I have a 91 toyota pickup 4x4 4cyl. It seems I have a fuel pressure problem. I recently had it running pretty decent after it sat for a yr! But when I changed the fuel filter last week, it hasnt ran right since. I have replaced the fuel filter again thinkin it was a defect. I am getting fuel to the injectors, but no fuel is getting to the return hose. I would really appreciate it if someone can point me in the right direction!

 

If no fuel is getting to the return hose, it could mean the fuel pressure regulator failed closed, in which case you are getting way too much pressure to the injectors. At a minimum it would run badly because it is too rich, with lots of black smoke.

More likely, not enough fuel is being pushed into the rail to reach the pressure at which the regulator will send it to the return line. Which means you will run very lean or not at all. Which is what I'm guessing you're seeing. You could have knocked something loose that is blocking the fuel line, or have a weak pump.

The best way to diagnose this is with a fuel pressure gauge. You'll need one that goes to at least 55psi (any one for "fuel injected" will work), and with the banjo bolts to connect. These gauges aren't free, but you'll spend a lot of time chasing your tail if you can't even tell if you have too much or too little pressure.

 

Thanks. Dont know much about fuel lines, pressure, etc., but wouldn't to much fuel pressure still cause fuel to go through the fuel return line? And what would cause to much pressure?