Hi all,
I am currently changing my fuel pump from mechanical to electric, I have purchased a facet solid state pump(mounted at the tank outlet),
Do I need to install a pressure regulator?
Engine is a X Flow running twin 40's
Cheers
not normally as they cut out once up to pressure. Some also allow you to adjust the cut off.
A pressure reg is always recomended - you are lookin for around 3.5 psi at the carbs......
You do not need a pressure regulator with this type of pump and DCOE carbs.
Regulators are a bad idea if not required as they place a restriction on the flow.
Xflo mechanical fuel pump is also fine to use with DCOE carbs.
Bet your glad you asked
I used that type on the Falcon after using the point’s type (unreliable). Never bothered with a regulator with either type and had no issues. If
you’re using a fuel return I'd use the standard mechanical pump as due to the pressure never building up the electric pumps just run and run. The
solid-state pump you interested in is designed for standard float carbs so won't flood them.
Thanks guys,
This pump is non adjustable, the reason I am replacing the mechanical pump is that on long straights on the track at around 6500rpm I experience fuel
starvation .
The new pump does not give output pressure, if more than 3.5 psi what will happen?
Cheers
if the float valve is not seating right it might force fuel past the valve and flood the float chamber. You'll soon know about it as the car will feel like the choke is on and get a bit smelly. Unlikely to be a problem though and you can get exactly the same problem with the original mechanical pump.
I've got a xflow with dcoe 40's and a facet fuel pump and I was told that I HAD to use a pressure reg, seems to run ok, or should I pull it
off?
Thanks, Alex.
Who said you had to and why, did they even give a reason? Feel free to fit one if you like as there is no downside so long as it can keep up with the
flow rate.
I would not bother myself as if it runs then no problem. The only thing I'd suggest is you fit the inertia kill switch used in fuel injection
cars to stop the pump in the event of a crash and the fuel line being cut. You wouldn't like fuel spraying all over the place would you.
Hmm, good point, I can't remember being given a reason! think I'll go pull it off and see what happens!
quote:
Originally posted by alexdj125
I've got a xflow with dcoe 40's and a facet fuel pump and I was told that I HAD to use a pressure reg, seems to run ok, or should I pull it off?
Thanks, Alex.
I'm running twin 40 DHLA's on my engine.
I also have a fast road Facet pump (4.5 psi?)
Without a regulator , the pressure overcomes the float needle, with fuel pouring out of the carb.!
quote:
Originally posted by PaulBuz
I'm running twin 40 DHLA's on my engine.
I also have a fast road Facet pump (4.5 psi?)
Without a regulator , the pressure overcomes the float needle, with fuel pouring out of the carb.!
Sorry, I'm going to disagree with those who said you don't need one......
Weber's like having a consistant flow of fuel, Something like a filter king is designed for the job (plus adds some more filteration to the
fuel).....Depending on which pump you have, those facet pumps can deliver upto 8 PSI, which is way too much....
A reg helps with any surge you may see, and ensures that the needle valves in the carbs never get overpowered....
If you have a <4psi pump then it's not stricktly required, but generally good practise.....
quote:
Originally posted by Jenko
Sorry, I'm going to disagree with those who said you don't need one......
Weber's like having a consistant flow of fuel, Something like a filter king is designed for the job (plus adds some more filteration to the fuel).....Depending on which pump you have, those facet pumps can deliver upto 8 PSI, which is way too much....
A reg helps with any surge you may see, and ensures that the needle valves in the carbs never get overpowered....
If you have a <4psi pump then it's not stricktly required, but generally good practise.....
Thats a fair point, but it's the higher than 4psi pulses that can have an effect on the needle valve...Too much pressure can effectively stop the
floats returning...I'll admit you would need a very specific set of circumstances to get this if you had a low psi pump.........
The purpose of the reg is to ensure this never happens, so you have to be 100% sure that your fuel pump is incapable of producing no more than
4psi.......Even the 'fast road' Facet pumps are rated between 4 and 5.5 psi (which means they are especially stable), and strictly speaking
thats too much for a weber.................
I would always go for a higher rated pump and fit a reg...that way, you can 100% guarantee you are getting the correct pressure at all
times.........
Paul.
Normal road Facet pump output of 2.5 to 3.0 psi.
Fitting a Fast Road or Competition pump won't make the car go faster. If more flow rate is needed a bigger pump and or fuel lines is the answer
not a higher pressure pump.
Most fuel starvation issues arise because of problems on suction side not the high pressure side of the pump.
Of course more pressure does not make you go faster!......
Read any weber spec, and it shows that around 3.5 - 4psi is the optimum Fuel pressure......Anything over this and it 'CAN' effect the needle
valve and float operation.#
So, the specs are below...Unless said person has the smallest rated pump, then there is a possibility of over pressure........By fitting a pump giving
slightly higher pressure than required (and regulator), you fully cover yourself for any fuel requirement, plus, if the engine is ever upgraded, you
don't need to worry about fuel.....
Spec Road Road Fast Road Competition
Pressure2.0-4.0 3.0-4.5 4.5-7.0 7.0-10.0
Clearly anything above fast road must have a reg...
Plus, whilst the pressure of the smallest pump will probably be more than adequate speeds and on a rolling road, it is quite possible that fuel
starvation might manifest itself if the car is capable of accelerating hard (which is exactly what seveneques are all about). Mainly because the fuel
pump is now trying to push a 'column' of fuel against the acceleration.
IMHO that is why it is best to have a pump of slightly higher pressure than required, and mount the regulator as close too, or better still in front
of the carbs