Need to upgrade Fuel System

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Walker434

Walker434

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Okay a lot of you know I recently put a fairly mild 360 magnum in my 71 Dart. I got the timing and carb issues sorted out so then I moved on to traction issues. Last night while doing a "hole shot" I noticed 2nd gear didn't feal really strong and the engine started "surging" at about 4,000 RPM.

I immediately went home and had the wife watch my under hood fuel pressure guage as I revved the engine. At 3,500 RPM in park it is still holding 5 pounds of pressure. When I revved it to 5,000 she said pressure dropped to about 3 pounds.

When I put this engine in I thought I would have to upgrade to a 3/8 pickup and 3/8 line to a new mechanical fuel pump. I would say that is what I need to do now.

Only strange thing is it didn't do this when I first put the engine in. Maybe it's just the pump getting weak? I am currently using the mechanical pump that came in the car when I got it. Anybody have any good recomendations for a street/strip mechanical fuel pump? Is the Carter mechanical pump good?
 
I had 2 carter pumps that put out 9psi. Had to install a regulator. Your 5/16 line should handle what you need, no need to upgrade to the 3/8" lines.
 
Unless you have about a 9 second car it's not the size of the line

Your car came with factory "carbon can" IE evaporative emissions. If that has been removed, the tank may not be vented. First thing to do is go for a "hard run," stop and immediately remove the fuel filler cap...............see if there's a vacuum in the tank.

Next is to suspect EVERY part of the fuel system front to rear

Sender / pickup, whether new or old, suspect fuel sock / plugged

Hose connection at tank, old, crimped, collapsed?

Fuel supply line, rusted gummed inside?

Any hoses at suction side of pump

Pump itself.......read the shop manual, "there's a procedure for that"

Fuel filter after pump

Where to start?

Probably at the connection from line to pump inlet, as that's fairly easy to get to and divides the problem between the two ...........pump and onwards, and supply line and back to tank

Shop manuals:

http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617

There's test procedures for pump vacuum, pressure, and flow capacity. I'd look up something high performance, like a 440-6 or hemi, and expect your pump to match that flow.

Use a vacuum gauge. The pump should be able to "suck" at least 12" Hg
 
Put a Holley 110 gpm pump on last night. Pressure is now rock solid and the surge is gone!! Since I'm not running mega horsepower I think I'm going to leave my fuel lines alone.
 
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