Fuel Pump fluctuation

I recently checked the fuel pressure on my stock mechanical fuel pump to compare pressure with factory specs. (73 coupe with 350) The gauge bounced from 3psi to 9psi - consistantly. Factory specs say 7.5 - 9psi. Is the bounce normal or do I have a defective pump?

Any help is appreciated!

defective pump...

your fuel pressure should not fluctuate like that..

and pulsation can damage your carb

unless your doing a strict restoration or just really cheap or really broke..

i would replace the mechanical pump with an electric.

I personnally like the holley blue series electric pump..

it comes with a regulator and youll get a much steadier fuel flow max flow is 110gph at 14psi, flows 88 gph at 9psi

cost is about 100$

here is the holley link
http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSFP/12-802-1.html

here is the price from summit
http://store.summitracing.com/partdetail.asp?part=HLY%2D12%2D802%2D1

This electric fuel pump has a free flow rate of 110 gph. It is designed to supply the fuel required by high horsepower race engines. Its rugged design provides constant fuel flow with no pulsation and is tolerant of contaminated fuels.

Agreeded.
When it first starts pumping it will pulse a lot due to the way the pump is designed. A good mechanical pump will pulse some, but not that much. When it reaches pressure after a few strokes, it should calm down. This is a function of a check valve inside the pump. Yours is leaking back.
A new or reman pump should cure it. The electric is a nice choice. Stock engines don't need the electric, but it can't hurt either.

Thanks guys! Your input is appreciated. Looks like I got a project ahead of me.

Aloha,

Bret