Aeromotive fuel system, boiling fuel in summer

[J's98Snake]

I have an aeromotive fuel system (A1000, with all the lines, filters, aeromotive regulator) on my 98. My tank is sumped.

I moved to Vegas from Florida and have only noticed this problem in Vegas in the heat.

When it's hot outside and the car gets fully heated up, my fuel pump gets noticeably louder. The normal quiet humm turns into a louder humm or even a buzzing sound. When I shut the car if it sounds like the gas is boiling in the gas tank. Vegas has sh_t @ss 91 octane.

I called aeromotive and they told me that the heat and something about the vacuum in the gas tank will cause the gas to boil when you shut it off. They told me to drop my tank and bore out some vent/vacuum valve that is located on the top side of the tank.

Anyone heard of this? I’ve had my tank out numerous times and don’t remember seeing a vent on top. The only thing I remember seeing is the factory fuel pump and fuel tank sender.

Anyway, before I drop my tank, any suggestions? I asked about a vented fuel cap and was told it was no good.

Thanks Jake

[fox88]

Have you tried wooden clothes pins on the fuel line? Its cheap and it works.

[J's98Snake]

Originally Posted by fox88

Have you tried wooden clothes pins on the fuel line? Its cheap and it works.

With 17 posts and a Jul 2012 registration month, I ASSume you're a troll.

Please stay out of my thread if you have nothing to contribute.

[mustangmatt8693]

Yes, I have heard of this. and the cure is just a larger vent hole in the tank and install a roll over valve while doing this is a good idea.

[J's98Snake]

Originally Posted by mustangmatt8693

Yes, I have heard of this. and the cure is just a larger vent hole in the tank and install a roll over valve while doing this is a good idea.

Thanks Matt, that sounds liek what the Aeromotive tech was telling me to do.

[CPURTELLII]

Yeah the rollover vent doesn't work at least on my foxbody. My car was doing the same crap in over 90 temps. At least you go ahold of aeromotive I left a message and never heard back. Keep us posted I want to know what fixes it it isn't over 90 hear usally just really hot this summer.

[Sickfox]

Mike Plummer over in the super-charger threads just added a vent to his tank and there is lots of pics.

[fox88]

Originally Posted by J's98Snake

With 17 posts and a Jul 2012 registration month, I ASSume you're a troll.

Please stay out of my thread if you have nothing to contribute.

I've been working on cars every day of my life since 1991. Google it. Its an old hod rodders trick.

[J's98Snake]

Originally Posted by fox88

I've been working on cars every day of my life since 1991. Google it. Its an old hod rodders trick.

Post a link and establish your cred

[tp355z]

I may be able to explain the cause. Perhaps then the solution will be more obvious.

All fluids have a required "vapor pressure" to remain in liquid form at a given temperature. That means: you can boil a fluid by either (1) raising the temperature or (2) lowering the surrounding pressure. If your fuel pump is PULLING from the tank - rather than pushing - and it's a high performance pump, then it is likely lowering the pressure in the fuel line and tank, allowing the gas to boil.

I would also suppose that this is occurring while the vehicle is running - it's just that you can't hear or notice it. If the gas tank is properly vented (so that it stays at ambient temperatures) then there's no reason why the gas should boil.

That's also why your pump sounds louder. It's working harder to pull fuel against the suction on the tank and/or is experiencing cavitation.

(Cavitation = boiling the pumping fluid in a pump by dropping the pressure too low)

Just my .02. I've never had much success with clothespins on solid fuel lines, so maybe I'm all wet. :P

[34blazer]

Im in vegass now too, only problem ive had with the higher temps is fuel vapor from the tank was being forced into the engine. the evap solenoid was stuck open and fuel vapor could freely enter the engine, worse after driving for an hour as the pressure increased. i had to pull so much fuel out of the tables, when i removed the gas cap(while running) the engine would lean out and stall. disconnected it completly and its fine. have you removed the gas cap when it sounds like its boiling?

[J's98Snake]

Originally Posted by tp355z

I may be able to explain the cause. Perhaps then the solution will be more obvious.

All fluids have a required "vapor pressure" to remain in liquid form at a given temperature. That means: you can boil a fluid by either (1) raising the temperature or (2) lowering the surrounding pressure. If your fuel pump is PULLING from the tank - rather than pushing - and it's a high performance pump, then it is likely lowering the pressure in the fuel line and tank, allowing the gas to boil.

I would also suppose that this is occurring while the vehicle is running - it's just that you can't hear or notice it. If the gas tank is properly vented (so that it stays at ambient temperatures) then there's no reason why the gas should boil.

That's also why your pump sounds louder. It's working harder to pull fuel against the suction on the tank and/or is experiencing cavitation.

(Cavitation = boiling the pumping fluid in a pump by dropping the pressure too low)

Just my .02. I've never had much success with clothespins on solid fuel lines, so maybe I'm all wet. :P

Thanks for the write-up!

[J's98Snake]

Originally Posted by 34blazer

Im in vegass now too, only problem ive had with the higher temps is fuel vapor from the tank was being forced into the engine. the evap solenoid was stuck open and fuel vapor could freely enter the engine, worse after driving for an hour as the pressure increased. i had to pull so much fuel out of the tables, when i removed the gas cap(while running) the engine would lean out and stall. disconnected it completly and its fine. have you removed the gas cap when it sounds like its boiling?

I have, immediatley nothing changes.

[34blazer]

Originally Posted by J's98Snake

I have, immediatley nothing changes.

was there positive pressure or vacuum?

[sjd3021]

jsnake do you have a full exhaust or dumps. if its dumps i heard the heat from the exhaust under the car can cause problems