A body in tank pump.

[Mopar Tim]

ok ill start at the start. Need car to stay looking original, not numbers matching or a race car. BUT a show car. Restomod. So puting in a non looking tank is out. This problem showed itself while looking for another problem. I have a 1466 Holley carb on top of original 273 4BBL intake. this is a DDart setup. Thought carb was starving for fuel because of dying after hard throttle blip then back to idle. Found out this problem is not related to fuel level in bowl, but I installed gauge and saw pressure not stable. AT ALL. goes down to less then 3psi. See above post. Mallory 4170 pump has to be DEF. Thinking of ways to make this work and be reliable. Holley red pump lost pressure as well. Not as bad tho. Im thinking they prob all do just no one has put a gauge on it to see while its running down the road. Just a guess about that tho.

 

[Mopar Tim]

Was looking for what I thought was a low fuel level in carb. I dont think that was the problem I was looking for but in the course of this investigation found wildly drooping pressure. Need a relaible soulution. Am I over stating the importance of stable fuel pressure? 4166 Holley carb. This is a OEM NOS carb!. used on DDART. Dont want to put back on Carter but I might. Original problem was motor stumbles and dies after hard throttle blip. Still dont know what that is! LOL.

 

[Mopar Tim]

Just got off phone with Mallory Tech support. Told me 5/16 line good for 270 HP. OK good with that. THEN they told me I needed to run a 3/8 feed AND a 1/2 return. This is a internaly reg pump. I am losing pressure at idle. Not at WOT so how is 3/8 line going to fix this? I am using a external reg but not required because the pump jas a bypass style reg built in.

 

[clifcuda65]

Have no idea as to why you are having so much trouble Mopar Tim...
On my 63 Valiant 340 car... I had the Holley 850 double pumper on a Tarantula intake with a 3/8 fuel line feed... none of this return line stuff... and never ever had fuel issues using the Carter P4594 electric fuel pump and it does not need regulators either..... And as I said... it ran constant low 11's and never had a fuel issue... and this also was a street driven car...

Personally... I have never liked the Holley fuel pumps!!!

 

[jos51700]

Fuel tank vent

 

[prrc]

It boggles my mind that ANYONE would want to put an electric motor IN a gas tank....its more quiet, but thats about it. I know its been done about 30 million times since EFI was mainstream, but external seems way more friendly. Ford Trucks, Mercedes, Volvo, etc mounted them outside. Mercedes hung them in a scrotum under their tanks on rubber hangers. Makes grabbing an EFI pump at the bone yard super easy, just Neuter a Benz!

most all electric pump are made to push not pull. This Is why they are in the tank.

 

[Mopar Tim]

Fuel tank vent

Gas cap is off doing same thing. Think I have found problem. Will let you know

 

[Mopar Tim]

It looks like the spring inside the pump is bad. Bypass spring, losing tension as it warms up. Am going to run all new lines, AGAIN, 3/8 and 3/8 return. ordered new 3/8 fuel pickup. Pain in the butt. Screwing pressure relief all the way down and just use bypass style regulator. Will let everyone know how it works. Tim