Didn't have time to tear into one this weekend but from the looks of the diagram im wondering if MSD didnt get to higher pressure via a longer adjustment screw. Would need to measure how much more could be added before the coils bind. From the drawing though I would think you should be able to dead head the pump with a long enough adjustment screw

Not sure when the last production run would have been, but guessing at 50 years old the OE springs may be getting a bit tired.

Click to view attachment

Just did a bit more searching... this is an interesting read on the pressure regulator

https://www.thesamba.com/vw/forum/viewtopic...s+inside++fails

Cant tell for sure but it looks like the adjustment screw may be a custom part, so swapping may be out of the question. Also looks like new ones from anywhere may have gone NLA sometime over the last couple years and if that post is to be believed these have a high potential for wear that will affect every used one out there.

May be time to look at other options

Knowing that 914 l-jet regulators are a direct swap (fitment wise) I started exploring what might be out there the the realm of cars that used similar systems.

914 L-jet regulators are non-adjustable, vacuum referenced and is supposed to give ~37-38 with zero vacuum. Those can still be had available new but isnt quite where we want to be...

Vanagon regulators are similar pressure wise


and then by some random luck i stumbled on this...

Bosch 0 280 160 256

vacuum referenced, 3 bar non adjustable. Would need an adapter on the inlet but other than that appears to be externally similar to a stock regulator.

https://www.amazon.com/gp/product/B00C818WG...45-cd78f07a84d8

Click to view attachment



This has some interesting candidates as well though i am not sure where they can be purchased. FPR 05-40 B (adjustable from 0.5 to 4 bar) and FPR 15-50 are of particular interest.

https://www.bosch-motorsport.com/media/down...minikatalog.pdf

This is interesting. In the latest bosch catalog it looks like they only offer rail pressure regulators now, but they have an adapter to convert a rail regulator into an inline regulator...

https://www.bosch-motorsport.com/media/down...atalog_2020.pdf

http://www.bosch-motorsport.de/content/dow...abs=50227595-4/

May be more bad news for d-jet

https://shopbhp.com/products/kit-car-fuel-p...ant=28302418369




Looks like adapters for the modern bosch regulators may be the way of the future for older cars. Perhaps one of our vendors could machine one thats a perfect fit for a 914


Edit:
I should have checked the dub shop first... Mario always has awesome stuff
http://thedubshop.com/universal-fuel-pressure-regulator/

that looks like it would fit in place of a stock regulator. Other vendors look to have a adjustable regulators that will fit that adapter that can be turned down to lower pressures, so may be a solution for d-jet as well

Well crap.

I have not had a chance to digest all this in detail, but your bottom line appears to meet my experience over the last few days: the OE fuel pressure regulator is becoming scarce. One of my core reasons for developing a Microsquirt for myself was as a low-cost alternative to declining D-Jet parts (and tunability for mods); one of my design parameters was to do that with as few parts as possible. I was working under the ASSumption that the FPR was readily available new; that appears to be flawed.

Aftermarket adjustable "return/bypass" FPRs are common, but they won't fit into the stock bracket. I may have to rethink this paradigm and come up with something around an aftermarket part.

Here's a 3-bar one. eBay ad claims (I think) it can be set higher:

https://www.ebay.com/itm/Fuel-Pressure-Regu...28/401379447531

Can't really tell what the hose fitting size is.

Searching for "107001001303 regulator" results in other sources for the same part, implying it's used on AMG Mercedes (if I am translating properly).

Your goals are the same that I had when I did my first install, only back then it was only the start of OEM d-jet parts supply drying up. Fuel pressure regulators going NLA is a fairly recent development though, from what I can tell sometime in the last couple of years. Its a bit of a surprise.

Take a good look at that part from the dub shop, i really think that may be the best bet. Using that 6AN to 5/16 barb bulkhead fitting it looks like it would mount in exactly the same way as a stock regulator, and the actual pressure regulator component is replaceable with modern Bosch of any pressure rating (or fully adjustable)

I think i may order one today just to play around with it.

Am I correct in inferring his non-regulator one is 3 bar?

That's probably what Mario was thinking you would use when he gave you an initial tune for the system.

His stuff looks nice, but I sent an email him to find out my correct options; I can't tell what threads he's machining into the body of his piece (AN-6? NPT?) so I don't know which fittings to order from him.

Clearly I want 5/16" barb fittings both ends, but I want the bottom one to use a bulkhead fitting so I can mount it on the existing bracket (if it's not too heavy). Those are available from Summit (and others) depending on the body threads.

Looks like it can come with a 3-bar Bosch rail pressure regulator, however the actual pressure regulator component is removable/replaceable so any pressure, including adjustable, that fit that form factor could be used.

Mario's response, paraphrased:

This:

Universal Fuel Pressure Regulator
Regulator Body Options: Singe Fuel Inlet
Regulator Options: 3 Bar - 43.5psi
Mounting Bracket: -6AN Bulkhead Fitting for Mounting
Fittings: (1) 5/16" Barb

Will get you this:

Click to view attachment

Seems like the way to go!

Mario 3-bar FPR procured and installed. Shows 41.5 psi on my Harbor Freight fuel pressure gauge kit. That's what we're going with.

You need to zip open the hole size on the bracket "one more larger" (Spinal Tap reference) using the HF step drill otherwise bolt in.

Tangentally related...so raise your hand if you knew that when you remove the flapper thermostat pulley to install an aftermarket cooler that the pulley step-stud is an open hole to the block (not a blind hole), and if you don't plug that hole it makes a freakin' aweful oily mess...?

Asking for a friend.