a few weeks ago i installed a raptor 150, big line kit, and drawstraw v. have an isspro mechanical fuel pressure gauge direct plumbed with a needle valve. fuel pressure at idle is 18 and drops to 16 if i stomp it. however when i get down to about 3/8 of a tank it begins to drop very easy can pull it down to 10 if i want. there is about 10 gallons of fuel at this level. cuz it took 24 gallons to fill up when this happened. i think this could be because i did not drill enough holes in the fuel bowl. i only drilled on 1/2" hole. is this not enough for fuel to flow into the bowl and keep up with demand when i apply the throttle? thanks a lot. wanna figure this out. thinkin about just gettin a sump and bein done with it.
fuel pressure issues
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yes i took out the stock lp. and snapped the adapter into its place. looks like the only way to figure it out is to drop the tank again. shoot. i will drill a few more holes and make sure fuel can enter the bowl easily. im pretty sure i pulled out everything in the bottom of the unit. if i remember there was just a little tan-orange rubber piece left... its gotta be that fuel cant get into the bowl fast enough when it cant just flow in over the top like when fuel level is over 3/8. thanks guys. any more ideas help:thumbsup:
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446 Posts
:agree2: you are 100% right, I learned right away that ya can't let it get below 1/8 tank or fuel pressure starts jumping around, but the sump is still a badass mod :thumbsup:
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1,460 Posts
I think I'm in need of a new draw straw or sump. I pressure will drop under 5psi with 3/4 off a tank left! But it only happens when turning or taking off at a stop sign
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446 Posts
With 3/4 of a tank? Never heard of that happening... do you have the newer DS-V or the DS-2? I think the 2 is a better (easier) setup but if you want a sump go for it, they are great, mine is from Alligator and the nice thing is not needing to drop the tank to install.
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I have a feeling my fuel gauge isn't totally accurate either. I can drive well over 100 miles after a fill up and the gauge will still be over F.
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I have one of the Vulcan DSV's that I installed last weekend. I noticed that once I got it down to about 1/8 tank today that my FP started dropping below 10psi, and when I was headed downhill it dropped to about 5! I left it running when I filled it up and it built back up to about 13. I drilled one hole, I think about a 9/16 size hole, in the basket durring the install. My gauge reads low and I think it has to do with the stupid isolator. Next mod is to do a needle valve and fuel straight to the gauge.
ya i think my hole is only 1/2 inch. that what it said in the instructions. wish i woulda drilled more when i had the module out. droppin the tank is a pain. but i would like to have all 35 gallons of fuel in my tank. ya i read about the isolator and saw how spendy it is. and just got the needle valve. im not scared of runnin diesel into my cab. its only like a trickle anyway once u close down the valve.
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