just a couple questions

My first question is, what would make my car misfire horribly and not want to idle, only when it is completely filled up, once it gets to 3/4 of a tank it runs perfectly fine.
My second question is, why wouldnt my speedometer work? I thought it was the vss and i replaced that with a known working one, and still nothing.
Any help will be greatly appreciated.

fuel pump going out? they dont like when you run the tank low. they overheat so with it filled it probly works better.

speed sensors are on your transmission. usually the wires are just fk'd and super dryrotted so check that. or speedometer gauge is bad lol thatd be a given.

^^^he said it runs like crap when the tank is FILLED not empty.

Bassboy is right, it only runs like crap when its full, it runs like its missing, very rough idle, and sometimes it when im taking off it will feel like its running on 2 cyl.
as for the vss, it was working fine when i pulled it from the other car, wires are fine, i just need to get another cluster to see if thats the problem.

oh my bad

hmm never heard of that, well its obviously a fuel problem.

check fuel pressure yet?

1990240Hatch wrote:My first question is, what would make my car misfire horribly and not want to idle, only when it is completely filled up, once it gets to 3/4 of a tank it runs perfectly fine.
My second question is, why wouldnt my speedometer work? I thought it was the vss and i replaced that with a known working one, and still nothing.
Any help will be greatly appreciated.

So i'm guessing your odometer doesn't work either but your tach does? Also may I ask how you know that your car runs good at 3/4 of a tank? Has it happened multiple times? From what I understand you filled it up, it ran like shit, continued to drive it reguardless. You thought it fixed itself when you hit 3/4 tank, filled it up again. It ran like shit, drove it reguardless still and once it hit 3/4 tank it ran good again?

yes the tach works, no the odometer doesnt and i have done it multiple times because my dad was driving the car and kept filling it up, and there would be times where it didnt act up, now that he fixed his truck and im the only one driving it i keep it off of full. I'm switch fuel pumps and the whole sending unit since i have a brand new one, but i was told it was my check valve in the gas tank and i will need a new tank.

yeah it might be filling up your evap canister ?