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Discussion Starter · #1 ·
Just noticed I sprung a leak on my 2nd fuel pressure regulator. The first one was a Purolator that ruptured a diaphram
(1 month), and this one is a Holley that appears to have developed a hair-line crack(1 month). I am about ready to remove the regulator completely and replace the fuel pump with one of less pressure, as I feel the regulator was also soaking up too much heat under the hood also. Besides, one less place to leak....

As I have said here before, I never had a pressure issue with the 32/36, just with this 38 DGAS. If I remember right, the pump is 5#. Before I send the money on another, lower pressure pump, I was wondering if a set of Grose Jets might allow the Weber to handle more fuel pressure?

Thanks for the help,

James
 

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Discussion Starter · #2 ·
Broke down and bought a new low pressure (1.5#-4#, 30GPH) fuel pump tonight from the local auto parts. It's a cheap Purolator ($30), but I figured I'd give it a try before I took the time to find a good one. I should have time to install it over the weekend. I'll keep everyone informed.

By the way....extra block is at the machine shop being bored and balanced as we speak.....Mo Power

Bestus,

James
 

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Discussion Starter · #3 ·
Got new fuel pump all plumbed up over the weekend. Seems to work without the regulator like I hoped, without flooding. The only bad thing is, boy does it sound obnoxious! I even have it mounted on rubber washers like the old one, but I can hear this one even at 40 MPH. I guess now that it's back together, I'll take my time and try to find a decent low pressure pump.
Any ideas where to look?
James
 

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Try and find a Rotary type pump as well if you can. Many electric fuel pumps are a diaphragm type, where current actually pumps the diaphragm back and forth using sheckvalves to move fuel. Those things vibrate pretty good and make a TON of noise.

I was always partial to the Mallory fuel pumps and regulators - of course they aren't as easy to find now as they used to be (for me at least). I've got a Mallory 140 I'm planning on using with a return style regulator. I was always able to get good, consistent fuel pressure with this setup in the past - and the return style system eliminates any fear of vapor lock sicne it keeps the fuel moving and cooler. Of course you do have to run an extra line back to the tank (for earlier models anyway). Oh - and the only mallory pump I was ever able to hear from inside the car was the lil-bitty 4070 I ran in my Beetle - of course is was up front with the gas tank - and I could only hear it with the engine off.

I believe Holley offers some rotary pumps these days, but I'm not sure about pressure specs.

Argh! I can't wait to get back to work on my baby - yet the hunt for (affordable) sheet metal continues!
 

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Discussion Starter · #5 ·
Chris,
I agree with you totally about the rotary type pumps. I actually bought a nice Carter pump last year. But....I never could find a place under the car to mount it where I felt it was safe, it's just too large.
James
 

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Different info on electric fuel pump

Racetep.com is now recommending 4 psi for the Webers and no regulators.

http://www.racetep.com/webfuelspark.html#webfuel

Per that site:
Fuel Pumps and Fuel Pressure:
Fuel delivery is critical to the proper performance of any Weber carb. From a basic 32/36 DGEV to a set of Triple Sidedraft DCOE's. Webers rely on a stable full float bowl in order to mix the fuel and air correctly. Mechanical pumps very rarely do this. They pulse fuel instead of giving a smooth even delivery and the amount of fuel varies with engine RPM.

A Proper Electric Fuel pump will give the best performance and most stable tuning for any Weber carb application. We use only High Volme and Low Pressure pumps. Webers work best at approx 4 psi of fuel pressure (Not 2 psi like many of the older books stated.) and you need Volume not Pressure to keep the float bowl full.

We ONLY use the Carter Rotary pumps. They are High Volume (60-70 GPH) but only 4 psi. This is PERFECT for all Weber applications from a Single 32/36 DGV on a Truck, Jeep or Car to a Triple Sidedraft setup on a Road Race car making 300 HP...This pump DOES NOT and SHOULD NOT use a Pressure Regulator for any reason. That is why we use it....


Carter 4070 Fuel pump with Mounting Bracket kit $95.00 Buy Now

Problem Pump and Regulator setups:
These are combinations that many of you are using and you could be experiencing problems because of it.

Holly Fuel Pumps with Regulator:
This is a very common combination and it has alot of problems. The pump puts out too much pressure so you have to buy a regulator for it. The Regulator is just a restrictor that inhibits flow. This causes a huge loss of Volume and overloads the pump causing alot of noise and premature failure. This results in the float bowl going low or empty under hard acceleration and causes cornering problems.

Facet Fuel Pump:
This is one of those little square pumps with the transistor mounted on top that make a ticking noise all the time. These pumps are TERRIBLE. No volume and High Pressure. These pumps have been sold for many years with Weber and Mikuni conversions and have cause many people alot of tuning problems. They are a pulse type pump that delivers almost no volume (usually less than the stock mechanical pump did) and usually at High Pressure. This cause flooding at idle and lean out conditions under high load. Do not use them....
 

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OK, I know it's not a Weber now, but I had a "tuned" 32/36 on my '72 GT before I went to my SSD DellOrto DHLA40 and used the same fuel pump then too. NEVER had a pressure or volume problem with this pump, though it IS a diaphragm, pulsing "demand" type. Best thing about it is that I picked it up in a "Pick-U-Part" yard . . . CHEAP. VERY quiet too! It's from a 1981 carbureted Honda Accord.
 

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Carter EFP . . . no more than 4 PSI!

asdasc said:
Has anyone every used one of these fuel pumps? I found them at Summit Racing for $59. One thing that surprised me is that the inlet and outlet are 1/4" and the general reccomendation with a 38 DGAS is to replace all your fuel line with 3/8".

http://store.summitracing.com/partd...rt=CRT-P4070&N=400415+307759+115&autoview=sku
You DID notice the 6 PSI rating on the pump, right? Carter has a pump of the same type that is rated at ~3.5 PSI which is the recommended one to use with Solex, Weber or Dell'Orto carbs. These "volume priority" carbs are very pressure sensitive . . . pressure should be kept low while ensuring adequate fuel volume is maintained. Carter electric pumps are an excellent replacement choice.

Here's my personal favorite EFP for Opel carbs.

 

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opelgt722002 said:
Racetep.com is now recommending 4 psi for the Webers and no regulators.

We ONLY use the Carter Rotary pumps. They are High Volume (60-70 GPH) but only 4 psi. This is PERFECT for all Weber applications from a Single 32/36 DGV on a Truck, Jeep or Car to a Triple Sidedraft setup on a Road Race car making 300 HP...This pump DOES NOT and SHOULD NOT use a Pressure Regulator for any reason. That is why we use it....


Carter 4070 Fuel pump with Mounting Bracket kit $95.00 Buy Now
I read that and bought the above pump from Summit (for much less - I think it was $59). I took one look at it and put it back in the box. It's a very nice pump, but in my opinion it is WAY overkill for a single Weber downdraft application. Maybe a full race engine with dual DCOE's would need a supply like that, but not a street driven Opel. I think it has 3/8" hose barbs too, which means adapters are needed, plus it weighs a ton. I'm trying to make the car lighter...

I returned it and bought the same one Otto recommends in the previous post. It has the right size fittings (5/16), comes with a filter, and is both lighter and smaller. I think it's for an Audi application. I'm sure it will be more than adequate.
 

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Thanks Otto and Bill,
That looks like a good set up, I will follow that picture, and run 3/8" from the back to the front of the car.

Thanks,
 

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When I replumbed my Gt the last go round, I followed Ottos and Jimskys posts, and pictures and have had no problems. The next Car will be done the same way as you are talking about Steve, except I'm trying to hunt down a fuel petcock to shut the fuel off from the tank. That way the filter can be changed without having to use a set of vice grips to crimp the rubber hose. I just haven't "searched" enough to find the thread. It's here I know it. :yup: Jarrell
 

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Gerotor pump

Bill Hoffmann said:
I read that and bought the above pump from Summit (for much less - I think it was $59). I took one look at it and put it back in the box. It's a very nice pump, but in my opinion it is WAY overkill for a single Weber downdraft application. Maybe a full race engine with dual DCOE's would need a supply like that, but not a street driven Opel. I think it has 3/8" hose barbs too, which means adapters are needed, plus it weighs a ton. I'm trying to make the car lighter...

I returned it and bought the same one Otto recommends in the previous post. It has the right size fittings (5/16), comes with a filter, and is both lighter and smaller. I think it's for an Audi application. I'm sure it will be more than adequate.
The one pictured is used on my 10.6:1, 2.2 DHLA48 SSD engined GT, still using 8mm (5/16") lines with ZERO problems!
 

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tekenaar said:
The one pictured is used on my 10.6:1, 2.2 DHLA48 SSD engined GT, still using 8mm (5/16") lines with ZERO problems!
True Otto, but remember that a sidedraft has about double the fuel bowl capacity of a downdraft. The downdraft needs a bigger fuel line for a given HP level. Twin sidedrafts have double the capacity still! Which is why you can get away with a stock fuel pump and fuel line diameter up to about 160-165 hp with twin sidedrafts....
 

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SO with that said, can I get away with 5/16 from the tank to the pump if I go to 3/8" right after the pump? I know that over the long haul, I will have a limit to the fuel flow, but will the extra capacity in the tubing augment the amount of the fuel in the bowl long enough for most street activity?

I won't be running full throttle for TOO long! I can see myself doing sustained cruise at 90mph, though, on occation.

I guess fear is removing the part that goes into the tank. If that breaks off, I have a whole new project to deal with.
 

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Ball valve

soybean said:
When I replumbed my Gt the last go round, I followed Ottos and Jimskys posts, and pictures and have had no problems. The next Car will be done the same way as you are talking about Steve, except I'm trying to hunt down a fuel petcock to shut the fuel off from the tank. That way the filter can be changed without having to use a set of vice grips to crimp the rubber hose. I just haven't "searched" enough to find the thread. It's here I know it. :yup: Jarrell
Jarrell,
I'd highly recommend a "ball valve" type of proper size for this . . . quarter turn (90°) operation, no flow restriction when open, positive shut-off when closed! Personal experience talking here . . .
 

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Good tip!!!!

tekenaar said:
Jarrell,
I'd highly recommend a "ball valve" type of proper size for this . . . quarter turn (90°) operation, no flow restriction when open, positive shut-off when closed! Personal experience talking here . . .
:cool: Thanks for the tip Otto, even thinking about two ball valves :yup: , one in front and one in back of the electrical
pump and filter alinement [for easy maintenance :p ]
 
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