[stratt134]

I have the pump mounted in the trunk, right in front of the fuel cell. I used a 1/2" ruber hose that is about 8" long to connect to the pump... no filter between the pump and the tank... is that bad?

[bigbadbowtie]

Think we posted at the same time :-).......read my post on the last page....

[Tech @ BG]

Originally Posted by stratt134

I have the pump mounted in the trunk, right in front of the fuel cell. I used a 1/2" ruber hose that is about 8" long to connect to the pump... no filter between the pump and the tank... is that bad?

Very Bad... That pump is a vane and rotor style pump. They are designed to push fuel, not pull fuel. They need to be gravity fed, and should have a filter before the pump. This can be a lot of your problem, especially if you can hear the pitch of the pump change. The only time the pitch of an electric motor will change is when either the load (amount of fuel being fed into it) or the power (amount of voltage it sees) changes. Double check your wiring, and voltage, but it sounds like you have a plumbing issue.

[1980 malibu 421 cid]

if you run a holley blue pump it is set at 14psi from the factory and you must run the regulator that came with the pump . the cause for your fuel pressure fluxuation is because the fuel pressure is bumping up against the regulator and the extra fuel has no where to go , the quick fix is run a return line between the reulator and the carb back to the fuel tank either 1/4 or 5/16 line will work fine i guarantee your problem will be fixed mark!

[SuperSport]

Same problems here. This has happened twice with a mechanical fuel pump and 2 different holley 12-804 FPR's.