TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. > The Motobrick Workshop

Spark and fuel but still no start????

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TommyT:
I need some help figuring out a no start problem with my 1990 K75S, 48 k miles. My bike started to miss at the very end of 100 mile ride in hot weather. During the last 2 miles the bike started to miss, at first slightly and it got worst, I would give it gas and it would start to go and then hiccup, miss, go, hiccup to the point I could not give it much gas under load. I limped it home and turn the bike off and left it til the next day. I tried to start it and there was no life at all, not even a sputter.

I was pretty sure it was fuel problem but I first checked for spark, that's good, also the plug was dry. I then check for fuel and pressure at the injector rail, 36 psi...good. I read that the Halls sensor can go bad when the bike gets hot, so I changed that after I read this:"The I.C.U. is in control of the L.E Jetronic. the fuel injectors are triggered by the Halleffect sensor(s) (Camshaft Position Sensors or Hallsensors) same as the ignition coils. The Fuel Injectors activate after the Hallsensors give there signal to the I.C.U. then to the L.E. Jetronic giving signal to ground the circuit for the Fuel Injectors. " But the new Hall sensor did not change anything. I would guess that injectors are not firing, since the plug was dry and I smell no gas while I try to start it. What should I check next???

TommyT:
4 pin plug, I cleaned it when I had the tank off..besides does that control the function of the fuel pump? I have 36 psi at the injector rail.

Laitch:

--- Quote from: TommyT on July 21, 2019, 09:16:31 PM ---4 pin plug, I cleaned it when I had the tank off..besides does that control the function of the fuel pump?
--- End quote ---
Yes. It supplies current to operate it.

 
--- Quote from: TommyT on July 21, 2019, 08:55:25 PM --- I would guess that injectors are not firing, since the plug was dry and I smell no gas while I try to start it. What should I check next???
--- End quote ---
Check the fuel injectors' function. Are you following a troubleshooting guide?

The Mighty Gryphon:
Loose connector at the Jetronic?  Seems to be lot of that going around lately.

TommyT:

 Check the fuel injectors' function. Are you following a troubleshooting guide?
[/quote]

Fuel injectors function check....pull a electrical connect and check for voltage jump on a pin in the connector while trying the starter?

No not following a guide, I usually do the check for spark/fuel and then work my down the path of the failure of those. I looked at the top reason list here on MB for no start. Cleaned the 4 pin, did the starter cleaning trick, ignition switch seems good, never had any random electrical problems in the past, up til now it has been solid since I owned it for over 5,000 miles. Is there a more detail guide here on MB I should follow?

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