CBR starting problem after installing alarm

dave.999 · Derestricted Danger Joined: 23 May 2016 Karma :

Hopefully you guys can help me cos i'm really out of ideas.
I have bought new alarm with immobiliser and tried to install it on my CBR 125. Everything looked well until I started the engine and open the throttle the engine slowly died.
When i put a spare battery in I was able to drive about 200metres and then it died. After it dies it wont start for a few minutes even with the charger leads connected. When it start if Im not touching the throttle it will run for maybe 30 seconds, if I open the throttle it dies very quickly.
I have checked the voltage on the battery and when the engine is running its 1-2V higher so the generator is working. When I checked the voltage on the ignition coil it also grows as the revs grow.
I know that I have touched lots of connections installing the alarm but now I have took it out checked all the connections twice and really cant find anything. I have also cleaned the air filter having the tank off but don't if that could affect something.
Any suggestions where should I look for the problem or how can i test it?

jaffa90 · World Chat Champion Joined: 06 Apr 2016 Karma :

Which alarm and is it carbed or fuel injected?

V2 · Nearly there... Joined: 06 Feb 2006 Karma :

If you had the tank off, pinched fuel line?? Random stab in the dark!

dave.999 · Derestricted Danger Joined: 23 May 2016 Karma :

V2 · Nearly there... Joined: 06 Feb 2006 Karma :

if its pinched it would start until the fuel ran out in the carb then it would stop until the carb slowly filled up through the now restricted fuel line.... Unless its FI, Worth a check though before you start buying and swapping bits!

jaffa90 · World Chat Champion Joined: 06 Apr 2016 Karma :

A cheap alarm has 2 wire connection,
any case is the vacuum pipe connected from the carb inlet manifold to the fuel tap ?

dave.999 · Derestricted Danger Joined: 23 May 2016 Karma :

I have checked the pipes and they are ok. When the engine was running i took off the vacuum pipe and there was good suction. Fuel pipe wouldnt fit where vacuum pipe goes.
I have noticed that the longer I leave the bike for longer it runs, when I left it overnight it run for about 5 mins. So thats right the fuel gets there very slowly.
Which part do you think can cause this? Is there any good way to test the petcock?

neptune8 · Nova Slayer Joined: 22 Nov 2016 Karma :

Could be a blocked vent hole in the fuel cap. Run it until it stops, and then quickly open fuel filler cap. If it is hard to open due to vacuum in the tank, then your vent hole is blocked.
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V2 · Nearly there... Joined: 06 Feb 2006 Karma :

Definitely sounds like fuel starvation, Either as above or run it with the cap open and see if the problem goes away, only way to test the tap is to pull the pipe off and see what flow you get out of it! Should come pissing out to use the correct term!