Car won't start with 1/4 tank of fuel

[AleroB888]

Originally Posted by Shiwnath

Hmm.... Any fuel pump in particular that you recommend? I'm doing a decent build quite soon which may benefit from a performance pump.

To troubleshoot this and catch it in the act will take some time and money, but replacing the pump canister is costly as well. And upgrading the pump is kind of complicated, you would have to allow a couple days of downtime to modify stock parts.

If it won't pump at 1/4 tank, and won't pump with 1/2 tank @ wide open throttle, a fuel pressure gauge can help.

Get the tank to 1/2 full (or as low as you feel safe with it), and a fuel pressure gauge hooked up under the hood. Then if it is starting up OK, try jacking up the front end to simulate the condition of WOT, making the fuel slosh to the back of the tank, and see if it will start. Or you can siphon gas out into a 5-gal container a couple gallons at a time. (A cheapish in-line add-on Autozone electric pump helps out for that).

If it does not start at some point in that procedure, and the fuel pump is the problem, the fuel pressure should drop, and you might hear a change in the pump's sound.

If you had a scanner hooked up, you would most likely see short term fuel trims (STFTs) increase at the time of failure (you can use that as an on-the-road diagnostic aid as well)

Or, you can get a pump assembly from a local parts place with a guarantee, and just replace the stock one. However, keep your original unit, it's probably better than most new replacements, and you can modify it with an upgraded pump when the time comes (but still may need a new sending unit to transfer to the stock canister).

If the pump itself is still good, and the venturi tube is defective, you may be able to fix that and not use a replacement, but at this point we don't know if the original sending unit is defective.... Keep the unit submerged in fuel as much as possible -- if you leave it out in air for too long it could seize up.