J Double

Is anyone using the Moroso pump spring (part#65770) in there Holley Blue and getting less pressure than with the stock spring? I made a last ditch effort to get the pumps pressure back up 15 psi but to my surprise with this new spring installed I'm actually seeing less

The stock spring has been stretched and for about 3 months I was seeing 15.2 at idle and 14.2 at cruise. Currently I'm seeing anywhere from 14.2-12.2 at idle and 10.2 at cruise. What I don't understand is when I start to roll into the throttle pressures will actually increase, sometimes up to 13 psi, but as soon as I let off the gas it'll drop down to as little as 9 PSI.

Thinking my stretched spring was the possible culprit I bought the Moroso spring. The first thing that caught my eye is this spring is less than half the length of the stocker. When removing the stock spring you really have to hold onto the screw because of the pressure the spring has on it. Putting the new spring in.......no resistance what so ever when I put the screw back in. Start the truck up and only seeing about 9.5-10.2 at idle, confused and a little po'd I didn't even take it for a drive

Does this Moroso also need stretched or is the Blue just destined for the bone yard?

BigBlue

You can get a rebuild kit for the blue for like $25 from autozone that includes a new holley spring, seals, and plunger. Check your bypass plunger. Rub it down real lightly with some fine emery paper and make it very smooth. Do the same for the bore. Also check your fuel filter. It might be dirty. I know on my Black, I never stretched the spring and I had to hold the little screw as well. Try stretching the moroso spring. It should be at minimum, the same length as the stock holley.

kyle@ftlb

I have the moroso high pressure spring in my holley blue and it gave me a little bit more than 1psi at all throttle positions. 15psi at idle, 12psi WOT. Sounds like your problem might be the pump though. I'd try and get it warrantied if possible.

J Double

With only a little over 6k miles on it I hope it don't need rebuilt. If that's the case I'd buy the RASP before I bought a rebuild kit. To be honest, I've been considering the RASP ever since my pressures started to drop but I thought maybe, just MAYBE....I could get off cheap and it would be the spring.

I'll take the pump apart this weekend and see if anything looks out of place. If nothing changes when I put it back in I guess I'll have to throw in the towel.

AlpineRAM

On my holley blue there were some burs on the plunger- after removing them and selecting the correct spring/shim combo from the toolbox (junkbox as my wife calls it) I've got 15 psi all the time

AlpineRAM