I installed a Holley Blue fuel pump on my truck yesterday. Here's what I've got going on - installed kit on frame rail w/ Vulcan big line kit. My fuel pressure was steady at 11lbs at idle in the garage. Put the truck into reverse and pressure dropped to 8lbs. Now I get on the interstate to come to work and my gauge starts bouncing between 5lbs and 15lbs so rapidly that it looks like a blur. The speed shop that I bought the pump from is going to replace it with a new one. I had been told that the pump that I have was used a demo unit at a drag race that they set up a booth at.
Question is what kind of realistic fuel pressure should I expect? And is there anything that I can do to increase the fuel pressure on the next pump if its still low? Just got my attention when the fuel pressure would drop down 8lbs without the comp tapped one more month of warranty on injection pump and that wire is tapped! Thanks

 

are you running the holley by itself or with the stock lp?with the stocker you should see over 20psi and may need a reg.by itself you should see a good 14 15 with those big lines you have

 

I'm running a holley by itself and I see 15 at idle and 11 at WOT. I do have -8 line from the tank to the vp. Do you have a mechanical gauge? If so, do you have a needle valve on it? If not, then put one on there. That'll help with the dancing needle. Also, you can try pulling the bypass plunger out of the holley and lightly sanding it down with some very fine sand paper or emory cloth and then very lightly sanding the bore down that it sits in. Sometime they are a little rough and cause low pressure.

 

Thanks for the responses. I do have a mechanical gauge, and will try out the needle valve with the next pump, probably install tomorrow morning. I am running the holley fuel pump only without the regulator. Blue, I assume that the bypass plunger is accessed by removing the screw on the left side of the pump (inlet side I believe) I'll check that out in the morning.

 

Yup. Really big flat head. I'm not running a regulator either on mine.

 

Needle Valve will solve all your problems! Mount it on line to gauge.... and close it down as low as you can (almost shut off) and still get a reading. Will eliminate rattle/jumping, extend life of gauge and work as a shutoff if you ever have a leak in the cab!

RJ

 

I will reiterate the needle valve. I thought I was going to damage my gauge it was jumping so violently. The needle valve will solve all your problems.

Brad

 

I also have the holley blue, with bully dog big fuel kit. Also have factory LP still inline. My FP at idle is 25 abd between 15 and 20 at wot. But my question is b4 the big fuel kit was installed my fp was very unstable idle around 15 then drop to 5 and a cpl of times pegged the gauge at 30. Have mech gauge with isolater.