On Tuesday, October 3, 2000 at 12:00:00 AM UTC-7, RD Thompson wrote:
> I have a Mercedes '78 450SL with CIS fuel injection that has spent
> more time sitting than driving (which is part of the problem, I
> presume).
>
> Anyway, my problem is hard starting when it is hot. When the car is
> cold it starts with no problem.. Just cranks a bit and fires off.
> When it is hot and you let it sit for more than a few minutes, it has
> to crank a long time before it will start and run. It gives a short
> burst as soon as you try it, but it is not enough to sustain it.
> After that initial burst, you need to crank a long time. (Thank God,
> or whoever, for good batteries). Lately, it seems to give a aarrgh
> aarrgh type of noise out of the engine compartment for a few seconds
> after it is shut off, but it does not last long enough for me to pin
> down where it is coming from although it does seem to come from the
> passenger side of the engine compartment.
>
> I think my problem is a dropping of the fuel pressure (I have no gauge
> way of measuring it) which lets the fuel drain out of the lines and
> then it vapor locks leaving me to crank on the starter until the fuel
> pump can overcome that vapor lock.
>
> I have replaced the fuel pump and fuel filter.....no change....the
> pressure regulator in the fuel distributor...no change and put new O
> rings in the injectors.....ditto.
>
> My next attack will be on the cold start valve although cold(?)
> starting is fine. Also, do the injectors maintain pressure at the
> injector itself or is it at the fuel distributor?
>
> What I need to know is if I am on the right track and if anyone has
> any other ideas. Parts replacement at a hundred bucks or more for
> each part sucks.
>
> Except for the warm hard starting problem, the car is a joy to drive
> and really has comparatively few miles on it.
>
>
> Thanks in advance.
>
> RD