W113 Pagoda SL Group > Drive train, fuel, suspension, steering & brakes

280SL 1968 won't start.

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Thierry du Laos:
Hi, my car had problems to start 4 months ago, and when she started, she ran on 4 cylinders. I had to go abroad 2 months, but when i came back she won't start anymore.
Ignition is correct, but when I open an injector line and crank, there is no fuel coming.
When I disconect the fuel line at inlet of the fuel injection pump the fuel comes out.
When I disconnect at the outlet of the injection pump, there is fuel also.
So I wonder what happens in the injection pump?
At the back of the injection pump there is two big solenoids. I believe there is one to open the fuel at start, but what is the second one for?
When I put 12 Volts at the upper one, I can hear it is moving!
Any suggestion?
How do these two solenoids work?
Thanks.

mrfatboy:
It sounds like some of your injection pump plungers are stuck.  I will let the pros chime in here to tell you how to test and fix since I have not done it before. You can also search on how to do the procedure on this forum.

The upper solenoid is the fuel enrichment solenoid. It always activates when the key is turned when starting. 

The lower solenoid is the fuel cut off solenoid that I believe activates when in 3rd or 4th gear AND when the throttle is not depressed. There is a microswitch on the left side firewall connected to the throttle linkage that detects no throttle.

ja17:
Hello Thierry,

If you have spark on time, fuel supply with adequate pressure and volume, and compression, your engine will star. A fresh set of spark plugs is a good and inexpensive place to begin, check fuel pressure and volume also.  You can check to make sure your injection pump is free by moving the rack back and forth, it should move freely. Yes the lower solenoid is a fuel shut-off emission device. If it is activated when the engine is off, the engine will not start. You can temporarily dis-connect it with no consequence.

Thierry du Laos:
Thanks for these great informations.
There is spark and I put a new set of spark plugs in when I finished to rebuild the car, not long ago.
I will check the lower solenoid this weekend. I just checked the upper one, so far.
And a scily question is: How do you move the rack? Is it through the control lever ( that is connected to the external control linkage)?

mrfatboy:
On the front of the pump (pointing to radiator) there is a black rubber cap that is covering the rack access hole.  You may or may not have the cap after all these years.

You can insert a 5mm bolt (memory?) into the access hole and screw it in. From there you should be able to push and pull the rack easily if it is moving freely.  The bolt should be about 30mm in length or so.

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