Fuel Rail Pressure Gauge for Testing

White Lincoln

1st Gear Poster
Oct 2, 2023
Vehicle Details
1994 Mercury Cougar XR7 all stock
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As promised, here is my question about Fuel Rail Pressure test gauges. I bought a kit the other day, turns out it did not have the Ford fitting for 1/4" Schrader valve. The company that sold it said they would send out the Ford fitting, but due to it being a Chinese's holiday, they would not be able to send it any time soon. I sent it back. I figured that if I waited for the part and my Amazon return limit ran out, I am stuck with a tool that may or may not work, and I am betting on not after reading a lot of the reviews. This led me to look at several kits on Amazon and it turns out, most of the gauges got reviews of the Ford fitting falling apart or, most just do not come with it.

I suspect to buy a good kit is going to cost me as much as taking the car to a mechanic and have them run the tests. I have several gauges, even an older fuel pressure gauge for non-Schrader test valves and was wondering if anyone has removed the fuel filter and hooked up the gauge there instead of using the Schrader valve or cutting the fuel line.

Any comments on fuel rail gauge kits that have worked for you? And any other ways to test the fuel pressure? This is one last part of testing this engine that I have yet to do because I do not have the Schrader valve fuel rail tester.

Thanks in advance for any feedback. This site is GREAT!
In my experience, on a vehicle with a factory return style EFI fuel system, fuel pressure is very rarely an issue. The pressure regulator is pretty simple, and short of the diaphragm rupturing, which will dump massive amounts of fuel into the intake manifold, it doesn’t go bad.

Having said that, if you suspect low fuel pressure is causing an issue, and you don’t have a pressure gauge, a quick and easy way to test it is to pinch off the fuel return line and take the car for a quick ride to see if the problem changes.
Thank you MadMikeyL, I will give that a try. I don't know if you recall, but last year I submitted a thread on replacing my fuel rail and I did replace the regulator with a new one, so I am good there.
Are you trying to install a permanent gauge or just a temporary test gauge (handheld)? If the latter some of the rental fuel pressure test kits you can rent from the parts stores usually come with an abundant number of adapters and fittings.
O'Reillys has a loan a tool fuel pressure gauge that includes a Ford Schrader fitting. Last time I borrowed it I had no luck getting a reading on either my Ex or Cougar. This was a brand new kit and about a month ago. I have used a kit from O'Reillys years ago that did work, though.
Before I bought the one I have, I used to go buy a cheap tire pressure Gage, use it on the manifold schrader valve, and dispose of it. The gas will kill the seals, so it won't work after that. Don't use it on tires after; you'd hate to fill your tires with gas vapor, lol.
Follow up:
My fuel rail pressure gauge came in today. I tried some chinese made one, (well, they are almost all made in china now), that did not come with a Ford fitting for our Schrader valves. By the time the would have gotten the fitting to me, my warranty would be out and I would not be able to return it if the gauge was crap. Since my last Actron compression tester I bought some 40 years ago worked so well, I bought a Actron CP7818 fuel pressure gauge that comes with the Ford Schrader valve fitting.

I went out to the garage and without reading all the right things to do when you hook it up - I'll be pickled If I don't have 32 PSI when running. And as soon as I turn on the key, the pump brings the gauge up to 20. Once the engine is turned over, it went straight to 32 and never waivered, high or low idle.

I don't need no stinkin' fuel pump!

Now, if I can figure out why I am getting codes 137 and 173 (O2 running rich), I'll be dipped. Everything has been replaced, seriously. The engine idles really good and runs great when cold to lukewarm. When its running at normal temp is when I have issues. I need to take it to a tranny shop and see if they can run some tests on the torque converter to see if that is an issue. I added a tranny cooler when I got the car, so I doubt the tranny is getting to hot. Maybe the tranny oil is too high.... hmmmm... check that tomorrow (yeah, right..)

Thanks for everyone's input into this matter. Hope I can return the favor in other posts.
From Kidd-7: "O'Reillys has a loan a tool fuel pressure gauge that includes a Ford Schrader fitting. Last time I borrowed it I had no luck getting a reading on either my Ex or Cougar. This was a brand new kit and about a month ago. I have used a kit from O'Reillys years ago that did work, though."

It was across town and they won't send it to their store up the street from me. i would spend 10 bucks or so just driving over there! Autozone was the same way... "Loaner is across town, go pick it up" <shacking head with disgust>
Yeah and that to bring it home and not work…. Well, good to hear you got one that does work, I’m adding that to my wish list.
Some notes on the Actron CP7818 fuel pressure gauge
The trick that I learned from reading the reviews, (which is really common sense):
1. Tighten the Ford fitting to the Schrader valve first using a deep socket and a wrench. Just snug. A lot of complaints where about the fitting leaking, but there is an O-Ring inside the fitting on the Schrader valve side that needs to seat tightly.
2. Tighten the gauge fitting to the Ford fighting with your fingers and get it as tight as possible with your fingers (which is basically snug).

A note from the manual I missed. Put some regular oil inside the Ford fitting to oil the O-Ring.

I used an empty Schmucker's Peanut butter jar, drilled a hole in the lid, just the size of the clear line and set it under the front tire so I would not kick it. The line they give is about 5 feet or so.

Actron also recommends emptying the release line of all gas and removing it from the release valve and empty the valve out too. Basically, try to get all of the gas out of the line the best you can.

I need to check the Town Car next.


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