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malcolm2 Samba Member
Joined: September 28, 2011 Posts: 1266 Location: Mount Juliet, TN
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Posted: Sun Mar 03, 2024 4:33 pm Post subject: Fuel Pressure Regulator |
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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??
_________________ My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing) |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51057 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Sun Mar 03, 2024 4:47 pm Post subject: Re: Fuel Pressure Regulator |
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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. _________________ Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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Слава Україні! |
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16926 Location: San Diego, California
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Posted: Sun Mar 03, 2024 9:59 pm Post subject: Re: Fuel Pressure Regulator |
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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.
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.
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.
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. _________________ Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16926 Location: San Diego, California
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Posted: Sun Mar 03, 2024 10:03 pm Post subject: Re: Fuel Pressure Regulator |
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Double post _________________ Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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airschooled Air-Schooled
Joined: April 04, 2012 Posts: 12688 Location: on a bike ride somewhere
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Posted: Mon Mar 04, 2024 10:52 am Post subject: Re: Fuel Pressure Regulator |
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Love the defroster switch for compartment lights
Robbie _________________ Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16926 Location: San Diego, California
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Posted: Mon Mar 04, 2024 1:36 pm Post subject: Re: Fuel Pressure Regulator |
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airschooled wrote: |
Love the defroster switch for compartment lights
Robbie |
Thanks to Ken Madson at thebusco _________________ Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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malcolm2 Samba Member
Joined: September 28, 2011 Posts: 1266 Location: Mount Juliet, TN
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Posted: Sat Mar 09, 2024 7:19 am Post subject: Re: Fuel Pressure Regulator |
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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. _________________ My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing) |
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74 Thing Samba Member
Joined: September 02, 2004 Posts: 7375
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Posted: Sat Mar 09, 2024 12:09 pm Post subject: Re: Fuel Pressure Regulator |
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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 Samba Member
Joined: January 24, 2006 Posts: 16926 Location: San Diego, California
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Posted: Sat Mar 09, 2024 1:13 pm Post subject: Re: Fuel Pressure Regulator |
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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 _________________ Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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malcolm2 Samba Member
Joined: September 28, 2011 Posts: 1266 Location: Mount Juliet, TN
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Posted: Sat Mar 09, 2024 1:20 pm Post subject: Re: Fuel Pressure Regulator |
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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. _________________ My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing) |
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74 Thing Samba Member
Joined: September 02, 2004 Posts: 7375
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Posted: Sat Mar 09, 2024 2:30 pm Post subject: Re: Fuel Pressure Regulator |
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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 Samba Member
Joined: July 02, 2012 Posts: 2715 Location: Hamble, Hampshire, UK
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Posted: Sun Mar 10, 2024 11:08 am Post subject: Re: Fuel Pressure Regulator |
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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.. _________________ Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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