Fuel Pressure Regulator
- DurocShark
- IAC Addict!
- Location: A Mickey Mouse Town
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Fuel Pressure Regulator
Found vacuum leak #2 today... The fuel pressure regulator.
From reading the Bentley, it appears that there's a single diaphragm that is operated under pressure by a spring and assisted by vacuum to drop pressure about an additional 7psi during high vacuum conditions (decel).
I yanked the vacuum line and plugged it. Now my part throttle stuttering is gone. (The idle was fixed by new points and the aux air regulator elbow.) I can live with losing a bit more fuel during decel for now.
Now here's my question: Does the fuel ever touch the diaphragm the vacuum is pulling on? Because if it is, then it would have to be leaking. But I cannot find any sign of leaks.
From reading the Bentley, it appears that there's a single diaphragm that is operated under pressure by a spring and assisted by vacuum to drop pressure about an additional 7psi during high vacuum conditions (decel).
I yanked the vacuum line and plugged it. Now my part throttle stuttering is gone. (The idle was fixed by new points and the aux air regulator elbow.) I can live with losing a bit more fuel during decel for now.
Now here's my question: Does the fuel ever touch the diaphragm the vacuum is pulling on? Because if it is, then it would have to be leaking. But I cannot find any sign of leaks.
- spiffy
- IAC Addict!
- Location: Walla Walla, WA
- Status: Offline
Re: Fuel Pressure Regulator
I am going to say that the fuel definitely touches the diaphram on the other side of the spring....it looks like it adjusts the pressure by changing the volume of the chamber on the front (front means front) of the regulator.DurocShark wrote: Now here's my question: Does the fuel ever touch the diaphragm the vacuum is pulling on? Because if it is, then it would have to be leaking. But I cannot find any sign of leaks.
Let me know if you want the regulator and I will hook you up.
78 Riviera "Spiffy"
67 Riviera "Bill"
67 Riviera "Bill"
- DurocShark
- IAC Addict!
- Location: A Mickey Mouse Town
- Contact:
- Status: Offline
Re: Fuel Pressure Regulator
Crap. I'm hitting the road for CO first thing in the morning. Grr...spiffy wrote:I am going to say that the fuel definitely touches the diaphram on the other side of the spring....it looks like it adjusts the pressure by changing the volume of the chamber on the front (front means front) of the regulator.DurocShark wrote: Now here's my question: Does the fuel ever touch the diaphragm the vacuum is pulling on? Because if it is, then it would have to be leaking. But I cannot find any sign of leaks.
Let me know if you want the regulator and I will hook you up.
- spiffy
- IAC Addict!
- Location: Walla Walla, WA
- Status: Offline
Re: Fuel Pressure Regulator
I also referenced vwbusrepairman's fuel injection manual.....DurocShark wrote:Crap. I'm hitting the road for CO first thing in the morning. Grr...spiffy wrote:I am going to say that the fuel definitely touches the diaphram on the other side of the spring....it looks like it adjusts the pressure by changing the volume of the chamber on the front (front means front) of the regulator.DurocShark wrote: Now here's my question: Does the fuel ever touch the diaphragm the vacuum is pulling on? Because if it is, then it would have to be leaking. But I cannot find any sign of leaks.
Let me know if you want the regulator and I will hook you up.
Consolation...I drove my bus for a 2 years with the regulator hooked up to the throttle body (damn PO).....I am chasing a fuel delivery/hot head temp problem and I have a HUGE trip coming up in two weeks...I feel your pain
78 Riviera "Spiffy"
67 Riviera "Bill"
67 Riviera "Bill"
- DurocShark
- IAC Addict!
- Location: A Mickey Mouse Town
- Contact:
- Status: Offline
Re: Fuel Pressure Regulator
Well, I'll call around to find one but I don't have a choice on leaving in the morning. :( Sucks. No wonder I'm getting 13-15mpg.spiffy wrote:I also referenced vwbusrepairman's fuel injection manual.....DurocShark wrote:Crap. I'm hitting the road for CO first thing in the morning. Grr...spiffy wrote:I am going to say that the fuel definitely touches the diaphram on the other side of the spring....it looks like it adjusts the pressure by changing the volume of the chamber on the front (front means front) of the regulator.DurocShark wrote: Now here's my question: Does the fuel ever touch the diaphragm the vacuum is pulling on? Because if it is, then it would have to be leaking. But I cannot find any sign of leaks.
Let me know if you want the regulator and I will hook you up.
Consolation...I drove my bus for a 2 years with the regulator hooked up to the throttle body (damn PO).....I am chasing a fuel delivery/hot head temp problem and I have a HUGE trip coming up in two weeks...I feel your pain
- DurocShark
- IAC Addict!
- Location: A Mickey Mouse Town
- Contact:
- Status: Offline
- spiffy
- IAC Addict!
- Location: Walla Walla, WA
- Status: Offline
- Amskeptic
- IAC "Help Desk"
- Status: Offline
Re: Fuel Pressure Regulator
If the pressure regulator is leaking on the vacuum side, it does not necessarily have to be a hole in the diaphragm where the fuel is indeed pushing against it. It could leak vacuum between the diaphragm and the crimp on the housing. I haven't seen one leak fuel or vacuum. I have seen the ball check lose its ability to hold back the fuel pressure when the engine is shut off and not throttle back the pressure under vacuum.DurocShark wrote: Does the fuel ever touch the diaphragm the vacuum is pulling on? Because if it is, then it would have to be leaking.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
- DurocShark
- IAC Addict!
- Location: A Mickey Mouse Town
- Contact:
- Status: Offline
Re: Fuel Pressure Regulator
Thanks.Amskeptic wrote:If the pressure regulator is leaking on the vacuum side, it does not necessarily have to be a hole in the diaphragm where the fuel is indeed pushing against it. It could leak vacuum between the diaphragm and the crimp on the housing. I haven't seen one leak fuel or vacuum. I have seen the ball check lose its ability to hold back the fuel pressure when the engine is shut off and not throttle back the pressure under vacuum.DurocShark wrote: Does the fuel ever touch the diaphragm the vacuum is pulling on? Because if it is, then it would have to be leaking.
Colin
I confirmed it's leaking vacuum, but cannot find any sign of fuel seepage at all. Even after driving home from CA. So it'll do as-is for now.
- VWBusrepairman
- IAC Addict!
- Location: Bloomington, Indiana; Children of the Corn
- Status: Offline
Re: Fuel Pressure Regulator
1. It wouldn't be online without the help of Durocshark to host itspiffy wrote: I also referenced vwbusrepairman's fuel injection manual.....
2. I served some jail time for the copyright enfringements for that stinkin' manual
3. glad it has been there to help you all
4. I am glad for numbered lists and fuel injection!
- DurocShark
- IAC Addict!
- Location: A Mickey Mouse Town
- Contact:
- Status: Offline
Re: Fuel Pressure Regulator
Sooo... How's Bubba?VWBusrepairman78 wrote: 2. I served some jail time for the copyright enfringements for that stinkin' manual
- spiffy
- IAC Addict!
- Location: Walla Walla, WA
- Status: Offline
Re: Fuel Pressure Regulator
Thanks to both of you....that manual is very handy.DurocShark wrote:Sooo... How's Bubba?VWBusrepairman78 wrote: 2. I served some jail time for the copyright enfringements for that stinkin' manual
What's that you say about the 'sisters'?
78 Riviera "Spiffy"
67 Riviera "Bill"
67 Riviera "Bill"