Fuel pump alternative on a 72 450SL - Page 2 - PeachParts Mercedes-Benz Forum

coleyjf · #16 05-18-2011, 11:46 AM

Hi there

I fitted one from these guys on my 300SL about 3 years ago and it runs like silk

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130507879709

Cheers - Jim

meltedpanda · #17 05-18-2011, 11:50 AM

I need this stuff so I can get to GTG's lol

Wish I could have made it but ... life gets in the way

rowdie · #18 05-18-2011, 12:02 PM

I have a bag of them. I will send you one next week.

Graham · #19 05-18-2011, 01:32 PM

Quote:

Originally Posted by coleyjf

Hi there

I fitted one from these guys on my 300SL about 3 years ago and it runs like silk

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130507879709

Cheers - Jim

Good price, but a 1988 300SL is not same as Ron's '72 D-Jet in flow or pressure or fuel plumbing.

One idea that came to mind was, if a higher pressure pump is to be used on a D-Jet, would be to install a pressure switch in the fuel line . Wire it in series with the fuel pump relay (or pump itself) so that it would cut off pump if pressure goes say over 40 psig. Probably cheaper than buying a D-jet pump. But need to find a properly rated pressure switch.

meltedpanda · #20 05-18-2011, 01:40 PM

Quote:

Originally Posted by rowdie

I have a bag of them. I will send you one next week.

once again - thanks

coleyjf · #21 05-19-2011, 01:38 AM

Quote:

Originally Posted by Graham

Good price, but a 1988 300SL is not same as Ron's '72 D-Jet in flow or pressure or fuel plumbing.

One idea that came to mind was, if a higher pressure pump is to be used on a D-Jet, would be to install a pressure switch in the fuel line . Wire it in series with the fuel pump relay (or pump itself) so that it would cut off pump if pressure goes say over 40 psig. Probably cheaper than buying a D-jet pump. But need to find a properly rated pressure switch.

The Pump is quoted as for all years between 71 - 89 but I'll bow to your greater experience

(I don't mean age ha ha)

jame.foreman · #22 05-19-2011, 05:28 AM

I was not aware of it. Please post the price of the fuel pump. And how to go about it?

Graham · #23 05-19-2011, 09:52 AM

Quote:

Originally Posted by coleyjf

The Pump is quoted as for all years between 71 - 89 but I'll bow to your greater experience

(I don't mean age ha ha)

I hadn't looked at that list of cars on the eBay ad.

There is no way you can physically mount that pump on an early 107 without some major plumbing and mounting changes and it almost certainly does not have the pressure relief that the D-jets should have. Don't believe everything you read in an eBay auction

It's hard to imagine why that pump costs so little. For cars where it is a direct fit, might be worth carrying one as a spare.

coleyjf · #24 05-20-2011, 02:16 AM

Quote:

Originally Posted by Graham

I hadn't looked at that list of cars on the eBay ad.

There is no way you can physically mount that pump on an early 107 without some major plumbing and mounting changes and it almost certainly does not have the pressure relief that the D-jets should have. Don't believe everything you read in an eBay auction

It's hard to imagine why that pump costs so little. For cars where it is a direct fit, might be worth carrying one as a spare.

Well as I said I fitted mine 3 years ago and it runs like a dream - It was identical in fittings, size,"weight" (it's not a lightweight "cheapo") and "plumbing" to the original (UK) pump I took off, though there may be some differences with fuel pumps on the US models as there are with other "fuel" related items on the non Euro SL's.

My point is not that it's "so cheap"

but why are the others "so expensive"

! It's only a pump when all said and done and it's not rocket science

Jim

Graham · #25 05-20-2011, 04:32 PM

Quote:

Originally Posted by coleyjf

It was identical in fittings, size,"weight" (it's not a lightweight "cheapo") and "plumbing" to the original (UK) pump I took off, though there may be some differences with fuel pumps on the US models as there are with other "fuel" related items on the non Euro SL's.

Don't want to prolong this, but for the record, the 1971-1975 D-Jetronic pumps (US and Euro) are quite different in the way they are installed from later cars like foley's '88 300SL. Ron's car is a 1972 D-jet and that is what we were discussing.

That eBay pump cannot be fitted directly to a D-jet car because the inlet is on the end, not the side. It is too small in overall diameter and would need a mounting sleeve. It also needs a hose barb type fitting with integral check valve on the discharge side. It is also likely longer than the D-jet pump, may add another complication.

No doubt someone with some ingenuity could make it fit and some probably will because the price is so low. But then it still does not have a suitably rated internal relief valve. The flow should also be checked, because I believe that D-Jet pumps circulate more fuel and have a higher flow and lower pressure rating than the later k-Jets.

meltedpanda · #26 05-20-2011, 10:01 PM

siding with Graham here, our old DJets, are a bit of a bugger when it comes to retrofitting anything, and specifics on fuel delivery are key piece to these cars running and running safely.

sundaygolfer · #27 06-02-2011, 07:14 PM

Ron
You may want to for a used 1975-78 280Z (non-turbo) fuel pump it is the exact same all the way down to the check valve on the side. Graham put me onto this last year and I was able to quicklly find a spare for $20.

Also,
The issue with fuel pumps is pressure and volume. There needs to be enough fuel volume for sustained max throttle to prevent little holes from showing up in the pistons.
Mercedes 450SL are tame and probably could handle a lean condition for short periods but Porsche 911 from late 60's and early 70's it was absolutely necessary to have a factory standard or racing fuel pump. Anything less and you will have a hole in the piston from the lean condition.

rocky raccoon · #28 06-03-2011, 12:15 PM

Many years ago I had an AC Bristol that was fitted with a POS British fuel pump. As could be expected, the pump failed somewhere in middle America while I was on a cross-country trip. I thoght I was badly focked with a borderline exotic car and no dealer or parts source within many hundreds of miles.

I was able to push it into a motel where I spent the night. The next morning I walked across the street to a GMC truck dealer. They looked it over and said they could replace and relocate the fuel pump with something they had in stock for a truck. They mounted the pump in a convenient place under the hood, rerouted some fuel lines and I was on my way.

The conclusion is; a fuel pump is a fuel pump. So long as it delivers adequate pressure and flow, it will work and perhaps more reliably than a high priced OE unit.

Graham · #29 06-03-2011, 05:38 PM

Quote:

Originally Posted by rocky raccoon

The conclusion is; a fuel pump is a fuel pump. So long as it delivers adequate pressure and flow, it will work and perhaps more reliably than a high priced OE unit.

Good story, but I suspect that wasn't a fuel injected engine?

Adequate is good, but perhaps rather proper flow and pressure according to original specs. (2L/min vs 2bar head at 12V and internal relief valve to safeguard fuel rail hoses. That is what the injectors and FPR are designed around.

If you know of any pumps that meet these specs other than Bosch and their Japanese equivalents as used on Nissan 280Z, please post details. Some of those aftermarket pumps may have the flow and pressure, but are very quiet about pressure relief (i.e Don't answer emails!)

rocky raccoon · #30 06-03-2011, 07:38 PM

It was not an FI engine but ... one would be hard pressed today to find an engine in any vehicle that is not FI and they all have electric fuel pumps. I don't want to go to the trouble to dig for the specs for something I don't need but I'm sure one could find what is needed with enough motivation and research.