Seriously bad question about fuses

[befunone]

I think this question will support why I am a "junior". I have 1966 euro 230sl. I am going through the car after it sat for three years.

Today at the shop, I took the fuse cover off. Fuse # 4 was blown. Indicates for fuel pump. Fuse #3 was fine. Appears to be also fuel pump. How is the fuel pump working if #4 fuse blown? Is #3 fuse a back up? We checked fuel pump and it has factory wiring.

Hmmm...

Thanks,

Ty

[georgem]

Ty,

Are you counting from the right end?

[66andBlue]

... Fuse #3 was fine. Appears to be also fuel pump.

Who says 
#3 controls the automatic transmission if you have one.
See: http://www.sl113.org/wiki/Electrical/Fuses

[Richard Madison]

Not an expert although I did have a recent wrestling match with a shorting Fog Light fuse which I managed to correct.

The Wiring Diagram for the 280SL shows #4 fuse going to the Fuel pump...#3 terminates and goes nowhere. I assume the diagram is for a manual shift car.  #3 has no connection in Manual car.

If the wiring is the same for your car, you have a logical impasse. If the wiring is original AND follows the diagram, the fuel pump should not work when #4 is blown. Perhaps you are counting from the wrong end (the diagram in the fuse cover shows the correct numbers)...or the wring path may have been changed as on many of these cars.

Richard M, NYC

[befunone]

Thanks to those that gave advice.

Recived new fuses in the mail yesterday. Went to he mechanics and put the fuse in. I did not get shocked and the car did not catch on fire LOL (inside joke to bad past experience playing with fuses)

What did happen was amazing. When I started the car, it started even beofe I had a chance to pump the gas. I thought this was a fluke, so I started the car again. Me and my father laughed and he commented it starts better then my 2009 cls550.

Here is the rub, neither of us drove the car for the last four years because while it always started, you had to pump the gas pedal and hope not to flood the FI if that is possible.  We figured we were just getting lazy. We have no idea how long the fuse has been burnt, but the car will start without the fuse, just not with a turn of the key.

We are excited to drive it next week to see if it has more power also because fuel pump is working again.

Best,

Ty

[George Des]

Sounds like the fuse you replaced was the one controlling the cold start device on the manifold. That would explain why you had to pump the accelerator before you replaced it.

George Des

[twistedtree]

I don't think pumping the gas peddle on a fuel injected car does anything.  On many carburetor cars there is literally a small pump in the carb that squirts gas down the manifold when you pump the throttle.  But not with fuel injection - that's what the cold start valve is for.

[ja17]

Hello,

Pumping a fuel injected car does very little. However, a lower position of the accellerator pedal  while cranking the engine, on these IPs, will move the rack to a richer position increasing the fuel delivery at the injectors slightly. This is a procedure which should not be needed but can be used to slight advantage, if you have other starting system issues.

You should be able to reach in the window and turn the key for an instant start hot or cold, without any accellerator pedal at all. The enigne should start and continue to run smoothly all during warm up. For best results, gently driving off during warm up is best for your spark plugs and engine in the long run.