I am installing an HSR on my 383. Its got 30 lb injectors and the stock regulator. With the pump on, motor not running, it holds perfect at 43. When turned off, it instantly drops to 35, holds there for like 5 minutes, then slowly drops to zero in about 90 minutes. Let it sit overnight and turn the pump on again, its primed in about a second or less. I have the plenum off and don't really smell any gas in the runners. My normal efi knowledge tells me that the regulator is bad and the injectors are not bleeding down because I should smell gas very easily. I am just not sure if this is normal for these holley regulators.

 

It happens to a lot of regulators. If it primes right up and starts fast you really shouldn't worry about it. Mine has been that way for 20 plus years.

 

The Aeromotive unit on my HSR holds no pressure at all after the pump turned off

 

That's what I was thinking. I just wanted to make sure though. Certainly can't hurt to ask. Thanks for the help.

 

yeah mine is the same way

 

Did you need to plumb the fuel lines to the rear of the motor? I was looking at mine and the inlet is in the rear

 

yes, this is one of those instances where in the rear is okay...lol

 

After running the car for about ten minutes, the pressure falls off to around 15 psi. I replaced the stock holley regulator thinking it failed like so many of them out there with a kirban. Installed and it worked great for about ten minutes again, then the same problem, down to 15 running. If I turn the screw out to lower pressure, it drops like a rock to 0, but when trying to increase the pressure, it will only get to about 25 before it closes the port and pops the fuse. The pump seems to strain now when building pressure, unlike before. Is it possible that the fuel lines are not up to par. I have a 3/8 feed and 5/16 return which I thought would be adequate. I am a bit of a loss on this one.

 

If its not the regulator, its your fuel pump

 

I tried to prime it this morning just for kicks and now I full pressure again and the pump sounded normal. Is the dang thing overheating somehow or by some strange coincidence its sucking in the sock on the bottom and partially blocking it? The pump is a walbro 255, I just have not heard of those going bad.

 

My thought was it may be the pump if its dropping pressure, because there is a check valve ball or something that keeps flow from reversing. Sometimes these wear out or fail and the pump wont hold pressure.

 

Well, I guess I am replacing the pump then. If its not one, its certainly another. At least I know now when it runs, it does run pretty good.

 

I think there are some tests you can do to check to see if its injectors, regulator or pump. Involves pinching off the supply and return lines to see what happens to the pressure. Try searching for diagnosing regulator/fuel pressure issues.

 

I will look into that. But it strange that now this morning all is good, at least for a few seconds I tried it. The 5/16 return line should be fine, isnt it. I have read up that a 3/8 would be ideal, but there are so many hsr swaps out there that use the stock lines and those I believe have been fine.

 

Stock lines can support almost 1000hp if you have enough pump behind them. Theres nothing wrong with the lines.

 

Thats what I thought but its good to hear it from someone else. Thanks again Orr for the help.

 

Orr is right, my pump check valve never worked (walbro) and I verified this by using vise grips on the rubber lines from the tank. It has been like this for years and no ill effects. As long as the pump is on, the fuel will not go back into the tank and there is no pressure loss at the rail.

The only real problem is if your diaphram doesn't hold your set pressure at the rail with the pump/engine running. I think the stock setup must be different in this design aspect than many aftermarket units.

 

When I got home, I tried a couple of testing methods and I think I have determined the pump is not up to par. Now it wont hardly build pressure like it did this morning. I pinched both the return and feed lines separately and could only get 25 psi max and the pump sounded like it was straining terribly. After two minutes or so, it would not build at all.

 

Well, after the new pump installed, still the same problem. I removed the regulator, but I really did not see anything obvious in the way of tears. I guess now I am going to call kirban to see what they have to say unless anyone has any other ideas because I am stumped.

 

My Aeromotive bleeds back down over a couple minutes. I believe it is due to the check valve in pump.....

 

Well, I found the issue. A friend of mine came over last night to help with the flow test and he also had a good regulator off his gn he was not using. Did the flow test and it was spot on per the chart. After that switched out the regulator with his. Primed the system and the gauge showed zero. He was in more disbelief than I was because he knew that regulator was good. I decided then to just try starting it and see what happens. Started right up like it should and idled fine. Gauge still shows zero while running. Something obviously got in the system and managed to take out the brand new gauge and regulator in one fell swoop. Kirban is sending a new diaphragm for free to at least fix that. Now I am more nervous as to what came loose. I had to replace one small section of rubber hose because it was not efi rated and add in about a half a foot where the old blue pump was and new filter is. I guess its possible that's where it came from even though I was very careful when making those changes. For now, I am going to leave that regulator on and run it for a while and see what happens.

**EDIT** As I am shopping for a new gauge because I won't use the summit one that I had, I realized that it was the gauge that went bad. I can't believe that I never noticed that the liquid filled gauge no longer had any liquid in it.