0-5 psi fuel pressure gauge

[tenders]

Very difficult to find but very useful to diagnose potential fuel delivery issues.

Stock fuel pressure gauges go up to 15psi but the Facet pump only delivers about 10% of that -- barely enough to move the needle.

I wouldn't put one on my instrument cluster but I would screw it directly onto the engine. If I suspect problems that this will troubleshoot I'm going to have to have my face jammed up against the carb in the cave anyway.

[Dave Neptune]

Yep

tenders, I have mine mounted next to the engine with a shut off valve on it tah feeds directly to the carb. All we have to do is look and know if the fuel pump is working correctly, no bleeping around and guessing!

Dave Neptune

[tenders]

Where did you find one with a range that's useful for A4 fuel pressures?

[sastanley]

tenders...google is your friend.

I did a search on "5psi fuel pressure gauge" and found one thru the RX7 club.

http://mrcmfg.com/catalog/product_info.php?cPath=108_112_125&products_id=163&osCsid=201427b62cdbd35d74be8ffbe26b8a74

[tenders]

Oh, Google and I go way back. I own a couple of Mazdas too, but not an RX7.

You googled for a 5psi gauge but that is a 10psi gauge.

http://tinyurl.com/22tmzur

Don't know that I'd spend >$50 for a gauge that doesn't fit the bill much better than the readily-available 15psi model for half as much dinero (or less). I would drop that much if Don sold a 0-5psi gauge.

[sastanley]

gotcha tenders, no worries...You are correct that was a 10 psi gauge. - I like your "let me google that for you" - I'd never seen that before - lol!

I like that one posted in the other thread that is liquid filled.

[rpowers]

Fuel Guage

I recently installed this one (see image) on my engine between the pump and carb. I have an extension tube off the T-fitting that goes about 12" vertical.

This allows me to watch the guage from the helm by looking down at my cockpit deck hatch (open) directly at the guage sticking up on the side of the engine.

Sweet!!!

(inexpensive on Amazon.com)

[roadnsky]

Here's my latest setup...

[rpowers]

Before or After

Wouldn't it be best to install the gauge after the polishing filter?

If the polishing filter is clogged and restricting flow...

[roadnsky]

Wouldn't it be best to install the gauge after the polishing filter?

If the polishing filter is clogged and restricting flow...

Yes, in theory, then you are sure you're getting pressure to the carb.
Currently, however, I'm trying to diagnose my fuel pump heating up, (arrgh!) so I've got it right after the pump to keep an eye on it's "direct" pressure.

Good eyes though...

[thatch]

"Nostalgia time"

Dave Neptune,
I actually took a ride in a factory, Mazda powered boat at lake Naciamento in the late 70's. It felt like an outboard but there was no "thing" hanging off the transom. Most of us were running V8's at the time so it sounded wierd to us.
Tom
P.S. How did the July 4th regatta turn out?

[rpowers]

Fuel Pump Re-circ Question

While we're on the topic of the Facet fuel pump:

What does the pump do when the float reservoir is full and the float valve is closed?

It seems to keep on humming (pumping), but does it recirculate fuel within itself? I've opened mine up to look at the mesh screen filter, and there is a ball-valve in the center. Does anyone know what goes on inside?

Also, what is actually doing the pumping.

Is it a membrane or some other mechanism?

[rigspelt]

While we're on the topic of the Facet fuel pump:
What does the pump do when the float reservoir is full and the float valve is closed?
It seems to keep on humming (pumping), but does it recirculate fuel within itself? I've opened mine up to look at the mesh screen filter, and there is a ball-valve in the center. Does anyone know what goes on inside?
Also, what is actually doing the pumping.
Is it a membrane or some other mechanism?

My notes scavenged last year from various archived posts (I did not track the sources):

"FACET fuel pumps have a small diaphragm which moves the fuel under pressure. The pressure is internally regulated by a small spring-loaded by-pass valve that has been preset for the rated pressure of the pump. It is normal for the pump to keep on pumping (making a clicking sound) even when the carburetor is full and the pump is operating against a dead-head, or zero flow, condition." (Don)

"Facet pumps click when running. Fuel flow is regulated internally by a spring-loaded bypass valve, so that the fuel is recirculated internally when the pump's pressure set point is reached. They push not pull"

Some Facet pumps have a check valve that prevents fuel from draining through the pump if the pump is off and there is a downstream carb leak. but I don't think the usual model used in A4s has that feature?

[roadnsky]

Some Facet pumps have a check valve that prevents fuel from draining through the pump if the pump is off and there is a downstream carb leak. but I don't think the usual model used in A4s has that feature?

According to the Purolator (Facet) specs on their site, there is no check valve.

http://www.facet-purolator.com/index.php?option=com_content&task=category&sectionid=7&id=14&Itemid=36

[hanleyclifford]

It is certainly no secret that low pressure gauges are readily available from a number of sources. But if this item were carried in the Moyer catalogue in the same section as the Racor filter there would be incentive to order one as part of a larger order rather than reading about it's purpose and value on the Forum, and then ordering it separately (and paying additional freight charges). Have we not seen thread after thread where this tool is valuable in diagnosis?