The Stovebolt Site Forums The Shop Area Engine Shop Fuel Pressure Question

Hi all. Got a 1949 Chevy Pickup with 1954 235 engine. Carburetor has been flooding. Rebuilt the carburetor and still flooding. Put another carb on it and it flooded too. Checked the fuel pressure and was pushing over 10 psi. Went and bought a fuel pressure regulator from Auto Zone and set it to 2 psi and all is good now. Problem is, I just quickly slapped it together inline from the fuel pump to the carb to see if that was the problem. Need to mount it, but not sure how to do it and make it look good with existing plumbing. Any ideas or has anyone else had to put in a fuel pressure regulator? Would like photos if you have done it.

Should be set to around 4lbs. 2lbs may not support top end under load, like a steep hill in high gear.

My 216 operates at 2.5 psi. The FSM gives a range of 2 - 4 psi for fuel pumps.

What kind of fuel pump are you using? If it's electric, buy one that operates in the correct range. If it's mechanical, figure out why it's putting out such high pressure. If it's an old, original style pump, send it off to Then and Now Automotive to be rebuilt. www.then-now.com

There is no reason you should have to run a regulator on than engine.

I long ago gave up on mechanical fuel pumps and have had 3 electric pumps since. One failed because the ground connection was corroded -- it tended to flood the carb after shutdown. It's now a spare on the shelf in the garage. Next trip it goes with me under the seat. I replaced it with another from Summit or Rock Auto, which failed about 4 years later on the road, requiring a $200 tow off I-5 near Willows CA. It flooded the carb after shut down too and sometimes at idle when hot. I walked to the O'Rilie's AP in Willows and got a Precision brand pump which states 2.3PSI on the box. Ran fine at full throttle over the Siskiyou Mtns.pulling my camper and feeding two Zenith 228 carbs on a 261. It idles consistently better and doesn't flood after shutdown. Lots of volume, low pressure, that's what you want. I haven't run it in summer to see if that low pressure causes vapor lock but occasionally the previous two pumps suffered that despite heat insulators under the carbs. Make sure you have a filter on the inlet side of the pump. There's no telling what lurks in the fuel tanks after you've filled up as stations with no filter at the pump (a rarity I seldom see).

The pressure a mechanical pump produces is controlled by the spring inside it. A lot of manufacturers use the same spring on everything they build, and it's WAY too strong. All the camshaft and lever does is raise the diaphraghm- - - - -the spring produces the pressure.
Jerry

I have occasionally been tempted to overhaul one of my original GM fuel pumps, I have several. But I wonder if they would be more reliable than a Chinese electric. Are there any universal electric pumps that aren't low-budget Chinese? Maybe quality Chinese? I now know not to use aftermarket mechanical pumps... but I wonder, if I was to dismantle a screw-together Chinese pump and replace the spring with a GM factory spring how would that work out? I'd hate to get stuck on the road with a failed one.

I'd talk to Then and Now about it. They can probably rebuild it for you with the correct components. Terrell Machine in Texasdoes land office business rebuilding brand new fuel pumps for collector vehicles.

I bought a Carter M2118 from Rock Auto. It states that max psi should be 5. When we put the pressure gauge on it, it was clocking over 10.

When I replace a mechanical pump with an electric pump, I use an adjustable pressure regulator which has a return line to the tank. I can dial in the specific pressure that I want and there will always be fuel circulating back to the tank, providing colder fuel to always be running through the line to the carburetor. I did this to a 1983 Firebird to prevent ACTUAL vapor lock due to the way the engineers routed the fuel line too close to the transmission in 1982 and 1983.