No gas!

[ted280sl]

I drove my 1969 280sl about 10 miles and the engine cut out. It seems the engine was not getting gas. After the car sat for 2 hours it stared right up. I filled up the tank and it did not change anything.
I have drained the tank in the past and cleaned the screen. Any thoughts about what could be causing this problem would be appreciated.
Thanks,
Ted
1969 280sl

[Bonnyboy]

This sounds very typical of a blocked fuel line - REMEMBER GASOLINE IS VARY FLAMABLE SO BE CAREFUL - double check the fuel tank to make sure its not full of scale or crud - then double check the flowerpot in the tank - it doesn't take much to start blocking the outlet to the fuel pump   I would then pull the rear return line off the tank and see if you get the required amount of flow and pressure (I can't remember PRESSURE and VOLUME but its in the archives) of gasoline when the fuel pump is on - if you don't get that volume go to the outlet of the fuel pump and check that and then work along the line to figure out where the blockage is.   There is a lot of flow going back in the tank so if it comes out with required flow out of the pump and not back into the tank there is a blockage -  .   

My maiden drive ended up on the back of a flat bed -  I thought my tank was clean but it really wasn't - so once I got back I took my tank to the rad shop and they cleaned it without killing the flower pot - then I checked output at fuel pump and found it to be low - I replaced the pump and still had issues after pump replacement so then I went to the return into the tank and realized I had another issue.  I found a kinked fuel line under a rubber grommet/strap all covered with undercoating.   I put a new solid fuel line in and all was good.   I had three issues - not just one. 
 

[BaronYoungman]

The rust particles can start swirling around get sucked into the screen and eventually block it, then when pressure falls by you turning off the car the rust falls back down, then the cycle repeats itself.  I suggest a clear (see through) inline fuel filter (Napa has a nice one) put between the tank and the fuel pump.  Check it every few months for rust, you see rust there you know you have rust in system.  Bob

[specracer]

Also if you have a "long" fuel pump, there is an inlet screen.

[Pawel66]

I was just going through this journey...

You have one filter in the tank, another in the inlet of the fuel pump (most likely), the third at the engine. Check all three, replace the filter element in the main one (at the engine).

To get to the filter in the inlet of the fuel pump you need a socket or a spanner 27mm or 24mm depending on the pump type, if I remember correctly. It may be difficult to unscrew this inlet fitting - I used the air impact wrench to do it.

I would strongly recommend (as in the post below) installing a flow-through filter between the tank and the fuel pump. Just make sure you buy one that has the 10mm fittings - to fit your fuel lines.

Then once all of this is done, you may want to check the fuel flow at the end of the return line - approx 0.8 to a liter in 15 seconds. If this does not happen, there is a blockage in the fuel lines or the pump does not pump.

[specracer]

Very true, I had mine out so could properly brace it. If its in the car, you will likely tear the rubber mounts, trying to use a wrench.

It may be difficult to unscrew this inlet fitting - I used the air impact wrench to do it.

[mdsalemi]

Hi Ted,

I had a similar if not identical problem some years ago. Turned out I had three separate issues, all with inter-related consequences.

1. Deteriorating fuel tank. If yours is the original you can be certain that fine rust particles will cause you an issue.
2. Compromised wiring to fuel feed pump. During the restoration, the restorer cut the wires to the fuel feed pump. When putting back together, he used wire crimp fittings. Great for a few years, but after a while they corroded, providing intermittent voltage to the pump. It doesn't like that...
3. Crane ignition shutter wheel contacting wires INSIDE distributor. Yes, as soon as this shutter wheel contacted the wires, it stopped turning and the engine died. Turned out the mechanic used the wrong size shutter wheel, too big for that -050, and after years of operating fine, it stopped.

Notice that two of those three issues were electrical...which all manifested the exact same "engine dying" situation.

I am constantly reminded of the old mechanic's saying that "Carburetor is a French word that means 'it's the electrical system', stupid" Found that gem in a repair manual on an old [British] Austin/MG car we once had.  Those SU carbs, weird as they were, rarely failed, but boy oh boy those Lucas electrical systems...So, always think there might be an electrical gremlin behind your issue!

[Tyler S]

Also if you have a "long" fuel pump, there is an inlet screen.

The short pump also has this inlet screen. You can usually tell if there is a restriction or starvation issue between the tank and the pump as the telltale pump whine disappears when the pump is running.

[ted280sl]

It seems the engine will run for approximately 15 minutes and then it dies. I was advised the fuel pump stops running and to first replace the relay as it might be failing. If that does not work to replace the fuel pump. Any expert advice would be appreciated.
Off the road for months.
Ted 280sl 1969

[Pawel66]

Ted, it is indeed very easy to notice that fuel pump stopped - you just do not hear it any more.

There is no relay to fuel pump. It is just powered from fuse No. 4 directly.

The others will chime in, but if indeed the fuel pump stops working after 15 minutes and its wiring is ok, then it may need refurbishing perhaps.

There are Members here who can help if the need for refurbishing is confirmed.

[rusty747]

Hi Ted
Just noticed a listing in 'Items For Sale" for a fuel pump that may be suitable for your car
Regards Rusty

[ted280sl]

It seems our cars have some minor differences. My 1969 US model has a time delay relay between the fuse and the fuel pump. After 15 minutes the pump shuts down and there is no power running to the fuel pump. It seems the time delay relay is no longer available. Any additional suggestions would be helpful.
Thanks,
Ted 280sl

[Pawel66]

Ted, I looked also at 280SL US Wiring Diagram, one that I have in the cupboard and one that is generally available in Technical Manual, where everybody can go. I found no relay. But if indeed on some cars the relays were installed - sorry.

In this case it may be quite simple to bypass this relay and see if it works perhaps..