hard start after warming

[rmmchl]

after i drive my car for a while in the heat-I have to crank it a lot to get it to start.I ran the battery almost dead yestersday. it runs perfectly-just hard to start after its been running in the heat............any ideas?

[DavidBrough]

Could be caused by a number of things depending on which car/IP set up you have but firstly are you using any throttle at warm start as about ¼ throttle always works best for me. You may also want to try a quick squirt from the CSV (no more than 1 second). You can do this by either applying momentary power to the intake solenoid or earthing the TTS via the W pink wire terminal while cranking the starter. Always assuming you don’t have this already fitted.

[rmmchl]

its a 250sl

[DavidBrough]

OK, I think that means that you don’t have the relay to operate the CSV at all temperatures so test wiring it to give you a quick squirt when hot may be useful. Hot start problems are quite common and assuming everything else is OK and the car performs well once started this is usually due to fuel leakage from the injector lines back to the IP or evaporation in extreme heat. I replaced the ball pressure valves in my IP which made a big difference.

You can usually work round this type of hot fuelling problem by fitting a CSV cabin switch which allows manual operation of the CSV whenever required. Firstly locate the Thermo Time Switch on the left front side of the head and connect a wire to the W pink terminal and run to ground through a switch in the cabin. This will allow you to activate the CSV when hot and will only work whilst the starter motor is engaged. You can also achieve a similar result by running a switched live wire direct to the CSV solenoid on the intake manifold but this is not recommended for permanent use as the switch will operate the CSV whenever closed so could be set off accidentally. The earth method will only allow CSV operation whilst cranking the starter.

To test if this will help connect a wire to the TTS W Terminal and find a good earth inside the car, then connect a test light between the terminal on top of the CSV solenoid and earth. Hold the TTS earth wire to ground and start the car breaking the ground connection after about 1 second. As you crank the starter the TTS earth wire will allow power to the CSV and the test lamp will light so you know the CSV has been activated, once you break the earth the lamp will go out and hopefully the car will fire straight away. Don’t leave the earth connected for too long or you will flood the engine and also don’t forget to allow about ¼ throttle when hot activating the CSV. If the lamp doesn’t light then you have a problem with the CSV itself or your earth wire which could have a bad connection to the TTS or a poor ground in the cabin.

If this works it may be your answer and save you having to replace the ball pressure valves in the short/medium term.

[ja17]

Hello,

Make sure your fuel filter is clean. A partially plugged  filter will lower the fuel pressure in the system. When the engine is hot, the fuel injection will be at it's leanest settings since the WRD will cut back fuel as the engine coolant warms.  As you know, the engine coolant temp. rises  for a short time even after the engine is turned off. Fuel pressure and volume should be checked next.

Now the complexity begins.  There two different starting aids on the 230SL engine. An early version described as (Version II) and a latter version (labled Version III).  (Version I was used in earlier model sedans).  Both versions (II & III) had provisions for aiding hot starts.  Version III had improvements made for hot starting. We will need to fid out which system you have so we can diagnose your problem. You  will need a 12 volt test light or voltmeter to begin. Early 230SLs can be easily changed to the latter improved starting if needed. Are you ready to begin?

[George Des]

I have found that when my 230SL is cold i.e. upon first starting. I crank the engine with the foot off the accelerator pedal. It usually starts immediately. When it is hot, I re-start with the foot fully depressing the accelerator. Don't know why, but this works all the time.

George Des

[hkollan]

George,

Seems that you came to the same conclusion as the guys who wrote the Owner's manual did. ;-)
(at least for the 280, and I suspect it applies to the 230 and 250 as well) Cold engine - NO pedal, warm start - operate accelerator.

[jmvsl]

My 64 230 SL, warks as follow a bit of accelerator when cold and it start inmediately and none when Hot and start inmediately...  it works every time for me.