LiteraCola

Good morning everybody. I just recently finished my A&A Vortech V1 install with their behemoth twin pump fuel system. The car runs and drives fine, but when I go to start it, I'm having some cranking issues. I first turn the key to ON and let the pump prime, while watching the FP gauge. It primes up to 58psi, and as soon as the pump shuts off, the pressure drops back to almost 0psi. Then when I try to start the car I have to crank it a couple times, and then try again and it starts. I was under the impression that there was a built-in check valve in the system. Where is this located and does anyone have any idea what might be happening? Like I said, the car runs and drives fine (albeit as fine as it can on a mail-order tune), and the cranking isn't a huge issue honestly; I just want to make sure the car is 100% right before I put her on the dyno. I haven't been into boost at all yet so I don't want this to potentially mess with the twin pumps coming on. Thanks for any advice anyone can give. I'll be sure to call A&A a little later in the day (different timezone and all) to pick their brains. Thanks

Jesse

all4spl

If you have a return line, there is no way to properly stop your return line from doing its job. Only thing I can think of is to not stop the pumps from priming?

95vettski

There should be a check valve either built in to the external pumps or somewhere on that external line. Give Josh or Andy a call and they will sort it out for you.

all4spl

That check valve is only so the fuel does not go the wrong way on the fuel line. It won't stop it from returning to the tank.

LiteraCola

That's what I was thinking too. Since there are two feeds, priming the system won't do anything but allow the fuel to flow back to the tank. Weird.

CamminC5

Why are the holley's coming on with IGN? Do you not want them on a HOBBS?

There's a check valve in the holley pump assembly to keep it from back flowing. That's the only one.

Where is your fuel pressure gauge sending unit mounted?

I adapted the twin pump from their single pump setup, but it was a few years ago.

LiteraCola

The Holley's aren't coming on with the Ignition. The stock pump is priming as it should, but the pressure drops off like a brick as soon as the pump shuts off. According to A&A, the newer style Holley pumps are designed to not need a check valve, something about the rotors and their close clearances yadda yadda yadda. The sending unit is attached to the regulator under the hood. A&A mentioned taking the regulator apart to inspect the diaphragm, spring, etc, but it's unlikely that there's anything wrong with a brand new regulator. I'm gonna tear it apart when I get the time.

etekberg

That's the job of the regulator

etekberg

Is your fuel pressure steady with the engine running? If yes, the regulator is probably working.

I would suspect a problem with a check valve, or perhaps you didn't get this newly designed pump?

Can you clamp the fuel lines somewhere for a test? Run the pumps with the car off, clamp the fuel line somewhere, turn off the pumps (quickly after the clamp), and see if your pressure bleeds slower.

If it does, you know you need a check valve.

If there is no change with the clamp there, try doing the same thing but put the clamp on the return line. If that fixes your problem, then your regulator has a leak.

LiteraCola

Yep, once the engine is running, the fuel pressure doesn't change at all. I'll give that a shot tonight.

95vettski

According to the pictures on A&A website it looks like the check valve is located pre pump. Do you remember seeing one? You could always pull the inner wheel liner and have a look.

LiteraCola

Mine looks identical, but it did not come with a 45 on the front side of the pump.

realcanuk

Should be a check valve before the pump.

helga203

This is right off their web site.
Our system is seamless and quiet. You’ll never hear the pump as it only comes on under hard throttle conditions, when it’s needed. There is a custom built check valve installed so that the system does not “bleed off” when the car is shut off. This means that the car will start right up after being shut off. Some aftermarket systems bleed the pressure off and require that the starter be cranked for 5 seconds or more to build pressure back up in the lines.

CamminC5

wonder if trash has accumulated somewhere in the system. Did you drill the tank?

LiteraCola

I did. But I jumped the Hobbs switches to run the twin pumps and everything ran fine. If there were trash in the system wouldn't it affect the way the car runs? The pressure stays steady at all times while driving. I only have that trouble on startup.

etekberg

I suppose it is possible you have some dirt in the regulator, leading to a situation where it can't completely close. It may be that the leak is small enough where it doesn't effect your ability to control fuel pressure when the pump(s) are running.

If A&A told you that you don't need a check valve because of a new pump design, that would be where I would investigate first. You could always just put one in anyway, two check valves won't do any harm. You could also run the return line into a bucket and see how much it leaks when the pumps are off. Lots of ways to investigate this problem.

Andy@A&ACorvette

DO NOT pinch the lines. They are PTFE lined, not rubber.
There is a very fine filter between the tank and the pump. Nothing is going to get through to the pump. The check valve is built into the pump assembly.
I would think it's the regulator. I'm thinking we should just send you a new one to test that theory.

LiteraCola

Here's an update for anyone interested (or for any future searches where this thread shows up)... I received the new regulator from Andy @ A&A, but before I installed it, I took the old one apart. I found a tiny shard of metal on the seat between the diaphragm and the return port. I cleaned the regulator inside and out with solvent and blew it out with compressed air. I should have reinstalled it to be sure that was the issue, but I installed the new one (after disassembling and cleaning it). I also found metal shards inside the new one!

Andy, if you're reading this, the quality of Holley's machining is definitely lacking. When the regulator was bored for the Inlet ports on both sides, burrs were left and it looked like it wasn't cleaned or deburred at all. Just something you might want to look into.
Anyways, I installed the new one and I no longer have the bleed-down issue. Also, I'm scheduled for Sept 26 with Frost for some dyno time. I'm pretty excited to finally get this car right and feel some BOOOOOST!

etekberg

Wow, two bad regulators. I'd definitely avoid that manufacturer. Good job finding the problem.