Installation of fuel pressure regulator.

[Erasmus]

Hello all,

The Old Lady has been having some vapor lock problems when restarting after 10-15 minutes. Allow me to elaborate a little.

When the car is at idle, I can hear the fuel pump ticking two-three times followed immediately by a loss of RPMs and a little rough running. This repeats itself every 10-15 seconds. Clearly, the pump puts too much pressure out for the float valves to handle and thereby forcing raw fuel into the system.

After the 10-15 minute break, the engine needs a lot of cranking before she sputters to life. When restarting, I can hear the fuel pump click 5-9 times to refill the bowls. If I disconnect the electrical wire to the fuel pump and try to start, the engine needs less cranking time before starting up.

Through this great forum, I have read all the possible causes and solutions and have purchased a Malpassi Filter King to lower the fuel pressure.

It would be an enormous help if some members that have the Filter King installed can send me some pictures of their installation.

Thanks a lot!

[Goldstar]

Hi

First i would take your email off the forum, all sorts of spiders etc will find it and spam you.

On the fuel filter I have a rubber hoss from the plastic pipe in the engine bay and then the filter then more hose to the carb feed. Dead easy. I'll see if i can find a picture but its push fit 8mm tails IIRC

[Always wanted a Stag]

I fitted a Malpassi Filter King to the bulkhead near the fuse box as per the attached photo.
Attached an angled bracket to the bulkhead having made a slit in the insulation pad IMG_9370.jpg

If you are careful with your measurements, you can still access the fuses behind the filter.

Used a couple of stainless steel braided fuel hoses to finish it off.

Hope that this is of some help.

Best regards
Paul

[Erasmus]

Hi

First i would take your email off the forum, all sorts of spiders etc will find it and spam you.

Good thinking.

[trunt]

I don't understand why there is a need for a pressure regulator?? surely if its getting flooded the carb float valves are weak -- the SU pump doesn't put that much pressure out maybe 1.5-3 psi?

Or maybe is this an aftermarket pump that puts out more pressure?

Anyways, this reminds me of a problem I had with an MGB, kinda the opposite but similar.

In this case the engine ran Ok at idle for 20 seconds or so then would start to stumble... then you would hear the tika-tika of the pump and it ran ok for a while. The cause of this was a pinhole in the fuel pipe from the tank to the pump. No fuel was leaking out but as the pump worked it was sucking air. This could be seen when I removed the fuel pipe at the carb and found the fuel spluttering out, instead of a nice even flow.
Don't know why this did not affect the engine at speed!!

[mike@thenook]

Hi Erasmus,

I fitted a Malpassi Filter King in the same position as Paul and having done so, I never get a problem with vapourisation or flooding. I rebuilt my carbs with Viton tipped needles but they would still misbehave occasionally.
Well worth it in my opinion

Cheers

[trunt]

Hello all,


When the car is at idle, I can hear the fuel pump ticking two-three times followed immediately by a loss of RPMs and a little rough running. This repeats itself every 10-15 seconds. Clearly, the pump puts too much pressure out for the float valves to handle and thereby forcing raw fuel into the system.

Firstly, nothing wrong with installing a fuel regulator, it can only do good things...

My understanding is that Vapor lock is where the fuel has boiled and has turned to gas, usually in the fuel lines and the carbs get starved because there is no fuel to them for a short while. Another form is where the float chambers are low due to the fuel boiling off. Its most common with mechanical pumps. With electric, when you turn the ignition on, the fuel is delivered and the float bowls are filled up fully before you attempt to start the engine. (tika-tika!)

As you say, Fuel pressure could affect hot starting if it is overwhelming the float valves, but this would not cause fuel to be "forced" in as the float chambers are (should be) open to atmospheric pressure, the fuel just drips into the float bowl and raises the level making the mixture over rich (until it overflows in extreme cases) i.e the fuel in the float chamber is NOT pressurised by the fuel pump.

This sounds like what you are experiencing, so I would suggest checking the float levels and valves as well, especially if you have a standard SU (2-3 or 3.8 psi depending on model) as it really should not be overwhelming the float valves and they may be on the edge of failing. Initially, you could remove the carb pistons and look down the jet hole, you can usually see the fuel (float) level, (sometimes shaking the car helps) Are they the same on both carbs? - leave the ignition on, does the fuel pump keep ticking? does the fuel level keep rising?? both are indications that the float valves are leaking.....

If you do have a high pressure pump then yes, the crappy valves cannot deal with much more than 5psi, so don't bother with all that!!

I hope that helps
Terry

[mopoole]

As an aside, I've thought about fitting a fuel regulator having seen quite a lot of stags with them fitted. I'm currently running with a Stagweber carb. What are the advantages and what pressure should it be set to? Sorry to highjack the thread but it seemed relevant.
Regards
Maurice

[Goldstar]

As an aside, I've thought about fitting a fuel regulator having seen quite a lot of stags with them fitted. I'm currently running with a Stagweber carb. What are the advantages and what pressure should it be set to? Sorry to highjack the thread but it seemed relevant.
Regards
Maurice

Hi Maurice, I would refer back to Stagweber for technical advice, they should provide that kind of info as part of their after sales service.

[richardthestag]

My lucas electronic fuel pump is pushing out 5psi. this overwhelms the float valves in the strombergs. Things came to a head when I found petrol in the air filter box!

I installed the filter king and regulated the pressure to the carbs down to 2psi and it runs smoother, starts easier and is a win win win

I fitted my filter king on the strut like this, only reason for doing it this way around is that the fuel input to the filter is routed the same as it would be for the standard in line plastic filter
IMAG2244.jpg

Before pressure was 5psi
IMAG2258.jpg

adjusted down to 2psi
IMAG2246.jpg

gauge removed and blanking plug fitted

[jbuckl]

Hi Mike,
I fitted a malpassi recently too, set it to 2.5psi.
Have also removed the su pump for the time being and am running a facet.
This was all in an attempt to improve a hot running issue that I cannot get to the bottom of.
Would like to return to standard one day (!)
What pressure is your filter king set to?

Hi Erasmus,

I fitted a Malpassi Filter King in the same position as Paul and having done so, I never get a problem with vapourisation or flooding. I rebuilt my carbs with Viton tipped needles but they would still misbehave occasionally.
Well worth it in my opinion

Cheers

[Erasmus]

Thanks everybody for your help so far. Has anybody mounted the Filter King in the trunk (boot)?

[MandM]

I fitted one of these,

[mike@thenook]

Hi Mike,
I fitted a malpassi recently too, set it to 2.5psi.
Have also removed the su pump for the time being and am running a facet.
This was all in an attempt to improve a hot running issue that I cannot get to the bottom of.
Would like to return to standard one day (!)
What pressure is your filter king set to?

Hi,

i seem to remember around 2psi.....

[HersnotHis]

I fitted one of these,

I did too following recommendation by Milothedog on here following fitting electronic pump from LD parts. I found fuel intermittently being discharged from float chamber overflow. Problem solved after fitting and setting to 2.5 psi. Fitted after standard filter gives lower cost alternative to Filter King.

HTH

H