Ok guys i unstalled a vulcan big line kit that reuns from the water seperator to my VP, and also ran 3/8 inch fuel line directly from my holley red which is rite next to the tank all the way to my stock Lp, i now have 17 PSI at idle, 11-12 cruzin don the road, and bout 5-6 at WOT. The larger line has helped do these numbers sound safe?

 

Safe enough to drive for the short term. It still seems that you should have better pressure than that. I believe that your pressure at idle should be close to the sum of the output of both pumps. I think that would be close to 20 psi at idle. If it were me I'd find a way to get that stock lift pump out of the system. I have no confidence in them.

 

I would say you're good to go. If you have a gauge in the cab that is. If the pressure goes down, time to take care of it. FSM says 5 psi is the allowed min for the LP, you are within specs. Also, you are not too high either, the Blue chip site (seems quite knowledgeable on this) says you don't want WOT pressure over 12 psi.
-P

 

I was racing a rice burner after work tonite, at the stop light it was idling bout 16 PSI, when the light turned green and i tied in to her, and i got to bout peak power the fuel preussre was a t 1 PSI, when i let of she went right back to 16-17. When it was flowdering aroung 1 PSI it never cut out just kept pullin strong. I am at a complete loss?

 

Should i swap the red holley for a Blue ?

 

A blue should flow more.

 

Wow. Another curve. I didn't realize that WOT pressure was a problem as long as it was below 20 - 25 psi.
What are you seeing with your Walbro setup? I don't get much below 14. I think that is probably fine but I am curious if you have fine tuned yours below that. I have the glacier poppet valve setup so I guess I would have to reduce the spring tension to adjust it or go to a regulator simular to yours. By the way kudos to your system and write up!

 

Weldman05...when buying a pump you should look for flow...GPH at a certain PSI. The Blue does flow more than the red, and the Black more than the blue. But do you still have the stock LP in? If you do, and you get a highflowing Holley pump, than the stock LP will be a restriction in the line. If you go with a high volume pump, ditch the stocker....unless you have already. You want to make sure that the only real restriction in the line is the VP44. Your bigline kit will go a long way to helping this. The fact that your pressure drops so much indicates that the current flow rate of your lift pumps is not enough to match the demand of the VP. Pressure, however is not the measure of flow. Some people jack up the pressure to 25psi or so just so they don't go below 15psi st the VP at WOT. This doesn't really solve the issue because you still have a drop in flow...I'd rather see 15psi at idle and 12psi WOT. This would indicate that the LP is capable of keeping up with the flow demands of the VP. As you eliminate restrictions your pressure will stabilize. But you also need to have a high flow pump.

I hope this helps.
-Geoff

 

I still have my LP on the side of the block. and th ered located on the frame next to the tank. What should i do? What should i change? If i eliminate the stock LP how do i go about doing that?

 

Good advice! My approach is to open up restrictions in the fuel system... the main ones being the banjo's and then decide what pump you want to use. That decision is very subjective, you have to do exactly what you are doing.. Research your options and decide what you want based on what you think is important. At this point because you allready a holly installed I would get one with higher flow / pressure to replace what you have and ditch the stock lift pump. These issues are why I went with the Walbro setup. Plenty of pressure, volume and a good reputation for reliability with parts available. I don't want to get stuck in the sticks with a bad fass. I have a spare walbro under the seat - the fass is too bulky and expensive for that. Good Luck

 

Ill offer some quick advice from my experience.

DONT TRUST YOUR GAUGE UNTIL YOU CAN CONFRIME IT WITH ANOTHER KNOWN WORKING UNIT.

I get calls all the time for low fuel pressure with our systems and it turns out to be a gauge issue. Eveyone wants to think what the gauge is telling them is gosple. I have also seen the Juice WAM's read low under WOT for some reason. One guy found his Juice was off by 7 PSI under load. Read correct under normal idle conditions. Might check that.

ALSO restrictions play a big roll with WOT pressure drops. Anything before the gauge tap that might restrict needs to be tested. That stock LP might be causing more probs then its helping with. That is why you will never see any of our systems work with the stock Carter LP.

96 GPH should be more than plenty for the VP-44…..so I don’t feel that is the issue here.

 

Thanks! The setup works well for me, although probably is more complex than most people care for.
This BlueChip site is the one I quoted on the 12 psi being the max desirable WOT pressure.
I played with my setup during these weeks and settled on a tuning that I like. I get 15 psi idle (16 on a cold morning), 13 psi cruise and 11-12 psi WOT hard acceleration. I got to this point by bumping the Walbro pressure up to 55 psi and the pre-filter pressure to 17 psi. I don't think this is exact science though and as long as your WOT is above 10 psi, I think this is acceptable.
I had a point one time when I dropped the Walbro high pressure to 35 psi to unload the pump, and that could not keep up with the WOT demand, it was dropping from 17 idle to 5 WOT. So I bumped the high pressure up and that took care of the WOT for good.
Cheers,
-P

 

Ok guys im back the truck still wont hold pressure at WOT. If i install a Holley Blue, and eliminate the stock LP what find of readings PSI should i get? And also what do i have to do to elininate the stocK LP?

 

The Drawstraw will be my next move if the pressure goes below 10psi WOT after I install my BD130's.