SchnellerUmsetzer

I took off the end cap on my fuel rail to install and installed a VDO fuel pressure gauge, and found that there was a ball bearing in there too.

What does the ball bearing in the fuel rail do?

Is it necessary to re-install the ball bearing?

Granite 944

"Is it necessary to re-install the ball bearing?"

Only if you don't want that stock plug fitting to leak like all getout. It is what seals that plug. 16 ft lbs of torque! (IIRC). Don't exceed that unless ya absolutely have to.

If your gonna run the VDO gauge on the car, than no. I don't think most would recommend running it on the car for any length of time, but, to each their own.

Oh, yeah. Put that ball and plug in a real good spot, so ya can find it again. Ya might need it again soon.

kevincnc

Sounds like a check valve, or at least it came from one. I can't figure out my muffler bearings either.

kevincnc

OK, not a check valve, but those muffler bearings...

Eyal 951

hahaha, mine went flying never to be seen again when i pulled the end nut to replace with a gauge. You do NOT need it for the gauge, but you do for the end cap.
Eyal

Zero10

It seals the cap. The cap just holds the ball on. If you don't use it, you are relying on the seal against the face of the rail, and on the threads to keep fuel at 35+psi in the rail. I wouldn't trust it at any times that I cannot see it.

SchnellerUmsetzer

Thanks

I did intall the VDO gauge with out the ball bearing. I figured that the ball bearing had something to do with sealing the end cap. I ran the car for awhile with the VDO gauge and found no leaking. I like the VDO gauge!

Thanks for the advise. I saved the ball and the end cap!

SamGrant951

I use the VDO guage only for tuning/setting fuel press - then out it comes and the factory ball bearing and cap go back in..I see no use to leave it in when the hood is closed and you cant read it anyways.

SchnellerUmsetzer

That makes sense.

I leave the VDO gauge installed just because I do not like to mess around with the fuel rail much any way no leaks means no fire. Thereby, when I installed the gauge I did not take it out!

However,
What you said makes perfectly good sense

Zero10

I have a fuel rail end cap that I drilled and tapped to accept an autometer fuel pressure gauge. I only use it for troubleshooting. Once I have established fuel pressure values, the factory end cap goes back on.
Just one less potential fire

Jfrahm

I do not recommend keeping a gauge under the hood full time. It's pretty useless except for setting base fuel pressure once or twice and it can become damaged or leak. As much as I like fire, I hate car fires.

You are better off with a test kit you can attach to the rail for testing, especially if the hose is long enough so it can be routed out to the cowl temporarily so you can see the gauge under load.

-Joel.

35thSLP

I have had my VDO on my fuel rail for about 7 months and 4K miles. No problems yet.

shredcrimson

SO i randomly found a bearing hidden under my intake. i believe it is this bearing.
I want to put it back in place? where would that be? it may have been from the PO or myself when i removed the fuel rail to clean the injectors. any help with pictures would great. thanks.

thomasmryan

remove the fuel rail test port cap and check.

wildcat077

Not a good idea to mess too much with 30 something year old fuel rails, i've seen too many 944's burn down because of faulty fuel rails that either
crack or people don't tighten the end cap enough.Unless you're tuning a race engine with an adjustable fuel pressure regulator i wouldn't
touch the fuel rail.

Just sayin ...

Cheers
Phil