This is the second time I notice this problem..

first time i was driving on the highway for about 100-200 miles i had 1/4 tank of gas left and then went to empty right away.. i got scared after driving 20-30 miles and went to fill her up and only put in 12 gallons.. so i thought the gauge is wrong.. no big deal..

today i came back hom again 150-200 mile drive.. i notice again gas went from 1/4 to empty. so i figure just like last time i still have a lot of gas left so i did'nt bother.. 5 miles before i got to my exit i started to hear noises.. turned out it was my fuel pump.. it did'nt really start to stall until i got off my exit.. and then i shut her down. so i thought i was wrong.. luckily my cousin had a spare gallon filled my car up and i was able to slowly drive to the gas station.. filled her up and guess what.. only 14 gallons.. wtf.. makes no sense i turned the car on and surely enough its showing full... has anyone seen / heard of this issue? Please help thanks.

 

Was it a whining noise, if it were, it was just your fuel pump screaming. Don't know why you would stall you had a good 3-4 gallons in the tank???

 

Yeah fuel pump loudness comes and goes... I have yet to pin-point the why and when's.

And I also noticed that when driving under half a tank that sometimes the gas gauge gets down to the light coming on... Then going to gas station to find out I have a good amount of gas still in her.

Not sure why the gauge goes to E like that, but I also noticed that when turning the car off... Then giving it a moment, then turn her back on... It resumes to a level higher then E.

So yeah noticed that too, but I don't push it... Better to be safe than sorry with running out of fuel... And I remember some saying never to go into boost when close to empty (good ways below half).

 

Yah i am sure it was the fuel pump.. it was whining for more fuel etc.. its walboro i can hear it on normal driving too but it was making a lot of weird noises like tis sucking up air instead of fuel which is expected if it is out of fuel..

Don't push the car.. if the lights flashing its running out of fuel.. don't assume. i thought about it and the only possible idea would be that the car is really not full of gas.. filled with 14 gallons but i think it can take another 4-5 gallons easily.. i am going to test this theory and let you know.. if it is true then the sending unit to the fuel gauge and the fuel flapper are related to each other.

 

sounds like when you replaced the fuel pump you messed up the electronics on the fuel assembly. The little floating thing sends a signal telling the electronics how much gas you have, I beat thats were your problem is

and I thought that the walbro do make more noise then the OEM pumps . . . ?

T

 

walboro does make more noise.. but the noise i heard was it sucking up air instead of fuel.. i just try to fill her up some more.. i put in 1 gallon and it overfilled... what means either my tank is not 20 gallon.. which i know it is as i have filled up 18 gallons before..... or there was 5-6 gallons in the tank.. sitting some where and the fuel pump can't get it.. but i thought the fuel pump sits pretty much at the bottom of the fuel tank how can it not get any of the fuel ... 6 gallons worth.

 

If it is anything electronics related then even though the car is dte with -- i should still be able to drive until the tank is completely empty. im guessing that the TN kit has some thing not configured correctly or the install did not go through correctly.. thus why i am asking TN owners and MIA for personal experience.

 

well....... it could be something with the driver's side of the saddle.

The Gs and Zs have a "saddle" style tank. There are essentially 2 tanks.....drivers side and passenger side. The pump is on the passenger. side. On the factory pump housing, there is a siphon tube that sucks fuel from the passenger side tank. I am not sure the setup on the Z and G coupe. I have a G sedan, and my pump housign is a little different from yours.

Anyway, check to make sure that the siphone tube is connectd to the pump assembly. I also recall Phunk (the formost fuel system expert on these forums) saying that TN's instructions to drill holes in the bottom of the fuel pump can is a very bad idea. IIRC, he said it can cause fuel starvation when below a 1/4 tank!

These might be the solutons to your problem.

 

You're on the right track. What's most likely happening is two things. First your float may be a little off. The second happened to me once near empty while carving canyons. The issue is that the Z/G fuel tank is divided. There is only one very small siphon hose that connects the two side of the tank. When the fuel gets very low if you take a left or right turn at anything approaching fast speeds all the fuel spills over to one side of the tank and the siphon hose cannot transfer it back to the other side fast enough. If it spills over to the drivers side then the issue you described is exactly what happens.

 

I can def see that but i was just on the highway cruising when it started to dying. its hard to say.. so far i have not really determine if my tank was really 100% empty or did i still have 6 gallons in the tank but not being sucked up by the pump. Like i said earlier I tried to fill her up some more after the 14 gallons and i was able to squeeze in 1 more gallon before it overflowed.

oh yah with my digital display shoting 23.5 mpg.. my car according to the guage has 550 miles left in the tank lol.

 

well....... it could be something with the driver's side of the saddle.

The Gs and Zs have a "saddle" style tank. There are essentially 2 tanks.....drivers side and passenger side. The pump is on the passenger. side. On the factory pump housing, there is a siphon tube that sucks fuel from the passenger side tank. I am not sure the setup on the Z and G coupe. I have a G sedan, and my pump housign is a little different from yours.

Anyway, check to make sure that the siphone tube is connectd to the pump assembly. I also recall Phunk (the formost fuel system expert on these forums) saying that TN's instructions to drill holes in the bottom of the fuel pump can is a very bad idea. IIRC, he said it can cause fuel starvation when below a 1/4 tank!


I think what your saying migh be my problem.. I think I am going to have to take it back to AAM and have them take a look at it and also check out why my car vibrates under decel around 3000 rpm..

also i am getting some slight pings around 2500-3500 rpm recently.. this just started about 2-3 weeks ago. I don't drive the car hard at all..

Is NOAH still at AAM?

 

Interestingly enough .. now that i remember that the first time this happened was right after i picked up my car from AAM after the TN kit installed..

although i never drove on the highway for 2 hours straight.. can't say for sure but i am def leaning towards something with the tn kit or the install.

 

if it happens again, pull the fuel pump housing out and have a look in the tank.

make sure you have some raps to sop up and fuel that comes out of the feed line when you disconnect it. After that, you need an 8mm wrench to remove the 6 small bolts that hold the fuel pump assemble into the tank.

I'm not sure what is involved in removing panels to get the pump on the Z though.

On my G, I had a walbro die on me one time, and I had the pump out of the tank in about 5 minutes to check the fuel level in the tank. of course, it is really easy to get to in the sedan. Open up the rear pass. door, pull the seat, and remove the tank.

 

I htink i'll try it just to see how to do it.. and if it does ever happen again i'll check it when the car is dead.. i think i am going to stay away from it happening again.. i just hope someone.. if they are unlucky and run into the same problem as me to check the tank.