Weber: Fuel pressure fade

[priobe]

Hello All,

I have noticed that when my motor starts to warm up with the IDA 48 the fuel pressure starts to drop off.

My current fuel setup:

IDA 48
Holley Blue Fuel Pump
-10 Feed
-8 return
Bypass Regulator
Fuel Pressure 3.0

After pinching the return side of the regulator I noticed the pressure increased and the car ran different at idle.

I have also seen others post the same information about the fuel pressure fading. Many comments have been made that this is normal. I would like to find out if you guys that are experiencing the same fade have a return line.

Also would like to know if you are using a dead head regulator(a regulator that does not need a return line) or a bypass (regulator with a return port)

Thanks

[priobe]

Can some help out with some info please?

[tommyboy]

Priobe,
I had a similar problem way back. I had an Inglese 48IDA setup on a stoker small block. I have since changed alot of what Inglese originally setup because it did not work right.
Focusing on the gauge, mine was located at the end of the fuel line after the last carb. Engine cold and running fuel PSI was good. As engine heated up to fully warm fuel PSI would read 0 on the gauge (I even swapped out a couple different gauges). Engine still ran fine with no driveability problems. I ended up installing an Autometer electric fuel pressure gauge and mounted it inside the car. Never had a problem since.
Also the original Inglese setup had their push button diaphragm style regulator. I found this to be way to restrictive. I set my car up to run strong on the track but can drive in daily traffic all day long. The following is how I setup my car:
- fuel safe fuel cell
- holley low pressure fuel pump (blue)
- fuel curve west fuel regulator (this regulator can support a 2000 hp motor. It has a low pressure side I have set at 2.5 psi and a high pressure side I have set at 6 psi . There is an elctric solenoid built into this regulator that I have chipped into my MSD igniton box with an RPM activated switch so at a more elevated engine rpm range the regulator switches to the higher fuel psi where the engine is using more fuel.)
- return line back to fuel cell
- I designed and built my own phenolic spacer plate, 1/2" thick. This is a single plate that resides iabove the manifold and below all four carbs which provides three functions:
1) It provides a very nice thermal barrier preventing the fuel from boiling in the float bowls
2) Allows me to turn the passenger side carbs 180 degrees around so all four carb throttle plates open the same direction(fuel lines enter on drivers side of carbs.)
3) Enabled me to build my own linkage with a center mounted shaft mounted to two roller bearing pillow block assemblies that bolt to the phenoilc plate and run straight down the center of all four carbs(front to back). Each carb has it's own adjustable link to this shaft. This allows the deletion of the interconnecting linkage between the two carbs on each side, hence better carb synchronization.
This all may be more than you wanted to hear but my system is safe and works very well.

Goodluck.

[tommyboy]

Priobe,
I had a similar problem way back. I had an Inglese 48IDA setup on a stroker small block. I have since changed alot of what Inglese originally setup because it did not work right.
Focusing on the gauge, mine was located at the end of the fuel line after the last carb. Engine cold and running fuel PSI was good. As engine heated up to fully warm fuel PSI would read 0 on the gauge (I even swapped out a couple different gauges). Engine still ran fine with no driveability problems. I ended up installing an Autometer electric fuel pressure gauge and mounted it inside the car. Never had a problem since.
Also the original Inglese setup had their push button diaphragm style regulator. I found this to be way to restrictive. I set my car up to run strong on the track but can drive in daily traffic all day long. The following is how I setup my car:
- fuel safe fuel cell
- holley low pressure fuel pump (blue)
- fuel curve west fuel regulator (this regulator can support a 2000 hp motor. It has a low pressure side I have set at 2.5 psi and a high pressure side I have set at 6 psi . There is an elctric solenoid built into this regulator that I have chipped into my MSD igniton box with an RPM activated switch so at a more elevated engine rpm range the regulator switches to the higher fuel psi where the engine is using more fuel.)
- return line back to fuel cell
- I designed and built my own phenolic spacer plate, 1/2" thick. This is a single plate that resides iabove the manifold and below all four carbs which provides three functions:
1) It provides a very nice thermal barrier preventing the fuel from boiling in the float bowls
2) Allows me to turn the passenger side carbs 180 degrees around so all four carb throttle plates open the same direction(fuel lines enter on drivers side of carbs.)
3) Enabled me to build my own linkage with a center mounted shaft mounted to two roller bearing pillow block assemblies that bolt to the phenoilc plate and run straight down the center of all four carbs(front to back). Each carb has it's own adjustable link to this shaft. This allows the deletion of the interconnecting linkage between the two carbs on each side, hence better carb synchronization.
This all may be more than you wanted to hear but my system is safe and works very well.

Goodluck.

[priobe]

Thanks for the reply Tommyboy,

Do you have any pics?

Also, what type of material did you use to make the spacers.


And did you change the regulator and the fuel pressure gauage at the same time?

[tommyboy]

Priobe,
I do not have any detailed pics a this time but I will get some.
The material I used is a "Garolite XX" through Mcmaster-Carr. I changed the fuel gauge first and later on upgraded to the more advanced fuel pressure regulator.

[jmimac351]

Originally Posted by tommyboy

Priobe,
I do not have any detailed pics a this time but I will get some.
The material I used is a "Garolite XX" through Mcmaster-Carr. I changed the fuel gauge first and later on upgraded to the more advanced fuel pressure regulator.

Tommyboy:

Did you find that incorporating the spacer effected the tune in any way? Any differences in idle, part throttle, etc?

Thanks.

[tommyboy]

jmimac351,
The spacer plate acts as a thermal barrier which helps alot during a hot restart. Without the spacer, after shutting off a hot engine, heat from the engine would heat soak the carbs and fuel in the carbs float bowls would boil over and load up the cylinders. It made for some hard/extended cranking restarts not to mention washing down the cylinder walls.
The setup I made is a totally custom piece that addressed three or four seperate issues. You can buy individual spacers and carb adapter plates to turn one bank of the carbs 180 degrees around but you end up using three gaskets per cylinder and you still have the less desired throttle linkage setup.

I have no tuning/driveability problems.

[SLHetal]

Priobe,
In addition to Tommyboy's excellent suggestions, you might want to go to the Porsche 356 Registry website and do a little research there. Many many Porsche 356 street cars and racers are equipped with Weber 44 IDFs and 48 IDAs. They often run into similar situations such as yours. Also the 4 cam 4 cylinder Porsches had numerous Weber issues/bugs over the years that have been resolved with a lot of information on line, again via the Porsche 356 Registry. Hope this helps.