Steady 5.5psi fuel pressure drops when warmed up

[Old Guy Bill]

The three factory style pumps with return ports I bought all fluctuated badly at idle, the one I went with lasted a month.
Put on an Edelbrock pump without a bypass and its supplies a steady 6 lbs.
It's been on almost a year.

 

[andybflo]

Absolutely normal on a liquid filled gauge.

They're usually only accurate cold. Early in my years of building cars with Mallory electric pumps, I chased the same non-issue.

You'd know if your FP fell that significantly. Don't believe the gauge. The truck is telling you it's fine. Believe it.

 

[elbpony]

Absolutely normal on a liquid filled gauge.

They're usually only accurate cold. Early in my years of building cars with Mallory electric pumps, I chased the same non-issue.

You'd know if your FP fell that significantly. Don't believe the gauge. The truck is telling you it's fine. Believe it.

I'll take the regulator out the line for a test and see how that changes or not changes. It runs perfect everytime and I am getting used to the uncomfort every Mile made

 

[Grit dog]

In short, I’ve never given a second thought as to putting a pressure regulator on a mechanical fuel pump system. Regardless of vehicle mfg, carburetor brand or brand of fuel pump.
Maybe there is a mechanical Chevy fuel pump that can blow the needle or seals on a carb but I haven’t encountered it.

 

[Conejo_K10]

I don't have a regulator on my K10 but do have one on my classic car. I noticed the pressure was ~9 psi cold and then dropped to 4.5 psi warm.
Most carbs want 4-6psi. At a higher pressure the float valve may be unseated dumping extra fuel into the intake.
Basic mechanical fuel pumps aren't that precise.

 

[77Dmax]

You need an isolator to get a proper pressure reading when dealing with such a low PSI. You're probably fine, as mentioned once the gauge is hot it's no longer accurate.

 

[Camar068]

3-4.5 psi is what the eddie's like regardless of what the directions say.....if your's is like a 1406. Verified by a phone call to them....long time ago lol. Quick call to them to discuss. Off the phone in less than 5 minutes.