Fuel pump dies - fuse blowing

[rwh]

On it's first long journey since I've restored it, our 230sl (#4523 - June '64) had an issue with the fuel pump and fuel pump fuse.  On the way to Monterey this past week to attend Legends of the Autobahn, the 100 mile mostly freeway journey there was uneventful -- car ran fine, no hesitation but the fuel gauge did misbehave (readings inaccurate and at times -- no reading at all). I'll deal with that later.  But the next day after arriving in Monterey, we drove the 5 miles from the hotel to Legends of the Autobahn and the car died just as we were pulling into the event.  The fuel pump fuse had blown. I replaced it and it drove fine for the next 20 miles of stop and go city driving.   Then, the fuse blew again. Replaced it and got back to the hotel 7 miles away no problem.  Next time we drove it - two days later, it was again a long, highway speed, uninterrupted journey home -- 100 miles. No problems. 

Any ideas as to why it blows the fuse after a few miles of stop and go city driving?  I will inspect the main fuel filter.  It has not been changed since  the engine was rebuilt 15 years ago -- 1600 miles ago.

RH

[Mike K]

It's most probably a result of dirty fuel; this causes jamming of the rotor vane in the fuel pump which then blows the fuse as the pump overheats. I had the same issue just after purchasing my 280SL a couple of years ago. I ended up replacing the 42 year old fuel pump as the rotary vane was completely pitted and scarred and the armature of the pump motor was finished.

Have a look at the Tech Manual, this is also described under "Background Information" : http://www.sl113.org/wiki/Fuel/FuelPumpRebuildLater

Best,

Mike

[Mike K]

Here's a pic of what happens to the fuel pump as a result of dirty fuel with debris. In my instance the fuel tank was corroding and the crud and rust was contaminating the fuel.
Also had to replace the fuel tank...

[rwh]

Thanks for the info. Two years ago the fuel pump failed and I removed it, and discovered quite a bit of hard, brown gel-like substance (the stuff they insulate the motor wire windings with had broken off) had clogged the pump. I cleared all that out, re-assembled the motor and it ran fine -- up until last week. I will inspect the current pump and the main filter to see what has happened and report back here. I will probably get a new pump just to eliminate it as a problem going forward.

[Mike K]

While you're at it, check the interior condition of your fuel tank as well, this could be another contributing factor.......

Mike