The V8 Owners Forum -

3.9 efi

try to do a pressure test on the fuel rail but can't find anywhere to plug the gauge into, no schrader valve here.

any clues welcomed please

You'll likely need to make up a fitting either at the fuel inlet to the rails, or adapt something closer to the pump itself, or maybe at any filter ?

I’m thinking of tee piece at the return pipe union. Far left in the pic above the regulator. Is the thread 1/8npt?

Cheers

I am not sure, but I don't think you want it in the return pipe. That is effectively zero pressure as it is just running back to the tank.

You need to be on the feed pipe side.

Chris.

return line is pointless, low pressure.

If you need to see pressure at the injectors, ideally it will need to be taken close to them, although in theory anywhere between the pump and FPR should be same pressure, give or take and assuming no problems in that system

In reality, at the rails you do not have a lot of options other than a suitable adapter.

I note there is a rail temp sensor, but pretty sure that is not drilled into the actual fuel path ? If it is, that might be another option for an adapter.

sorry chaps its my ignorance that's part of the problem. The feed pipe I now know is the upper pipe in my pic and the return pipe if after the regulator. If you don't know that then you don't know. I didn't until earlier today.

Ignorance is the best position to learn from

Are you absolutely sure there is no Schrader valve on the rail and it's not hiding under something or "disguised" somhow?

Unfortunately your inlet has a screw on fitting for the rail so you really need a T piece with simlar male and female connections to break it into that line which may not be so easy to find. Also your regulator is the standard item fitted directly to the rail so no easy way to tap in there, I have a remote regulator which allows me to break in at that point.

I note that the fuel temperature sensor has a sealing ring on it which indicates a good chance that it does break into the fuel system, if I get a chance I will check the one on my spare rail and let you know, will be weekend before I get a chance though (and that's if I can find it!)

Morning, I’ve checked the rail several times top and bottom, no valve. Looking at borrowing a tee piece via a friend of a frien who has an old school garage. I’ve changed the fuel temp sensor (stupidly expensive for what it is) and I’m fairly sure the hole is blind.

Thanks for your help.