What is best electric fuel pump for 67 250 SL

[n/a]

What is the best choice for a replacement electric fuel pump on the 67 250 SL?  I would prefer to not spend a fortune; this is not a restoration, so function is my only concern.  I do want to be sure to have correct pressure and volume.

Brian Collins
Dallas, TX

Brian

[ja17]

Hello Brian,
Check with your local Bosch distributor. He may list a later bosch replacement pump as a substitute for a lot less money. Later fuel injected cars required even higher volumes and pressures so these pumps are capable of running these W113 engines. I have seen various substiutes work fine. I have also seen many fail miserably. Plan on doing a fuel pressure and volume check afterward or you will not succeed.
The biggest pitfall is to use a high pressure pump with not enough volume. The car will run fine for a while but then begins running poorly as time goes on. The next morning it runs fine again and the cycle repeats. Someone else out there may have a good combination to relate.
Myself I have substituted a (W107) 450-SL,SE etc. etc. (many models 1972- 1974) fuel pump and it has worked just fine in a W113 for many years. It is the early Bosch pump for the EFI (electronic fuel injection). It is fairly inexpensive new at the local Bosch distributor. This pump is about half the size of the original. It is feed fuel by gravity as are the originals. They have a spinning impellar which circulates large volumes of fuel at high pressures. These systems all have fuel continually circulating back to the fuel tank so large volumes of fuel are required. A little creative engineering is required to come up with a good hanging method. Remember these pumps are gravity feed fuel and should be hung with their fuel intakes nearly level with the bottom of the fuel tank.

The later CIS injected cars had an even stronger pump which substitutes for the earlier cars. So I suspect that any of these later Bosch fuel pumps are capable also. I think a minor modification was needed on these latest pumps to decrease the fuel pressure. I will have to research this. Anyway plan on doing the pressure reading and volume test. Keep us up to date! Good luck.

Joe Alexander
Blacklick, Ohio

[Bob G]

Joe:
If your a purist and want the factory orginal fuel pumps are they availible throught Mercedes and what should we expect to pay?

Bob Geco
1968 280SL

[ja17]

Hello Bob,
The originals are rebuildable in most cases and the rebuild kits (new brushes and some seals) are very inexpensive. Some suppliers offer rebuilt units exchange. The later version original units are available new from Mercedes. I am not sure what the current price is but I believe it to be somewhere between $500.00 and $700.00. I am sure Tom Hanson can input here.
A W108 Mercedes sedan donor car of that era can supply a good used or rebuildable spare! In fact you may be able to buy the whole car for less than a new pump!

Joe Alexander
Blacklick, Ohio

[George Des]

Both of the original pumps are rebuildable--depending upon how far gone they are. I've done a number of both types. The later style is definitely easier to rebuild because there are no ball bearings and it uses a completely different sealing system. The later type also has an armature that is constantly immersed in fuel which allows it to run both cleaner and cooler. The fuel actually carries away the brush carbon dust that so often chokes up the bearings on the earlier versions causing early failure. The major cause of failure of both these pumps is dirty fuel and allowing the pumps to sit idle for long periods of time. This causues the fuel to congeal and harden in the impeller and seal assemblies. What often happens is that once the impeller is stuck, efforts to run the motor either burn it out or destroy the mechanical seal arrnegment in the older pump. The major problem with rebuilding these--especially on cars that have seen hard winters--is getting the pump apart without breaking all the screws. The housings on both these pumps is alluminum alloy with steel screws and there is a natural tendency for these to "weld' themselves in place wqhen expsoed toa wet, salty winter environment. They torque off very easily. I've seen some very nasty specmiens though brought back to useful life with a little ingenuity and care. Bottom line--don't throw out your old pumps if you've got some time to play around in rebuilding them. Can give you some tips if you need them.

George Des

[hands_aus]

I rebuilt my old style pump with great advice from George Des.

MB wanted AUD $65.00 AND AUD $35.00 EACH for O-RINGS. I went to a local seal and bearing shop and bought petrol tolerant correct size O-RINGS  for $0.65 and $0.35 each plus bearings. Total price AUD $14.00 I didn't replace the bushes because I figured that they had another 37 years of wear in them. I could have bought generic bushes for AUD $25.00 a pair.

MB wants AUD $900.00 for the new style electric pump.

It was a project worth attempting myself because I had nothing to lose and lots of money to save and spend on some other project. There is always some other project!

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Naj ✝︎]

I Have following info on the pump from a W124 as used by our MB club SL advisor:

The Bosch number I was given for the pump is:
0 580 646 070.(Pressure 3 bar) However there is no eq. MB number for this.
Also look at this pump which has an MB eq:
Bosch...............MB
0 580 254 950....002 091 59 01  Late W124
Pressure also 3 bar

To make a good install, (See Picture)may also want to use:
124 478 12 40 Mounting Bracket
124 478 02 37 Dust Cover
124 478 02 82 Mounting ring 2 needed.

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naj

65 230SL
68 280SL

[n/a]

I called a local Wholesale Bosch distributor.  They stock a new Correct Bosch unit for $410.

Also can buy the unit from the 450 SL for $188 or the 280 SE 4.5 pump for about $350

I stopped at a local shop on the way home and they suggested a higher pressure Holley pump with an adjustable pressure regulator and seemed to think it would cost about $100.



Brian

[Shvegel]

I used the entire Bosch pump assembly out of an early Saab 900 including the mounting boot and the outlet fitting(79-82 I think). There are two versions of the Saab 900 pump assy the later one has a black tank assy at the lower end and the earlier one has just a screen at the end, this is the one you want. The Saab unit has a huge rubber boot where it attaches to the fuel tank(the top of the pump is out of the tank and the bottom is in) I cut the boot off the assembly(new pumps do not come with the boot)and just leave a strip of the boot and the hose clamp that attaches it to the pump. Then I cut the screen off the inlet leaving the plastic that covers the inlet fitting on the pump which makes the inlet the perfect size for the inlet hose on the car. I loosen the clamp and slide it over one of the three legs the original pump was mounted on and tighten the clamp. This makes a really nice,clean rubber mounting. All that is left is to attach the inlet hose and the outlet hose (the pump assy has a barbed "Banjo" fitting which I cut the original line off of) and a little rewiring and it has worked really well for the last 8k miles.
 I also have grafted a Bosch/Saab fuel pressure regulator into the outlet of my injection pump which incorporates an accumulator and check valve so my car will hold fuel pressure long after shut down. This has eliminated any hard starting issues and rarely do I have to crank the car for more than 2 or 3 seconds.

[Ben]

quote:which incorporates an accumulator and check valve so my car will hold fuel pressure long after shut down.

I'd be interested in hearing more about this. I usually prime the system first thing in the morning for about 10 seconds before cranking. It starts instantly if I do this but if I dont it cranks for an extra 5 seconds or so !

Where exactly did you put the valve, what does it look like. Has anyone else fitted one and if so what type and where ?

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Naj ✝︎]

Brian,
Please let us know which pump you choose to fit
naj

65 230SL
68 280SL

[n/a]

Years ago I had a 67 250SL- and no money. The pump quit, and after pricing a replacement Bosch pump, which I couldn't afford, I got the flow specs from Bosch and bought (from Jeg's or Summit Performance) the electric fuel pump from the Holley Pro-Jection EFI system. That was eight years ago or so- I think it is still running around in there. It worked fine. It cost about $110.

[hands_aus]

Brian,
If the existing pump is an MB original, why not try fixing it yourself?
Could be in-expensive and interesting too?
What have you got to lose?
If it doesn't work THEN buy a replacement pump.
As George Des and I said, these old style pumps are repairable.
Also they have correct pressure and flow rate for the car.

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[n/a]

I bought this car with an aftermarket fuel pump already on it and did not get the OE pump.

Brian

Brian

[hands_aus]

Thanks Brian.

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[n/a]

Here is the final follow up on my 250 SL fuel poor running and fuel pump swap.

Thanks to Dan who got me on the right track checking fuel Volume and pressures, and thanks to Will Samples for lending me his OE fuel pump that I happened to notice on his engine stand....that allowed me to determine that the car would run reliably once it had a proper fuel pump on it........It also allowed me to drive the car long enough to determine that the car had a faulty ignition switch that would intermittently shut the car down after hitting small road irregularities such as pot holes and expansion joints...........(no wonder this car could not be diagnosed properly by local shops)

Thanks to Pheroz Tenga who donated the 124 fuel pump sitting in his garage for possible swap candidate, my SL is now running and reliable.

Naj and Kieron gave me the tips on how to do the swap for a clean install and it came out great.  The rubber rings, mounting bracket and cover had to be ordered from Germany (twice)but were inexpensive and gave a professional look and mounted the pump in the perfect location.

I did have the output side of the pump tapped to accept an SAE thread hose nipple from Home Depot, also used a right angle elbow (I enlarged the bore a bit with my power drill) that cleaned up the routing of the output line and needed to also make up a hose reducer again from bits at "Home Depot's" plumbing department to make the transition from the fuel line exiting the fuel tank and meeting the larger diameter fuel hose entering the fuel pump.  

All threaded connections were wrapped in special petrol resistant teflon tape; again from the Home Depot building supply plumbing department.

Thanks To everyone who helped me along the way.

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Brian