I've tried everything to make my 90 Ranger 2.9 run right, complete tune up but I keep geting a code 41 exhaust gas switching always indicating lean. The truck has no power but starts up fine,i DONT HAVE A PRESSURE TESTER TO TEST the fuel pressure at the rail, but after turning the key on I tried releasing pressure on the rail at the test port very little fuel with very little pressure came out. I went to the fuel filter,disconnected the line and really got sprayed! but its a new filter and its not pluged could my problem be the fuel regulator and the OS sensor?

 

Some people have had success checking the pressure at the rail with a tire gauge. (I haven't...I guess it depends on the gauge.)

The code you're getting could be a result of the fuel starvation problem, if in fact that's what it is. Did you check the filter for blockage while you had it disconnected?
I'd start there, then move up to the regulator. Disconnect the vacuum line from the regulator and see if there's fuel present. If so, it's a sign that the diaphragm has a hole in it, but that's not the only thing that could be wrong with it. Don't assume that it's fine if there's no fuel present there. You really need to be able to check that fuel pressure. I've done it by relieving the fuel pressure (I just give the Inertia switch a sharp rap to trigger it with the engine running and wait a few seconds till it dies) and then removing the core from the Schrader valve (it sits in there deeper than in a tire valve stem, that's why some pressure testers won't work, so it takes a long core remover) and then clamp a piece of hose to the valve with a pressure gauge (cheap ones can be found at the hardware store for about 6 bucks) clamped in the other end. Reset the Inertia switch, turn on the key and check the KOEO pressure, then start it and check the KOER pressure. You want to see about 40 PSI or so with the engine running.

Don't worry about that code 41 till you get the pressure sorted out. Hope this helps.

 

thanx for the info, I was outside, so I thought that I would try something, I turned the key to on, went under the hood and useded a screw driver to release the pressure.
very little fuel came out, and even less pressure, I installed a new filter three days ago, it was the org. and had some brown crap inside. think it's gotten to my regulator?

 

The original filter on a '90? Okay...! So which side was the brown crap on, just the tank side, or both sides? You might want to disconnect the fuel line from the regulator and flush it out. Stick the line into a clear plastic bottle and run the pump for a few seconds, see what goes into the bottle. It's possible that the brown crap has gone through the system and is causing a blockage somewhere, maybe at the regulator.

 

I used a pressure gage and got 40pci (key on engine not runnin) 40psi when running slite increase during driving and small increase during driving, could the injectors be pluged?

 

That should be sufficient pressure, so that wouldn't seem to be the problem. If you have a spring-lock disconnect tool, (you can get them at auto parts stores for about 5 bucks) you can disconnect the lines as I mentioned above and flush them a bit, see what comes out.

To check for plugged injectors, start the engine and listen with a piece of hose at your ear with the other end on each injector. (If you use black rubber hose, be careful around the plug wires. Black rubber hose contains carbon and can conduct electricity. A zap on the ear wouldn't be fun!)

You should hear a sharp, metallic clicking or buzzing sound from each injector. Any injectors that sound dull when compared to the others are probably partially plugged. You can run a can of injector cleaner through the system, added to the fuel tank and probably see some improvement within a fairly short time, if the truck is drivable as it is. If you want quicker results you can remove the intake plenum to get to the injectors easier, remove the fuel rails (it's really more like a mainfold on this engine) and pull the injectors and clean them by hand with carb cleaner and a plastic bristle brush, like an old toothbrush. Be very gentle with them, you don't want to bend or otherwise damage the pintle.

Be sure to relieve the fuel system pressure before taking anything in the fuel system apart.

I guess it's about time to move on to the code 41. It's possible that could be at the root of your problems after all.
First, pull the plugs and check them. Do any seem black? Do they all seem black except one that seems normal? If so, that could be your plugged injector. The O2 sensor will get a lean reading from the one cylinder and tell the computer to richen the mixture to compensate, and you could actually have fouled plugs. Your mixture would be rich, but the O2 sensor sees it as lean.

If the O2 sensor is not working, the computer can also interpret that as a lean condition and generate the appropriate code. An open or short-to-ground between the sensor and the computer results in a 0volt signal, which is similar to a lean mixture signal so the engine runs rich.

 

well did a compression test today All are above 100psi.; only do them dry,it was geting dark outside also regaped the plugs and found that three of them were black like you said. should I pull those injectors?

 

The black ones would indicate the cylinders that are running normally, that the computer is trying to enrichen to compensate for the lean ones. If you're going to pull the injectors rather than trying to clean them with a system cleaner that you pour in the tank, I think I'd pull them all if there's only 3 that are black. Kinda makes me think it's something else though...

Try doing what I said above and listen to the injectors with the engine running, see if you can hear a difference between the the injectors for the cylinders with the 3 black plugs and all the rest.

 

learned something new today those plugs that were black, with the engine running I can pull the wires off and it makes no differnce in the idle. pulled the right bank valve cover 4,5,6 to see if the cam had flatten, all springs depressed completely and came all the way up. I switched the plugs around bad ones where the good ones went and no differance. installed new plugs no diff. Where else should I look.

used a hose like you said to hear the injectors, and they all has the same clicking like sound...Where else should I look.

 

Check for spark on those cylinders. It could be as simple as bad plug wires, or even a cracked dist. cap making the spark jump around. Maybe the problem is spark-related rather than fuel -related.

 

changed the wires and cap twice

 

Well, then I guess we can rule that out...you said the compression was okay on all 6.
Maybe we're back to the injectors again. I was working on my suster's Crown Vic a few months back, and it ran like crap, you could hear and feel a definite miss at idle, which became worse when you sped it up. I couldn't pin it down to any 1 cylinder, there was a slight drop on all 8 when I disconnected the plugs one at a time. Turned out to be dirty injectors. We just pulled and cleaned them all.

 

I changed two sensors one on the fire wall and the other on the the passanger side of the intake, no diff. going to look for an os sensor next, wish me luck......and thanx for all your help

 

oH YEA I also found a very small exhaust leak between the exhaust manifold and crossover meet, could this be the problem, but the leak is so small

 

If it's so small a leak that you're just now noticing it, I don't see that small leak that far downstream would cause any problem.