Mallory Series 110 low pressure fuel pumps with no pressure

[rayaapp2]

So I must be doing something wrong.

I have 2 cars with these pumps. 1 71 240Z with a stock L24 and 1 71 240Z with a 5.7L lt1. Both have the same exact series 110 mallory fuel pump installed. BOTH of these pumps produce a trickle of fuel and no pressure while they sit in the back next to the tank and make a ton of noise. They occasionally try to make pressure and oscillate in pitch. I purchased the brush and seal kit for the one in the stock l24 car. It made no real difference. I have heard the internal regulator tends to stick on these pumps because of a design flaw and how the adjuster screw is threaded down into the relief plunger. I have also heard that this usually causes a problem with high pressure. I installed(borrowed) a Holley pump in the SBC car and viola! fuel pressure! Aside from tossing two pumps in the trash and having to buy 2 new pumps what can I do. Im really hoping someone here has ran into this issue and has figured out the solution.

 

Help?

[BluDestiny]

Have you tried calling Mallory? Might be able to get a warranty repair of try are new.

[Lazeum]

I've got a 4070LP Mallory pump on my 240z with triples. Fuel pressure has never been higher than 2 psi whereas previous Carter 4070 pump was in need of a regulator to limit pressure to 3.5 psi. Flow however is high with the pump, just not a lot of pressure and adjustment at the pump did not make any change.

 

 

 

 

 

[Pyro]

I gave up on using pumps that use motors with brushes.

 

I recommend that you use a msd efi 2200 pump with an Aeromotive return style fuel pressure regulator. I forget the aeromotive model number, but it comes with 2 springs, one for low pressure and one for high pressure. So if you ever decide to add fuel injection then all you need to do is swap the spring.

 

I helped a buddy do this setup on his V8 powered Z. He had a carb for the last 3 years but is now adding efi.

[rayaapp2]

Apparently after some playing around I have determined that the internal regulator springs gave out after sitting for long periods of time. Both pumps. I added a spring from of all things a pen and suddenly I have pressure and volume. These pumps put out very little volume with no pressure strangely. When they build even 1psi and they begin to flow, before that apparently they do nothing but make noise. The chart says they flow best around 3psi.

So thats that for now. Ill likely switch pumps out at a later time.

 

These pumps are long past warranty anyway.