Power loss issue, WHY?! (Fuel related sorta)

[Mysterio]

My car runs great once I fill the tank up to full. But once I've run the tank down about 2-3 gallons I start to get intermittent power loss. While I'm driving I can feel it ever so slightly losing power then going back to normal, kinda like fuel cutting but not as bad, just very slight. And sometimes when I'm accelerating at a decent ammount it will actually do a fuel cut type thing for a second then drive normal.. But then once I fill the tank back up it's perfectly fine.

What could cause this? I can't seem to notice anything, WOT, half throttle, it does it anytime, cold or warm, whatever.. But once I fill the tank back up it's fine. Then I run down a few gallons and it starts doing it.

The car idles fine & I can rev it up to 6 grand without a problem just sitting there not moving. But when driving It's definetly doing something funky.

Anyone had any problems like this, or any idea what the cause could be?

[turbovanman²]

Have you recently changed the fuel pump? sounds like you have a bad connection from the pump to sock or pump to sender and thats why it works with a full tank.

[Mysterio]

Have you recently changed the fuel pump? sounds like you have a bad connection from the pump to sock or pump to sender and thats why it works with a full tank.

Haven't done anything to the fuel pump yet. I was thinking something similar to that, but how am I supposed to run the tank down low and then empty the rest out to pull the old pump out? Lol.. I can't get any lower than like 3/4 of a tank full without it driving decently bad the rest of the way.

Also, the car is an 87 charger shelby. It has 2 fuel pumps, one inline and one intank. If I buy a 255 in tank pump, replace the intank with that, and just get rid of the inline pump, will that work fine?

[turbovanman²]

Haven't done anything to the fuel pump yet. I was thinking something similar to that, but how am I supposed to run the tank down low and then empty the rest out to pull the old pump out? Lol.. I can't get any lower than like 3/4 of a tank full without it driving decently bad the rest of the way.

Also, the car is an 87 charger shelby. It has 2 fuel pumps, one inline and one intank. If I buy a 255 in tank pump, replace the intank with that, and just get rid of the inline pump, will that work fine?

Unhook the fuel line and turn on the fuel pumps, drain into a gas can.

Yep, install the 255 and remove the inline one. Perfect.

[Mysterio]

Awesome. I just ordered a walbro 255 pump today from FWDPerformance. Should be here soon then I'll drain out the gas and replace the in-tank pump. Once I do that we'll see how things are running and I'll keep ya guys updated.

Thanks for the help.

[turbovanman²]

Excellent. Just pay close attention to the old pump, you might be able to see where its bad. Also replace the fuel filter.

Did you know that if you hook the coil + to power, it turns the pump on?

[Mysterio]

Excellent. Just pay close attention to the old pump, you might be able to see where its bad. Also replace the fuel filter.

Did you know that if you hook the coil + to power, it turns the pump on?

I replaced the fuel filter recently thinking old + clogged fuel filter might have been the cause, but it wasn't. So this is my next guess.

No, I did not know about the coil to turn the pump on. I do now though, thanks

[jre97]

Just a shot in the dark but on my lebaron I had an issue with the pins in the fuel pump plug in. One of them came loose and wasn't making good contact. the car would run fine and then loose power and or stall if you hit a bump or had enough gas in it to slosh around. It took two fuel pump changes and alot of head beating to figure it out. I even tried an inline pump and it would not suck through the in tank pump for some reason but if you have this problem there is a nipple on the sending unit that has a pickup that drops down into the tank ( I assume for carb cars) you can move your fuel line to there and it will pick up fine but it does not have a sock on it and would recommend putting a filter before the inline pump.