90 Civic Si stalling problem

My 1990 Civic Si stalls as I am coming to a stop less than 25 mph when
the gas tank is at half or less than half. When it is over half it
runs perfect. So far I have replaced the fuel pump and fuel filter.
One thing I noticed which was weird my friend got diagrams from our
local honda dealer for replacing the fuel pump. It is supposed to be
located under the rear seat under a silver panel. I disassembled this
and all I found was the fuel gauge. After dropping the tank I located
the fuel pump on the back left side of the gas tank.
My suspiscion is that an aftermarket fuel pump was put in the wrong
area of the tank thus when the tank is less than half full then pump is
not pulling fuel. This makes sense to me because when coming to a stop
the gas would shift to the front of the tank(where the fuel pump should
be located) and since it is located at the back of the tank the fuel
pump is just sucking fumes and very little gasoline.

Does this make sense, any suggestions? My next step was to relocate
the fuel pump at the OEM location(under the rear seat) and perhaps it
would reach the bottom of the tank better and would fix my problem?

 

wrote in

There may be baffles in the tank to limit fuel sloshing around.

I'd get an OEM fuel pump and install it,putting it back the way it was
originally.
You may need a new fuel tank,if the aftermarket fuel pump needed new holes
for installation,or if it's some custom or oddball fuel tank..

 

not on that vintage civic - the pump can only be accessed by dropping
the tank.

the sender unit, that's correct.

possible, but the pump is correctly located. make sure the feed pipe's
not bent and goes to the bottom of the tank properly. is the tank
dented at all?

i'd make sure there are no other problems first.

again, look for other problems first. has the idle been set correctly
and does the iacv work properly? if you do all that, drop the tank and
check the pump. in fact, you may as well replace it since dropping the
tank is a real pita and you don't want to be doing it again any time soon.

 

As far as the layout of the fuel gauge/pump I was incorrect.
Everything is assembled as it should be just was a bad connector for
the sock filter
Okay so I put in my old fuel pump and noticed there wasn't a joint
connector or a sock filter hooked up. So I emptied out the fuel tank
completely and found the joint connector/sock filter floating around on
the bottom of the tank. I hooked this back up and reassembled
everything and it seemed to run fine(I think it is because the joint
connector and sock filter add about 1 1/2'' of length to reach the
bottom of the tank which makes a dramatic difference in suction for the
pump). The next day I was driving it and it got down below half tank
again and started freaking out worse than before. I am guessing the
connector just sucks and won't keep the filter connected. My next step
is to go down to autozone and get a new connector(maybe a hose perhaps
2'' or so long) with some clamps and reattach everything and pray it
holds and the problem is fixed.

 

Very interesting work. Did you find any rust or water in the tank?

When you pull the pump again, would it be possible to take photos?

 

Okay so I dropped the tank and pulled the fuel pump out. The joint
connector was missing along with the sock filter. I went to autozone
got a new sock filter. The design had changed instead of having a
joint connector to the sock filter the sock filter just connects to the
bottom of the fuel pump and the gasket goes overtop of it for a snug
firm fit.

So In the end:
Problem: Fault joint connector that connects to the sock filter on the
bottom of the fuel pump

Solution: New sock filter without the joint connector.

This had to be the weirdest solution as I have asked many mechanics
about my problem and none had this as a solution so I guess I was
pretty lucky. Now my 90' Civic Si is running sweet. Thanks for all
the help everyone.