P0174 on a 5.0

[Melon]

I'm a bit puzzled as to which direction to go with solving this. On cold start, it takes 4 or 5 tries to get it started and for the first few minutes, it had a rough idle. It does smooth out and runs good. At part throttle, it drives fine. But anything past half throttle, it almost acts like it's starving for fuel maybe? It gets to 3500 RPM and won't go any higher and doesn't up or downshift.

Fuel and air filter were changed within a month ago. I was thinking the TPS or early signs of a failing fuel pump until the P0174 code came up. Any searching I've done, it seems like all I can find is V6 related and not V8.

Thanks for any help. I hate to send it to the shop for something stupid that I can easily do myself. I just don't have the funds to start throwing parts at it.

 

[koda2000]

Have you cleaned your MAF sensor? Be sure to use MAF cleaner and don't touch it with your fingers.

P0171/P0174 codes are very common with the SOHC V6 engine. They usually indicate a vacuum leak somewhere. They indicate the same issue on any engine. Vacuum leaks can be anywhere are are difficult to find. A smoke test is probably the best way to locate leaks.

 

[Melon]

I did attempt to clean the MAF, but I don't think the cleaner is all that great. It seemed to evaporate very quickly.

I'm hoping it isn't a vac leak, those can be a pain to find :/

 

[koda2000]

Areas to check (in no particular order):

Leaky power brake booster (hissing noise when you step on the brake pedal)
PCV hose and grommet
Hoses to/from purge solenoid, located under the battery
Small plastic vacuum lines and connectors to/from the vacuum reservoir ball, located in the passenger side fender
Vacuum line to heater control valve
Fuel charcoal canister lines at rear of vehicle, located above the spare tire
Intake manifold gasket leaks
HVAC controls and lines in the cabin (rare unless you've been messing around under the dash)

There are a lot of places to check. That's why pressurizing the system with smoke is helpful.

 

[Melon]

Leak charcoal canister... I have been getting the occasional P0442 as well...

 

[SoHK_alumni]

Sounds very much like a fuel pressure issue:

Engine off, the fuel pressure is bleeding off so it takes a could cranks of the engine to get the fuel pump to re-pressurize the system. To test, try slowly cycling the ignition from off, to run, back to off and repeat 3 or 4 times. Give the key on a half second or more to run the pump. If the engine starts on the first try after cycling the key, it's a pretty sure sign of a loss of pressure.

So to the engine performance issue. If you're not getting adequate pressure to the injectors, the engine will reach a point where it can't produce any more power and you'll get a lean running condition.

There should be a pressure test port on the fuel rail.

Both the pressure leak back and the low running pressure can be caused by the pressure regulator, the pump or the pump canister itself.

Usually, a vacuum leak will offer the worst symtoms at idle, fuel pressure issues while the engine is under load.

 

[koda2000]

To test your fuel pressure you'll need a fuel pressure gauge attached at the fuel rail On a 2000 you should see around 65-67 PSI at the rail. If your fuel pressure is low I would think you'd be getting lean codes on both banks and not just one, but it's possible it's fuel pump or fuel pressure regulator related. Sometimes the fuel hose from the pump to the FPR (or the piece from FPR to the hard line) can develop a split and bleed off fuel pressure. Do you still have your original fuel pump? I find they start giving you trouble between 150K-200K. All but one of mine failed around this mileage, but all of mine began with intermittent operation during cold weather.

 

[Melon]

My Explorer has 140k on it. Wouldn't surprise me if the pump is going.

Update:

Now I'm getting a P0171 to go with the P0174. Plus I got P1151 yesterday. If I let it idle long enough, the idle seems to drop and gets "lopey" like an old school muscle car with a hefty cam. After a minute or so, the idle comes back up to normal.

Fuel pressure regulator? I'm off work today so I'm going to try to hunt down the FPR.

 

[koda2000]

Your fuel pressure regulator (FPR) is part of your fuel pump assembly and is located inside the fuel tank. I don't believe the FPR is available as a separate part. It's a pretty simple device. It rarely fails. More likely your fuel pump is starting to crap out. Only way to know what's going on for sure is to check the fuel pressure. I wouldn't go into the fuel tank w/out replacing the fuel pump and its hoses.

 

[Turdle]

It very well could be a failing pump assembly.
However, you might swap the fuel pump and pcm relays with others like them in the relay box , while checking the sockets they plug in to for damage. I've seen these "plugs" get loose, so I give the relay tabs a very slight twist with needle nose pliers to make the connection tight. Also, check the wiring to the fuel pump inertia cut off switch which is up on the inside firewall, at the passenger foot area. Sometimes the plug gets kicked and causes a poor connection.

A vacuum gauge would do wonders here, just to verify there is not a vacuum leak.

 

[tomtom1427]

Had exact same code recently and went through ALL of the motions to figure it out. New fuel filter and checked fuel pressure a the rail. Cleaned the MAF sensor, checked for vacuum leaks, you name it. The problem ended up being a small exhaust leak between the exhaust manifold and the first O2 sensor. Replaced the pipe and all is good with the world.

 

[Melon]

Because I lacked the space, I took it to a local shop. Turns out, one O2 sensor was bad. And the fuel pump is on its way out. It had around 30 psi when they tested the pressure.

I'm amazed at the cost for a Ford fuel pump - 600 bucks. They said they were going to shop around because that price is crazy.

 

[RandomNerd2000]

Just get a Bosch pump to rebuild your assembly, a sock, and a new fuel filter, mine locally came out to like $130, but I was in somewhat of a rush, it'll be less online. Your O2 sensors likely weren't bad, however, changing them never hurts, the upstream ones control fuel trim, downstream monitors the cats. 30 PSI is too low for a 2000, spec is 62 PSI if I remember correctly.

 

[koda2000]

I've installed the below Bosch fuel pumps in all my 2000/2001 5.0L's (and in a 2001 4.0L SOHC) in the past 2 years. All worked out perfectly and you can't beat the price if all you need is a pump. The only other parts you need to buy are a fuel pump strainer and a new fuel filter. Fuel pump assemblies are quite expensive and usually unnecessary as long as your fuel gauge and pressure regulator are working.

http://www.ebay.com/itm/Electric-Fu...ash=item1a02b6faa3:g:AKgAAOSwjVVVn-P1&vxp=mtr