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How do you fit a fuel pump regulator?

I can see a lot of 750 owners put on a fuel pump regulator and though with the 906 the Weber runs better, there is still work to be done to get her right. Seems from searching the threads that adding a fuel pump regulator that gives control of the fuel pressure and the chance to tweak the pressure is worthwhile. So, I'll fit one e.g. like Holley 12-804. But how do I actually attach it? And what advice is there around that eg Fuel Pressure Gauge?

[EDIT: After testing with a fuel pressure guage I concluded there is no absolute need for a fuel regulator for the Paso 906, since the original setup feeds 1.5-1.8psi at the Weber ie its under not over the 3.5psi that caused problems on the 750s. However, there may be a loss of petrol delivery at high speed at 1.8psi since the demand at high speed is more. If you do want to bring the pressure up to the common Ducati 2.5 - 3psi...

The Spectre type inline regulators are no good on the Paso 906 because of the return line, so the holley 12-804 regulator is the best choice, as most Ducati people recommend - reduces the fuel pump pulsing, too.

All Weber people say the existing pulsing electric pump is not good - the reason is that pulsing can affect the fuel delivery, however if you install the Holley it goes between the Fuel pump and the carb evening out the flow.

I did manage without the holley at first by restricting the return line by using 3/16th fuel line and poking a 190 main jet into the line at the tank end. This gave me ~2.8psi, But I think the Holley is better because it takes away the pulsing issue.

To fit the holley also get a fuel pressure gauge and put it between the holley and the carb. This means you will be able to check the pressure as you set it. Connect the fuel and return line to the Holley and connect up as per instructions that come with the Holley. Take the lock nut off the Holley. With the tank on but seated back so you can see the guage, open the fuel cock and start the bike. Take the fuel cap off for a while and then put it on - just to help settle the pressure. It should also be cleared of air after a few minutes. Adjust the Holley with a screwdriver to the 2.5 - 3psi. Turn off the bike, put on and tighten the lock nut. Then replace the guage with just fuel line from the Holley to the carb. Done.
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this may be cheating as i have a 750 sport, but my regulator is simply placed inline directly before the lines entering the carbs. strangely enough i have dellorto carbs, so i suspect the regulator was installed before the carbs were swapped, but they didn't remove the regulator. fine by me, gives me a few more options.



as for what sort of regulator: this is what it says on it:



hope that helps some. i didn't install it, bike came that way! i think they are pretty cheap- 20 to 30 us $

The regulator just goes inline between the fuel pump and carb. 3PSI seems to be the best setting from what has been posted here. Do a search for it, there have been a few threads about it.

Hi.
The regulator you have "jetboy", does it have an return line? If so, how does that work?
Regards
Klaus

no return line- its pretty basic little unit. seems to work, but like i said, i have dellorto carbs now anyway. 3psi seems fine.. when i got it the PO had it set at 2psi - i think dellortos can handle up to 4, so i bumped it up one. i cant actually tell the difference.

jetboy wrote:... my regulator is simply placed inline directly before the lines entering the carbs...

Thanks. Helpful. I have ordered a dial type like yours. also helps to see where it goes. My guess is I just cut the fuel line and fit it (with fuel off).

With the Dell's it will gravity feed on a Paso just fine. The sport or ss needs the pump.

906 has a return line. I am presuming the fuel pressure regulator goes strait after the fuel pump, which is before the return line connection, is that right?

I´ve fitted a Holley 12-804 regulator to my 750 set @ 2.7 psi.
I still have a return to the tank by using a tee joint between the regulator & carb (renewed all the fuel hoses as well).
Have´nt had much of a chance to give it good test but starts and revs ok

I put the fuel pressure regulator on and set at 3psi and a K&N filter while I was at it.

It started with some popping (new) and backfiring (which sometimes happened before). I presumed, because when setting up the regulator the petrol drained out of the fuel pipes, so expect she would take a little until petrol flow got through again to the carbs.

I then noticed a leak where the return fuel line connection is, so I had to take the air box off to get at that and put that back together.

Now it won't start. Some popping still (new) and turning over but wont start.

Another variable is on the last ride I put in some regular fuel instead of premium -
actually was running better at lower revs.

Maybe flooded?

Any ideas?

it does not take much to foul the plugs when messing around with fuel and air mixture. pull them and see if they are clean. - sometimes its worth just putting in new ones since its only gonnabe like 5 dollars and then you know they are good.

also im not sure about the weber, but perhaps you need to prime it? take your air filter off and use some starter fluid and see if that starts the bike -

If you use a return line you need a regulator with an outlet for the return line like the Holley . if you use a two outlet type regulator with a return line on this kind of low pressure system the regulator is useless and the carb will get little if any flow, it will all go out the return line without ever opening the regulator. Even with the correct type of regulator you need a gauge between the carb and the regulator to get the pressure adjusted to 3 PSI. A simpler method would be to restrict the return line with some old jet sized to provide a measured 3 PSI at the carb.
Also Plug fouling is more likely to be due to poor ignition operation assuming your choke is not sticking and your float check valve is set up properly

I am now unsure of the position of the regulator and the type to have.
I have put the Spectre Fuel Pump Regulator in place "A" as per image below,
but bike not starting.

"higgy' says, "if you use a two outlet type regulator with a return line on this
kind of low pressure system the regulator is useless and the carb will get little
if any flow, it will all go out the return line without ever opening the regulator".

Do you mean if I had put the Spectre at place "B"? If that was what you were thinking I still get your point that pressure is displaced into the return line.

So, now?
1. Maybe position "A" as I have it, needs checking with a guage at place "B",
which would tell me the pressure at carb (involing adjusting the Spectre until
guage at 3psi) - what do you think?
2. higgy, your idea of the limiting jet - would it be the same if I put the Spectre
in the return line (place "D"), so it holds back the pressure at 3psi, ie the end
for the carb going in the direction of the return to tank?
3. "higgy's" your idea to put a limiting jet (I dont have old jet's - you mean put
a jet into the return line itself - what size?
4. Put in Holley 12-804 in place "C".

Can I do 1, 2,3 or 4?

Yes you could put the two line type regulator in the return line,any where in the return line. The inlet towards the carb the outlet toward the tank Tee in a pressure gauge between the return line and the carb/pump any where it doesn't matter as long as it is after the pump and before the regulator. and adjust the regulator for 3 psi on the gauge. Once you achieve 3psi take out the tee and the gauge and ride ducati boy ride. . Very good you are paying attention go to the head of the class The way you have it now won't work
As for the size of the jet to add to the return line in place of a regulator there was an old post here a while back Don't remember the size of the jet seems to me I recall it was an old main jet
put in the return line, not as good as a properly adjusted regulator but it would work. You would have to figure out the size of the hole required to get the pressure correct.
On the Holley type, Jou gotit mahn inlet side line from the pump, pressure regulated outlet to the carb and relief outlet to the return line,gotta get these last two correct! put the gauge in the carb line and adjust..
On my 906 I took out the T and put the regulator in place made it easy to find a mount for the regulator. Actually I never mounted mine found the lines did an adequate job of keeping it outta the way of things. In the end I took the regulator out, needed the room for a nice set of dynatek coils and just never put it back I found the coils/wires and new o-rings on the idle jet holders fixed most of my issues which sounded just like your issue.constantly fouled plugs and rear cylinder cutting out. On mine when it acted up choking helped so I had an air leak to find, the o-rings.
On a side note I have been working on the jetting for my weber/906. Just got an LM-1 to help me get it perfect. will allow me to fine tune the et's I have to make since no one has the et's I need any longer

I'll try out my cheapest option being changing the Spectre to the return line.

On the side note, yes the overall aim is getting the 906 running just right:
I saw your post on jetting and ordered from http://www.piercemanifolds.com
a 4.5 aux vent, idle 70 - also from another poster's tip, I also ordered a pump jet 60 to try.

As above I also now have a K&N filter. I will look at coils in this process some time.

I got a book on Webers by Pat Braden to try and understand the weber.

I also phoned a Webber specialist in NZ (Murray) he said take down the
psi to 1.5!, leave all jets except increase the pump jet from 40 - 60.
the other thing he mentioned is webbers like warm air.