Fuel Pressure Gauge

[hessank]

I searched but could not find any install tips for a guage on the schrader connection on the fuel rail. Is there anyone with an install picture?

The benefits of this gauge is tremendous.

Please and thank you

HK

[alexza4]

wich guage are you using? ECS?

[diagnosticator]

I searched but could not find any install tips for a Gage on the schrader connection on the fuel rail. Is there anyone with an install picture?

The benefits of this gage is tremendous.

Please and thank you

HK

There are fittings in fuel gage kits to fit the fuel rail pressure test port.

The fitting is designed to seal the fittings during the attachment process, before the schrader valve inside the test port is opened.

It is not recommended to connect a mechanical fuel pressure gage to the pressure test port on the fuel rail. The high pressure fuel in the gage signal pressure tubing if taken inside the cabin, is a huge safety problem. Instead, use an electrical pressure sensor and an electrical pressure gage. Iinstead of tapping into the pressure test port at the fuel rail pressure test connectioin, tee into the fuel line after the fuel filter, down steam from the filter in the fuel line feeding the fuel rail.

[Greg@DTH]

There is zero need for a fuel pressure gauge. Big fire hazard. You can test the fuel pressure with diagnostic equipment if you suspect something, but honestly, what will you do if the pressure is low?

[hessank]

I am thinking of installing a liquid filled gauge in the engine compartment. I have one installed on my PORSCHE 928 for over 5 years now and it works great. Told me when my check valve was passing and last year it indicated when my fuel pump died.

I am not plumbing the hose to inside the car, just a local gauge. I was wondering if it required a special gauge to depress the schrader fitting?

HK

Thanks

[Greg@DTH]

Wrong place to put the gauge if you want one. Put a T fitting before the fuel rail. The rear port is not designed to have a gauge attached. Like I said, risk outweighs the benefits.

[alexza4]

the gauge ECS sells is designed to go inline on the supply line before the rail. does that gauge also considered unsafe?

[dougyfresh]

Do you want your car to burn to the ground? You don't want to go there. A very select few of us have. Okay. maybe one that I personally know of. but still..

fuel pressure monitoring is only needed during tuning if you suspect your fuel rail is not getting the pressure it needs. Not needed during normal operation. ESP with how the fuel line comes into the engine bay on the passenger side and up over the HOT exhaust.

[alexza4]

i personally have no interest (nor need) in installing the gauge... just asking, since there's a thread about it...

[hessank]

There is no danger in installing a gauge designed for that purpose. It's no different from any other connections in the fuel system. At anytime an OEM connection or hose might leak or break and cause grief. So if properly installed, there should be no additional danger. Lots of racers have local gauges and there are benefit to knowing what your fuel pressure is. If the fuel pressure is low, then maybe your filter is plugged or your pump is about to crap out. If the pressure dies overnight while the car is parked, then the check valve is gone and that's why you have to crank the car longer before it starts. . It allows self diagnosis to rule out the fuel factor in no start situations that's plentiful on the forum. It's also great for those of you who have bumped up your fuel pressure to match other mods (to add more air to the engine) etc. etc. etc.

Of course this is just my opinion. I like to tinker with my car and not take it to the mechanics for every fault. Been ripped off once too many times. That's why I recently bought my own smoke machine (<$100) after I witnessed the benefits to ensure my evap system stays tight (in another post). So far this has worked for me and my car is running great.

Thanks Greg & Alex. I will be using the ECS gauge and will also look at the t-fitting you wrote about.

HK

[alexza4]

no problem... hey where did you buy a smoker for under $100?

[quickaudi07]

I had a fuel gauge installed in my VR6 GOLF and didn't do crap. Pointless. No need for fuel gauge. Maybe oil pressure, or vac, or other crap. But fuel. lol seriously ???

[hessank]

"Quickaudio" please don't take this the wrong way, but any instrumentation is useless unless you know what to do with the what its telling you. If you read my previous threads you will see that a fuel pressure guage tells ME a lot, albeit not information for everyone. Same reason I do not have a Boost Gauge while others have it.Different strokes for different folks, I guess.

Alex: Google "Chauvet 1100". It's on sale for $99 but I purchased it used from a surplus DJ store going out of business for less. You modify the cap where the smoke comes out to accept a hose and then use reducers/duct tape to get to a hose that would blow smoke into any fitting on the manifold. Any fitting not leak tight will have smoke coming out. Use a good radar lamp to see the smoke. The fluid/smoke is harmless because you breathe the same at parties and discos.

[alexza4]

Alex: Google "Chauvet 1100". It's on sale for $99 but I purchased it used from a surplus DJ store going out of business for less. You modify the cap where the smoke comes out to accept a hose and then use reducers/duct tape to get to a hose that would blow smoke into any fitting on the manifold. Any fitting not leak tight will have smoke coming out. Use a good radar lamp to see the smoke. The fluid/smoke is harmless because you breathe the same at parties and discos.

Thanks man!

[B6 Dude]

A fuel-pressure gauge can be a good diagnostic tool and tuning tool, but there are other gauges that would get priority in my car. If I suspected a fuel issue, I'd just mount a fuel-pressure gauge then, or some basic diagnostic info can be had by pushing in the schrader valve (using a screwdriver wrapped with paper towels) to see if there's fuel flow. If you're tuning and suspect fuel flow dropping off at high rpm/load, then a fuel-pressure gauge can be very helpful.

For the type of gauge -- don't use a mechanical mounted in the cabin -- that's VERY unsafe and don't bother with a mechanical mounted on the hood unless you own a camaro :) . Use a small mechanical mounted directly on the rail (under the hood), or use an electronic gauge if you want it in the cabin. Do not use an oil pressure gauge for fuel-pressure use, even if <insert major racing parts company> tells you it's okay to do so. The diaphram-type oil pressure sensors are not designed for fuel.

To answer your original question though, a standard schrader valve is 1/16" NPT (not sure if that's what the Audi uses), but you just need to unscrew the stem, mount the adapter, and mount the fuel-pressure sensor, using teflon tape. Use teflon tape only on the back threads, because you don't want any of it to break off and get into the fuel stream. Try to support the sensor mechanically if it looks like it's weighing down the fuel rail, etc, or use a braided line to mount it a bit further off, and mount the sensor on the firewall etc.

Cheers,
-Neil.

[rbj325]

Not to steal this post but... I've been having a cold start issue and it might be fuel pressure related. What is my best option for getting fuel pressure for diagnoses purposes. Can I get a gauge that I can attach to the end of the fuel rail?

[F16HTON]

You have a cold start issue because you are using Genesis 380cc injectors with APR stage 1+.

Youy can fix it with Lemmiwinks.

[rbj325]

You have a cold start issue because you are using Genesis 380cc injectors with APR stage 1+.

Youy can fix it with Lemmiwinks.

How so?

[Greg@DTH]

How so?

By adjusting the startup enrichment.

The APR programming is not happy with Genesis injectors, that is why the recommend using the TT225...they did not pick the TT225 because they hate people and want them to spend more $$ on injectors, they did it because the Bosch products are of a higher quality, have the correct spray pattern and are very consistent.

[FORCE_FED_DUB]

genesis injectors are made from bosch components, have the correct spray pattern, and flow close enough to the same amount of fuel. APR likely chose TT225 injectors because they are OEM. Bosch 380cc injectors on the other hand have the wrong spray pattern for a multi valve head.