Regulator is mounted on the firewall.

Is your regulator before or after the fuel rails? You'll get some heating of the fuel by going into the engine compartment, but probably not as much as going through the rails. We were fine for about 100 miles of steady driving. By 125-150 miles it had heated the fuel in the tank enough that the fuel pressure was dropping, pump was getting real loud due to aeration of the fuel from the heat. On Power Tour there were several other cars stuck on the side of the road or fighting the same symptoms. Most were not brand new builds, and had not ever had the issue before; but they had also never been driving 200-300 miles per day like you do on the Tour, so the short trips around town will probably never shows the issue.

Jody

Regulator is after the fuel rails -- so the fuel is fed to the front of the passenger rail - out the back - looped to the front driver rail - out the back to the regulator mounted on the firewall - where it returns to the tank.

I ASSumed the fuel was moving continuously through the system... only "stopping" / or "slowing" as required to build pressure (the regulator - doing it's job ala a thermostat on the coolant side of things).

If the pump is whirring away without any fuel movement -- then wouldn't we have another issue --- CAVITATION?

Here's pix of the rails etc as I plumbed them.... no comments from BENT about my work please!!!




http://i919.photobucket.com/albums/a...rtStack002.jpg







I pulled the other pic off there - it's too blury to post... and didn't add much anyway.

although the stainless hard lines and braided lines look good they do act like a heat sink. The fuel is moving through the system, but getting heated quite a bit in the hard lines and rails.

Usually if you enter in the front then you'd use a short line from rear of one rail to the other and exit in the front also (opposite rail you entered). So if you wanted the regulator hidden in the rear then enter in the rear also. Your way works, just adds even more stainless hard line to heat the fuel though. Bottom line, if you're not having problems with the fuel pressure dropping on long runs you should be fine. Large pumps aggravate the situation, but you do have some of the ingredients of the problem scenario with all the hard lines and front mounted regulator.

Not sure what you meant by the cavitation issue....... were you speaking of a rear mounted regulator? In that case the regulator still bypasses to the tank, just at the rear of the car, not the front. Still fuel moving through the pump like your setup, but without the hot fuel back to the tank. If you want to see if you might have an issue you need to take a 100-150 mile drive down the freeway, watch the fuel pressure, or pull over and feel the tank. If the fuel is heating the tank you'll know it, the tank will be hot to the touch. There are tons of cars with front mounted regulators that have no problems, it just takes the right combo of parts and conditions to cause the issues we had. Big pumps running full speed, hard lines and rails heating the fuel, long runs, etc. I've been mounting the regulators in the rear for years without any issues. Many people have said you can't do that, I don't argue with them. I know the later Vettes, GTO's, etc. all had the regulator in the filter on the frame rail, with the bypass off of that, only one line to the front and work fine. They do bump the fuel pressure, probably to help guard against any fuel boiling from the fuel in the rails; I've run from 43 to 58 psi at idle, never seemed to make any difference, no problem either way.

Jody

Cavitation is what happens to liquids when they're being pumped but not moving... so it "stirs" bubbles in the liquid...

Think of it as your tires spinning -- it looks great but you're going nowhere...LOL

I was thinking that if the fuel was not moving continuously - that you'd have TWO issues -- no movement leads to pump heating up - and if you toss in cavitation - caused by a pump that is "spinning it's wheels" - then you're also going to loose pressure - since we know bubbles don't move like liquid (ala air in a brake line)

Jody --

I HAD to run the lines the way I did -- because the intake is so tight to the distributor...

I originally wanted to feed the rear pass side -- loop the front - and out the driver rear... just couldn't get 'er done that way and be able to hook it up etc.

The way I had to go was to install the motor - and then just be able to hook up the front feed... as the looping could be built and set up "on the bench".

As it is - to stab the distributor - the rear passenger side TB's have to come off... It's REAL tight back there! Real tight.

In what situation is the fuel not moving continuously through the pump?

Jody --

Maybe I'm just not trackin'

I guess what I'm trying to find out is -- why would the fuel be heating up - if it's always moving throught the system (as it should be) then it should be cooling off - even assuming it's being heated a bit while in the rails - It's got a return trip via SS lines (heat should be dissipating) - back to a fuel tank that should also be dissipating the heat - given the volume in the tank vs the volume in the return line...

So I guess where I'm lost is -- the fuel pump overheating... Or maybe I need to go re-read what Mark was saying? I may have misunderstood the whole thread!! LOL -- It wouldn't be the first time!! :cool:

let me say this, and see if it makes sense. I don't think you realize how much those rails, stainless lines, and engine compartment can heat the fuel before it's returned. On that Chevelle where Scott and I made the ice bucket solution for the return fuel, just to finish the Power Tour, the returning fuel was so hot that you could not touch the copper line in the trunk at the inlet to the ice chest. It actually was melting the ice chest................... The other thing was the too large A1000 pump running full blast without a controller to slow it down; that heats the fuel some also.

Jody