Cold start simply takes too long.

[mail2neil]

Hi Chaps,
Got a minor problem with my '88 300E W124 M103 200k miles.

When I start the car in the morning, or after it hasn't been started for a while, its just simply takes too long.
It'll always start firsts time, but there's just too much whirrrerrerrerrerrrerrererrere before the brrrruruuuummmm.. if you know what I mean? :?
(I'm after a whirr'k'k'brooom).

Now, in the last month I've serviced and cleaned the engine.
The HT leads, sparks, oil etc are all new.
So, I reckon ignition coil or timing..

What'd'ya think?
Any advice?

 

[mail2neil]

update;-

Just tested the ignition coil with one of those clever sparky Lucas things - no problems.

Now I'm thinking Ignition timing, or perhaps initial pre-start fuel pump mechanisms?

 

[Spike]

Fuel pump relays often misbehave on W124's but aren't cheap (about £80 IIRC) Can you hear the pump priming on the first click of the key?

You could test the timing using a cheap strobe light from Gunsons.

Just wondering if your cold start mechanism is working as it should and that all your vacuum hoses are correctly sealed.

I think you are on the right lines though.

 

[guydewdney]

there is a fuel pump non-return valve taht may be leaking...

try turning the ign off and on a few times befrore the next start (i.e. to pos 2 not 3(start) to get the fuel pressure up

if that works - it may be said valve..

 

[Nightsoil]

My 300E 24V does the same thing - only randomly :?: sometimes it fires up instantly and sometimes it has to turn over a few times :?:

I'm experimenting at the moment to see if it's fuel related by leaving ignition at #2 to get fuel pressure right up before starting..

 

[mail2neil]

My 300E 24V does the same thing - only randomly :?: sometimes it fires up instantly and sometimes it has to turn over a few times :?:

I'm experimenting at the moment to see if it's fuel related by leaving ignition at #2 to get fuel pressure right up before starting..

But the pump only builds up pressure for a fixed amount of time doesn't it? Thus, leaving it on 2 will just allow fuel to return should the valve theory be correct. The way to go, must be to turn it to 2, wait for the whirring, turn back to 1, and repeat a few times, then start??

My car only takes a while when its been left for a while, so first experiment will be tomorrow morning - I'll report back.

 

[mail2neil]

update

..Tried the 2 position fuel pump four times this morning in a row, then tried to start the car.. sounds slightly different, but still doesn't start instantly.
I will try and borrow a strobe next.

 

[guydewdney]

can you hear the fuel pump buzz for a few seconds each time?

can you borrow a fuel pressure meter?

 

[mail2neil]

Yeah, I hear it buzz..
I'll try and find someone with a meter.

 

[Arnie]

I've had the same problem on a '97 300GE since acquiring the vehicle, a year and a half old. I have tried everything except tweak the injection system mixture enrichment screw, which a friend said was the problem from experience with his E300. In the early days, the dealer also had a few goes while still under warranty, but to no avail.

I've tried all the things ususlly mentioned such as plugs, leads, distributer, fuel pump and the Fuel Pump Relay to no avail, so I'd really like to know what else it could be before I mess with the ingejtion settings.

Funny thing is that I know someone with a similar, but much older and more neglected car that always starts on the frst click of the key, no matter what.