Cold start issues

[movenon]

From your figures I would replace the caps to start with.  How is your spark without the caps on ?  How ever that's not going to solve the low voltage problem.  You can't get voltage or current at the end if it's not there to start with.

I would go back to the beginning of the circuit how is your battery voltage?  Be aware that you can have voltage and not enough current.  A quick and dirty test is just use some jumper cables and jump from your car battery (assuming it is good).  I had a brand new battery once for the FJ that had good voltage but would fall flat on its ass under any load.  You did the jumper configuration and mentioned that it fired much quicker when you jumped it... IMO the weakest link and highest wear item is where it starts at,  the battery.  Resting voltage should be close to 12.7 volts for a good acid cell battery.

If you can get it running what is your charging voltage ? It should jump up to 13 plus volts. Max is 15 volts.

You can have voltage loss at any of the connectors. Even from the back side of the fuse box, interlocks, run stop switch etc.

In the end, yes you can have bad coil or coils but somehow I don't think they are that bad.  I might be wrong someone else can give there opinion on that.

Jumper the battery,  check to see how much spark you have without the plug cap on ?

Pick coils I think are just a switch control or signal for the CDI.  Will not effect low or high voltage. It is just a magnetic pulse.  If a coil is absolutely dead then there might be a signal or switch loss.  Pick up coil winding spec is 120 ohms +- 10%
George

[FJ_Hooligan]

How are you ohming the coils?  Are they completely disconnected?

[JMR]

Pickup coils 160 ohms manual says 132 max

Plug caps resistance 5k ohms manual says 1k max

Coils primary 3.8 and secondary 13k ohms . Manual says 3.2 max for primary, secondarys in spec.


Now when i test for spark im getting some spark from right coil but none from left. So i switched the inputs and put the right input on the left coil and got some spark also. Doesnt seem like much though.

Now cranking voltage at coil inputs is 10 volts on both inputs when going from positive to a ground, but if i go between the two input pins on the right coil i get a voltage whilst cranking but no voltage between two pins on left coil, not sure if that is normal?

Anyone got ideas where to go from here based on this info?

How are those readings different when the engine is hot? I posted earlier about checking valve clearances as valves that are too tight will make cold starting very very hard as the engine cannot build compression. Most folks are more interested in possible electrical issues rather than simple mechanical ones. (electrical problems have a more mystical quality I guess). While it may be electrical I have personally cured well over 100 "cold start" problems (when I owned my bike shop) with a simple valve adjustment.

[Flynt]

are you SURE all the "choke" mechanisms are working and are synchronized?  If they are not, you'll get pretty much exactly what you describe on the starting behavior...  spark issues aside.

Frank

[Fj.itis]

Would i have valve issues if I've got 160 psi across all 4? Valves done 2500 thou ago.

With out plug caps on spark was exactly the same.

Measuring coils with them disconnected.

Battery is lithium and putting out over 13 volt normal and voltage regulator is new and working fine. Battery kicks the motor over very quick as its 240 cca

I just let it cool again and come back out kicked it over with choke on but it didnt start then took choke off again and it started right away. Its like there is to much fuel for the spark when its on choke but then turn it off after fuel has dissipated a bit and it fires.

Is it normal for the choke to kill the engine when you turn it on when engine is warm? It sounds like the choke is flooding engine.

[Fj.itis]

are you SURE all the "choke" mechanisms are working and are synchronized?  If they are not, you'll get pretty much exactly what you describe on the starting behavior...  spark issues aside.

Frank

Yeah i had the carbs off two days ago and could see the plungers moving in and out as i played with choke. Not sure on the synchronised thing but they are all moving together. Is it possible to be letting to much fuel in as if i leave choke on while cranking it will backfire like there is to much unburnt fuel in there.

[movenon]

Would i have valve issues if I've got 160 psi across all 4? Valves done 2500 thou ago.

With out plug caps on spark was exactly the same.

Measuring coils with them disconnected.

Battery is lithium and putting out over 13 volt normal and voltage regulator is new and working fine. Battery kicks the motor over very quick as its 240 cca

I just let it cool again and come back out kicked it over with choke on but it didnt start then took choke off again and it started right away. Its like there is to much fuel for the spark when its on choke but then turn it off after fuel has dissipated a bit and it fires.

Is it normal for the choke to kill the engine when you turn it on when engine is warm? It sounds like the choke is flooding engine.

160 psi, damn, you wanta trade.... .   

Have you done a plug reading?  And you are sure that all the choke plungers are seated in all the way..

Why do you want the choke on when the engine is warm ?  I guess you can flood it that way, certainly run like crap. I only need my choke on when stone cold.  After it has been running I can start it an hour later without the choke.

George

[Fj.itis]

Would i have valve issues if I've got 160 psi across all 4? Valves done 2500 thou ago.

With out plug caps on spark was exactly the same.

Measuring coils with them disconnected.

Battery is lithium and putting out over 13 volt normal and voltage regulator is new and working fine. Battery kicks the motor over very quick as its 240 cca

I just let it cool again and come back out kicked it over with choke on but it didnt start then took choke off again and it started right away. Its like there is to much fuel for the spark when its on choke but then turn it off after fuel has dissipated a bit and it fires.

Is it normal for the choke to kill the engine when you turn it on when engine is warm? It sounds like the choke is flooding engine.

160 psi, damn, you wanta trade.... .   

Have you done a plug reading?  And you are sure that all the choke plungers are seated in all the way..

Why do you want the choke on when the engine is warm ?  I guess you can flood it that way, certainly run like crap. I only need my choke on when stone cold.  After it has been running I can start it an hour later without the choke.

George

Yeah plugs read fine after a good ride, there is nothing wrong with the bike other than this cold start issue that has just surfaced. Choke plungers cant be pushed in anymore when choke is off, so im assuming they are seated. The problem seems to be when cold and choke is on, bike doesnt want to go.

I dont want the choke on when warm just trying to ascertain if that it is normal function which im sure it is, as it pumps the fuel in there, so definitely not blocked and have no idle issues at all.

[Dogsbestfriend]

I know that I keep saying it but try cleaning up the main earth on the back of the engine or do like I did and fix an extra earth to the starter mount. My 3cv turned into a hissy mare overnight. One day starting and running well and then nothing or spitting and banging while firing on odd cylinders. It took me several days to find the problem and five minutes to fix it.

[movenon]

Would i have valve issues if I've got 160 psi across all 4? Valves done 2500 thou ago.

With out plug caps on spark was exactly the same.

Measuring coils with them disconnected.

Battery is lithium and putting out over 13 volt normal and voltage regulator is new and working fine. Battery kicks the motor over very quick as its 240 cca

I just let it cool again and come back out kicked it over with choke on but it didnt start then took choke off again and it started right away. Its like there is to much fuel for the spark when its on choke but then turn it off after fuel has dissipated a bit and it fires.

Is it normal for the choke to kill the engine when you turn it on when engine is warm? It sounds like the choke is flooding engine.

160 psi, damn, you wanta trade.... .   

Have you done a plug reading?  And you are sure that all the choke plungers are seated in all the way..

Why do you want the choke on when the engine is warm ?  I guess you can flood it that way, certainly run like crap. I only need my choke on when stone cold.  After it has been running I can start it an hour later without the choke.

George

Yeah plugs read fine after a good ride, there is nothing wrong with the bike other than this cold start issue that has just surfaced. Choke plungers cant be pushed in anymore when choke is off, so im assuming they are seated. The problem seems to be when cold and choke is on, bike doesnt want to go.

I dont want the choke on when warm just trying to ascertain if that it is normal function which im sure it is, as it pumps the fuel in there, so definitely not blocked and have no idle issues at all.

Hard to trouble shot via the internet sometimes  Here is a picture of how those 4 plungers should look when all the way in.

George

[FJ_Hooligan]

The 4 hoses that aren't there anymore.  Are they still open to atmosphere? 

[Fj.itis]

Yeah still open.

Plungers are well seated going off that pic.

I would of thought if it was a fuel issue, id have problems even when warm. The spark this thing produces is really faint, anyone care to pull a plug and see what their spark looks like? Maybe a photo if possible?

[FJ_Hooligan]

Years ago, I recall someone smarter than me posting that the CDI ignition will not produce a big fat spark.

Is that an "all or nothing" symptom?  IOW, does it try to run off of 2 cylinders like it's dropping one of the coils?

Or, does it just not want to run on any cylinders when the choke is on?

[Fj.itis]

Nah not dropping any cylinders, just no signs of life when cold cranking and choke is on. Have to turn choke on and off to get it to fire. The last time i tried just jumping it from car with choke on and it still wouldn't fire, as soon as i turned choke off no throttle it fired right up.

Im going to borrow a set of coils just to humour myself and at least eliminate one potential problem, will post back and let you know what happens.

Thanks guys for all your input really appreciate and take on board all suggestions.

[movenon]

Nah not dropping any cylinders, just no signs of life when cold cranking and choke is on. Have to turn choke on and off to get it to fire. The last time i tried just jumping it from car with choke on and it still wouldn't fire, as soon as i turned choke off no throttle it fired right up.

Im going to borrow a set of coils just to humour myself and at least eliminate one potential problem, will post back and let you know what happens.

Thanks guys for all your input really appreciate and take on board all suggestions.

Without looking at the wiring diagram the 12 volt line (R/W) might have to travel trough the clutch switch and possably the run/stop switch ?  If they do you might clean them up or for a test just bypass ?
George