Can Ruptured Fuel Reg Cause Lean Afr?

[denisonnd]

Hi everyone.

If you take vacuum hose of fuel reg and smell petrol that's a fault fuel reg right?

My question is will it only cause car running rich or will it also make car lean out under boost?

Another thing, my fuel reg vac hose came off by itself. What can cause it

[GTSBoy]

It's not just a vac hose. Sees boost too. Therefore when they are found to be off they either came off mechanically, or were blown off by pressure.

As to the nature of the fault. The smell might indicate that it's broken, but then again, it might not. The test for a fuel pressure reg is to put a pressure gauge on the rail and see what happens at idle and under load.

[89CAL]

I would think if the diaphram was wrecked then you would get fuel out the nipple with the vac line off and car running

Not 100% on this, there may be a safety in place but just my assumption of what would happen

[scotty nm35]

I would think if the diaphram was wrecked then you would get fuel out the nipple with the vac line off and car running

Not 100% on this, there may be a safety in place but just my assumption of what would happen

This is exactly what happens.

Should run rich though, not lean out I would have thought, but who knows.

[denisonnd]

Thanks for answers.

It was not just the smell but liquid as well. So I assume diaphragm is leeting fuel through. Do you guys think I should a new reg? I'm worried it might lean out under boost

[scotty nm35]

Yes, it definitely needs replacement or possibly repair. What brand is it?

[denisonnd]

Tomei

[scotty nm35]

Are you sure it's Tomei? There are some Very good knockoffs getting about...

[Gts-t]

A fpr will raise fuel pressure as intake manifold pressure (boost) increases. So it will be lean when boosting.

Likewise as manifold vacuum increases a fpr will lower fuel pressure. So it will be rich under vacuum

[denisonnd]

Thanks Gts30t. I was excpeting this is the case