6.9 Fuel Pumps

[Oversize]

Can anyone confirm the old part number supersedes to 0020919701 ? It seems the new pump has a much smaller diameter than the old one, which would suggest it won't deliver as much fuel. Stranger still is the fact it appears the same as a 300/420/560 pump and even thought they're all smaller engines, they use two pumps in series and not just one. What's going on?

 

[motec 6.9]

It's my understanding the 6.9 pump is the Bosch 040 600hp pump .

 

[Helmet]

Can anyone confirm the old part number supersedes to 0020919701 ? It seems the new pump has a much smaller diameter than the old one, which would suggest it won't deliver as much fuel. Stranger still is the fact it appears the same as a 300/420/560 pump and even thought they're all smaller engines, they use two pumps in series and not just one. What's going on?

Yes they are only making the small pump now. When you purchase the 9701 part number it comes with a plastic sleeve that fits the larger bracket. We have been using these for a while now with no problems.

 

[SEL_69L]

As I understand it, fuel pumps are a bit like human kindeys, inasmuch as their capacity to do the job is many times in excess of the minimun reqirement to do the job.
A fuel delivery system has supply and return lines, and it is via the return line that the extra capacity (delivery rate) is taken.

The smaller pump should still do the job easily.

 

[Styria]

Yes they are only making the small pump now. When you purchase the 9701 part number it comes with a plastic sleeve that fits the larger bracket. We have been using these for a while now with no problems.

Helmet, I am just not quite sure if I understand properly when you refer to pump body sizes, and the use of the plastic sleeve. From what I have observed over many years now, all pumps that I have had an involvement with have had that plastic sleeve, and that applies to genuine Bosch Pumps as well. I have bought replacements (not always Bosch) and I have just re-used the old plastic sleeve when fitting the new pump.

To take matters further, the W126 cars use two separate pumps that are definitely much reduced in size when compared with the units fitted to the W116 cars including the 6.9. It would seem to me that the two smaller pumps operate in tandem, presumably in an effort to duplicate the strength of the larger single unit. However, I stand to be corrected on that. Incidentally, I am unaware that the larger bodied pump is no longer available. Regards. Styria

 

[Oversize]

The pumps with the bigger diameter are NLA though most aftermarket suppliers but I haven't checked genuine ones through MB outlets. The smaller pumps come with a thick sleeve that acts as an adapter where an old pump would normally take up the whole space.

Always use a blue plastic sleeve on an old pump since they stop corrosion between the bracket and pump body. I found installation easier if you pull the sleeve off the pump and correctly position it in the bracket first. Then you can easily slide the pump into position. BTW the blue sleeve don't like being soaked in petrol....

 

[Oversize]

I'm considering upgrading the single 6.9 pump to a twin setup from a 420

 

[Styria]

Mark, any particular reason - these pumps, as a rule, give very little trouble - if any. They are extremely long lasting and, whatsmore, they give you a fair bit of warning characterized by an increased humming noise. I have had Gleaming Beauty just short of twenty years, but did replace the pump about eight years ago due to the previously referred to humming noise. Today, the pump can still barely be heard. Filter replacements, say at two year intervals, is recommended. That's what I do, and I think it helps to prolong pump longevity. Regards Styuria

 

[Oversize]

I just struggle to get my head around the fact a 300SEL uses two pumps and yet MB seems to think a 6.9 can get by with just one (old type superseded)!

 

[Styria]

I just struggle to get my head around the fact a 300SEL uses two pumps and yet MB seems to think a 6.9 can get by with just one (old type superseded)!

..........but Mark, the two pumps are much, much smaller than the single pump. Whilst I am not certain about this, it would not surprise me if the delivery capacity would be identical. Someone will know. In any case, you will soon be able to examine the twin set up versus the single unit. Regards. Styria