Hot Start problems

[rustyvolvo]

My 450 is having issues with warm/hot starts.  Started all winter without any issues but summer weather is returning to the prairies and now it won't start unless it has been sitting for an hour or so, even after a short drive.  It starts fine cold and there are no drivability issues.  When the engine won't start the starter acts oddly.  When I rotate the key position to start, the engine cranks normally.  If it doesn't  start after a few rotations I let go of the key and allow it to return to the run position.  When the key returns to the run position the starter continues to crank the engine over at the same speed.  If I turn the the key to the Acc position the starter will stop.  Once the car sits for about an hour it will start within two rotations of the engine and run completely normally.  Any ideas where to start looking?  Thanks.

[Willys]

I would hazard a guess and say the starter has either a bad connection either power or ground or the starter is on it's way out, sad to say.  Check the ground from engine to body which is at the rear of engine and attaches to body behind engine, it's a braided corroded wire which usually disintergrates when old.   IF it is key related as you are somewhat hinting at.....I'd spray some lube down the key hole and work the tumblers well. Not grease but more fluid type lube...lol.
Hope this helps...?   Changing the starter isn't a fun job unless you lower the sub frame and get real room to get your hands where they need to get to.

[Mjolinor]

 

It is normal behavior for smart cars to do that. You only need to hold it in the "start" position for a moment and it will turn over until the engine starts unless you turn the key off the run position. They are all like that.

 

In your case ( in my opinion) the crank position sensor is faulty, replace that and you are good to go.

 

 

[MikeT]

Yes, just flick the key once and if the engine is well it will start, no need to hold the key in the "start" position.

 

Your fuel pump circuit in the SAM may be going, so best to get an external relay in there pronto. And for the two low beams too.

[rustyvolvo]

My car has always started within a couple rotations so I didn't realize that it would continue to crank until it started on its own.  Kind of embarrassed I didn't know that now.  OK so check crank position sensor and fuel pump circuit in the SAM.  The low pressure fuel pump always hums for about 5 seconds before I go to crank it even if it does not start when hot. I can check the ignition switch as well.  Thanks for the suggestions.

[Mjolinor]

You can't check the crank sensor other than to prove by replacement.

 

They rarely store fault codes and usually work when cold but stop working when hot which is what yours seems to be doing.

 

They are cheap enough not to worry about but can be stressful to change.

[Willys]

4 hours ago, Mjolinor said:

They are cheap enough not to worry about but can be stressful to change.

IMHO, this is one of the nastiest jobs if things don't go well....just saying....check EVERYTHING else before going after this job....just my bent nickle's worth....take it or leave it.
Open up San, check all connections in the engine bay for issues, corrosion bent pins, not pushed in all the way, anything.....if that crankcase sensor is seized into the bell housing, you are in for a fight!
It can be tested I think double check here and over at Evilution for a test such as continuity or a pin out check, I'm sure I have done this but can't remember well enough to suggest how, yes I'm getting very old and forgetful......augh!!!!!!  It is just basically a magnetic type switch after all...