Fuel Delivery Troubles to a Weber 48IDA
 

I am having all kind of fuel delivery problems. I am running a 13B 4-Port with a large StreetPort, Weber 48IDA, Holley Blue Fuel pump, Holley Fuel pressure Regulator and no return line to the gas tank. 6 AN Fuel Stainless Braided lines. The RX-2 runs fine as long as I don't stomp on the accelerator. If I do, the car stumbles really bad to the point of shutting off. At first I thought there was dirt in the tank. Took care off that by flushing the tank and the fuel lines. Then thought the voltage was dropping off, causing the fuel pump to bog down. Voltage is fine. Some people are telling me that the Holley fuel pump and regulator are not the right set up for the Weber. Some recommend I use a Carter fuel pump. Some recommend I use a CB Performace rotary pump. Both Carter and CB pump will suffice and I would not need a fuel pressure regulator. This one got me by the balls. I have checked the fuel pressure and it is at a constant 4.5 psi. Any suggestions?

Carb just may be way out of adjustment or your ignition may not be working correctly. Do you have access to a wideband o2 system? If not, do you have an in-cockpit fuel pressure readout? If not, you can run a line to a fuel pressure gauge and hold it down with your windshield wiper so you can read it while driving. You should verify fuel pressure when the issue occurs. If pressure doesn't dip when it dies it is not fuel supply system related.

accelerator pump not giving large enough squirt or needs adjustment

holley blue is 14 psi so you definitely need a return or it will flood. Holley regulator is fine. its best to use the RX-2/RX-3 stock carb inlet since it has a return. whoever said that this is not a good set-up knows jack. :lol::lol::lol::lol:

stumble? first, we need to know your set-up as in venturies, idle jet, etc etc

I was thinking accelerator pump too. But is it only an off idle thing or can you bring the car up to a rev then stab the throttle and will it do the same?

Get a little more information on when and where you are having the problem. Will help diagnois the problem.

if you think its the accelerator pump, then back it up or wacky will say bullshit!!!:lol::lol::lol:

I am taking your advice and going with the wideband O2 check. I am really concerned with the fuel pump and regulator setup. I drove the car over the weekend fighting the urge to stomp on the accelerator. It drove fine. Started missing once I got on it hard. I will keep everyone posted. But again, what fuel pump can you or anyone recommend. Racing Beat has the Mallory. $175 for the fuel pump and $100 more for the regulator. That is a bit pricy.

What regulator should I use for the return line. Stock inlet way gone.

Did you have the whole setup running well before this problem arose?

If not then prove fuel delivery as advised above, if all good then change out your accelerator pump to prove that, Holley red pump with return line and your current regulator will work good, check the jets and venturies also, they would need to be spec'd for your porting.

i'm thinking that the pump travel is running out before full rotation of the throttle plate. gradual rotation is fine, but it's the quick rotation making the squirt not sufficient. maybe not the whole problem but maybe some of it?

You want to run a return style 3-port regulator. That's a good idea. You don't need to buy a new regulator to change to this setup though. A 3-port regulator is a 2-port regulator with a built-in tee. If you replace the 2-port regulator you have now with a tee and put the regulator between the tee and the tank return line it will function the same as a 3-port regulator. If you look inside a 3-port regulator you may be able to see what I mean. As for the pump... You should be fine. 14psi is what it is internally regulated at, the max pressure it will put out. The regulator contols the pressure the carb sees. I ran EFI pumps with my carb setups before. I recommend using them too. They have lots of flow and are dead quiet.

3port regulator as in mallory and others are expensive. since you already have a holley, use one port for return and the remaining for gauge and supply to carb.

I'm leaning more on the idle jet.

1. Verify adequate fuel pressure
2. Verify proper float adjustment
3. Verify jets and chokes are around the right sizes based on others experience
4. Start tuning

It could be helpful if you showed us some pics of your setup.

You can check the accelerator pump setup with the engine off by watching the booster nozzle when you advance the throttle with your hand. Fuel should come out as soon as you advance the throttle. The amount of fuel delivered by accel pump may be the issue, but we would need more info to tell. Can you rev the motor all the way out if you sneak into full throttle early in the revs? Try a 2nd gear pull from low RPMs like 2000.

+1


If the idle jet is too small you will get a stumble just off the lean idle. Can you play with the throttle and get the RPMs up? If it idles good otherwise you are probably pretty close, might just go up the next size and be ok.