I'm looking for a fuel pressure gauge to check my 71 D-Jet fuel pressure. Pelican has a kit to test FI fuel pressure but I was looking for a simple gauge that I could permanently attach to the fuel line.

Pelican FI Fuel Pressure Tester

I got a cheapy gauge at Oriellys. Doesn't have to be specifically for fuel.

Harbor Freight has two of them. One low buck gauge and a master kit with a bunch of fittings that I think would work for CIS.

A permanently installed fuel pressure gauge, especially a relatively cheap one, is, IMO, just another potential leak. Failing fuel pressure is one of the least common running problems.

The Cap'n

Look through Jeg's offerings. http://www.jegs.com/i/JEGS+Performance+Pro.../41043/10002/-1

I got the Fuel Pressure Gauge Kit from 9x Auto here: http://www.9xauto.com/914a.htm

(Although I still haven't installed it...)

I've gotten mine through Summit racing in the past but frankly, I've seen the Harbor Freight one and it looks to be the same without the 'Summit' emblem. I think the Summit one was $15. HF much less.

I got mine from Jegs, IIRC.

I think it was only 20.00 bucks or something.

Pretty much all odf the units out there have a 1/8'' NPT fitting to mount them.

I just plumbed mine right into the fuel inlet to make it permanent.


Ron

I really only want to check or set the fuel pressure since I haven't done that after converting the engine back to FI. I'm in the process of setting the AFR and need to check to make sure the fuel pressure is correct.

This test kit from HF looks interesting especially if it fits the port on the fuel rail between the injectors.

HF Fuel Pressure Test Kit

As already said, almost any pressure gauge will do. I used a water heater pressure gauge + 1/4" NPT hose nipple + 12" of 3/16" fuel hose. This will stay on the fuel rail test nipple with a hose clamp. Zip tied the gauge to the engine deck lid cable release housing. Got me through FI rehabilitation, establishing best fuel pressure and diagnosing an intermittent fuel pump failure. Took it off after I thought everything was kosher. Somehow, most likely because I'd read the Cap'n warn someone else against it, I didn't loose the test nipple plug screw.

Get the master kit from Harbor Frieght.

This is the biggest bang for the buck.

If you are doing D-jet ...IMHO...no need to mount it in the engine compartment.

The kit has every fitting you need in case you need to check any other FI system.

I bought the HF master kit and checked the fuel pressure. During the 2 sec pump run and running, the pressure was 27 lb/sq-in.

Is this ok or should I adjust it to 28.4-29.6 as per the repair manual?

If it runs good I would probably leave it alone (1.4lbs could be your gauge).
Lower pressure will mean slightly leaner mixture so if you are having and lean mixture symptoms I would bump it to specs.

Jim

It's not likely to reach full operating pressure in the 1.5 seconds of pump running you get when you turn the key on ....................

Obsession with irrelevant minutiae is often caused by a lack of understanding of how things work. I get phone calls all the time from 356 weenies who want to know measurements that they can't find in the books. They cant find them because they aren't in the books, and that's because they're meaningless and Porsche didn't care what that particular spec was.

I have to tell you that in nearly 40 years of working on 914s I think I've replaced ONE fuel pressure regulator, and had to adjust maybe 3 or 4, probably because they'd been futzed with. If your fuel pressure isn't what it should be, odds are it's a bad pump (low pressure) or a pinched line (high pressure). Incorrectly connected hoses fall in there somewhere, but the car usually won't run in that case. Oh, and the most common fault: someone's been in there before you ................

The Cap'n

I don't know the accuracy of the gages folks are installing, but, you can rest assured that after X months of being installed and subjected to vibrations and heat cycles that the accuracy is no longer what it should be. All gages used for quality measurements require calibration at specific intervals, usually 6 months.
I wouldn't leave one installed either due to another place for gas to leak.
Tom

I like that observation and sometimes recognize it in myself. The Cap'n describes "Sophmoric:" ...overconfident of knowledge but poorly informed. ... Merriam Webster. Engines are complex and my intellect is not very, and I tend to hang on tightly to familiar but inapplicable concepts when facing the unknown. However, given that everywhere you look someone has written how important fuel pressure is to tuning a 914, Spoke's question is not irrelevant minutiae.

Tom raises a good point -- over-reliance on an unreliable tool. For $20 I would not expect a HF gauge sufficiently calibrated to indicate a 7% variation from FP specifications. My rule for HF is only things with three or fewer moving parts and have no measurement function. For me, the value of the HF gauge would be to indicate fuel/no fuel, or, once the motor is running right, establish a baseline pressure # for that gauge.

Thanks for all the input. My only reason for checking the fuel pressure is part of tuning the engine's AFR. Before I adjust the MPS because it is running a bit lean, I wanted to make sure the fuel pressure is correct. I am now done with this.

As far as the calibration of the tool is concerned, this would apply to almost any measuring tool regardless of the manufacturer.

Case in point: my 2008 BMW 328xi; the speedometer is about 4 MPH higher than reality. This is a huge pain as I'm always bumping up on the max speed I'm comfortable with.

I checked the BMW speedo with my GPS which when in my '95 A6, '97 A6, '98 A4, and '07 Volvo S60, is spot on with each of these vehicle's speedos.

What did you determine? Was low fuel pressure causing the lean AFM?

ALL gauges that we as the consumer are willing to buy are off to some extent. Unless you buy a certified and calibrated gauge $$$, you are only getting close. We send gauges to calibration all the time, brand new, from a good U.S. vendor, and can see as much as 15-20% variance.

Tom is right. Vibration kill gages. Glycerine filled gages resist vibration and are a smart choice. Also, a gage's operating parameter should mimic your needs. That is; if your set point is 29.6 then a 30lb gage is going to give you the most reliable reading. I wouldn't trust a 30lb readout on a 0-300lb gage.

I calibrated gages for a while some years ago. most new gages were badly off from the factory. Any ones used for quanitive readings had to be recalibrated every year or 6 months. Lots of gages on USNavy ships and the gage cal shop was a busy place! Engine rooms on Navy ships have LOTS of vibration. And 76-914 is so right, vibration kills the mechanisms after several cal cycles.
My point was about ones staying installed and being adjusted for XX.X pounds. Today that may be pretty close, 6 months or a year down the road, it is reading different and you adjust it. OK, what did you adjust it to? Probably just getting further off. As an indication that you have a working fuel pump and have pressure, sure that would be OK.
Tom