The Stovebolt Site Forums The Shop Area Engine Shop Fuel pressure

OK, I don't know if I am "tilting at windmills" here, or if this fits under the "don't fix what ain't broken" rule. The Pontiac engine in my '55 has a 1405 Edelbrock carb. I put a fuel pressure gauge in the line. It has about 9 lbs of pressure. Edelbrock reccomends 5.5 lbs. The fuel pump appears to be a stock Pontiac item. So I bought a fuel pressure regulator. Put it in the line and it only dropped the pressure down to about 8 lbs. The pressure regulator did not come with any instructions, as to which way to turn the regulating screw to adjust the pressure. I turned the screw out with no change in pressure at all. Then the regulator started to drip gas and I shut the engine down and took the thing off. As an aside, when I put the fuel line back together with a new filter, now I have over 10 lbs on the gauge. I think I need a frosty beverage or three....

Is it an electric fuel pump?? Most regular cam operated fuel pumps generally are rated at 3-5 lbs of pressure.

John

The pump appears to be a stock Pontiac mechanical one, Must be a hipo pump?

I would bet if you turn the adjuster in, pressure will drop. I think it takes spring pressure to hold off the fuel pressure. 3 to 4 will be plenty, the carb will lean out slightly with less pressure, so a float adjustment might be needed if it runs right as it is. If it smells rich, then less pressure will cure the smell and make it run better.

You might have a high pressure mechanical pump installed, Carter made them and still does. It will have screws around the middle, where stock pumps are crimped together. The Carters can be taken apart and the base rotated.

If it runs right, doesn't flood over, smell decent at the tail pipe, then don't worry about it.

Joe

That makes sense, Joe. Pump has screws around the middle. I'll try hooking up the regulator again, and use permatex on the fittings, as teflon tape was not sealing well. Engine runs great, but does blow alot of black on my driveway on cold startup,(exhaust pipes point down). I don't have the choke hooked up and usually give the accelerator a couple of pumps in the morning, and the big Poncho starts right up and idles nice.

No more than 7. It will over load the needle and seat

That's the scarey part, Hollow, I've been driving it like this for almost a year now!

If it doesn't flood I'd say to with it. Can you see fuel pouring into the bowl at idle? Like a fountain? If not, keep on keepin on

What pump are you running? And never use Teflon tape on fuel lines. They deteriorate and turn to crap to plug the carb.

Pump appears to be stock mechanical pump. As far as using teflon tape on gas lines, brain fart on my part, will use permatex in the future.

You'll be fine with a mechanical. It's not a high output right? It's when you get into electric high flow that you see flooding at idle.

I run (2) 110gpm pumps right out of the tank and (Y) in to a single line to my regulator then carbs. Set at 7psi. If you've been driving for years and you don't flood or go through spark plugs like mad, I wouldn't worry.

What part of so cal are you in? Pictures like San Bernardino but it could be east San Diego for all I know.

Seems to be a hi output pump, its putting out 10lbs pressure at idle.

Holy cow! 10psi! Get the regulator and a pressure gauge. I use a cheap mr gasket fuel pressure gauge - $15 I believe. Set it to 5-6. Happy motoring.

Ya, I got the Procomp #2851. It didn't come with any directions as to how to set the pressure. And the Mr Gasket gauge. I'm in Moreno Valley, just a little NE of you.

It has to be online somewhere, or if it's like my holley regulator, turn it out to lower the pressure. I'm surprised you trucks runs at 10psi. You will probably have to tune the carb afterwards.

Any progress cap'n?

OK, yes we have progress! Took the fittings out of the pressure regulator and cleaned off the teflon tape and put them back together with Permatex. Installed the regulator back in the fuel line and adjusted the pressure down to 5.5 lbs. Reinstalled the filter ahead of the regulator, and all is well. May be my imagination, but the engine seems to run "crisper", but it is certainly much better seeing the lower pressure at the gauge now! Went over to my friends house after working on the truck for a swim in his pool and a couple of cold frosty ones, summer is here, for sure, in Southern California!

Excellent. Had me some frosties after my concrete pour today. Never durin work, but when were done we send a guy to get some brews. Glad you fixed it! 5.5 is perfect. Probably crisper because it's not loading up so much at lower rpm. Take care boss

Thanks guys for your help with this, the high pressure could have been a problem. I like having the pressure gauge in the fuel line, it great to be able to see whats going on with the fuel system.