engine and drivetrain Anyone using a Holley Fuel Pressure Regulator with Mechanical Fuel Pump?

[xr4tic]

Anyone running a Holley regulator with a mechanical fuel pump?  I got the 1-4psi version and can't find a good spot to mount it since it needs to go between the fuel pump on the head and the carb.

 

I've got a Weber 38 I just rebuilt, and I'm having issues getting it tuned and want to make sure my fuel pressure is correct.

[TobyB]

Yeah, I hung one off of one of the vacuum bosses on the intake manifold.  I think I found a second bolt hole, but I don't remember where...

 

And I then killed 2 of them in pretty short order- the pulsation from the pump beat the hardened sealing ring out of the aluminum

body.  I was shocked- it chewed them to pieces, though.  Twice.  So I changed to a Mallory regulator and an electric

pump, and that fixed it.  For a stupid amount of money and work.

 

What happened to me,

 

t

[xr4tic]

Thanks, I was afraid that I would have to go down the electric pump route, I really just want to get the car on the road before winter comes.

 

I checked the fuel pressure, and it's running between 4 and 5 psi, which is too high for a Weber

[Harv]

I'm no expert but I've never seen anyone run a regulator with a stock mechanical fuel pump. I know what your saying about the Webber fuel psi but I think that's more for DCOE's. The 32/36 and 38 can tolerate the stock pump in my experience. 

 

John

[xr4tic]

Fuel pressure does matter on the 38 and 32/36, lots of documentation out there saying not to exceed 3psi on them, and I'm above that.

 

Maybe it's one of those things that would have been fine if I didn't know (ignorance is bliss), but now that I know I'm out of spec, I need to fix it.  Plus, I'm having issues tuning it and don't want to waste time trying other things if this is the cause.

 

 

[TobyB]

I couldn't get my 38 to idle at all without a regulator on the mechanical pump.  The pressure was about 5,

but had spikes quite a bit higher at high revs.  NO idea why...

In retrospect, I should have tried different pumps- I think that was the root

cause of the problem.  By the time I trashed the second regulator, I was pretty

frustrated with the whole mess, and I had several electrics sitting around.

  Messed up a couple of needle seats on the 38, too.

 

Wrong pushrod?  Bad pump?  I dunno- sold the whole mess a few years ago...

 

t

 

[xr4tic]

What kind of idle issues?  On mine, I have to have the idle screw (the one that opens throttle plate, not the idle mixture screws) in almost 1.5 turns, but I keep reading it's supposed to be only 1/2 turns max.  It just idles way too low and has hard starts at 1/2 turn.

['76mintgrün'02]

I thought the max was 1.5 turns.  Are you sure it is only .5?

I think I can actually hear it interfering with those little 'ports', when mine is turned in too far.

Does the sound change when you turn it in past 1.5 turns? (while running)

[xr4tic]

From what I've read, the 32/36 can go up to 1.5 turns, but the 38 is supposed to be 0.5 turn max.

 

You can verify it by checking to see if the throttle plate covers the progression hole, but you have to pull the carb to check it.

['76mintgrün'02]

Okay, I have the 32-36.

Progression hole = 'port' in my description 

 

Half a turn is not much adjustment.

 

 

Does fuel typically come out of the progression holes with the plates closed/at idle?

It must, or this would not be an issue, correct?

I do hear a 'wet sucking sound' when I turn the idle speed screw in too far.

Does your carb sound any different as you turn the screw in?

I am just wondering whether there is any audible indication that the plates are obstructing the P-holes.

I should make a little video of mine, to show what I am talking about.

 

As you have probably noticed by now, I don't really know what I am talking about.

I sure would like to help, though.

 

Spark then fuel, right?
What is your current timing equation/situation?

 

[zinz]

I am no fan of the replacement Pierburg mechanical pumps.  I just put one in the neighbor's pool after months of fighting it.  Replaced it with an electric and corresponding regulator and my fuel delivery issues are done with.

 

Mounting a regulator between the mechanical pump and the carb would be a challenge... I suppose you could run a longer length of hose from the pump and mount the regulator on the fender, perhaps above the booster?  ... I don't know, I wouldn't like all that extra fuel line in the hot engine bay.  

 

After my latest experience, I'd recommend an electric pump in the trunk... I also installed a check valve between the fuel tank and pump to prevent fuel draining back into the tank.  My '75 now starts right up every time and with the installation of the regulator, I was able to experiment with how higher pressures effect the Weber's behavior. ...anything over 3lbs and it gave me hard, hot restarts and poor running at lower rpms. 

 

Ed

[xr4tic]

Here's a good post about the progression hole:  http://www.jeepforum.com/forum/f8/weber-set-up-tune-discussion-1051137/

 

I double checked my timing yesterday, 25 degrees at ~1400 RPM.  It's an "002" non-vacuum distributor with an XR3000 ignition box and PS50 coil

[xr4tic]

Thanks everyone for the responses, looks like I'll be installing an electric pump setup to fix the fuel pressure issues.

 

If that doesn't help my idle issues, then I'll probably have to re-jet the idle circuit.

[Russell74Fjord]

On ‎9‎/‎6‎/‎2016 at 7:33 AM, zinz said:

I am no fan of the replacement Pierburg mechanical pumps.  I just put one in the neighbor's pool after months of fighting it.  Replaced it with an electric and corresponding regulator and my fuel delivery issues are done with.

 

Mounting a regulator between the mechanical pump and the carb would be a challenge... I suppose you could run a longer length of hose from the pump and mount the regulator on the fender, perhaps above the booster?  ... I don't know, I wouldn't like all that extra fuel line in the hot engine bay.  

 

After my latest experience, I'd recommend an electric pump in the trunk... I also installed a check valve between the fuel tank and pump to prevent fuel draining back into the tank.  My '75 now starts right up every time and with the installation of the regulator, I was able to experiment with how higher pressures effect the Weber's behavior. ...anything over 3lbs and it gave me hard, hot restarts and poor running at lower rpms. 

 

Ed

 

I'd love some specific on the pump you used and the regulator and check valve, I want to do the same thing,

 

Toby too, what are the specific parts you used,

 

and any recommendations  from both of you, pro or con on what you used,

 

TIA,

[zinz]

My parts came out of the stash of stuff in the garage...  The regulator was a Mr Gasket and the pump is a "clicker" style, I believe it's a Holley.

 

This thread has a lot of info