Fuel Pump backflow valve type

Walt Fricke · 08-23-2013, 01:16 PM

The new fuel pump I purchased has a "short neck," with the valve to keep residual pressure in the system built into the fitting around which the banjo on the fuel hose fits. The one I am replacing has a "long neck," with this valve built into the neck, with just a fitting for the banjo.

Alas, the new valved fitting is larger in diameter (about 11mm) for the banjo than the old one (about 9mm). So the old banjo won't fit over the new valved fitting.

Temporarily, I swapped fittings. However, this means the system won't hold pressure after the key is turned off. That shouldn't affect starting and running, but will affect hot starts (I've never been entirely sure why this is, because the pump should pressurize the system PDQ, but it seems it does).

Anyone know what fitting I need - smaller banjo/cap size, but with the valve built in?

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by Walt Fricke

The new fuel pump I purchased has a "short neck," with the valve to keep residual pressure in the system built into the fitting around which the banjo on the fuel hose fits. The one I am replacing has a "long neck," with this valve built into the neck, with just a fitting for the banjo.

Alas, the new valved fitting is larger in diameter (about 11mm) for the banjo than the old one (about 9mm). So the old banjo won't fit over the new valved fitting.

Temporarily, I swapped fittings. However, this means the system won't hold pressure after the key is turned off. That shouldn't affect starting and running, but will affect hot starts (I've never been entirely sure why this is, because the pump should pressurize the system PDQ, but it seems it does).

Anyone know what fitting I need - smaller banjo/cap size, but with the valve built in?

Walt,

Get the correct adaptor with built-in check valve that would fit the existing banjo fitting and the new FP. I had encountered similar problem before when I installed a new replacement FP like what you have now. My option then was to install a bigger banjo fitting and cap with the new FP and remove the smaller banjo.

By sheer luck, I found an old adaptor (with built-in CV) from a 944 FP in the parts bin. This is a common metric adaptor for FP. You should be able to find this part easily. HTH.

Tony

TibetanT · TibetanT's Garage

Walt:
I have a fuel pump such as the one you show here available if you are interested from a 1978 911SC. That way no changes would be necessary.

Walt Fricke · 08-24-2013, 08:56 AM

Ed - well, since I already have a new pump, and it is installed, I'll pass. Looks like Pelican carries an M12x1.5- M10x1.25 CV (for some reason I couldn't remember the standard name for this, so described it by function). Ought to work. The car is a '77 Euro 2.7, upgraded to SC specs, but still has the original fuel lines, including the smaller banjo. Bolting on different parts is easier than changing a banjo crimped onto a line. If I ever replace the line, or have it out of the car again (I hope not), I might change banjos.

This will be the first non-Bosch pump I have used for CIS. Bosch costs about $280. Walboro is about half that. This pump, said to be all US made, looks nice and is under $50. This sort of looks like the deal too good to be true, but we'll see. I have a spare pump I had used on my track only car which I can use if this one doesn't work, or doesn't last very long. I just have to remember to toss the spare into my trailer.

Walt Fricke · 09-10-2013, 11:14 AM

Well, I struck out.

Part number 911-608-211-00-OEM from Pelican arrived, but it turns out to be just a fitting, and not a fitting plus a check valve. Right sizes and threads, but not what is needed for a fuel pump which does not incorporate a check valve to couple with the 10mm banjo of a 1977 2.7 911's fuel lines.

I was going on guess work for the part number, including the fact that this one was more expensive than others listed. Plus it was the only one listed in the needed sizes.

What I need is a fitting with check valve included for a 10mm banjo. Maybe that only exists for the 12mm banjos?

Otherwise, my options are to use the pump I had (turns out my no start problem was the distributor rotor - a long story), another spare I used in a 2.8 race motor, or to skip the check valve altogether.

My understanding is that the reason you want to keep pressure in the fuel lines until the engine gets cold has to do with the boiling point of gasoline. The higher the pressure, the higher the boiling point, so there is less likelihood that it will be hard to restart a hot engine on a hot day.

In my case, I am thinking of sitting on the grid at the race track with the engine off, and then having trouble getting it restarted when the one minute warning is given. Is this going to be a problem? I can disconnect the interconnect which prevents the fuel pump from pumping unless the engine is at least cranking (air flowing into the engine, moving round plate up, opening circuit, allowing fuel pump to run via pump relay), which would allow more pump pressurization faster than a lot of cranking.

Doesn't seem to be an issue where cold starts are concerned - when I put in another rotor the engine fired right up. And did so as I checked two other spark coils I had gathered to see if the coil was the problem.

But engine never got warm.

Now that the engine runs, I can back the car out of the trailer to do any further swapping. Getting it jacked up far enough so I could crawl under and access the pump was a challenge in an enclosed trailer.

I suppose I could use my bargain pump as a spare for the race motor, as EFI doesn't need a check valve.

Flat6pac · 09-10-2013, 12:43 PM

Walt, I have the nut that covers it
928.110.475.01
I dont have the correct banjo.
Bruce

JFairman · 09-10-2013, 01:11 PM

FWIW, if you ever need a 12mm cap nut it's 928-110-475-04
Pelican Parts - Product Information: 928-110-475-04-M100

eastbay · 09-10-2013, 01:19 PM

What's your tolerance for pain?

Facing the same issue I went to the local pick'n'pull and found all the requisite larger banjo's, caps, washers and fittings in and on various older Mercedes diesel and gas models. Cost was less than $10 for a large selection of fittings and I now have plenty of spares.
Fitting the larger banjo to the polyamid line was a snap using a home made wood die that was posted on PP previously. I now have a SC style pump in the original location in rear of the car.

Walt Fricke · 09-11-2013, 05:06 PM

Eastbay - in the front of the car the line is rubber. I suppose I could use a cutoff wheel to slit the crimped holder, pull out the 10mm banjo, and slip in a 12mm banjo. Then hose clamp it? Not sure I want to do that, though, on the pressure side of the pump.

It may be that a 12mm to 10mm CV fitting simply does not exist.

The 10mm cap I just bought from Pelican has PN 900-070-010-02. I have a 10mm cap, but got a new one just to have a spare and so on. But I hadn't thought about a cap, should I use the 12mm approach. I have two 12mm/12mm CVs. The 928 PN is for 12mm threads?

eastbay · 09-12-2013, 08:58 AM

"It may be that a 12mm to 10mm CV fitting simply does not exist."

Hey Walt, that is the issue I faced. Maybe there is one out there, but I could not find it.
On my 75 the check valve was inside the stem of the small sized banjo. Pelican shows this combo banjo/check valve as still available, 911-608-901-00-OEM US $54.00, but you are still left with the 'clamp' issue onto your existing fuel line. For myself, I thought if I have to mess with the fuel line anyway, I would put in the larger straight through banjo fitting. That way the check valve is an easily serviceable separate piece in the future.

BoxsterGT · 09-12-2013, 12:50 PM

The 75 model uses a Polyamid line from its rear pump to the accumulator. The 10mm Check Valve Banjo looks like this...........

This was early in the design of the Bosch CIS systems. Not long after, Porsche superceded this to a larger 12mm banjo and moved the pump up front.

The DIN standard for a 8mm Hose is a 12mm Banjo. If I had my choice, I would go to the latest design and the larger of the two available.

Len

BoxsterGT · 09-12-2013, 01:13 PM

Walt-

I can send a new E-85 hose like this to you with a 10mm or 12mm Banjo........

Crimped at the Banjo, you will have to use a good Norma or Oetiker hose clamp at the Tunnel end.

Len

UMC-SF · 02-02-2015, 02:20 PM

Len,

Can you by any chance make some braided oil hose (ID 8mm, OD ~14mm) with an 8mm banjo at one end? I'd need two hoses approx 385mm and 290mm long (from centre of banjo to open hose end)

Hugo

--

Walt-

I can send a new E-85 hose like this to you with a 10mm or 12mm Banjo........

Crimped at the Banjo, you will have to use a good Norma or Oetiker hose clamp at the Tunnel end.

Len

[/QUOTE]

BoxsterGT · 02-02-2015, 04:02 PM

Hugo- Sorry but I do not have this 8mm banjo. I will look into the availability but yours is the first request for this size and hose combination.

Best to email me directly. NO PMs.

Len at Autosportengineering dot com