Fuel question

[lazarat]

Have the 20 GPH electric pump close to tank. Old steel line connecting to rubber hose to pump, rubber line from pump to original frame mount steel line, then rubber hose to filter then carb.

On occasion, when running awhile, I hear the fuel pump going nuts, and the filter is bubbling like crazy. Yesterday when on the way back from a show on the interstate, I had the Holley 650 opened up, and after a few minutes of that, its starts to act like its running out of fuel and bucking. I slowed down in the right lane to give the pump time to catch up. (This has happened before)

When I got off the interstate i can hear the fuel pump "going nuts"...that is, louder and cavitating? Filter bubbling like crazy.

The rubber line from steel frame line runs up between water pump and engine (SBC) to carb, but not too close, has room. Questions:

Is it getting to hot?
Is the pump still too small? Had a 9 GPH when I got the car.
Should I install a new steel line to rubber from tank?
Is it an all of the above situation?

Thanx.

 

[I-R-POPS]

I've had the same issues on several rides and here is my go to cure. This is what I do on every thing I build to avoid it.

I put in a new in tank fuel pump, a good inline filter, a pressure regulator with a pressure gauge and a fuel return line to the tank.

Make sure you're not running too much pressure to your carb especially if you're using an Edelbrock carb.

It works for me and my Mopar addiction.

Good luck.

 

[Old Iron]

I'm with POPS
I just cut to the chase and replace all the lines, pump and filter with new stuff.

 

[MercuryMac]

If the pump is going crazy, it's trying to keep the pressure up but can't. Maybe there's a little piece of something that catches under a valve in the pump and holds it slightly open. My guess though is that you have a cracked line in the intake side of the pump, probably right in the tank. Does the problem occur when you have a full tank of fuel or mostly when you are below half full? When the gas is covering the 'in tank' line crack, the pump will suck gas and everything is cool, but when the gas level falls below the crack then the pump starts to suck air.
Good luck.

 

[Dr Crankenstein]

I also believe your pump is starving. What's your tank/pickup arrangement?

.

 

[lazarat]

Cracked line, starving for fuel.

Hiding in plain sight, what looked like a good hose on the suction side turned out to have a crack on the top that was unseen. Plus, this hose was also a bit oversized.

This problem i was having also did occur when the fuel was low in the tank. The outlet is a bit above the bottom of the tank, as it has the sweep inside where the sock filter should be. Also the bends in the outlet line curved a bit upward, I brought all in line so there was a better flow, replaced the short hose to pump with a better fit and have the steel line up against the pump secured by said hose.

We shall see, going to make sure fuel doesnt get too low, I am sure it will be fine and thanx for responses.

 

[sneakysnake]

My thoughts are check the line between pump and tank. Like said above sounds like having a cracked straw, sucking in air some where. Hopefully it's not in the pickup tube in tank.

 

[BlueNorther]

also electric pump don't like to suck gas uphill, the pump should be as low as possible so the gas is almost gravity feeding the pump. and the rear filter should be between the tank and pump, to keep rust and other debris from wearing the pump out.

and a 20gph pump ain't going to feed most engines at full boogie.

 

[lazarat]

also electric pump don't like to suck gas uphill, the pump should be as low as possible so the gas is almost gravity feeding the pump. and the rear filter should be between the tank and pump, to keep rust and other debris from wearing the pump out.

and a 20gph pump ain't going to feed most engines at full boogie.

Recently, again, the car was starving for fuel. (only when I open all chambers on the Holley) Yes I should step up to a higher GPH.....but!

On a hunch I decided to check the prescreen on the electric pump. Sure enough, it was clogged with pieces of the rubber hose that previously cracked. The tank is clean and spotless. I also rerouted the line from tank that feeds it, knocking out about 10 inches of line, and yes there is a slight slope from tank to pump. The front float of the Holley also was out of adjustment.

So now all is well, may still step up the pump, will see, and I don't drive this above 90 too long.