erratic fuel pressure; pressure drops with key off

[jimk]

Now that I can get a good reading with my pressure gauge, I see that the pressure occasionally drops to 5 psi and the engine stalls. I replaced the pressure regulator but the problem still exists. I also replaced the fuel pump 2 weeks ago as it was shot.

Anyone have ideas about how to troubleshoot this? I'd like to disconnect the fuel supply line and measure pressure at the line but I have no idea how to connect the gauge to the quick disconnect fitting.

 

[tqmx1]

Have you changed your fuel filter ?

 

[jimk]

Have you changed your fuel filter ?

Yes - changed with fuel pump.

 

[Mr Anonymous]

Curious where you were able to find a fuel pump? I'm guessing you were sold a regular Taurus pump.

Anyway, at idle it shouldn't matter. I'd check the voltage at the pump to see if maybe you're losing power due to a bad connection, high resistance, etc.

 

[intimdatr]

Mine did this, ended up needing a new a tank because when i did the pump i knocked a bunch of the rust loose from the car sitting for 10 years.

 

[93markVIII]

happened in the 69 cougar as well. rust clogged up the pre filter and it would't do anything but idle.

 

[jimk]

Curious where you were able to find a fuel pump? I'm guessing you were sold a regular Taurus pump.

Anyway, at idle it shouldn't matter. I'd check the voltage at the pump to see if maybe you're losing power due to a bad connection, high resistance, etc.

Yeah, I had to replace the tank also (when I changed the pump). It had plenty of garbage inside of it.

Whether it's the lower lph pump or the correct one, I don't think the pressure should vary erratically. I'll rig a voltmeter to check the supply at the pump.

 

[SHOZ123]

I connected a fuel pressure gage to the fuel rail one time for temporary testing of the pump under load.

Get enough 1/4" ID hose so when connected to the gage there is enough hose to place the gage in front of the driver at the windshield wiper and still reach the fuel rail test valve.

Take the schrader valve out of the test fitting and slip the hose over it securing well with a hose clamp. The secure the gage with a wire tie or something.

 

[jimk]

I connected a fuel pressure gage to the fuel rail one time for temporary testing of the pump under load.

That's about what I did, using my pressure gauge. Pressure drops as low as 5 psi, then comes back after a few seconds. My next step is to rig a voltmeter to the pump to see if the problem is electrical.

By the way, this is the 3.4 I got from you ~6 years ago.

 

[SHOZ123]

That's about what I did, using my pressure gauge. Pressure drops as low as 5 psi, then comes back after a few seconds. My next step is to rig a voltmeter to the pump to see if the problem is electrical.

By the way, this is the 3.4 I got from you ~6 years ago.

It's not my fault.....

 

[jimk]

It's not my fault.....

Didn't mean to imply that! I'm actually pleased that it runs as well as it does after sitting so long. A dead battery, bad fuel pump/tank, no AC and this fuel pressure issue are the only known problems. None are directly related to the engine.

 

[SHOZ123]

I'm trying to remember the engine. I think it was one I went to Missouri and got. Still have two more if you want to trade up for low miles.

 

[jimk]

I'm trying to remember the engine. I think it was one I went to Missouri and got. Still have two more if you want to trade up for low miles.

Not just yet - I've still got 4 years left on my 10-year warranty ... right ?