Fuel starve when braking with less then 1/2 tank

[dwhacks]

So I've got this car from my brother. A 92 cb7 EX (canada) and i've done a few mods to it and the regular maintenance stuff. Now over the last week I've got a strange new problem I didn't have before. I used to be able to run the tank to a 1/4 or less and then refill without problem but then all of a sudden it started to stall when coming to a stop. Not always, but more and more often. I decided to go on a longer drive and test it out and it was getting worse and worse. Cruising down the straight at 100km/h and then slowing down for a 50km/h corner I would put in the clutch and tap the gas to rev match and nothing would happen. You can hear the throttle open up but not gas goes. Then where there are less forces from slowing down the gas works fine (this all happens very fast). So I thought its fuel starving and went to the gas station and filled it up. Sure enough, no problems. I cant make it stall like that or even dip in the revs.

My brother installed a new fuel pump 2 years ago. I installed a new fuel filter 2 months ago and my brother has changed the filter ever year before that.

Any ideas? could the fuel pump be bad again? It doesn't lag under acceleration.

Could it be the pressure regulator? Is there a way to test it without a special pressure gauge that threads into the fuel rail?

Could the "sock" or something else have fallen off of the fuel pump some how?

Could it be the injectors? any way to know?

[Raf99]

So I've got this car from my brother. A 92 cb7 EX (canada) and i've done a few mods to it and the regular maintenance stuff. Now over the last week I've got a strange new problem I didn't have before. I used to be able to run the tank to a 1/4 or less and then refill without problem but then all of a sudden it started to stall when coming to a stop. Not always, but more and more often. I decided to go on a longer drive and test it out and it was getting worse and worse. Cruising down the straight at 100km/h and then slowing down for a 50km/h corner I would put in the clutch and tap the gas to rev match and nothing would happen. You can hear the throttle open up but not gas goes. Then where there are less forces from slowing down the gas works fine (this all happens very fast). So I thought its fuel starving and went to the gas station and filled it up. Sure enough, no problems. I cant make it stall like that or even dip in the revs.

My brother installed a new fuel pump 2 years ago. I installed a new fuel filter 2 months ago and my brother has changed the filter ever year before that.

Any ideas? could the fuel pump be bad again? It doesn't lag under acceleration.

Could it be the pressure regulator? Is there a way to test it without a special pressure gauge that threads into the fuel rail?

Could the "sock" or something else have fallen off of the fuel pump some how?

Could it be the injectors? any way to know?

I would agree with the fuel pump or sock. Park on a very steep downhill and try revving it, also try a uphill too.

[oyajicool]

My old Civic acted the same many years ago.

Inside the fuel tank, there's a small tub surrounding the pick up for fuel pump. This tub is there to prevent fuel from shifting during hard braking even with low on fuel. So, the fuel is there to run the engine.

There are several path for fuel to get into this "tub", but those are likely blocked due to rust and scale. That is causing the fuel starvation.

You may have to remove the fuel tank and clean it as I had to do.

[dwhacks]

Well I tried parking on a hill with 3/4 tank and I have no problems. I will try it again when it gets to half.... this is weird!

I guess I'll add dropping the tank to the list of things to do this winter when I get the motor rebuilt.

[wed3k]

check the depth of your fuel pump pickup. happened to me on an aftermarket pump so i had to reuse the old sock/pickup

[dwhacks]

Figured it out. Dropped the tank and pulled the pump. Sure enough the pump extension/sock had fallen off. The plastic extension tube on the new sock that was installed about 3 years ago was made out of 3 pieces of plastic, not one solid piece like the original. I guess the glue they used gave way because it fell apart. Wish I knew what brand it was so I could warn you against using it, but I'm not sure.