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Tue Jul 26, 2011 11:53 am

I am running a holley to control the fuel pressure to my IDAs. I swear the thing is as steady as a ninety year old with parkinsons!! I wanna smash it. It's causing my carbs to idle erratically and I'm looking to replace it with something more reliable. Any ideas ?

Tue Jul 26, 2011 9:24 pm

is your fuel pressure set at the correct psi for the carbs you are running?

Wed Jul 27, 2011 5:27 am

That's the problem..... I'm aware that IDAs like 3-3.5 psi. The regulator is not supplying a steady regulated amount of fuel.

Wed Jul 27, 2011 7:14 am

http://vwparts.aircooled.net/Adjustable-Fuel-Press...ulator.htm

http://vwparts.aircooled.net/Mallory-Adjustable-Fuel-Pressure-Regulator-4309-p/mallory%204309.htm

are both very good, one is deadhead and the other return style

c.ruber wrote: That's the problem..... I'm aware that IDAs like 3-3.5 psi. The regulator is not supplying a steady regulated amount of fuel.

Wed Jul 27, 2011 6:02 pm

c.ruber wrote: That's the problem..... I'm aware that IDAs like 3-3.5 psi. The regulator is not supplying a steady regulated amount of fuel.

I have a similar issue and suspect the Holley Red 7psi. pump is overriding the Holley 1-4psi. regulator at idle. I have it set at an elegid 3psi, but the idle goes way rich from time to time even after full tune and 13.8-14.1 AFR range is set and steady. It can be as rich as 11.89 some times and the second I hit the off switch to the pump my AFR jumps right to 13.8 instantly without touching the throttle. During a cruise it will read anywhere from 11.89 on up to 14.1 each time I stop at a light. If it's rich and I apply the throttle to 2000-2500rpm is reads 13.5-14.0's or again kill pump power to achieve the same AFR.

I will try the CB rotary 3.5psi. pump and compare.

Wed Jul 27, 2011 7:30 pm

a return style regulator will work better with a high volume pump like the Holley.

Wed Jul 27, 2011 8:02 pm

First, c.ruber, I apologize for the hijacking, but this is a problem I've had since installing the fuel pump/reg and maybe my issue will help you?

Second, John, I would upgrade to the Mallory reg. in a heart beat if my Holley pump didn't sound like an old Craftsman air compressor. I am switching it out to the Carter/CB type pump to enjoy a quieter and self regulated 3.5psi pump. It should be enough for my engines' needs and then I can remove the firewall mounted reg. to make room for a CSP breather box. :wink:

I am curious to know where the bypass line goes to from the Mallory regulator? Top of tank or?

Wed Jul 27, 2011 8:19 pm

return usually back to tank. The additional FLOW of a return system cools the pump.

I hate Holley Pumps, they are WAY too loud.

Wed Jul 27, 2011 8:29 pm

Having a 69 Beetle, I could dump the return into the filler neck, correct?

Wed Jul 27, 2011 9:14 pm

:idea: Pressure reg problem got me recalling my own problem.

Have a 1776cc Turbo and it started slowing down like out of gas etc and then die. Would wait a couple of mins and it would fire up and I would drive a mile and the same thing again. What the heck is going on. Have a glass see thru filter and it is 1/2 full of gas so figure I'm okay there. No sign of bubbles or filling up after stopping. I'm stymied. Pull off the hose to the DCOE...with ign disconnected I activate the pump on the coil to see the gas flow into a rag...drip...drip...drip. Remove the carb top and the bowl is EMPTY. 16 gal tank is fairly NEW as are the fuel lines.

I'm a mechanic and know the line in my car is not plugged. Remove the press reg and run the line directly into the carb and drive home.

Have a spare reg and when checking air flow found a difference. Installed the 2nd one and the car is working fine now.

Took the older unit apart and could not see any problem as it is all metal....but still the press number dialed was not correct.

Things can go wrong with the most unexpected part on an engine.

Steve

Thu Jul 28, 2011 6:49 am

Thanks for the input. I have long suspected the regulator now I have a couple of choices to go on. Doug

Thu Jul 28, 2011 7:32 am

c.ruber wrote: Thanks for the input. I have long suspected the regulator now I have a couple of choices to go on. Doug

I spoke with someone who is running the CB rotary 3.5psi pump on a 2387cc, FK89, 48IDA 12.9sec Ghia with no issues and absolutely no lack of fuel supply. No regulator to fail, stock size VW type cloth hose and factory tunnel hard line to the rear.

I am running a similar, albeit less cam/carb, engine with same VW type cloth hose and factory tunnel hard line to the rear as well. Starvation has never been an issue all the way up to 130mph. I pull 6500rpm in 3 gears when needed and can get 12.50AFR all the way to 6300RPM in 4th. I just need a more reliable source!

A V8 buddy has a spare Mallory bypass reg on the shelf for me to try, but, I would rather ditch the Holley system and go to the Carter rotary type since this is a daily/weekend warrior driver and the Holley noise actually got to me. :roll:

Thu Jul 28, 2011 7:34 am

[email protected] wrote: return usually back to tank. The additional FLOW of a return system cools the pump.

I hate Holley Pumps, they are WAY too loud.

Thank you John.

Thu Jul 28, 2011 1:06 pm

Well I figured I would do something other than wait for new parts, so I went into the shop and fired it up. Realize my shop is 80*+ inside from the sun, so my oil temps are always preheated to 65*+ when I check with thermo-stick. It started fine as usual, idled clean at 15.67AFR with a few normal pops, then I apply a steady throttle, very slowly to 1500, then to 2000RPM for a moment, then let off to idle at 950prm and it's down to 14.5AFR. Give it a moment and it hits a low 12.5, 12.3, 12.22AFR steady.

So, I dropped my fuel pressure from 3.2psi down to 2.25psi. The idle AFR climbs to 15.67 and levels out to 14.5AFR. I bring it up to 2.5psi and go for a drive with an idle of 14.0-14.2AFR. The drive felt fine and all was proper, the idle froze at 13.9-14.1 at every stop! I got home, raised the fuel pressure up to 2.75-2.95(?), [gauge reads just under 3psi] and took another short drive. I can easily detect a power loss with pressure under 2.75psi and it seems very happy just below 3psi on the guage. The idle AFR steady at 13.7-13.98 before and after last trip at 2.75-2.9psi.

All noise aside, it seems to hold steady when dialed in there. No more fuel smell like last week and no more rich idle. Either way, I am going for the CB rotary 3.5psi pump for piece of mind.

Hoping this helps. :wink:

Thu Jul 28, 2011 3:01 pm

most people realize fuel pressure doesn't matter. Let me elaborate.

"Everyone" says to set the floats to this, and run that fuel pressure, with the goal of getting the desired FUEL LEVEL in the bowl and emulsion well. Then the carb works properly.

But what is not discusses is that the float mass also changes the fuel level. As does the fuel pressure. As does the float VOLUME. As does the fuel DENSITY.

if you really want to get it right, you have to set the FUEL LEVEL (not float level). It is true that within "most" parameters one sets the other, but there are advantages to setting fuel level instead. Here are 2 examples.

If you have 2 carbs on the same engine, one float is heavier than the other, the fuel levels will be different on each despite the same float level setting.

You can see the fuel level if you remove the emulsion stack on the DRLA/IDF/IDA carbs. With full fuel pressure (running), where is the fuel? You can move the float adjustment as needed to raise or lower the fuel level, so that the main circuit's operate the exact same.

Another thing you can do in a race engine, is set the floats, and measure the fuel level at your 3.5psi fuel pressure. Now change the fuel PRESSURE to 6psi, and recheck your fuel level. You'll have to raise the float levels to get the fuel level back where it was, BUT you'll have the advantage of 2x the flow as what you had before, with the same fuel system.

THINK

Thu Jul 28, 2011 4:13 pm

The funny thing is, I had the pressure dialed last month and something changed...maybe the fuel from another station? I run Mobil 93 and Sunoco 93 to keep it simple. It seems to run best with those two choices. I have run many others and even though performance was acceptable, I could tell the difference when it mattered.

Anyhow, I had been playing with fuel pressures since setting the floats at just 6mm/13.2mm, the engine told me it was good there. I started at 2.5psi and worked on up to 3psi to find it was a rocket and the AFR was spot on. Something changed, maybe fuel pump spike, regulator sticking, who knows. All I did was adjust it down, then worked back up to please the seat of my pants all the while keeping the idle and tune within my specs.

Since my last update I have taken a ride to get groceries and it was near flawless again. I hit the highway, then backroads and stopped off to see some friends while it idled. The AFR at idle was still 13.8-14.1 even after goofing off in lower gears, it recovers quickly now and returns to idle without hesitation. Maybe I'm the idiot that went too far on the pressure, maybe my gauge is not as accurate as once thought? I did compare to another 1-15psi gauge with like results...means nothing to me really without science proving it.

Even after a few displays of power it never smelled like gas, not once! I do see/feel my 35-4000RPM transition leans a tad with the lower pressure, but I will double check the fuel level and work from there.

Thu Jul 28, 2011 6:01 pm

Good info!!!!

Fri Jul 29, 2011 9:39 am

John, thanks, that last bit made me realize what I overlooked. I need to take my vacation soon, too many 12hr. days/nights fck'n up my smarts! :oops:

Fri Jul 29, 2011 9:48 am

Once you find what float level and fuel pressure works, you can then measure the fuel level, then change the pressure (as desired) and make a quick change in float height, to wind up with the SAME fuel level that your carb wants, with the increase in flow that you need. This lets you operate outside the restrictions of "3-3.5psi" that weber says you must adhere to.

If you do this I recommend getting Viton Needle/Seats, not the brass ones, they seal much better, which is needed under the higher pressure. We have both Brass and Viton here in many sizes.

Fri Jul 29, 2011 11:07 am

I'm working with Dell 48's and as I understand it, you stock jets for them as well.

I just swapped out the 70 idles for 65's and did the mixture routine to end up with 13.7-14.2 AFR. I upped the pressure from 2.75lbs. to 3.2lbs. in small increments while twisting for best lean idle in between each pressure increase. I have it at 13.89+/- AFR with just over 3lbs. and it sounds much more repsonsive and idles very smooth. Once I get it to my liking I will check the fuel level and adjust from there. Now I will road test after the re-tune and go from there. I just might be able to run 62's after all???? :idea:

Now I know where I fck'd up and I can only laugh at myself for the carelessness that got me to this point. I am usually very tired from working and should not try to tune my Bug until I have a coma. :lol: Lots of simple mistakes that create bad situations and loads of frustration. :x

Reading your repsonses sparked my brain and it all became clear, thanks again. 8)