I have a 2003 TJ with the same issue others are having the the bad check valve letting fuel back into the tank after a while. I have a couple of questions maybe someone can answer.
From what I've been able to find, it looks like the actual check valve is built into the electronic pump motor itself. I came across a breakdown of the bosch pump (the electric pump, not the whole assembly) and one of the features it highlights is the one way ball check valve. I see allot of people saying the fuel pressure regulator is the cause of the gas leaking back into the tank. I'm not so sure after seeing that. Which would explain why when people replace only the regulator it doesn't fix the issue. But if you replace the whole assembly (the electronic pump) it fixes it. Also, I've read reports of people installing a check valve AFTER the fuel pressure regulator and causing damage and or fire! Not good! Probably causes an excess build up of fuel pressure because the fuel pressure regulator cannot do it's job. Hence the name "fuel pressure regulator".
Anyone have any success using a check valve BETWEEN the pump and the regulator? You'd have to remove the regulator from the top of the assembly and put it there. It's not the safest thing, I know, and I'm not saying I'm gonna do this but it's just a thought. Since the bosch 67726 is nearly impossible to find. I don't want to wear out my ignition switch by turning it off and on three times every time I need to start it. But I don't want to replace the fuel pump every 6 months to a year either by using an aftermarket pump.
At this point it looks like a Delphi pump may be the only solution.
From what I've been able to find, it looks like the actual check valve is built into the electronic pump motor itself. I came across a breakdown of the bosch pump (the electric pump, not the whole assembly) and one of the features it highlights is the one way ball check valve. I see allot of people saying the fuel pressure regulator is the cause of the gas leaking back into the tank. I'm not so sure after seeing that. Which would explain why when people replace only the regulator it doesn't fix the issue. But if you replace the whole assembly (the electronic pump) it fixes it. Also, I've read reports of people installing a check valve AFTER the fuel pressure regulator and causing damage and or fire! Not good! Probably causes an excess build up of fuel pressure because the fuel pressure regulator cannot do it's job. Hence the name "fuel pressure regulator".
Anyone have any success using a check valve BETWEEN the pump and the regulator? You'd have to remove the regulator from the top of the assembly and put it there. It's not the safest thing, I know, and I'm not saying I'm gonna do this but it's just a thought. Since the bosch 67726 is nearly impossible to find. I don't want to wear out my ignition switch by turning it off and on three times every time I need to start it. But I don't want to replace the fuel pump every 6 months to a year either by using an aftermarket pump.
At this point it looks like a Delphi pump may be the only solution.
