1994 Ford Aerostar 4.0L V6 with fuel delivery issues.

[cfield19]

I’ve been chasing an issue on my '94 Ford Aerostar 4.0L V6 and could really use some advice.


Here’s what’s going on:

• It’s very hard to start, especially after sitting for a while. The longer it sits, the worse it is.
• Sometimes it’ll fire up for a second and then stall.
• Once it warms up, it runs okay, but initial idle is super rough.
• Really struggles under load (hills, highway speeds), which it didn’t used to do.
• Engine shudders sometimes under load, and there’s a whining noise from the passenger side when this happens.
• I hear a metallic whirring/whining sound from the fuel pump area — same sound on both old and new pump.
• Fuel pressure test reads near 0.

Parts replaced in the last 2 months:

• MAF
• Water pump
• Thermostat
• Spark plugs & wires
• Fuel pump (in-tank) & fuel filter

 

[BrooklynBay]

Did you check the cps, and the fuel pressure regulator?

 

[cfield19]

I have not, Good way to test those? or just go ahead and replace them?

 

[Josh P]

When the fuel pump was replaced, was the pickup tube, sock replaced as well?

 

[BrooklynBay]

I have not, Good way to test those? or just go ahead and replace them?

Turn on the electrical system with the key switch but don't crank the engine. Turn the engine pulley with a ratchet or a breaker bar. You will hear the fuel pump prime each time the engine pulley rotates.

 

[cfield19]

When the fuel pump was replaced, was the pickup tube, sock replaced as well?

yes i replaced the entire pump assembly

 

[Josh P]

Depending on the fuel pressure tester, the valve stem in the test port has to be removed to get a reading. I've had testers that wouldn't push the stem in. As stated in post 2, test the fuel pressure regulator. A bad fuel pressure regulator can flood the engine, make it run rough and stall at idle. Personally, since the engine runs, I wouldn't touch the cps. You usually get a no spark no start condition when those fail.

 

[410Fortune]

Zero fuel pressure
Put power to the pump manually and check again

You have a clogged line a pinched line, a bad pump or a faulty pressure gauge
You can press in the schrader valve on the test port and see if fuel sprays out? If you actually have close to zero pressure then it won’t spray out
If it comes shooting out then you have an issue with your tester and or / test port

 

[BrooklynBay]

Did you check the fuel pump relay, and the inertia switch behind the front kick panel? Maybe there's no voltage on the pump.

 

[Josh P]

The first post states it starts and runs. Fuel pressure must be above 0 for that to happen.

 

[cfield19]

Yes, I have realized since posting that my fuel pressure gauge doesn't seem to fully depress the valve therefore giving me a reading of 0. It runs, has had really rough starts though. fuel pump primes no problem. I'm pretty certain at this point it is the fuel pressure regulator. I will purchase the part today or tomorrow and hopefully get it replaced this week and see what happens

 

[Josh P]

Yes, I have realized since posting that my fuel pressure gauge doesn't seem to fully depress the valve therefore giving me a reading of 0. It runs, has had really rough starts though. fuel pump primes no problem. I'm pretty certain at this point it is the fuel pressure regulator. I will purchase the part today or tomorrow and hopefully get it replaced this week and see what happens

I don't have any tips or tricks to replace it. A few beers and a lot of patience.