What maintains the fuel line pressure when the care is off?

[siteunseen]

It seems like I sent one with Steve when I sent him the fuel pressure gauge you have?  It was working when I removed it.  I put a new fuel rail on mine and had to use a FPR from a '78, only one inlet.

[EuroDat]

I can't edit that post but this thread talks about the check valve in the original fuel pump. It works like a valve stem for a tire but backwards, it lets fuel leave but not flow back in.

That photo has a small error. It would be better to call the " check valve " the pressure relief valve. Its meant to relieve pump pressure back to the pump inlet. It generally relieves at about 55 to 65 psi. When you clamp the FPR return line shut, the pressure you see is this relief valve pressure and not the maximum pressure the pump can produce.

The check valve is in the replacable discharge nozzle.

Edited November 25, 2015 by EuroDat

[Consigli]

You can try zcarsource

 

http://www.zcarsource.com/fuel-damper-280z-280zx-75-83-new_8_77824_52489.html

zcarsource & motorsport don't have the Fuel Damper part number 22675-N4205. Motorsport says they are unobtainium even from Japan. Anyone have a viable aftermarket substitute part number? The link given at the beginning of this thread doesn't look anything like the original part. Thanks. 

[Zed Head]

The link given at the beginning of this thread doesn't look anything like the original part. Thanks. 

This thread is about maintaining fuel pressure, not fuel dampers.  You've inserted yourself in to someone else's thread.  And you're not even on-topic. Starting a new thread of your own might get better advice.

 

Try Oscar.  http://www.datsunstore.com/fuel-pressure-dampener-7583-p-95.html

 

Any damper from an older fuel-injected car would probably work.  Browse the local wrecking yards.

[Redwing]

It seems like I sent one with Steve when I sent him the fuel pressure gauge you have?  It was working when I removed it.  I put a new fuel rail on mine and had to use a FPR from a '78, only one inlet.

Are you talking to me?

If so, I do not remember if sent, or remember if it was installed. I do have the gauge installed.

I guess Steve will need to answer this.

Thanks,

Jai

[Patcon]

I have a 1978 280Z with a leaking Fuel Damper. Does anyone have a NOS one for sale? Its part number 22675-N4200 or 22675-N4205. Thanks! 

I will look to see what I have...

[EuroDat]

Jai,

The pressure leak down mentioned in this thread is mostly a problem with hot engines. I don't think you have this problem. I have not seen you mention cranking for long periods when hot.

I fitted a gauge and noticed this problem. The pressure would fall to zero in a minute. The hot engine would then cause vapour lock pushing more fuel through the check valve back to the tank.

I know EFI doesn't normally suffer from vapour lock, the pressure is normally high enough to prevent it, but my gauge would read 0 psi and then its possible with a hot engine. Sometimes it would take upto 10 seconds to get it started again.

When it was cold it would start reasonably quickly, but run really rough for a couple of seconds then run ok. I think that was because the cold start valve had less resistance (bigger hole) and would add fuel atlower pressures. That way it would start ok, but then rough until pressure built up.

A lot of searching and I found the check valve on the internet and that solved the problem. Still have a couple spares if someone needs one. It now starts in 1-2 seconds even after sitting 2 months.

Edited November 25, 2015 by EuroDat

[Redwing]

Jai,

The pressure leak down mentioned in this thread is mostly a problem with hot engines. I don't think you have this problem. I have not seen you mention cranking for long periods when hot.

Thank you for this information Chas.

Jai

[siteunseen]

Are you talking to me?

If so, I do not remember if sent, or remember if it was installed. I do have the gauge installed.

I guess Steve will need to answer this.

Thanks,

Jai

Honestly, they hardly ever go bad and are difficult to replace.  Steve probably realized your's was working properly when he put the pressure gauge in-line and saw the readings.  It's the aftermarket adjustable FPRs that leak down so fast.  Most of the time the injectors are dripping out the pressure.

[SteveJ]

Honestly, they hardly ever go bad and are difficult to replace.  Steve probably realized your's was working properly when he put the pressure gauge in-line and saw the readings.  It's the aftermarket adjustable FPRs that leak down so fast.  Most of the time the injectors are dripping out the pressure.

Precisely. The fuel pressure wasn't leaking down, so I didn't see a need to replace the FPR.