17 replies to this topic

[Tom Hampton]

Ok... I'm probably going to answer my own question while typing this, but here goes anyway.

Short version : is there a strong case to be made for having a dedicated Guage for fuel pressure?

3 hours ago I had assumed the answer as "yes". But, I've about talked myself out of it. I was actually getting ready to click checkout on the thing.

My car is a 1.6. I have a tuned afm, afpr, and wide band o2, and. Daq (racepak)

I was going to buy a Guage with a Daq output and feed that to my Daq. But, the more I think about it, I can't really see a reason that I would ALWAYS want to know fuel pressure (ie, as part of my primary scan on straights).

Obviously, I need to know fp when I'm adjusting it, and I might occasionally be interested during a tuning or practice session, but I can't seem to justify a need on every session or even every day.

The alternative I'm considering is to just get a pressure sender and wire it directly into the Daq. Then I can program my dash to display the fp whenever I'm interested and display something else when I'm not.

[Bench Racer]

Tom, my fuel pressure gauge is mounted near the windshield wiper outside the cockpit in plain view for the driver. I have no data recording.

[Tom Hampton]

Thanks bench. If you had data would your driver have use for the Guage all the time?

[Bench Racer]

Even with data, I'd leave the fuel pressure gauge in place. Immediate knowledge without data download.  

[pat slattery]

Dave I assume you are using a mechanical gauge, if you have a AIM products you can have the info recorded on your data logger and also visible on the gauge.  

[Johnny D]

I just have the gauge that attaches to the FPR but I see the advantage of the fixed one in site.

If anything happened and it dropped,FP going south, pinched line in contact, the engine would go lean, you could save your engine from blowing up if you catch it fast enough.

J~

[Keith Andrews]

I use the gauge for adjusting fuel pressure as you describe.  

 

The time I found it most important though was when my alternator started to go.  My car is a 99 so I don't know if this applies to a 1.6.  When the alternator wasn't putting out good power the fuel pressure dropped significantly, running extremely lean.  I could see that on the A/F gauge and Fuel Pressure gauge and no damage was done to the engine.  Any instrument that will get my attention to save the engine is worth it.  Running it into your data sounds good to me.  

[Muda]

Don't know about 1.6's but in my '99 the fuel pressure drops about 4 lbs. under load.

Hard to know exactly where you are without data or a gauge in the car.

[Bench Racer]

my '99 the fuel pressure drops about 4 lbs. under load.

Ya got to feed those torque monsters.  

[dfuser]

I have 2 a mechanical liquid filled mounted by the AFPR, this makes it is to see and adjust when tuning or diagnosing a problem while working on the car.  I also have a digital inside the car in plane view of my eyes and camera to monitor while racing.  It also has a data logger output.

[Tom Hampton]

Bill-

 

I think you're the first person with data and a guage (let alone TWO).  I understand why people have a guage without data....but:

 

What is your reasoning for the dedicated guage in the cockpit, given that you have a data logger (did you have a specific reason for wanting to have a dedicated guage in plain view)?

In hindsight do you find it useful (would you miss it if you didn't have it)? 

What are your decision options and criteria for the over/under range values on the guage?

 

PS: Go Team X-Factor.

[Glenn Davis]

Bringing back a thread from the grave...

 

I am planning to mount a fuel pressure gauge on a 2002.  I want to remote mount the sender on the firewall, so what is the best way to tie into the fuel system?  Are there any standard fittings I could tap into?

[Duncan]

Bringing back a thread from the grave...
 
I am planning to mount a fuel pressure gauge on a 2002.  I want to remote mount the sender on the firewall, so what is the best way to tie into the fuel system?  Are there any standard fittings I could tap into?

Doesn't your fuel pressure regulator have a port for a pressure gauge?

[Glenn Davis]

Doesn't your fuel pressure regulator have a port for a pressure gauge?

It does have an extra port.  Can the sender be mounted in the trunk and be accurate, or does it need to be closer to the fuel rail?

[RussMcB]

It does have an extra port.  Can the sender be mounted in the trunk and be accurate, or does it need to be closer to the fuel rail?

I was wondering the same thing.  Is the pressure at the fuel rail always exactly the same as at the FPR outlet in the trunk?

 

[RussMcB]

I purchased a FP gauge and am now trying to decide about a sender location.  I'd like for it to be in the engine comparment after the Mazda regulator.

 

Does anyone make a handy male/female/1/8"NPT fitting to fit our Miata fuel lines, something like this in concept?

 

If not, does anyone know a good source for parts to fab something like it?

 

TIA.

[RussMcB]

Circling back to this thread because I've made a little progress (but still haven't found the 'ideal' adapter I desire).

 

This one from Aeromotive (PN AEI15120) is pretty close, except:

1. It's $60
2. It has an extra -6AN port I'd need to plug (the 1/8"npt port is on the back side)
3. a 90 degree turn would work better on top of the Mazda regulator.

Here's a couple of places to purchase:

http://www.summitrac...parts/aei-15120

http://paceperforman...ccess-port.html

 

[RussMcB]

Circling back to post my impressions of this Aeromotive part mentioned above.

 

I bought it, in spite of the high price, because it seemed pretty close to perfect (with its easy installation and 1/8" npt port).

 

The only obstacle was the unneeded -6AN port, a little tougher to plug than I expected.  I had a simple male plug on hand, but the female port was too deep, so I had to cobble together a couple of AN parts to create a plugged port.

 

If I was doing this from scratch, I'd use the -6AN port for the fuel test port.  That would work pretty well.  I didn't, because my car already had a plumbed test port and it wasn't worth the hassle of changing.