Full tank of gas makes my car barely run.

[mazur]

Just recently got my car running. It began with a half tank of gas. It ran great and was very quick. This morning I drive it several miles to a gas station.

I filled her up all the way and after maybe 30 seconds of driving it startting hesitating real bad and begin to sound like it was misfiring and wouldn't accelerate and then it would just die. After turning it back on it would be fine again for only 30 seconds.

I don't understand it. How can it run perfect for a little while each time after restarting it? And it seems to rev fairly fine when not under load.

[backtrail69]

Bad gas?

[Mr.SWISS]

What O2 are you using?

[mazur]

Bad gas?

No...this is the best gas in town. It is not pinging.

[mazur]

What O2 are you using?

Stock E30.

[static]

check your maf and vacuum leaks. Also, (for whatever reason ) you might not be getting enough fuel to the rail (pump, filter, etc)
Try resetting your ECU too.

[mazur]

check your maf and vacuum leaks. Also, (for whatever reason ) you might not be getting enough fuel to the rail (pump, filter, etc)
Try resetting your ECU too.

No vacuum leaks that I can detect. Just switch out my chip and same thing happens. It seems like the fuel pump is not up to the task of supplying the fuel. The car runs fine right after startup probably because the fuel pump primes the rail.

I let it idle for a bit then tried to start driving. Starts falling on its face just trying to get rolling in first!

Can just having a larger mass of fuel in the tank affect pump output like this?

[bdi_fc]

If you haven't changed the fuel filter lately, do it, even if you don't think it's the cause of the issue. It's quick and easy.

[Mike B.]

My guess would be bad gas, clogged fuel filter, or faulty fuel pressure regulator.

[Mr.SWISS]

Also the E30 O2 sensor has different parameters than the M/S50 motors. Unless the car was an M42.

[mazur]

Also the E30 O2 sensor has different parameters than the M/S50 motors. Unless the car was an M42.

That might be so, but the car was running perfect for two days till just this morning.

[PiercedE30]

how could the e30 o2 sensor be any different than the m/s50? it puts out a 0-1v signal no matter what (both m20 and m50). it doesn't matter which o2 sensor you are using (obviously with the exception of a wide band).

[e30polak]

it might be a prob with the fuel lines/sensor used in the e36's evap system that may cause this, but don't quote me cuz i might be wrong

[triggrhaapi]

Here's what I would do: siphon out half the tank and see if it changes how it runs. If so, then you've isolated the problem being the pump, otherwise you'll want to check your fuel pressure regulator, then check the car for CEL codes.

[euroshark]

Are you stopping the pump as soon as it clicks? If you are pumping after the automatic shutoff like a lot of people do... *click* - *pump* - *click* - *pump* -*click* - *pump*... you may have flooded the expansion tank for the fuel system, and this could be part of the problem... Maybe.