fuel dripping out of the exhaust where the 3 pipes go into 1 and now its not even trying to start. I removed the plugs and cranked it over and fuel is flying out of the plug holes.  With all this fuel and vapour around I'm not going to check for spark with a plug against the engine casing so I'm wondering what to do next. Problem #1 is what caused such excessive fuelling? I suppose I have to wait for it to evaporate then investigate for spark. The bike was starting and running 100% before I removed the tank. Any ideas welcome, thanks in advance guys.
Andy :dunno2:

[kris]

Could you have incorrectly re-connected the various fuel lines? Did you much with the fuel regulator at all? Shooting in the dark but wanted to reply. Never fun when the kids are sick...

[Liverpool Brick]

Hi Kris,
As far as I know everything is back as it should be but I will double check before going further. As for fuel regulator, I don't think I touched it. I merely took all the stuff out of the tank (pump and sender) and rebuilt it. I need to refer to the manual about messing with the regulator but as I said I don't think I touched it. I suppose cranking and cranking and cranking without it firing can put fuel into the exhaust but I'm just concerned about the amount of it.
Andy

[Liverpool Brick]

Hmmmm, took the Motronic box out and removed the plug - water ingress! Possible cause of not starting. No corrosion so must be recent. I'll dry it and try again to start. Still concerned about the amount of fuel that found its way into the exhaust. I'm going to have to take the exhaust off and drain it - that's how much is in there.
Andy

[The Mighty Gryphon]

I am thinking fuel pressure regulator, or the connections to the tank are backwards(i.e. fuel is flowing backwards through the regulator and putting the full pressure of the pump on the injectors).  Combined with no spark, I could see a lot of fuel everywhere.

[Liverpool Brick]

Thanks Gryph,
Unfortunately its now dark and I'm working 'til the w/e. I'll pick it up again on Saturday and post my findings.
Keep them thoughts coming.
Andy

[K1300S]

I am thinking fuel pressure regulator, or the connections to the tank are backwards(i.e. fuel is flowing backwards through the regulator and putting the full pressure of the pump on the injectors).  Combined with no spark, I could see a lot of fuel everywhere.

that was my first thought. if the feed and return lines to the tank are reversed, the pump is bypassing the regulator and putting way too much pressure to the injectors.

or...if the ecu is not providing ignition, then yes, turning it over and over will just keep dumping unburnt fuel in the exhaust.

[Laitch]

Still concerned about the amount of fuel that found its way into the exhaust.

Checking the oil for fuel infiltration might be a good idea, too, Andy.
That bike's fuel system should be an L-Jetronic; granted, a rose by any other name would smell as sweet but getting one to produce blackberries would be problematic.

[Martin]

 :2thumbup:What's happening is either a faulty temperature sensor ,or a bad connection.Try cleaning first with contact cleaner and keep it greased lightly with Coppercoat or something
similar .If that dose not work test the sensor, I don't know the values but somebody should be able to help you.In an emergency in order to limp home you need to remove the fuel injection fuse ,if your battery is low remove and dry out plugs and cylinders.Replace plugs and start the motorcycle it will run with what fuel has been left in the cylinder. Now comes the tricky bit as the bike starts to die replace the fuse while its still running(An assistant does help).It will run ragged but judicious use of the throttle should get you home.
Regards Martin

[Martin]

A bit more information the temperature sensor is linked to the computer, and if you have a bad connection or a faulty sensor it will over fuel and flood the engine.A bad connection is the most likely fault.If you have small hands it is possible that by removing the air snorkel on the RH side and lifting the hose. You may be able to remove the spring retaining clip with a thin bit of wire with a hook on the end.Once you have done this you can remove the connector & clean it .It is advisable after cleaning to coat the connections with Coppercoat or dielectric grease.Just thought you might like to know the fuse for the pump is the 7.5A. Number six down from the top, mine is labelled in German Kraffstoffp.This will disable the fuel pump and allow you to burn off excess fuel.I have tried to take a couple of photos follow arrow, after removing snorkel and lifting hose look underneath & you should see the switch.I have seen this problem on 2 different motorcycle.
Regards Martin

[Liverpool Brick]

Excellent info Martin, thank you.
I'm off work tomorrow so will get back to the job and update asap.  :2thumbup:Andy

[Liverpool Brick]

Hi Folks,
SORTED! I think the problems I was having were due to either water ingress into the Jetronic plug or everything being dry after completely removing all the fuel. Anyway after drying out the excess fuel in the exhaust, charging the battery and unjamming the starter relay it started almost first push of the button. Thanks to everyone for their input, its much appreciated and keeps this site probably the best when it comes to shared know how.
Thanks again and keep 'er lit.
Andy :2thumbup: :riding:

[K1300S]

Yeah!

[Martin]

 :clap: It's always a relief when you solve a problem ,thanks for letting us know what it was.
Regards Martin.

[Elipten]

Ride man ride. It is the most important preventative maintenance