2.3L ('83-'97) 95 2.3l confused and need major help

[Chuckyc19977]

So I got a 0171 code and went got new 02 sensors put them on fired the truck up check engine light still on while I was under there noticed didnt have a cat yup went and got q cat put that on there will start but I have to floor it ok maybe something with the cat took cat back off put the pipe that was in it back in it its still doing same thing. I have to hold my foot to the floor it runs like your flooring it then it sounds like you got no gas then it runs like your flooring it again just flutters back and forth like that. Any help would be great oh and I did check the inertia switch and the red button was down even pushed on it to make sure. As right now im thinking fuel pump fuel pressure regulator or possibly a fuel filter? Any other ideas and can these parts be cleaned like maybe I sucked something up in them

 

[RonD]

First off, O2 sensors are not used until engine warms up for 3 or 4 minutes, so on cold start they are not used
So new O2s are not the issue

Not sure what "cat yup" or "q cat" mean?
Assuming cat converters

If exhaust is clogged it can cause similar up and down RPMs

The "gas pedal" on a fuel injected engine is actually an "air pedal", it was on a carb engine as well but on carb when you pressed pedal down it actually squirted gasoline in to the engine, on fuel injected engine it doesn't, just adds more air

P0171 System too Lean
This means computer was having to add more fuel than it calculated
It can be because of a vacuum leak on the engine
Or low fuel pressure
A plugged exhaust will also cause P0171

Computer doesn't have a fuel pressure sensor, in 1995 Ranger it just expects 30psi pressure at the injectors
A vacuum leak is far more likely , but at 25 years old the fuel pump could be failing
Fuel pumps usually just quit working, so no start at all

If "cat" did mean cat converter then remove it and try starting engine without any exhaust hooked up, to see if system past the cat is clogged up

 

[Chuckyc19977]

I tried to pull cat converter off and start it still not running. Did pull the upper o2 sensor and it is covered in dark black soot. Whats the best way to clean a clogged exhaust and ill have to look up how to find a vaccum leak i have sprayed soapy water on everything and the truck made no different noises like it was sucking it in thats why I went with the 02 sensors but now that you told me that it could be low fuel pressure for the code ill start looking into that also. Thank you

 

[Chuckyc19977]

Could it possibly be a bad fuel pressure regulator?

 

[RonD]

Yes, FPR on the engine is set for 42PSI pressure, but has a vacuum line attached to maintain about 30-35psi when engine is running
Check that vacuum hose for gasoline, if found replace FPR

If vacuum hose is clean, remove the fuel line on FPR, this is the OUT line back to gas tank not the IN line
With hose off put a towel down under the FPR's port
Turn key on, fuel pump will run for 2 seconds, NO fuel should come out of the FPR's port, if fuel squirts out then FPR is bad

 

[Chuckyc19977]

How many psi do I need at the fuel rail to start the truck and keep it running 30-35?

 

[RonD]

1997 and earlier, running pressure should be 30-35psi
Engine will start with pressure down at 10psi, then fuel pump should come on full time and bring pressure up to 30psi within 1 or 2 seconds

 

[Chuckyc19977]

So checking the pressure at the fuel rail with a pressure gage without it running wont work?

 

[tomw]

Pressure should develop in the fuel rail when the key is turned from OFF to ON. The pump should run 3-5 seconds at that time to insure pressure in the fuel rail. A pressure gauge attached to the fuel rail should show the 30-ish pressure being built up. If the pressure builds and drops off immediately, then you have several possibilities. A stuck injector can flood the intake with excessive fuel, and also allow pressure to drop quickly after the short 'prime' fuel pump run. A leaky FPR can allow fuel to return to the tank or back down the fuel line, again dropping pressure. A FPR can also allow fuel to leak through the diaphragm, out the vacuum line and feed excessive fuel to the engine. You can use a smell test for fuel vapor on the vacuum line to see if it leaks, or do what RonD suggested.
tom

 

[Chuckyc19977]

Pressure tested it last night. Key on engine off only had 10 psi at the fuel rail

 

[Fredness]

Fuel Pump
Fuel Pressure Regulator

Regulator is cheaper/easier, but not likely the problem.
How many miles?
When (if ever) was the pump replace (and with what)?

 

[tomw]

If you have to do the pump, just disconnect electricals(brake/reverse/tail/license/turnsignal) and the half dozen Torx. Raise the front end of the bed and prop up using some 2X4s(or a box or ???) for access. You can lift it slightly and move rearward a bit but I don't think it has to be completely removed. It is a lot easier than dropping the tank. FWIW.
Was the 10psi during the short prime run? You can cycle the ignition and it should repeat(that was the emergency instructions in the first EFI from 1985 if you ran out of gas), eventually building pressure. If it is maxed out at 10psi, it is the either the pump, the filter, the pickup 'sock', or the regulator. The last would be allowing fuel to flow back to the tank rather than build pressure. It could be a leaky injector just filling the intake with fuel, so open the throttle plate partially and sniff a bit to see if it is flooding... I think the pressure would be higher even with a leaker.
tom

 

[Chuckyc19977]

So got the fuel pump today got it in fired it up truck fired right over which is all fine but now I still have the 171 code. So I started following vaccum hoses and found out the one vaccume hose to the egr ( it was green and it's a hard plastic line) was broken inside the line wrap. Went to part store got new hose and replaced it with new hard line got everything back together and still have the code. Did not find any other vaccum leak

 

[RonD]

If the long term fuel trims were high from failing fuel pump then it will take a few days of driving for P0171 to clear

P0171 System too Lean (Bank 1)<<< does NOT mean engine is "running Lean"

It means computers calculated fuel mix was Lean so computer is/was opening injectors more than 15% longer to get a good reading from the O2 sensor
So at no time was engine ever running Lean, you would have lots of pinging if it was actually running lean

Computer keeps a running record of fuel trims, saved as LTFT(long term fuel trims) if fuel pump was slowly failing so pressure was low then LTFT in memory would be more than 15%
So with the new pump the fuel trims will be -15% until LTFT starts to come down from driving

If P0171 hasn't cleared in 4 days of driving then you may still have an issue, from an air leak, but WAIT the 4 days

 

[Chuckyc19977]

Ok ill do that thabk you ill keep you posted