I have not bought from them, but I believe that is Bosch's on-line site. If you search for the Bosch number (ending with 999), you may find other sellers in Europe at slightly lower prices. May be worth comparing freight costs.

Kind of odd that Bosch USA don't market that pump. But it may be same pump that dealers of Classic Centre sell under the MB part number.

ADDED: Did a quick check and this seller in Ireland seems to have good prices and low shipping cost.
https://secure.micksgarage.com/proddetails.aspx?pid=1381733&pk=A7501 The picture appears to be of the original pump, not the 999 pump.

It would be interesting to know which pump this on line seller sells as A0010917101.
http://www.oediscountparts.com/parts/index.cfm?make=Mercedes-Benz&year=&searchText=0010917101&action=oePartSearch&siteid=215242

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Found internal relief valve set pressure on line so using this thread to save it:


This is what Robert Bosch says about the fuel system (obviously a translation!)

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

so is the total pressure in the system supposed to be at that 28.5 psi or is that just what the regulator cuts it down to just before the injectors and the fuel pump will run a higher psi?

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W211 '03 E320 | W108 '72 280SEL 4.5

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Actually, the pressure regulator in the D-jet system is downstream of the injectors; it returns excess fuel to maintain pressure at the injectors.

And yes, system pressure is 28.5 psi, and yes, the pump is capable of more.

Correct, but it seems that a number of new owners get this wrong.

There are a number of different rail configurations, but one way or another, the feed from the pump/filter enters the fuel rails at the FRONT of the engine where the flow splits to the L and R banks. These flows recombine IN the FPR and fuel then returns to the fuel tank after first passing through a non adjustable damper.

2 bar is the pressure spec, but owners often experience hot start problems at that pressure. Others have bumped this up to 32-34 psig, but this causes a richer mixture which may require mps to be adjusted.

The pressure at the pump exit is only slightly above the rail pressure. Unless something like a blocked fpr or a blocked line restricts flow. Then pressure will be higher and the relief valve inside the OE fuel pump will open to safeguard the system. This apparently occurs at 71 psig, according to one Bosch document.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

wait so running a higher pressure pump will help alleviate hot start issues?

i live in Arizona, and in the summer i can honestly only drive my car to one place and then i get the dreaded hot start issue. it's to the point where in the summer months if i stop some where on my way home from work (grocery store) i'm waiting a half hour just to get the car to turn over again when i want to leave.

this was one of the reasons also for changing the pump someone told me that changing the pump may help.

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W211 '03 E320 | W108 '72 280SEL 4.5

http://i66.photobucket.com/albums/h2...ps9b542eaa.jpg http://i66.photobucket.com/albums/h2...ps5723c50f.jpg

You don't need a higher pressure pump. The djet pump can produce more than enough pressure. It is the FPR that sets the pressure.

You could try adjusting the FPR so that the pressure in the fuel rail is about 32-34 psig. Without also adjusting the mixture, you will be running rich so mileage will be worse, but if that helps with hot starts, it's better than not running at all. Keep your tank full and try switching key on and off 3 or 4 times before actually trying to start (that will move some cooler fuel from tank into fuel rails). Some owners have even installed a switch to bypass the fuel pump relay so as to run the pump without switching on and off numerous times (pump only runs for a few seconds when key is turned on, but then stops until starter is activated)

You may have other issues. One you should check, is the timing. If timing is retarded (or even set to spec!), the engine will run hot. Try setting timing so that it advances to about 25-30 BTDC when revved to 3000rpm. It will run cooler without any loss of power. If it won't advance that far, then you have other problems.

If you can find ethanol free fuel, that too might help.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

is adjusting the mps something that is fairly easy to do? or something i should take to someone if i am not familiar with it?

another issue i was having with the old fuel pump was that it would not always prime. do you think that has something to do with the actual pump or something in the wiring?

someone had told me about wiring the cold start injector to a toggle button but that is honestly my last resort.

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W211 '03 E320 | W108 '72 280SEL 4.5

http://i66.photobucket.com/albums/h2...ps9b542eaa.jpg http://i66.photobucket.com/albums/h2...ps5723c50f.jpg

It's easy enough to do, but you have to have a means of measuring the %CO or AFR. This requires an exhaust analyzer. It also requires a knowledge of the specs for %CO at different engine load conditions. You would have to find a shop that still knows something about these old Djets. For a start, I would just increase fuel pressure as suggested.

Perhaps you have a dirty fuel tank. If this happens only when the tank is ,say 1/4 full. Then a blockage of the fuel return venturi inside the tank is likely. How do you know the pump does not prime?

The hot start problem is caused by lean mixture. Not enough fuel flows through the injectors. So any way of getting fuel into the intake manifold may help. That is why some have tried the cold start valve fix. But wiring the valve is not so obvious, so do some research before trying this.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

oh ok yea then i ill def be taking it some where for that.

i bought the car from a reputable shop here in town, it was a garage find. the previous owner (shop owner) was going to keep it for himself so he did everything to get back up and running and cleaning the tank was one of them. when i went to do the fuel filter and pump all the lined under the car were new, the gas was very clean from the outside (almost looked new), and when i pulled the gas it was all clear so i don't think the tank is dirty.

i say the pump doesn't prime because when i turn the key to the second position sometimes you can hear the pump prime and others you can't, and when i don't hear the pump prime i would try it a couple times and still nothing. i have not paid attention to the fuel levels though to see when it does and does't prime.

i do also get this build up of pressure in my tank though that is only released when i pull the gas cap, someone told me it may be a return line that is clogged? would that be something inside the tank or one of the lines that comes off the filler neck?

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W211 '03 E320 | W108 '72 280SEL 4.5

http://i66.photobucket.com/albums/h2...ps9b542eaa.jpg http://i66.photobucket.com/albums/h2...ps5723c50f.jpg

If you sometimes don't hear pump run, it could be an electrical problem. Either bad connection, or a failing fuel pump relay. Relays are cheap so not a bad idea to switch it anyway and keep old one as spare. Check the electrical connections near relay and at pump itself. Also, replace all old fuses with ones with brass tips. You may just have a poor contact at fuse.

There is a venturi inside the tank that the fuel return line passes through. If you have fuel starvation only when tank is below 1/4 full, it is possible that the venturi is blocked. No easy fix, but one 107 guy on Benzworld was able to clear it with a piece of wire. Discussion going on there at present.

You should do some fuel flow measurements at return line in engine bay (line leaving fpr and fuel damper) with full tank and with les than 1/4 tank. You will have to jumper relay or apply 12v directly to pump using a battery to keep pump running for long enough. Flow should be 1 litre in 30 sec. If it is lower when tank level is low, venturi may be blocked.

Fuel Tank Strainer, Fuel Tank Insides, Swirl Pot, Return Line Venturi - Mercedes-Benz Forum.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5