stall out when below 1/2 of gas
11-14-2005, 12:56 PM
#2
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
RE: stall out when below 1/2 of gas
Sounds like it could be Vapor Lock. Try getting a different gas cap, vented variety. A way to test for this is when your car cuts out, take the gas cap off and you'll get a loud hiss. If you get that then your getting a vaccuum in your tank and it's causing fuel starving. The vented gas cap will keep this from happening by allowing the gas tank to equilibrate as fuel is sucked out.
11-23-2005, 12:41 PM
#4
Thread Starter
Join Date: Nov 2005
Location:
Posts: 27
RE: stall out when below 1/2 of gas
i bought a new gas cap and it is still stalling out could it be somthing with the fuel pump. could the fuel pump just off track or something. what other things would you suggest because i want to save droppind the fuel tank for last.
11-23-2005, 02:07 PM
#8
Join Date: Oct 2005
Posts: 15
RE: stall out when below 1/2 of gas
The caps on a 90 are not vented, the tank is vented to the charcoal cannister (I think). They test my cap each year at emissions to see that the cap is not vented or leaking.
I'd suspect the fuel pump, or the pump inlet line. If the inlet line deteriorates or comes loose, I bet that would do what you have. My pump lasted about 200K, if I remember correctly. Started getting intermittent. If yours is old, you might want to do it anyway. My bet is that if you pull out the pump assy, you will see the problem. You might need those little fuel line separation tools; I can't remember.
Let us know..
I'd suspect the fuel pump, or the pump inlet line. If the inlet line deteriorates or comes loose, I bet that would do what you have. My pump lasted about 200K, if I remember correctly. Started getting intermittent. If yours is old, you might want to do it anyway. My bet is that if you pull out the pump assy, you will see the problem. You might need those little fuel line separation tools; I can't remember.
Let us know..
11-23-2005, 02:50 PM
#10
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
RE: stall out when below 1/2 of gas
the cap...not the engine.... 
You can either get a fuel pressure guage and test the fuel pressure to see if it's the fuel pump or do a more involved test.
To test the fuel pump without a pressure tester you can do a simple (but involved test) if it's carbuerated disconnect the line going into the carb and run a line into a bucket. For fuel injection you need to find the bypass or purge valve (usually has threads on it like a tire valve on the fuel rail and hook a fuel compatible line to it)
You can also depressurize the fuel system, disconnect the fuel filter then repressurize the fuel system with the line going into the bucket. Some pumps run continously until they reach a threshold pressure and since the line is disconnected, it won't ever reach that. (let the pump run for 30 seconds)
Turn the engine over for 30 seconds and measure the amount of fuel you get. Compare this to the gph or lph rating of the pump. (doing simple math to make sure you keep things in perspective). A mechanical fuel pump will be good or bad, no inbetween. An electric pump that is flowing lower than rated is clogged and needs to be cleaned/replaced. If the pump come out okay then it could be a fuel pressure regulator.
You can either get a fuel pressure guage and test the fuel pressure to see if it's the fuel pump or do a more involved test.
To test the fuel pump without a pressure tester you can do a simple (but involved test) if it's carbuerated disconnect the line going into the carb and run a line into a bucket. For fuel injection you need to find the bypass or purge valve (usually has threads on it like a tire valve on the fuel rail and hook a fuel compatible line to it)
You can also depressurize the fuel system, disconnect the fuel filter then repressurize the fuel system with the line going into the bucket. Some pumps run continously until they reach a threshold pressure and since the line is disconnected, it won't ever reach that. (let the pump run for 30 seconds)
Turn the engine over for 30 seconds and measure the amount of fuel you get. Compare this to the gph or lph rating of the pump. (doing simple math to make sure you keep things in perspective). A mechanical fuel pump will be good or bad, no inbetween. An electric pump that is flowing lower than rated is clogged and needs to be cleaned/replaced. If the pump come out okay then it could be a fuel pressure regulator.