FI Fuel Pressure Gauge - perm install

[TX82FIAT]

Can anyone share a picture of a permanently installed fuel pressure gauge on a fuel injected care in the engine bay. I know a lot of testing is done off the Cold Start Injector. However, I was looking for a preventive measure to monitor fuel pressure. I'll be under the hood this weekend replacing the fuel pressure regulator and back by the gas tank replacing the fuel filter. I'm 90% certain a new fuel pressure regulator will fix the problem based on the symptoms. 1. Gas mileage on a trip from San Antonio to Austin and back was about 1/2 of normal mileage. 2. Engine hard start and then high idle after warm up. 3. Noticed a little fuel on top of the regulator, when I pulled off the vacuum hose it had a little fuel in it indicating the diaphragm had failed. Car ran well, no black smoke, acceleration was slightly off just really the hard start and high fuel consumption. Considering preventive measure to plumb in fuel pressure gauge and not sure where ideal location would be and how you all may have set it up. I like the idea of adding Fuel pressure to my checklist before a drive given the damage that can occur if you run too rich or lean. Thoughts, open to ideas.

[SteinOnkel]

This is one my other car w/ open source EFI.

Basically, it's an Aeromotive unit with a gauge. Not cheap, but you don't want to go cheap. It's fully adjustable, but honestly I've never really messed with it. Set it to 42PSI or whatever you want and off you go.

Make sure to run plumb it into the fuel system after the fuel rail. So it's basically in the return circuit. And you can grab a constant manifold vacuum from wherever. It's got three outlets plus a port for the gauge. I just bolted mine to the firewall.

[spider2081]

I have been thinking of installing one in place of the clock on our 1981 FI Spider. Electric fuel pressure gauges are expensive especially compared to electric oil pressure gauges. The pressure senders look very similar and i have been considering trying to use an oil pressure gauge for a fuel pressure gauge. The chance of a fire scares me.
Also mechanical fuel pressure gauges are much more reasonable priced but the idea of a fuel line running to the dash tests my comfort level.
So far I haven't done anything.

[SteinOnkel]

Why would you need it in the dash? It doesn't change. A good fpr will hold the set pressure regardless of vacuum (or boost).

[spider2081]

Why would you need it in the dash? It doesn't change. A good fpr will hold the set pressure regardless of vacuum (or boost).

I was thinking new Fuel pressure gauge would look better than a clock with yellow crystal and it would be interesting to see just how steady it does hold, I have used a test gauge in the cold start hose of a number of cars and the fuel pressure does fluctuate with rpm changes. I think knowing fuel pressure is a good troubleshooting aid.

[SteinOnkel]

Why would you need it in the dash? It doesn't change. A good fpr will hold the set pressure regardless of vacuum (or boost).

I was thinking new Fuel pressure gauge would look better than a clock with yellow crystal and it would be interesting to see just how steady it does hold, I have used a test gauge in the cold start hose of a number of cars and the fuel pressure does fluctuate with rpm changes. I think knowing fuel pressure is a good troubleshooting aid.

It really isn't. The only time I've ever looked at it was diagnosing a no-start. Turns out, it helps when you have fuel in the tank...

If you really must know what's going on while driving, tape an old smartphone into your engine pay pointed at the gauge and record a video as you drive around.

[greenspider]

An air/fuel ratio meter for fi would be cool to replace the clock.

[SteinOnkel]

An air/fuel ratio meter for fi would be cool to replace the clock.

If you can find one that doesn't completely clash with the rest of the vintage look of the Fiat.

This one might be a contender:

https://www.vwispwest.com/113018041BK.html

[rridge]

It's very helpful to be able to check fuel pressure when diagnosing fuel injection problems. Modern cars come with port on the fuel rail that allows a pressure gauge to be quickly connected. On a Spider pulling the hose off the plastic nipple on the cold start injector to connect a gauge will sooner or later damage both the hose and the injector. If you forget to depressurize the fuel rail it can also result in face full of gas. A generic pressure port with Schrader fitting and fuel resistant seal can be added to the flexible fuel line between the firewall and the fuel rail.

A permanent mechanical fuel pressure gauge under the hood is a fire risk. Only one thin metal diaphragm separates you from a spray of high pressure fuel from the gauge's vent hole. If you do it use the best hardware. If you need something to monitor mixture while driving a wide-band O2 sensor with dash gauge both safer and more informative.

[SteinOnkel]

And yet, 99% of the cars I've seen with fuel pressure gauges have them in the engine bay. Also one glance at the gauge will tell you if the system is depressurized. And lastly, the gauges are liquid filled (with a clear oil, I believe). That way, the only liquid that ever comes out of the vent port isn't gasoline.

Aeromotive charge $250 for the regulator and gauge. They know what they're doing.

[greenspider]

80 FI: I believe my fuel pressure is too high after failing my smog test with high CO. I disconnected and blew out the fuel return line from the tank end and heard a pop, possibly gunk blockage in the hose (ethanol related?). I’m hoping that it wasn’t a check valve that blew out.
When installing a temporary diagnostic fuel pressure gauge at the CSI hose, would the pressure reading be accurate if instead of installing a “t”, the hose to the CSI were disconnected at the fuel rail and the gauge connected at the rail port? Of course the electrical to the CSI would also be disconnected disabling it altogether. I don’t want to damage the CSI nipple and will test after warm-up anyway. Thanks, Tony

[rridge]

Yes, you can connect the pressure gauge directly to the fuel rail in place of the cold start injector hose. High pressure in the fuel rail can be the result of a blocked return line, perhaps due to return line deterioration. It can also be the result of the vacuum line from manifold to fuel pressure regulator being pinched or disconnected. And of course the pressure regulator itself can be defective.

[greenspider]

Thanks rridge. Could the test bung just before the cat be used for an O2 sender for an air fuel gauge?