Can't get the engine started at every 2nd hot start

[CHB]

i've just completed my wiring and now i run into a new problem. the engine start right up at every first start. the whole system idle smooth and no problem observed. then i shut it off and check couple the datalog i've made. then when i plan to restart it again, the engine simply won't start. i have sparks and fuels, but the starting just don't happen.
then i pull the fuel pump fuse out and crank the engine, it started right up but dies immediately (as fuel pump is not running). put back the fuse, crank it and it fired up like having a set of new spark plug.
what would have gone wrong here?
by the way, my MS2 only control fuel as i run an external ignition system.
before this the engine run just fine, no problem at all.

[Vios-GT_07]

sounds very familiar to a problem i had, which turned out to be a faulty fuel pump..

it could also be your engine is flooding? and pulling out the fuse means fuel in the engine is burnt off, then run dry, then it runs properly again... but yea it doesn't explain why it doesn't flood the first time.. hmm..

[The Real Roadrunner]

try trimming the fuel down on cranking as it sounds like its flooding on startup. but check fuel pump control also it may not be firing on the second start up.

[The Real Roadrunner]

another thing could be a feedback ulse thru the injector which will flood cylinders during shutdown but its not overly common so i didn't think of it straight away.

[Grega]

when u get it going does it blow tonnes of black smoke (ie: unburnt fuel)

[CHB]

yes tons of black smoke.. i think i've fixed the problem but it still very to started up. i just Disable the After Start Enrichment. so far it still starting good all the time, but lazy..

[Grega]

you don't have a cold start injector which is being pulsed as well as the rest of the injectors perhaps, or, its flooding the engine at shutdown?

[kemicalx]

mm, Kind of sounds like your engine management is running as if every start is a cold start. ie.. it's dumping lots of fuel on startup.. so once it's up to operating temp it floods and probably fouls your plugs.

*shrugs*

Do you run an individual cold start injector or does it just trim up your normal injectors for cold starts? Can you specify in your MS2 the cold start fuel trim against coolant temperature points? (i presume you can) if so, what is it set at?

[oldcorollas]

you should follow the tuning manual (megamanual)

get it started, warm it up, then tune the idle areas and low throttle/rpm.
then turn off and turn the afterstart enrichment for hot.. then let it cool down and do the cold enrichment etc...

just do it methodically and stop stuffing around ;)

edit: this is of course assuming you don't have leaking injectors..