Fuel pressure regulater installed...problem solved

[colonel mustard]

Fuel pressure regulater installed...problem solved, at least I think.

so after my edelbrock carb fell apart, I decided to put a HOLLEY 670 offroad carb on my truck a few months ago. for the most part it worked great right out of the box, but always seemed to run rich...and didn't seem to have near the pick up or power delivery my old edelbrock had. this was strange to me as Holley has a much better reputation.

I tinkered with setting the carb up. air fuel. timing. experimenting with different accelerator cams. all of them seemed to help a little in there own way...then I installed a fuel pressure regulater and gauge. I was getting 6-6.5 psi pressure at the carb. I backed it down to 3.5 psi and man it really woke the truck up.

all my power loss I have experienced when I changed to Holley had returned plus some.

my question is, why did lowering the fuel pressure seem to be sooooooo much better for performance?

 

[Preston]

Very good question Steven, let’s do some research on that, let’s hear from the experts on the site.

 

[Arkansas_V8]

Running leaner always makes more power. Just how lean is safe?

Play with jetting, but always have solid fuel pressure.

 

[4WDKC]

excess fuel does not mean excess power. You need to make sure the engine has the 14.7:1 afr at idle and while cruising and 12.5 ish:1 at wot. reducing the pressure this much with a carb that runs rich will cause it to lean out. Problem is you may run out of fuel in the carb a better way it to adjust pressure to correct setting for the carb (6 i think) and then jet the carb correctly to get your AFR where it is needed.

 

[Old60Driver]

Just spit balling here, but if you increase fuel pressure, you may be increasing 'head pressure's in the bowl. IF that's the case, then you could potentially have fuel being dumped in, prior to the engagement of the secondaries. Just a thought, and probably not a good one! Lol

Regardless, glad you got it figured out. Looks like I'm adding a pressure regulator to my list of things to look into!

 

[SirRobyn0]

I'll do my best to answer the question at hand. So here is the thing. Fuel is under pressure after the pump until it reaches the bowl in the carburetor. The float, needle and seat in the carburetor work to stop or slow down the flow of fuel into the carburetor to maintain a set level of fuel inside the float bowl. The float bowl is not pressurized the fuel in the bowl is then drawn into the passages in the carb and into the manifold. So if there is to much fuel pressure the fuel will come in past the needle and seat when it shouldn't resulting in to much fuel in the bowl, which can the result in to much fuel getting into the engine or in extreme cases it can flood externally too. To much fuel results loss of power, fuel economy and host of other issues.

It seems to me that when swapping to a non-stock carb a fuel pressure regulator is good insurance the aftermarket carb will operate correctly. I'm glad it solved your problems.

 

[AuroraGirl]

I'll do my best to answer the question at hand. So here is the thing. Fuel is under pressure after the pump until it reaches the bowl in the carburetor. The float, needle and seat in the carburetor work to stop or slow down the flow of fuel into the carburetor to maintain a set level of fuel inside the float bowl. The float bowl is not pressurized the fuel in the bowl is then drawn into the passages in the carb and into the manifold. So if there is to much fuel pressure the fuel will come in past the needle and seat when it shouldn't resulting in to much fuel in the bowl, which can the result in to much fuel getting into the engine or in extreme cases it can flood externally too. To much fuel results loss of power, fuel economy and host of other issues.

It seems to me that when swapping to a non-stock carb a fuel pressure regulator is good insurance the aftermarket carb will operate correctly. I'm glad it solved your problems.

careful, robyn, you might upset some angry old men who insist regulators will lierally kill you OwO

 

[SirRobyn0]

careful, robyn, you might upset some angry old men who insist regulators will lierally kill you OwO

Thanks for that Taylor, you got a smile and a chuckle from me and you have no idea how much I needed that right now.