[Scott65]

He posted earlier he's using tanks gpa 5, that's 340lph I believe.

[JLMounce]

A standard -6 feed and return line should be okay for a 340lph pump, although that pump is overkill for the setup.

If there's not a kink or some other obstruction in the return line, I'd think about going to a -8 line. Or as mentioned, the hoses are on the wrong inlet/outlet at the fuel hat, or are otherwise swapped. If for instance you were trying to return fuel through the fuel filter in the wrong direction, that could cause this issue.

[gman005]

I will double check the lines.

[gman005]

Everything looks good.

[gman005]

The pump I bought was recommended by tanks. Am I supposed to have more than one fuel filter? The one I have is a 10 micron that came in the fuel line kit.

[JLMounce]

Only one filter is necessary if you are running a pump in the tank. The fuel pump sock acts as the "pre-filter" that would typically be installed if you were running a frame pump kit.

Take the return line off the throttle body and blow through it. You should be able to push a good amount of air through it, fairly easily. If it's hard or impossible to get air through it you may have a kink or debris in the line, or the tank is not vented or not vented well enough.

Before you can really do anything you've got to determine why you're running 70lbs of fuel pressure. Either the return line is backing up and causing pressure creep or it's also possible the fuel pressure regulator is bad.

[Formulajones]

A sign of the possibility of the return line being too small, or maybe blocked as JLmounce said, is if you can't adjust the regulator any lower than the 70 lbs. you're seeing.

Either the regulator is bad, or you have a back up in the return line.

I'm assuming you've already tried adjusting the regulator down to no avail.

[Scott65]

Does this unit vacuum reference? Or is it static pressure and the ecu takes care of the rest? Reason I ask is for how it needs to be set to the 58psi number.

[JLMounce]

If this is a basic sniper system, it should have a non-adjustable built in regulator at 58psi. It should also be seeing a vacuum reference that reduces pressure to approximately 43psi in low load situations.

The internal regulator can be bypassed by purchasing a block off plate and then running an auxiliary regulator after the fuel rails. I have heard of instances where these internal regulators have failed, but it's pretty rare. I'd still be leaning more towards some sort of obstruction in the return fuel line.

[Scott65]

Does it use a vacuum line, or the map sensor signal?

[JLMounce]

Originally Posted by Scott65

Does it use a vacuum line, or the map sensor signal?

It should be using a vacuum line. It's not entirely necessary to do that, early FiTech models actually didn't vacuum reference. All that really does on these systems is make the low load fueling a bit easier on smaller, less powerful engines.

A lot of these systems have the injector to handle about 630 hp and when you put it on a 190hp replacement small block, you end up with duty cycles so low that the injectors aren't firing properly.

I've never run my system vacuum referenced and it's smooth.

[Formulajones]

Chris at EFI System Pro actually recommends running a vacuum reference regulator on all the setups he sells. I found this out later.

I've always had a vacuum referenced regulator on both of our cars (Aeromotive 13301) for probably 20+ years with carbs, never ran a vacuum line to it though. Continued to use it the same way when the Holley EFI went on both cars and worked fine. Just swap out the spring for the EFI pressure and done.

Wasn't till about a year later talking to Chris about some tuning the subject of vacuum referenced regulators came up. He suggested running a vacuum line to it, as it lowers the fuel pressure at idle and light cruise situations and makes tuning those fuel tables much easier, more stable.

Even with the vacuum on the regulator, it still shows about 54-55 psi of fuel pressure at idle, and with more vacuum at light cruise it's about 52-53. So it's not a huge change anyway, but it did clean up those areas in the fuel table a pinch. Of course WOT vacuum drops and it jumps right to 60 PSI.

[gman005]

Holley is sending me a new regulator. Ill try and blow through the line today. All I wanted to do is drive my car. LOL.

[JLMounce]

I know you purchased this second hand. Did the original owner mention anything about how it ran for him, or what it was on prior?

Your issues have all the hallmarks of a bunch of trash running through the system. Like the thing was plumbed to a dirty fuel tank with little or no attention to filtration. The stuck injector and apparent stuck FPR scream foreign material.

[gman005]

He said it ran fine. I just ran a line to a gas can and the pressure was at 68 psi. So I guess I'll replace the regulator.

[Scott65]

Might wanna consider scrapping the Holley regulator and using a conventional return style regulator. I think someone in this thread mentioned a block off plate available to do just that.

[Formulajones]

Originally Posted by gman005

He said it ran fine. I just ran a line to a gas can and the pressure was at 68 psi. So I guess I'll replace the regulator.

That's sure starting to sound a lot like what JLmounce mentioned, some trash went through it, got the injectors and the regulator.

I lean more towards Scott's recommendation and prefer the conventional return style regulator plumbed into the line somewhere convenient. I know, more work, more money, not what you want to hear.

Scott, I made a datalog today. Soon as I change it to a format to email I'll send it your way.

[Scott65]

Sounds good, thanks

[Formulajones]

I was just doing some reading. Many guys don't recommend running these big fuel pumps with the stock Holley Sniper internal regulator, the fuel pump will blow right through it. The stock Sniper internal regulators are meant more for stockish type builds that only require small in tank fuel pumps.

They recommend blocking that regulator and going with an external return style regulator.

This subject just came up from someone trying to run a 340 LPH pump through the Sniper internal regulator and it won't regulate the pressures.

[gman005]

Maybe Ill change the fuel pump to a gpa 4?