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malcolm2
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PostPosted: Sun Mar 03, 2024 4:33 pm    Post subject: Fuel Pressure Regulator Reply with quote

When you turn the screw on this thing, shouldn't the pressure change......

How sensitive are these? My gauge maxed out at 1.5 with the screw pretty much maxed in to the body.

I am gonna take it off and see what the gauge says.... I think I will open the Som-beach and see if it is full-o-crap. What is going one here??


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busdaddy
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PostPosted: Sun Mar 03, 2024 4:47 pm    Post subject: Re: Fuel Pressure Regulator Reply with quote

malcolm2 wrote:
When you turn the screw on this thing, shouldn't the pressure change......

Sure, as long as the end of the line can bleed off into something, if it's deadheaded into a non running or idling carb you won't see anything happen for quite a while.
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What is going one here??

Since it looks like a Chinese clone of a Chinese clone I'll speculate they left out a few critical parts or machining steps in the interest of cost savings.
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aeromech
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PostPosted: Sun Mar 03, 2024 9:59 pm    Post subject: Re: Fuel Pressure Regulator Reply with quote

Two answers. The first is replace your pump.

The second is why. Today Telford and I ran into the same issue. I had relocated, wired, and plumbed in a Facet pump (age unknown) into a 1972 bus with a Holley FPR and dual Webers.

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Once the engine started we expected to be able to adjust the FPR to about 2 PSI but the gauge showed no pressure. The engine did continue to run though.

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We removed the gauge and it tested good. We used a mighty vac to pressurize the line out of the pump and the gauge responded.

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So then we slaved in another pump and got good results. The point is that the original Facet pump provided flow but not pressure. I’ll be sourcing a new pump this week.
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aeromech
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PostPosted: Sun Mar 03, 2024 10:03 pm    Post subject: Re: Fuel Pressure Regulator Reply with quote

Double post
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PostPosted: Mon Mar 04, 2024 10:52 am    Post subject: Re: Fuel Pressure Regulator Reply with quote

Love the defroster switch for compartment lights Very Happy

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aeromech
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PostPosted: Mon Mar 04, 2024 1:36 pm    Post subject: Re: Fuel Pressure Regulator Reply with quote

airschooled wrote:
Love the defroster switch for compartment lights Very Happy

Robbie


Thanks to Ken Madson at thebusco
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malcolm2
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PostPosted: Sat Mar 09, 2024 7:19 am    Post subject: Re: Fuel Pressure Regulator Reply with quote

The bus sat all week with the regulator screw at the same spot that I got super low PSI. The screw was fully IN.

I start her up and the gauge was at 3.5 psi. D-side carb was popping. Too much fuel, I guess.

I turned the regulator screw 2 turns OUT and went to bed. I will check the PSI again this morning. I will keep doing that til I can get the 2.5psi to stay put and run the bus normally again.

I am assuming that the pressure just needs to time to regulate itself.
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74 Thing
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PostPosted: Sat Mar 09, 2024 12:09 pm    Post subject: Re: Fuel Pressure Regulator Reply with quote

Typically those liquid filled gauges need to be burped by removing and reinstalling the rubber plug in the back otherwise the pressure readings will be all over the place.
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aeromech
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PostPosted: Sat Mar 09, 2024 1:13 pm    Post subject: Re: Fuel Pressure Regulator Reply with quote

74 Thing wrote:
Typically those liquid filled gauges need to be burped by removing and reinstalling the rubber plug in the back otherwise the pressure readings will be all over the place.


Nope
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malcolm2
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PostPosted: Sat Mar 09, 2024 1:20 pm    Post subject: Re: Fuel Pressure Regulator Reply with quote

I kept slowly turning the screw. Run it, let it sit. Check again. Finally hit a spot where the gauge moved when i turned screw.

Stopped at 2.6. 😝 Needle does move a bit as i rev and release.
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74 Thing
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PostPosted: Sat Mar 09, 2024 2:30 pm    Post subject: Re: Fuel Pressure Regulator Reply with quote

Do what works for you but liquid filled pressure gauges are known for heating up and being inaccurate unless you burb it especially in a hot environment like an engine compartment. Not sure why you would need one mounted permanently in the engine compartment anyways. Verify it with an accurate test gauge then remove it.

https://www.youtube.com/watch?v=CCM7zdRzMFI
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mikedjames
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PostPosted: Sun Mar 10, 2024 11:08 am    Post subject: Re: Fuel Pressure Regulator Reply with quote

Some pressure regulators need to drop pressure from input to output to open the demand valve.
If your fuel pump is low pressure to start with, there's nothing to spare for dropping pressure with the regulator.

Others flow at zero pressure and then shut off as the output pressure increases to the correct output pressure.



A regulator that drops pessure to flow would show as correct pressure with the engine stopped, and drop as soon as the engine runs.

In that case, you may not need the pressure regulator at all. Check the input side pressure.

Alternatively fit a higher pressure pump on the inlet side of the regulator, it will most likely work perfectly with a pump that puts out 5 or 6 PSI..
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