weird fuel regulator noise (E85)

[TXEnginerd]

I posted this in the Terminator section but in case it's E85 specific I'm posting here too.

Background: I recently upgraded my lethal budget return system to dual 465s and an -8an feed. Still utilizing stock rails and their frps adapter for the regulator. These upgrades were for E85.

Issue: I'm currently working on perfecting my idle (tuning myself) and during each session I typically load 2-3 new tunes and let the car idle for 5 minutes or so each tune after coming up to temp. After about 10 minutes or so, I start to hear the sound captured in the video below. Fuel pressure reading on the regulator's mechanical gauge drops 2-3 psi from my base of 40 but it doesn't jump around at all. Just a consistent 2-3 psi lower than base. If I pull the fuse on either pump the psi drops a little more but the sound stops but that happens when I disconnect either of them - it's not pump specific. And you can definitely tell the noise is coming from the regulator or where the regulator connects to the rails.

My guess is that the regulator has something wrong with it or the fuel is getting too hot between loading the new tunes and letting the car run. When I come back the next day and first start working on it, the noise is not there until after fuel has been flowing for about 10 minutes. I just don't know if this is a symptom of fuel getting to hot or not.

The car does not actually run any different when this is happening. The AFR is the same but I don't think the injectors are short of fuel at only 2-3 psi lower than what my target is. Also, my electric fuel pressure gauge (at shrader valve location on rails) reads a constant 58 psi regardless of whether this issue is happening or not.

What do you guys think?

[video=youtube_share;OWIklgeepIY]http://youtu.be/OWIklgeepIY[/video]

 

[Turbo98]

It almost sounds like air is getting into it. How much fuel is in the tank and what kind of tank/baffle?

 

[TXEnginerd]

Yeah, that's what I think is going on too. It's a stock 03 Cobra tank and is about a quarter full. I've pretty much decided what I'm going to do to fix it:

1) Short term - keep the tank at least half full.

2) Long term - modify the return fuel line inside the tank to direct returning fuel away from the pump socks and outside the baffle. Right now it's just dumping the fuel right on top of the pickups and when the level is below the end of the hard return line tube, I think that is causing lots of air bubbles to be created.

 

[Turbo98]

It's hard to say what exactly is going on. It goes away when you disconnect one pump so it seems it's sucking the baffle dry with two pumps. But that doesn't make sense if the return is dumping back into the baffle. But maybe since you are moving so much fuel even at idle, it is creating enough air bubbles to create that issue. Moving the return outside the baffle area may create a problem also. Then I can almost bet the baffle will get sucked dry a lot faster. I think a better option is to run only one of those pumps at idle/light throttle. Then have the other one kick on with a Hobb's under boost. Just a thought.

The only weird thing about the whole deal is that it takes 10 minutes of idling before it starts.

 

[WIPLASH1]

What part # is it? I'm running the small black Aeromotive regulator that looks just like that with twin 465's and E85. While my setup doesn't make that noise it IS very very loud. The only thing I can attribute to it is just the shear volume and velocity that's moving through it to regulate so much fuel at idle. The regulator is mounted to my drivers side inner fender, but it's so loud it's about as loud as my HVAC fan being on HI.

I'm probably going to end up changing it for a bigger one (this has -06 in/out).

 

[tnkucan]

Change you're fuel filter my division x regulator was making the same noise then went away when I changed the fuel filter

 

[JeremyH]

Sounds like valve chatter, likely due to cavitation. Are you running both 465 pumps all the time? If so that's over 900lph of flow banging through there at idle, which will quickly add heat to the fuel, also those pumps put out around 250 watts of heat each. So you could be getting vapor in the lines/rail/regulator. 40psi base pressure is often too low to prevent the fuel from vaporizing especialy when the rails are heat soaked hot day etc. Try turning it up to 60psi and see if the chatter stops is what I would do first. Next would be get a new/better regulator. I run the Fore f2i it a zero chatter design and runs very quiet.

http://www.foreinnovations.com/product_p/15-902.htm

My next recommendation would be to run the second pump on a controller, hobbs switch etc so it only comes on in boost or when needed.

 

[TXEnginerd]

Sounds like valve chatter, likely due to cavitation. Are you running both 465 pumps all the time? If so that's over 900lph of flow banging through there at idle, which will quickly add heat to the fuel, also those pumps put out around 250 watts of heat each. So you could be getting vapor in the lines/rail/regulator. 40psi base pressure is often too low to prevent the fuel from vaporizing especialy when the rails are heat soaked hot day etc. Try turning it up to 60psi and see if the chatter stops is what I would do first. Next would be get a new/better regulator. I run the Fore f2i it a zero chatter design and runs very quiet.

http://www.foreinnovations.com/product_p/15-902.htm

My next recommendation would be to run the second pump on a controller, hobbs switch etc so it only comes on in boost or when needed.

Thanks for the feedback. I just setup a hobbs switch for the second pump. I did notice it still happened the other day BUT that was after I drove it around for about an hour. I'm not saying that's how long it took but I think it's at least longer than the original 10-15 minutes. I actually think it's more of a fuel level issue than heat since it doesn't happen above 3/4 of a tank.

Before I go to the expense of trying another regulator, I'm going to modify my hat so that the return line doesn't dump right on top of the pump pre-filters. My theory is that as the level gets lower, that is pushing some fuel in the sump away from the pumps and introducing air into the system. I'm going to re-route it into the side of the tank using submersible fuel line and nickel-plated fittings.

 

[JeremyH]

Good deal, the hobbs will definetly help, my 465 is on a hobbs switch as well. The more fuel in the tank, the better capacity for the fuel to remove heat, submersible in tank pumps are cooled by the fuel so keeping them covered cant hurt. I always try to stay above 1/4 tank for this reason. Easy test to see if it is vapor is to turn up the regulator to a higher pressure while its making the noise, the higher pressure will raise the boiling point and if that is the problem it should shortly subside.