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Fuel Rail Schrader Valve


Active Member
Sep 6, 2023
My XLR/V(s)
2005 Crimson Pearl
So this morning I was diddling under the hood while waiting for my laptop to boot so I could connect my old OBD II tools to the car. Anyway ... I removed the cap over the schrader valve on the fuel rail and some fuel shot out. The car wasn't running. I've never seen this before. I had hooked up my mechanical fuel pressure gauge to the rail last weekend to test the fuel pump. Everything checked out A-OK at that time.

Then I started the car. Lo & behold fuel started shooting out of the shrader valve. The cap was still off. I wanted to see if the valve was leaking. It was WAY more than leaking. I shut the engine down before it caught on fire and tightened the schrader valve. It was a little loose. Not much, but a little. I started the car again and fuel continued to shoot out of the schrader valve.

At that point I removed the core and replaced it with a new core for a car/bike tire. I started the car again and no more fuel shooting out of the valve. But ... I'm not sure if the core for a car/bike tire is the correct core. It seemed to fit and for now has solved the leak problem but the seal around the core of the replacement is rubber. I think the one that leaked is Teflon. Has anyone had to replace this core? Do I need to shop for a gasoline tolerant schrader valve core to replace it?

I would not use a tire valve . as you said the fuel pressure valve is different. It most likely got bent when you installed the pressure gauge or got speck of trash under the seal.
As far as the pressure is concerned, its not uncommon for fuel lines to to remain pressurized in modern cars with no returns. The service manual specifically says to de-pressurize when working on the fuel system as this behavior is expected.
Here's a 'fuel rail specific' Schrader valve, and there's others to be had out there as well:

Keep in mind, just like tires, a Schrader valve is there only as a convenient method to access the system. Most important (goes for tires big-time), it's to have a good cap installed. It's the cap that really does the work and in theory, it's all one really needs. (would make for very inconvenient tire pressure checks without the valve of course). ;)


I finally got the car running reliably and had time to dig into this valve. There is a GM substitute part: 88894338. This is the Schrader Valve Core only (No cap). I picked one up at Autozone for under $10. It fits, it seals, its teflon, and it works with the Fuel Pressure Gauge (Tester).

I had a tire valve core in place in the Fuel Rail for almost 9 months without any problems. I used a "Slime" brand core but it fits, seals, and works with the Fuel Pressure Gauge. The seal is rubber instead of teflon. No idea how long it would hold up over time but in a pinch it will work until you can get the GM part above. Or when the GM part above is no longer available.

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