1985 k100Rs will not start

[aldan0392]

The injectors should pulse a stream of fuel, not a spit and not a mist.  Be careful with the rubber orings and you can just clean the injector screens and flush the injectors with carb cleaning solvent and compressed air.  i use a 5 Vdc power supply to open the injector while flushing solvent thru it with a syringe and small tube. 

I think I have found the problem and symptoms seem to match, I retested my Air Flow meter and it shows some unwanted results, will go to my friends place this sunday to test it, he has 93 k75, flow meter should be the same, will see how its going to go....

[aldan0392]

The injectors should pulse a stream of fuel, not a spit and not a mist.  Be careful with the rubber orings and you can just clean the injector screens and flush the injectors with carb cleaning solvent and compressed air.  i use a 5 Vdc power supply to open the injector while flushing solvent thru it with a syringe and small tube. 

I think I have found the problem and symptoms seem to match, I retested my Air Flow meter and it shows some unwanted results, will go to my friends place this sunday to test it, he has 93 k75, flow meter should be the same, will see how its going to go....

[aldan0392]

I think that I have found the problem, will see tomorrow, I retested the Air Flow Meter and I see some numbers not looking too good, tomorrow I spoke to the guy that has 93 k75 so I could come to his place and test my meter just by plugging in to his bike, if his bike will do the same thing as mine than I'll just go and get new flow meter. Also, I've read some Russian forums, and people say that it is common symptom for all late 80s German make car that use the same flow meters, cars just will not start, or have bad power, not stable idle... hopefully that would be it, parts are not expensive. Good thing is that I don't have any air leaks no more, so bike should run better than before lol))

[aldan0392]

Went to my friends place yesterday and plugged my flow meter to his k75, bike started like nothing happens, so my air flow meter is good. And at the same time I plugged the EFI module (silver box) to his bike, everything runs well. Gave the bike to the bike shop next to my work place, will see if they will be able to figure is out... If no, will pick it up and test every single wire under load to see if anything changes....

[kennybobby]

You may want to replace the fuel lines, it looks like the original line from the fuel pressure regulator return line back to the tank.  Any lines that have been previous-owner changed are suspect based upon fuel hose ratings.

i recently pulled some fuel lines that had swelled shut internally, likely due to the incompatibility with ethanol.  The exterior looked fine, but the rubber lining was just a soft gummy mess.  It's hideous what the ethanol has done to IC engine systems.  There are various specs of fuel line, SAE 30R6, 30R9, 30R11, etc, that are made for regular or pressurized lines and submersible lines.   Avoid the 30R6 for anything, even your lawnmower.

[Laitch]

You may want to replace the fuel lines, it looks like the original line from the fuel pressure regulator return line back to the tank.  Any lines that have been previous-owner changed are suspect based upon fuel hose ratings.

+1

Did you ever establish the current output of your battery when at rest, at idle and at speed—regardless of how old it is?

[aldan0392]

Here is more of what I have done so far.
BIKE STARTS WITH SOME QUICK START FLUID, If I get it to Idle it will start but as soon as I touch throttle it will cut off
*Compression: 134 - 140 All cylinders
*No vacuum leaks
*New intake manifold rubber boots
*New Vacuum cups on all cylinders (little rubber cups)
*New vacuum hose from intake manifold to transmission
*Fuel filter new
*Fuel pressure tested today (36psi connected Fuel Gauge in parallel), so my fuel pump, and my fuel pressure regulator are doing what they supposed to do
*Air Flow meter (tested my original on different bike, works) bought new one works the same way
*Temperature Sensor (I have 2, both working good, both tested)
*EFI module "silver box" plug it to different bike and works just fine
*Tested all wires that come to the "silver box" all of the get signal
*12v LED tested injectors THEY GET SIGNAL
*If i put 1000ohm resistor in series to the wire for the temperature sensor, so bike assumes that it is very cold it will start and Idle, and if I pull the injectors out they spit fuel. If bike thinks that is it very cold it trows lots of fuel, if I put everything back to normal it spits, but not much. (I assume my injectors are not clogged up if depending on temperature they throw more or less fue :dunno2:l)
*Little ball from fuel return line is out
*If I pull the plugs out they are wet

How does the bike understands at what RPM it is working? May be it is not getting signal, or it throws fuel, but at wrong time?
May be I'm getting spark, but at wrong time (but why it starts with quick start)
Any thoughts? I'm completely lost.....  :dunno2:

[Martin]

Make sure you have a good connection from the connector to the temperature sensor. It definitely sounds like it's temperature related.
Regards Martin.

[kennybobby]

The Jetronic gets the RPM signal from the Ignition Control Unit located behind the steering stem under the fuel tank.  The ICU gets Hall Effect Sensor signals of crankshaft position and from that can calculate top dead center and rpm to know when to fire the ignition, and it sends that signal to the jetronic box also to use for injection triggering.

Seems odd to have wet plugs but just spitting injectors with a good temperature sensor connected.

i would pull the injectors and check the screens for debris and bench test them to ensure they are not clogged.  Then inspect the rail and all fuel lines, thru the FPR back to the tank, plus fuel pump and filter, and also check for water and debris in the bottom of the fuel tank.  This is the only way to verify the integrity of the fuel system.  After that it is an electrical issue.