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hi,
i have this weird problem where if my fuel tank goes below 1/3 my car doesn’t accelerate as well/quickly. everything else seems to be normal. no check engine lights. i realize this is a very vague problem and i might just end up keeping the level high to avoid it but i was just wondering if you guys could think of anything.
2009 honda fit (manual trans) by the way
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Could be nasties in the fuel tank or perhaps a something is obstructing the intake from the tano to the fuel pump, but only when it gets low enough. Might have something floating around in ghe tank, and when the fuel level gets low enough it gets sucked up blocking the pickup tube.
[quote=”joediffy345″ post=115474]hi,
i have this weird problem where if my fuel tank goes below 1/3 my car doesn’t accelerate as well/quickly. everything else seems to be normal. no check engine lights. i realize this is a very vague problem and i might just end up keeping the level high to avoid it but i was just wondering if you guys could think of anything.
2009 honda fit (manual trans) by the way[/quote]
I would say it is definitely fuel pump related.
The lower the fuel level in the tank the harder the in tank fuel pump must work to deliver the required flow. Looks like it can no longer handle the flow requirements under acceleration when the fuel tank level is low.
How many miles on the car now?
In the time you owned the car have you usually let the fuel run down below the I/4 level before you refill? .Fuel pumps on Hondas rarely go bad (if they’re OE) so I would take that off the table for now. Given that it is related to fuel level, I would say you might have contamination as some have suggested. It could also be that someone has already installed a fuel pump and didn’t install it correctly. It could also be that the baffles inside the tank have broken loose and are causing an obstruction. In summary, you might want to get a look inside that tank.
Good luck and keep us posted on your progress.
[quote=”cam0888″ post=115486][quote=”joediffy345″ post=115474]hi,
i have this weird problem where if my fuel tank goes below 1/3 my car doesn’t accelerate as well/quickly. everything else seems to be normal. no check engine lights. i realize this is a very vague problem and i might just end up keeping the level high to avoid it but i was just wondering if you guys could think of anything.
2009 honda fit (manual trans) by the way[/quote]
I would say it is definitely fuel pump related.
The lower the fuel level in the tank the harder the in tank fuel pump must work to deliver the required flow. Looks like it can no longer handle the flow requirements under acceleration when the fuel tank level is low.
How many miles on the car now?
In the time you owned the car have you usually let the fuel run down below the I/4 level before you refill? .[/quote]Fuel level has nothing to do with fuel pump operation. However the fuel does cool the fuel pump. Running your tank low often can overheat a fuel pump and cause it to fail prematurely.
no_common_sense pm’d me this
My imagination is wandering off to something a lot less likely for your power problem. Next time you get down to a third of a tank, just try slowly cracking open the gas cap and listen while you open. I’d be listening for it to sound like it’s sucking in air. I’m kinda wondering if the EVAP vent is clogged somehow and you’re gradually getting a vapor lock in your fuel tank. It’s a shot in the dark, but worth a quick crack of the cap.
Good Luck
what do you guys think?
personally i would think any noise while taking off the gas cap would just be pressure being relieved.
I don’t think it has anything to do with the evap system. If it did I believe you would have other issues. Based on your description it has to do with fuel level. That being the case I would be looking inside the tank for the cause of the problem. Luckily for you you don’t have to drop the tank to access the gas tank. I believe you have access in the hatch area or under the back seat. Look for a round plate with a wire going through it. Should be attached with a few philips head screws. Under that will be access to the fuel pump/sending unit. Remove that and have a look inside.
Good luck and keep us posted.
And if you don’t come up with anything by pulling the sending unit, I would do a fuel pressure test in those exact conditions(low fuel level in tank) just to see if you are getting adequate pressure. As Eric suggested if you run less than 1/4 of a tank you risk damaging the pump because the fuel provides cooling and lubrication for the pump bearings. I run tests on just about everything as part of my diagnostic because it gives the customer and myself some valuable insight as to what is going on. If the test is relevant to the issue I run it!
Fuel goes through the pump motor, that’s how it gets cooled. So, as long as you don’t run out of gas and then spend time trying to start the engine on an empty tank you are not going overheat the pump.
[quote=”barneyb” post=115669]Fuel goes through the pump motor, that’s how it gets cooled. So, as long as you don’t run out of gas and then spend time trying to start the engine on an empty tank you are not going overheat the pump.[/quote]
I’ve spoken to fuel pump engineers on this and they say the most common cause of pump failure is running for extended periods of time with low fuel. The fuel pump being IMMERSED in the fuel is what cools it, not the flow through it. When the fuel gets low the pump is exposed and as a result is not cooled as well.
Not trying to be a dbag, just pointing that out.
If the engineers thought it necessary to have the pump immersed they would have put the fuel pickup above the pump.
[quote=”EricTheCarGuy” post=115725][quote=”barneyb” post=115669]Fuel goes through the pump motor, that’s how it gets cooled. So, as long as you don’t run out of gas and then spend time trying to start the engine on an empty tank you are not going overheat the pump.[/quote]
I’ve spoken to fuel pump engineers on this and they say the most common cause of pump failure is running for extended periods of time with low fuel. The fuel pump being IMMERSED in the fuel is what cools it, not the flow through it. When the fuel gets low the pump is exposed and as a result is not cooled as well.
Not trying to be a dbag, just pointing that out.[/quote] +1 and if the fuel level is low the pump can get airated, and we know how air overheats things(brakes, engines, etc etc.)
[quote=”barneyb” post=115734]If the engineers thought it necessary to have the pump immersed they would have put the fuel pickup above the pump.[/quote]
I don’t see how leaving that much fuel in the tank would be efficient. 🙂 That said, they do often construct baffles and also pump housings to keep the pumps submerged in fuel.
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