Flooding when starting cold (below 45F). Possible causes? (Page 1/1)
cebix OCT 28, 05:10 AM
'85 duke auto w/AC.

I have this thing when starting cold and on a cold day (about 45F and below) and I can't pinpoint what's causing this.

It'll start after a few cranks like everything's fine but die almost instantly. Then it won't start on its own, I can crank forever, unless I floor the gas pedal so it'll clear out the flood - so just a few cranks more with the pedal floored and it starts up. Then it'll misfire pretty badly for a few seconds like it's missing on one or even two cylinders until it settles for the idle. This lasts just a few seconds and then it runs great all day.

Like clockwork every morning the same thing. Has anybody had a similiar problem? Where to start looking?
cebix NOV 01, 11:01 AM
Bump. Anybody? A slightest clue?
fieroguru NOV 01, 12:13 PM
During cold starts, the ecm relies on the air temp, coolant temp, MAP and stored values in various tables for fuel, spark etc. There is no ecm feedback loop, so if you are seeing an overly rich air fuel ratio, then I would start the focus on what would cause that.

A rich condition can be caused by:
Excessive fuel (leaking injector, high fuel pressure (clogged regulator or return line, etc))
Insufficient air (clogged air filter, clogged cat, etc)
Sensor driven enrichment (usually temp sensor reading a much cooler than actual temp, could also be the MAP reading a vacuum leak as more engine load, could also be the TPS set too high so the ECM isn't operating with the idle parameters).

I would check for leaking injector (maybe the seals leak more when cold),
Verify fuel pressure,
Check for a dirty air filter (try the startup one morning w/o the air filter),
Check for clogged cat (remove the O2 sensor from the pipe, but leave it connected and do a cold start to see if it stays running - don't run it long)
Check the air and coolant temp sensors (on cold start, measure their resistance values and then look them up for the corresponding temps).
Check TPS voltage closed and open.
Check for vacuum leaks
Swap out the MAP with a known good one (not a really good way to check).
cebix JUN 14, 05:36 PM
It's an old post but for future reference I recently fixed this problem.

It was the fuel injector. I replaced it since all other things failed and that cured it. The old one wasn't leaking and just by looking at it the spray pattern looks the same to me. Never really tested the injector itself.

It cranks twice as long now (weird) but never floods. Starts first time and runs, no stalling.

[This message has been edited by cebix (edited 06-14-2020).]