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ghett0man

  • Karma: +0/-0
Fuel pressure issues
« on: June 27, 2016, 02:48:48 PM »
Ford 460 stock internals (except the cam) with a holly DP 750.

Went to fire the boat up before the trip and gas shot up out of primary vent tube. So I checked the floats and all was good as well as the needle and seats. Cranked it again and another geyser of fuel blew thru the vent tube. So I switch the primary and secondary needle/seats and the same thing happened again.

Check the holly website and they said anything over 7 psi will cause a flooding situation. I was at 8 when cranking. So I got another fuel pump rated for 6.5 psi and all was good.

Went out for some bug runs and at 4K RPMs I would lose all pressure, but if I stayed under 4K rpm all was good. Ran into Parker and got some needle/seats and put the old 8 psi pump on and all was normal.

My question is how is everyone else configuring their fuel delivery?  Are my needle/seats gonna go bad every year?  Should I just keep some on hand?  Or should I get a 8+ psi fuel pump and regulate it down? 

I've search here on the boards and didn't come across a thread with the same issue as mine. I know the different options out there with self regulating fuel pumps, but I'm fine with a mechanical, or do I need a higher volume pump with a lower PSI?

I'm just a little confused with holly saying 7 psi is bad, but my I need something rated at 8 psi to run over 4K.

Thoughts?


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Bunger

  • Karma: +6/-0
Re: Fuel pressure issues
« Reply #1 on: June 27, 2016, 03:03:47 PM »
It Sounds like u have a volume issue not a pressure issue. How many gph is is your pump and how big are your fuel lines?


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Bunger

  • Karma: +6/-0
Fuel pressure issues
« Reply #2 on: June 27, 2016, 03:05:17 PM »
I think the pump giving u 6psi doesn't pump enough fuel once you get into the high rpms. And most carb guys have told me to run between 5.5-6.5 and anything over 7 you'll start having flooding issues


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ghett0man

  • Karma: +0/-0
Re: Fuel pressure issues
« Reply #3 on: June 27, 2016, 03:19:22 PM »
Running 3/8" lines from the tanks to the pump and 3/8" lines from pump to carb with a fuel filter in between.   I was suspecting the volume was to low but I'm not sure how to calculate the volume needed to run.

Is the higher pressure blowing the o rings out on my needle/seats?  They hold for a year or so and then can't handle the pressure? 

Thanks for the responses so far.


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steves86ta

  • Karma: +41/-0
Re: Fuel pressure issues
« Reply #4 on: June 27, 2016, 04:11:02 PM »
where is your pump mounted/what kind of pickups are you using?
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Bunger

  • Karma: +6/-0
Re: Fuel pressure issues
« Reply #5 on: June 27, 2016, 04:46:59 PM »
I think u just need to right pump. I love my electric pump with a regulator. Only other thing I'd check is the fuel lines or filter being clogged. Other than that I'd say just a shitty pump


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steves86ta

  • Karma: +41/-0
Re: Fuel pressure issues
« Reply #6 on: June 27, 2016, 04:57:21 PM »
I have a brand new Holley regulator of you need it
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ghett0man

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Re: Fuel pressure issues
« Reply #7 on: June 27, 2016, 06:17:14 PM »
The pump is mounted in the normal mechanical pump Spot off the side.

I put my old pump back on with new needle and seats and all is good.

So the needle and seats were bad but I replaced them a year ago.

So I was wonder if this is a common problem. The 8psi pump blowing the seals every year or is something else going on. The boat was in the garage all year and wasn't outside.

I have options, but I'm just trying to figure out the best configuration based off of others experience. I don't wanna just buy parts to try and figure it out if others have had this issue.

So maybe a 5.5-6.5 psi pump with more volume than a stock 460 fuel pump? 

Or a higher PSI pump regulated down to whatever my sweet spot would be?




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ghett0man

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Re: Fuel pressure issues
« Reply #8 on: June 27, 2016, 06:17:52 PM »

Quote from: steves86ta on June 27, 2016, 04:57:21 PM
I have a brand new Holley regulator of you need it
I might take you up on that Steve. I'll PM you later. Thanks


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Bunger

  • Karma: +6/-0
Re: Fuel pressure issues
« Reply #9 on: June 27, 2016, 06:26:20 PM »
I know if I were to go to a mechanical pump I would have one built by clay smith.


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jimpen

  • Karma: +68/-0
Re: Fuel pressure issues
« Reply #10 on: June 27, 2016, 07:41:12 PM »
I run a Holley mechanical pump with -10 fuel lines regulated at 6.5 psi. The motor is 850 hp. It will work fine you just need the volume and a regulator.


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78hallett

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Re: Fuel pressure issues
« Reply #11 on: June 27, 2016, 09:09:37 PM »
I run the Holley 130 gph mechanical pump regulated down to 6.5psi on a mild 450hp 460. Works great.


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ghett0man

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Re: Fuel pressure issues
« Reply #12 on: June 28, 2016, 10:29:46 AM »
Thnks for the info guys. I think I know which way to go.


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