Temp readings FYI

[siteunseen]

Goofing off today I took some measurements on my 280 with the aluminum fuel rail. It goes up and down 20 degrees every few seconds. I guess that's when the excess dumps after the fpr opens up?

Anyway the car was 80 degrees cold in my garage before starting. The higher numbers are of course after a quick romp.

Fuel rail room temp...

Hot closer to the return hose...

Front of head...

Rear...

#3 header runner...

Head at room temp...

Oh yeah (don't tell my Mom) but here's my next purchase. @JLPurcell didn't you buy something similar to this? Thanks for any advice. Cliff

 

Edited September 15, 2019 by siteunseen

[cgsheen1]

No wonder Nissan started using a fuel temperature sensor on the VG30E...

[siteunseen]

Fuel pressure raises when above 131F from what I've read so far.

Seems like the FPR would open up and recirculate the fuel if it was hot enough.

Vapor lock, "vayre intressting". 

 

 

[jonathanrussell]

Your 280z is a 76 isn't it? Your intake manifold is the 75/76 variety that doesn't have the webbing between ports. My 75 has a heat shield though that attaches to the underside of the intake manifold. I can't see a heat shield in your photos. If there isn't one, you might reinstall, or locate one and install.

If that doesn't cool your rail, you could also wrap your headers or shield them with something like what I used for my 240z manifold.

heat shield material

 

 

Edited September 16, 2019 by jonathanrussell

[SteveJ]

This post has me thinking. (And that's a dangerous thing.) I noticed that in my fuel injection conversion, the car runs fine at first, and it acts up after it gets warm. I currently have the system dead-headed.

I'll try insulating it first, and then if it still acts up, I'll add a return to the fuel rail.

Thanks for the inspiration, @siteunseen.

[JLPurcell]

On 9/15/2019 at 6:54 PM, siteunseen said:

Goofing off today I took some measurements on my 280 with the aluminum fuel rail. It goes up and down 20 degrees every few seconds. I guess that's when the excess dumps after the fpr opens up?

Anyway the car was 80 degrees cold in my garage before starting. The higher numbers are of course after a quick romp.

Fuel rail room temp...

Hot closer to the return hose...

Front of head...

Rear...

#3 header runner...

Head at room temp...

Oh yeah (don't tell my Mom) but here's my next purchase. @JLPurcell didn't you buy something similar to this? Thanks for any advice. Cliff

 

 

Yes, Just on the other side of the TAXA Tiger Moth trailer in my garage. 

[Zed Head]

On 9/15/2019 at 3:54 PM, siteunseen said:

Goofing off today I took some measurements on my 280 with the aluminum fuel rail. It goes up and down 20 degrees every few seconds. I guess that's when the excess dumps after the fpr opens up?

Are you sure that your heat gun isn't catching some of the head and it's cooling passages?  The FPR would have a steady flow through it, it doesn't pulse like the thermostat does.  The thermostat has a chunk of wax in it that melts and solidifies over and over.  That's why it pulses.  The FPR has a spring and a diaphragm that just move based on vacuum and fuel pump pressure.

If you put a piece of cardboard behind the rail and measure again it might stop pulsing.  If it does pulse it seems more like a fuel pump thing, with the flow rate changing.  Maybe a voltage pulsing causing the fuel pump to pulse.  Who knows it might actually go all the way back to your alternator/regulator.  Maybe it's dying or engine RPM has it on edge.

Edited September 17, 2019 by Zed Head

[Captain Obvious]

All that, and those guns are questionable about aim and area of the target. And there's also emissivity concerns. Good for ballpark, but I wouldn't lend too much credibility to the numbers.

[siteunseen]

True. Distance has a lot to do with this particular model to.

Trying to keep it on the same spot and get a photo is tough. I use it at the restaurant to argue my point. Temperatures will get us in trouble with the health lady.