Fuel Pressure Gauge? Where to mount, type, etc?

[baloo]

Have an 87 3.2 that is lining up (over the past 2 years, yah) to get turbo'd.

Having read a considerable number of Pelican forum posts, I want to mount a fuel pressure gauge. I have done some searches for "fuel pressure gauge" and the number of posts with those three words is overwhelming -- and I haven't chanced on any that give me the info I need.

So, a few questions:
1) Where is the best place to mount the gauge itself? In dash? In engine bay?
2) Where is the sender (if electric) or gauge mounted in the fuel line?
3) Type gauge to get? ...brand name, digital vs analog, etc?
4) What pressure range to get? I have been seeing that the fuel pumps are about 75psi. If so, do I need one that goes 80, 100, 120psi?? Higher?
5) Is a tell-tale high-reading useful?
6) Size fittings to use?

7) Anyone have any pictures showing the final installation?

Thanks.

[aston@ultrasw.c]

I have toyed with a FPG, currently it's not working

1) I would have to say in-dash. Knowing what the fp is when you are looking into the engine bay is not very useful.

2) I removed the nut from the end of the fuel pump that secures the banjo. I drilled and tapped it to 1/8" npt then installed an AN fitting. Works great, no leaks.

My original plan was to use a real pressure gauge with an isolator: no gas behind the dash. Well it sucks. Bleeding air out of the system is a major pita, and before long it is reading zero again.

So my recommendation is an electronic sensor and gauge. A bit more expensive but way less aggro.

[BoxsterGT]

I have the fittings & Line to connect a mech gauge or a sender at the 3.2 fuel rail......





If you want the gauge inside on the dash its best to do a VDO pressure sender at the motor & run wire up to the gauge.

Sent one of these to a fellow Pelican recently but have not yet received photos of the install. Perhaps he will chime in.

Len at Autosportengineering dot com

[The cap'n]

What benefit do you see in having a constantly operating fuel pressure gauge? It's been my experience that the pump either works or it doesn't. I don't recall ever seeing a pump failure (in a German FI equipped car) in a lower than normal pressure mode.

The Cap'n

[scarceller]

IMHO - why bother with FP gauge. You'd far better off with a Wide Band O2 setup and a AirFuelRatio gauge. Knowing the AFR is much more meaningful than just FP. AFR readings is what really needs to be monitored as these take into account FP, Air Leaks, bad Injectors, poor ignition, ... and you really want to know how the engine is burning fuel not just FP.

I use this gauge with a WBO2 controller and sensor:
G5 Gauges: Air Fuel Ratio Guage

You can get the entire kit with the gauge controller and sensor like this:
Innovate 3822 G5 Wideband Air Fuel Gauge LC 1 Kit | eBay

Or you can get the kit with this gauge for less:
Innovate 3844 MTX L Digital Wideband Air Fuel Gauge Kit | eBay
But I don't like the way this digital gauge looks in our cars.

[aston@ultrasw.c]

Originally Posted by The cap'n

What benefit do you see in having a constantly operating fuel pressure gauge? It's been my experience that the pump either works or it doesn't. I don't recall ever seeing a pump failure (in a German FI equipped car) in a lower than normal pressure mode.

The Cap'n

Lets say I get a miss-fire at WOT, I can glance down and check the the fp is where it should be.

To your point, I did change the pump at 210,000 miles just to be on the safe side - it was working just fine

[aston@ultrasw.c]

Originally Posted by scarceller

IMHO - why bother with FP gauge. You'd far better off with a Wide Band O2 setup and a AirFuelRatio gauge. Knowing the AFR is much more meaningful than just FP. AFR readings is what really needs to be monitored as these take into account FP, Air Leaks, bad Injectors, poor ignition, ... and you really want to know how the engine is burning fuel not just FP.

I use this gauge with a WBO2 controller and sensor:
G5 Gauges: Air Fuel Ratio Guage

You can get the entire kit with the gauge controller and sensor like this:
Innovate 3822 G5 Wideband Air Fuel Gauge LC 1 Kit | eBay

Or you can get the kit with this gauge for less:
Innovate 3844 MTX L Digital Wideband Air Fuel Gauge Kit | eBay
But I don't like the way this digital gauge looks in our cars.

That's a very good point! And its about the same price as the electronic fp sensor and gauge.

[baloo]

Originally Posted by scarceller

IMHO - why bother with FP gauge. You'd far better off with a Wide Band O2 setup and a AirFuelRatio gauge. Knowing the AFR is much more meaningful than just FP. AFR readings is what really needs to be monitored as these take into account FP, Air Leaks, bad Injectors, poor ignition, ... and you really want to know how the engine is burning fuel not just FP.

....But I don't like the way this digital gauge looks in our cars.

Yep, installing wideband AFR gauge (from AEM).

However, from what I have been reading here on Pelican over the past two years, fuel delivery is often an insidious problem, leading some skilled Pelicaners chasing false leads when the main problem was a slight decrease in fuel delivery. The simple addition of an FP gauge should give me more pinpoint diagnosis.

However, the several comments about air leaks due to gauge installation is sobering.
Simple is always better.

However, there have been some great suggestions on where/how to install a gauge.

I'm thinking about electronic gauge with sender (worries about live gas travelling thru a tube into the cabin with a mechanical gauge).
Per Scar, am a little concerned about the looks of a non-matching gauge on or under the dash.

[scarceller]

I put my 2" AFR gauge in a mounting Pod and it sits on the dash, far left hand side against the Window Frame post. If I get a chance I'll post a pic.

[baloo]

Originally Posted by BoxsterGT

I have the fittings & Line to connect a mech gauge or a sender at the 3.2 fuel rail......





If you want the gauge inside on the dash its best to do a VDO pressure sender at the motor & run wire up to the gauge.

Sent one of these to a fellow Pelican recently but have not yet received photos of the install. Perhaps he will chime in.

Len at Autosportengineering dot com

Len,
I'm pretty sure it's an electrical sender/gauge that I want to use. Can you PM me with details of what you have and how I'd mount it?
Thanks.

[porwolf]

I eventually want to install an electric fuel pressure gauge and Voltage meter in my center console. Similar to the setup here:

In-dash fuel pressure gauge for CIS

[baloo]

Originally Posted by porwolf

I eventually want to install an electric fuel pressure gauge and Voltage meter in my center console. Similar to the setup here:

In-dash fuel pressure gauge for CIS

Thanks PORWOLF. Great link to know about!

[aston@ultrasw.c]

Detail pics of adding a 1/8 NPT fitting to the fuel pump cap nut

928-110-475-04-M1002

[HawgRyder]

The only point that matters in the fuel system is right before the distribution to each cylinder.
Any where else can be affected by clogged filter/pinched hose/bad injector/etc.
If the fuel pump maintains correct pressure...and the flow to each injector is correct...then a missfire or similar in one cylinder will be almost impossible to see (so quick..by the time you look at the guage it's already gone).
I would spend my money elsewhere if I were you...but it's your car so go for it.
Bob

[gumba]

A fuel pressure gauge saved my 3rd fuel pump. Due to bad gas, after driving for 15-20 minutes the engine would die and feel like it ran out of gas. I thought the pump was bad and replaced it, happened again a few months later. That's when I added a in cockpit electric f.p. gauge. Turns out after 15-20 minutes of driving my fuel pressure would drop from 3.5 (carbs) to 1. When I saw that happen I could baby the car home on the back roads. A few of my friends were also having fuel issues and someone finally figured out it was bad gas, which the gas company finally admitted. We all filled at the same place. After the gas issue was resolved, my pressure went up from 3.5 to 7, which I wouldn't have noticed without the gauge.
Yes, I run a a/f gauge. The gauge did show the a/f's going lean, but the fuel gauge showed why.
The down side to the electric gauge is they are voltage sensitive. If the battery is slightly down the pressure will read lower, then will come up as the battery charges. In my case is was 1 psi. Also compared to the PMO mechanical pressure gauge in the engine bay the Holley gauge reads 1 psi higher, and the SW reads 1 psi lower.

[aston@ultrasw.c]

Originally Posted by HawgRyder

I would spend my money elsewhere if I were you...but it's your car so go for it.
Bob

QQQQ

[porwolf]

Originally Posted by gumba

A fuel pressure gauge saved my 3rd fuel pump. Due to bad gas, after driving for 15-20 minutes the engine would die and feel like it ran out of gas. I thought the pump was bad and replaced it, happened again a few months later. That's when I added a in cockpit electric f.p. gauge. Turns out after 15-20 minutes of driving my fuel pressure would drop from 3.5 (carbs) to 1. When I saw that happen I could baby the car home on the back roads. A few of my friends were also having fuel issues and someone finally figured out it was bad gas, which the gas company finally admitted. We all filled at the same place. After the gas issue was resolved, my pressure went up from 3.5 to 7, which I wouldn't have noticed without the gauge.
Yes, I run a a/f gauge. The gauge did show the a/f's going lean, but the fuel gauge showed why.
The down side to the electric gauge is they are voltage sensitive. If the battery is slightly down the pressure will read lower, then will come up as the battery charges. In my case is was 1 psi. Also compared to the PMO mechanical pressure gauge in the engine bay the Holley gauge reads 1 psi higher, and the SW reads 1 psi lower.

Looks like the solution for stable fuel pressure reading would be to power the gauge with a DC/DC converter/stabilizer to make power solid 12V.

[baloo]

Originally Posted by aston@ultrasw.c

Detail pics of adding a 1/8 NPT fitting to the fuel pump cap nut

928-110-475-04-M1002

Aston,
Wow. Thanks. No leaks?

[aston@ultrasw.c]

Nope none at all.

Obviously thread part way and then check the fit. Also make sure the tap is on axis. Use a drill press and turn the chuck by hand to start the thread.

...and use a good gas resistant sealant.

[baloo]

Originally Posted by aston@ultrasw.c

Nope none at all.

Obviously thread part way and then check the fit. Also make sure the tap is on axis. Use a drill press and turn the chuck by hand to start the thread.

...and use a good gas resistant sealant.

Aston,
Thanks.
I am unfamiliar with using a gas resistant sealant on pipe threads, unless you mean something like Teflon tape?