Walboro Fuel Pump question

[BoxsterGT]

Some folks are now using a Walbro fuel pump on their 3.2 Carreras as a lower cost replacement for the original Bosch. I was told our host offers this pump but could not find a listing under "Walboro".

The outlet size on a Walbro fuel pump is 10mm. I believe the outlet on the Bosch pump is 12mm or greater.

Since all of the Porsche fuel system fittings downstream from the pump are either M14 or M16 (on the later 3.6 models), will using this pump with its 10mm outlet have any negative effect on performance?



Joe- Thanks for the spelling check.

[jmonitto]

I don't believe the host sells it. It's spelled Walbro, and for the GSL392, its 10mm in and out.

I have however, run these pumps to 450HP, and 60PSI of fuel pressure on turbo 4 cylinders using -8AN line without any pressure drop off issues on higher boost.

[jmonitto]

Here's a link to the pump on Summit.

Walbro GSL392 - Walbro High Pressure Inline Fuel Pumps - Overview - SummitRacing.com

[Ramathorn]

I got mine off of ebay (nib) came with a new check valve as well. I too have been running walbro in many of my other cars with no issues what so ever.

[BoxsterGT]

Hi Joe-

This Walbro pump is Hi-Pressure, and if the flow rate is adequate it could be a good substitute for the expensive Bosch. It was likely designed for the popular Asian 4 cyl imports.

With its small 10mm fitting size, the only way this pump can be used in our cars is with a AN adapter. Nothing else is available so far that I have found.

I have called Germany to see if I can get a match. There is one Metric fitting available that may possibly be modified to fit our fuel systems directly. I am looking into this and will post the answers. Perhaps this will become the lower cost altrnative of choice.

Len at Autosportengineering dot com

[will hung]

Originally Posted by BoxsterGT

Hi Joe-

This Walbro pump is Hi-Pressure, and if the flow rate is adequate it could be a good substitute for the expensive Bosch. It was likely designed for the popular Asian 4 cyl imports.

With its small 10mm fitting size, the only way this pump can be used in our cars is with a AN adapter. Nothing else is available so far that I have found.

I have called Germany to see if I can get a match. There is one Metric fitting available that may possibly be modified to fit our fuel systems directly. I am looking into this and will post the answers. Perhaps this will become the lower cost altrnative of choice.

Len at Autosportengineering dot com

Cool. Very interested in what you find out.

[hcoles]

I've used this company to get adapters, could be some ideas there.

Adaptall Inc. - Specialists in the Conversion of Hydraulic Adapters & Fittings

[BoxsterGT]

Thank you. Not listed in their katalog. I appreciate the suggestion.

Len

[hcoles]

what is the exact complete description of the fittings on the car side, upstream and downstream of the pump, when the stock pump is removed? Can the then exposed fittings be further removed? I propose M14 is not enough info. to nail down what it is, a picture would help.

[BoxsterGT]

The fitting sizes are all over the map. It all depends on the model year, but even within the same year & model Porsche seemed to use what they had on the shelf at the time.

Most early models 911 used M14x1.5 fittings, though the 3.2 Carrera used M16x1.5 as well.

This 3.2 model also used a mix of 9.5mm hose to the fuel rails and 7.5mm hose as the supply from the filter and a M16 adapter fitting at the filter outlet. The filter inlet was M14x1.5.

Part of the change occurred when the fuel pump was moved up to the front sometime in the early 80's.

The Polyamid tunnel lines used either M14 Male Flare fittings or M14 Male Cone fittings. Have not found yet if there was a specific production change or if they just used what was available.

I do know everything from the 964 models on use M16x1.5 fittings with the majority of lines on the motor being Polyamid tube which is far more durable than the rubber hose. Trouble is, its very hard to modify for backdating or conversions.

Go figure.

Perhaps someone else can help with specific data on this. When exactly in the late 70's or early 80's did the factory move the fuel pump up to the front where it once was with MFI in the early 70's?

Len

[jmonitto]

Originally Posted by BoxsterGT

Hi Joe-

This Walbro pump is Hi-Pressure, and if the flow rate is adequate it could be a good substitute for the expensive Bosch. It was likely designed for the popular Asian 4 cyl imports.

With its small 10mm fitting size, the only way this pump can be used in our cars is with a AN adapter. Nothing else is available so far that I have found.

I have called Germany to see if I can get a match. There is one Metric fitting available that may possibly be modified to fit our fuel systems directly. I am looking into this and will post the answers. Perhaps this will become the lower cost altrnative of choice.

Len at Autosportengineering dot com

It's probably the most wide used aftermarket pump in all realms, they have direct fit for everything from an Acura, to a mustang.

I checked XRP the biggest step they make is m10x1.0 -> -6AN. What size is the Polymaid line?

-Joe

[BoxsterGT]

I am working on an adapter for M10x100 up to M14x1.5 or M16x1.5 which are the standard fitting sizes for our Porsches.

The Germans do not offer this combination, as its too big a step. This is like a choke on the flow of fluid thru a line. Its hard to believe the supply side of this pump from a tank is also M10. What is the ID of the 10mm fitting on this pump? Is it 5 or 6mm?

I checked our shop and we do not have a fuel fitting that small. Our Porsche 911s have a supply hose at the tank with a 12mm ID. I cannot believe this pump works on a 450 hp motor, but I learn every day.

Len

[porwolf]

I have been using a Walbro pump for my 79 SC for one year now. No problem so far but I did not put many miles on it. I got it to replace the original gummed up Bosch pump. I wanted a cheap (50.-) pump in case the tank is not clean enough and the pump gums up again. Walbro pumps (sometimes listed as Hayg pumps) come in both Bosch versions, with or without internal check valve. My 79 Model has the pump output fuel line Banjo fitting for the internal check valve. The pump output has an internal 12 mm thread. Into that goes an adapter with a 12 mm male thread on one side and a 10 mm male on the other side. Then a 10 mm banjo fitting attached to the fuel line is screwed to that. The banjo fitting is part of the fuel line to the engine. One 12 mm and two 10 mm copper crush washers are needed to seal the connections.

[BoxsterGT]

Thank you guys for the info.

I just went on evilbay & found a Walbro pump with a 1/2in slip fit inlet & a 12mm Banjo outlet that they claim matches the Bosch pump for a 3.2 911.

This I can work with & have fittings to match. Saves me a lot of effort & expense to come up w 10mm fittings to adapt to our fuel systems.

Just hope it works. At the price I paid I can buy a spare.

Len

[Ramathorn]

I think thats basically the same one i got (sounds like it at least).

[Gordo2]

I put one on my '83 SC after the original Bosch died in 2004. No problems, direct fit with the fittings that were supplied. Can't seem to find the receipt to figure out the part/order #.



For the cost, I was more than impressed and recommended Pelican carry them.

Good luck, Gordo

[BoxsterGT]

Gordo-

The pump I just bought looks like the original shown at the lower center of your photo.

A Black body with a slip-fit inlet and a M12 Banjo at the outlet.

On some posting or ad I read it says that all true Walbro pumps are made in the USA. I think that implies that some are not or that some are not really Walbro pumps, just copies. When my pump comes in I will post the info I get.

This made my day, not having to find 10mm fittings that had to be machined & really compromised the application.

Thanks all you Pelicanheads and our host, you are the best.

Len