"How To" Build your own Fuel Pressure Meter

[cj]

I read the topic on Adjustable Fuel Pressure Regulator and since there was a question concerning the missing FP meter on the “second hand” regulators, I thought the following info might be of your interest.

This is a short “how to” on building a Fuel Pressure Meter (FPM). I already have my assembled (no single parts pics), but it’s a simple part to build, so assembled pics aren’t hard to understand.

Total spend - about 8 euros.

Parts needed:
Tightening bracket – 2 pieces
Liquid proof fuel hose (about 50 cm long)
Liquid meter (manometer)
Three way metal splitter (T-type)
Hose flange (adapter for the hose insertion) – 2 pieces

1 step: Insert the hose flanges into both opposite ends of the splitter.
2 step: Connect the fuel hose to one of the flanges and tighten it with the bracket.
3 step: Insert the second bracket on the loose end of the fuel hose – you will need it to secure the connection when installing the meter into the car.
4 step: Connect the Liquid meter with the middle free end of the splitter.

Pretty much that is the whole thing!

Now, inserting it into the car: (no detailed pics, sorry, I might do it sometime later)
1 step: Locate the Fuel Pressure regulator.
2 step: Find the fuel hose that goes into the fuel pressure regulator (on the down side)
3 step: Unplug the hose and plug it into the free hose flange of the FPM.
4 step: Plug the loose FPM hose into the fuel pressure regulator and tighten the bracket to ensure the connection.
5 step: You’re done installing! Now comes the hard part - Read and analyze!

a better suggestion:

Here is another “how to” that differs from the one described by the additional 1 m long liquid proof hose. The assembling is pretty much the same. This time do not connect the manometer directly to the metal splitter, but use the 1 m hose. The reason is that you will need to read the info from the meter while driving. Why while driving? Because the fuel pressure might differ at different engine rpms. When setting the fp you want it stable through the whole rpm band and that’s the way to be sure – extend the 1m hose with the manometer under the back of the hood and put it below the windshield wipers (facing the interior). Do your tests and when done, either disconnect the FPM from the car or secure the hoses in the engine bay.

Parts needed:
Mounting brackets – 4 pieces (2 more to tighten the 1m hose)
Liquid proof fuel hose (about 50 cm long)
Liquid proof fuel hose (about 1 m long)
Liquid meter (manometer)
Three way metal splitter
Hose flange – 3 pieces

Hope this helped!

[jamiemirror]

Especially for engines with billet fuel rails - the most simple and solid solution is to drill the hole in the rail, make the correct thread in the hole and just screw the manometer.
PS: CJ, are you sure that your manometer is fuel-proof ? I already broke the same unit and I think that it is fuel-proof but I prefer another one - just to be sure and to avoid fuel leaks.
PS: The price is cut to under 6EUR (with industrial standart manometer) excluding labour costs.

[cj]

jamiemirror Wrote:PS: CJ, are you sure that your manometer is fuel-proof ?
PS: The price is cut to under 6EUR (with industrial standart manometer) excluding labour costs.

As far as my experiment went - yes, i didn't have any leaks and the manometer did a good job. Regarding price - my device actually costed like 5.50 eur, but depending on the manometer and assuming that you need the extra 1m hose, add another buck or two.

[filh]

Sorry for my late response , but I was on holiday, Just a question: did you notice a power improvement by raising the fuel pressure , and if yes , what was your prefered pressure . Do you run stock injectors or else .
Thanks
Filh

[cj]

I have an Apexi Rev/Speed Meter installed (like the G-Tech Pro Comp gauge toy). I set it to measure mid-accelaration from 80-120 km/h. I put in third gear and perform the test a couple of times. This is how i meause my mods - no gear change, no tire roll out.

Now to the question: no, i did not notice any improvement. As a matter of fact i got way slower times. My quarter mile times worsen with 1-2 secs, depending on the fuel pressure settings. Now i use the regulator but it's set to the stock pressure.

Additional note: i changed my stock fuel pump since it was anable to keep the pressure more than 3.0 bar at high rpm. The test above was made with the new pump wich kept 4.0 bars without any problems through out the whole powerband.

regarding the injector question: yes, they are stock. I did performed another test - i used i wide band meter to see if the injectors are feeding enough fuel (a/f ration stuff...) and i found out that the a/f mixture was good enough - 12.5! So now i decided not to play with the f/p regulator untill more air is introduced to the engine or valves are replaced!
...or both

[filh]

thanks CJ for your very clear response and good advices
Filh

[Brian]

A word of caution regarding in-cabin fuel pressure meters. They can be very dangerous if they're damaged. Imagine, your passenger smoking a cigarette, and fuel spraying all over... fooomp!

Here in Canada and the USA, and in-cabin fuel pressure gauge is illegal. To have one, you need an "isolator" to keep the live fuel in the engine bay. Race car fabrication shops can source these devices.

[Ivan141]

Quite true Brian...I would only install one inboard like this for tuning purposes, but even then it's usually only interesting to see if the fuel pump can maintain the correct pressure. Does anyone know of a pressure sensor that can be wired to an analog gauge? I imagine something similar to the oil pressure sender might be worth a try, that way you could keep the sensor inside the engine bay and put the gauge anywhere you like. My only concern is the safety of such a setup..

[LevinGT]

they have electrical fuel pressure gauges, but they are more expensive then oil pressure gauge.
Electrical Fuel Pressure Gauge