Fuel pressure adapters
12-12-2017, 03:51 PM
#17
Drifting
If still available, I'll take one - I have been looking for something like this.
01-02-2018, 07:25 PM
#19
Chronic Tool Dropper
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Received the custom personalized replacement, more than wonderful! It will be put to good use. Hats off to Geo55!
01-03-2018, 11:15 AM
#21
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01-03-2018, 11:27 PM
#24
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That's a nice piece. Well done!
However........
I get to see quite a few 928's.....
And I've always been intrigued by fuel pressure gauges on the end of the fuel rail....
Who needs to know to know the fuel pressure at the rail....on a continuous basis? And if you really wanted to know the fuel pressure everyday, wouldn't you want to know what it is when the car is driving down the road?
And how accurate do you think one of those Summit Racing 1.5" gauges are....vibrating on the end of the fuel rail....when you can tap on them with your finger tip and get a 5 pound change?
If I need to know fuel pressures, I put on my super accurate Bosch fuel injection gauge (isolated from engine vibration), look at it without the engine off (fuel pump running), look at it again with the engine running, and take it off.
Immediately.
No more information needed.
Done.
However........
I get to see quite a few 928's.....
And I've always been intrigued by fuel pressure gauges on the end of the fuel rail....
Who needs to know to know the fuel pressure at the rail....on a continuous basis? And if you really wanted to know the fuel pressure everyday, wouldn't you want to know what it is when the car is driving down the road?
And how accurate do you think one of those Summit Racing 1.5" gauges are....vibrating on the end of the fuel rail....when you can tap on them with your finger tip and get a 5 pound change?
If I need to know fuel pressures, I put on my super accurate Bosch fuel injection gauge (isolated from engine vibration), look at it without the engine off (fuel pump running), look at it again with the engine running, and take it off.
Immediately.
No more information needed.
Done.
__________________
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
01-04-2018, 12:24 AM
#25
Chronic Tool Dropper
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my use of this includes adding a quick-disconnect fitting to it so I can easily connect my big-gauge-on-a-hose fuel pressure tester. Honestly, I've used he gauge on my own 928 a couple times. Once it was the first weapon selected when I found the FP relay was weak and the engine showed symptoms of pump failure. A fortuitous episode. I used it again when screening for possible low performance causes in a guest car. It's a pretty short list. It's still part of the diagnostic toolkit, essential when you need it. When testng is complete, the original rail cap needs to back on. There's no such thing as an acceptably small fuel leak and fire in the engine bay.
Folks diagnosing performance issues inturbo or supercharged cars may be ineterested in running fuel pressure. Add a pressure sender that interfaces to a dash display and data logger. For everyone else, the combination of the fuel delivery test and the pressue testing described in the WSM tells you everything you need to know.
Folks diagnosing performance issues inturbo or supercharged cars may be ineterested in running fuel pressure. Add a pressure sender that interfaces to a dash display and data logger. For everyone else, the combination of the fuel delivery test and the pressue testing described in the WSM tells you everything you need to know.
01-04-2018, 08:15 AM
#27
Rennlist Member
Hi guys,
I received this great adapter, very quickly, and I'm very thankful.
Does anyone have a favorite fuel pressure gauge with a 1/8" NPT male connector that I can connect to this. I thought I had one, but cannot find it. Can you recommend on?
Thanks,
Dave
I received this great adapter, very quickly, and I'm very thankful.
Does anyone have a favorite fuel pressure gauge with a 1/8" NPT male connector that I can connect to this. I thought I had one, but cannot find it. Can you recommend on?
Thanks,
Dave
01-04-2018, 11:03 AM
#28
Captain Obvious
Super User
Super User
my use of this includes adding a quick-disconnect fitting to it so I can easily connect my big-gauge-on-a-hose fuel pressure tester. Honestly, I've used he gauge on my own 928 a couple times. Once it was the first weapon selected when I found the FP relay was weak and the engine showed symptoms of pump failure. A fortuitous episode. I used it again when screening for possible low performance causes in a guest car. It's a pretty short list. It's still part of the diagnostic toolkit, essential when you need it. When testng is complete, the original rail cap needs to back on. There's no such thing as an acceptably small fuel leak and fire in the engine bay.
Folks diagnosing performance issues inturbo or supercharged cars may be ineterested in running fuel pressure. Add a pressure sender that interfaces to a dash display and data logger. For everyone else, the combination of the fuel delivery test and the pressue testing described in the WSM tells you everything you need to know.
Folks diagnosing performance issues inturbo or supercharged cars may be ineterested in running fuel pressure. Add a pressure sender that interfaces to a dash display and data logger. For everyone else, the combination of the fuel delivery test and the pressue testing described in the WSM tells you everything you need to know.
01-04-2018, 12:06 PM
#29
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A true drybreak quick disconnect that won't leak under any condition (without connecting a second corresponding plugged off dry break fitting) is very tough to find...and afford.
01-04-2018, 01:42 PM
#30
Chronic Tool Dropper
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Challenge comes to how you disconnect any gauge and adapter, especially a hose-mount, without dribbling some fuel. A dry-break QD would be awesome, but it's function is obviated when you remove the adapter from the rail.
The Geo55 adapter is handy but there's no reason to believe that it indexes the same on the different fuel rails it might meet, so some kind of swivel will be needed if you put a gauge directly on the adapter. If this is just for your own car, great -- just assemble a gauge to it so you can read it, and it will always index to the same direction. If you use a rear-port gauge, you are limited to how big a gauge you can use, so the gauge may be hard to read accurately especially with parallax error. If you are just looking to see if there's somewhere near correct pressure, then by all means use a small rear-port gauge and you'll minimize the amount of fuel released when you remove it.
Options list includes adding an intermediate adapter of some sort, maybe a Schraeder-style test port similar to what some 'murican cars use. My pressure gauge kit has a connector for that, and seals itself as it's disconnected. With the correct test port installed, leakage will be limited to the volume right at the end of the test port. But... You'll still have some fuel to manage when you remove the adapter, as the rail will want to drain out the open end.
For myself and my own situation, I also use the fuel rail connection to support a canister-style fuel injector cleaner. With a QD on the Geo55 adapter, I can use a pressure gauge or connect the injector cleaner without having to go in and out of the tapered pipe threads repeatedly. My adapter came personalized with 1/4" pipe threads in it (vs the 1/8" standard) to directly accept the common QD I use for both. The injector cleaner gets used on different cars besides my own 928, so again a QD is the solution to any possible indexing or other fitment concerns for the various cars.
---
I currently use a modified factory fuel rail end cap, installed only when a connection is needed. It has a 1/4" straight thread hole tapped in it, and a hollow fitting screws in there for the hose on the outside. The outer end of the hose has a QD fitting on it that connects to either the pressure gauge or the injector cleaner. The Geo55 adapter offers sealing at the end of the main rail body with the o-ring, vs. using a 1/4" compression ferrule in place of the sealing ball-bearing ball in my modified factory cap. Mine works, but use isn't as clean and elegantly simple as the Geo55 adapter.
---
Just curious -- How many people really use a fuel pressure gauge on their L-Jet/LH/LHA (non-CIS) cars? As I mentioned above in post 25, I've only used the gauge a few times on any 928 in the gauge's 30+ year life in my tool collection. How many have actually performed a fuel delivery test as described in the WSM? How many have gone deeper, adding a second port to do the delivery test at rated system pressure? These are all interesting uses, but I'll casually speculate that only a small minority of folks here have ever actually gone through all the steps when diagnosing a fuel-related performance problem.
The Geo55 adapter is handy but there's no reason to believe that it indexes the same on the different fuel rails it might meet, so some kind of swivel will be needed if you put a gauge directly on the adapter. If this is just for your own car, great -- just assemble a gauge to it so you can read it, and it will always index to the same direction. If you use a rear-port gauge, you are limited to how big a gauge you can use, so the gauge may be hard to read accurately especially with parallax error. If you are just looking to see if there's somewhere near correct pressure, then by all means use a small rear-port gauge and you'll minimize the amount of fuel released when you remove it.
Options list includes adding an intermediate adapter of some sort, maybe a Schraeder-style test port similar to what some 'murican cars use. My pressure gauge kit has a connector for that, and seals itself as it's disconnected. With the correct test port installed, leakage will be limited to the volume right at the end of the test port. But... You'll still have some fuel to manage when you remove the adapter, as the rail will want to drain out the open end.
For myself and my own situation, I also use the fuel rail connection to support a canister-style fuel injector cleaner. With a QD on the Geo55 adapter, I can use a pressure gauge or connect the injector cleaner without having to go in and out of the tapered pipe threads repeatedly. My adapter came personalized with 1/4" pipe threads in it (vs the 1/8" standard) to directly accept the common QD I use for both. The injector cleaner gets used on different cars besides my own 928, so again a QD is the solution to any possible indexing or other fitment concerns for the various cars.
---
I currently use a modified factory fuel rail end cap, installed only when a connection is needed. It has a 1/4" straight thread hole tapped in it, and a hollow fitting screws in there for the hose on the outside. The outer end of the hose has a QD fitting on it that connects to either the pressure gauge or the injector cleaner. The Geo55 adapter offers sealing at the end of the main rail body with the o-ring, vs. using a 1/4" compression ferrule in place of the sealing ball-bearing ball in my modified factory cap. Mine works, but use isn't as clean and elegantly simple as the Geo55 adapter.
---
Just curious -- How many people really use a fuel pressure gauge on their L-Jet/LH/LHA (non-CIS) cars? As I mentioned above in post 25, I've only used the gauge a few times on any 928 in the gauge's 30+ year life in my tool collection. How many have actually performed a fuel delivery test as described in the WSM? How many have gone deeper, adding a second port to do the delivery test at rated system pressure? These are all interesting uses, but I'll casually speculate that only a small minority of folks here have ever actually gone through all the steps when diagnosing a fuel-related performance problem.