I've about had it with my '94 Ranger. Issues since day one. Imagine the following scenario:

You're driving down the highway on your way to work doing 55-60mph in 5th gear on a LEVEL section. Everything is fine. Then, all of a sudden the truck's speed starts dropping off and feels a bit rough. You give it more gas. Nothing. Truck is doing about 45mph and the RPM's are not changing. You drop to 4th gear and apply the throttle. No change. Nothing! RPMS will barely change even w/ the gear change!

At this point you have 2 options:

1. Ride out this tantrum and eventually the engine power will surge back to where it should be. Truck starts driving normal again (until it decides to have another tantrum).

2. Drop to 3rd gear and mash the gas pedal. Now the truck will start gaining power and speed, a bit rough I might add.

After choosing one of the above options, the truck will run as it ought to; like nothing was ever wrong, till it decides to do it again.

1994 Ranger S/C 4x4; 4.0L/5spd.; 3.73LS rear/31x10.5x15; 265/75/R15 Stock tire size.

What have I done (within the last 2K miles):

Cleaned MAF
Cleaned IAC, then replaced w/ new one, no change, put old one back on.
New Fuel Filter
New TPS, voltage test seemed to indicate it was faulty
New PCV valve
New air filter
New Motorcaft upper and lower intake gaskets
New Felpro Permadry Plus VC gaskets
New Thermostat, old was was stuck open
New ECT, did this for good measure while intake was off
Check resistence in coil pack; seemed fine
Ran 2 cans of seafoam thru engine
*New Motorcraft Plugs and Wires after seafoam flush
New Clutch and Slave Cylinder, Old Pressure plate had collapsed fingers
Replaced fluids in tranny and rear end

I have 2 codes:
327 EGR circuit below min voltage (is this a DPFE issue or EGR solenoid)
*172 O2 Bank 1 Lean (could code 327 possibly throw this?)

Is it possible for either of these two codes to cause the symtoms I have?

* Prior to replacing the plugs and wires, the truck had fairly new plugs and wires (cheap ones) on it. The truck was giving me fits as described and I came to find out the wires didn't seat properly in the coil pack. Replaced with Motorcraft wires and plugs. Truck ran MUCH better. Symtoms desrcibed were gone. Now they're back?

The plugs that were in the truck were Autolite copper cores. Plugs from EVERY single cylinder looked good. No signs at all of a lean condition in bank 1, which makes me wonder about the O2 code.

When the clutch was being replaced at the garage we ran into a problem. The truck refused to start. It would crank all day long, but would not fire. We had spark, fuel, and a grocery lish of codes. Came to find out there was a bad ground. Fixed that and it fired right up. All but the above codes went away. At this time we also checked the FPR (good) as well as the rail pressure. I don't remember what it exactly was, but it was with in spec (~35psi IIRC). After the truck was shut down, the fuel psi held at ~40 psi.

Also, I recently took a 200+ mile trip in the truck. 98% was all highway driving at speeds ranging from 45mph (construction zone) to 65mph. The truck only managed ~16.5mpg (usually ~15mpg Highway!). How anyone is getting 18-20+mpg is beyond me.

Could I have a fuel pump on its way out? This problem is intermitent, but happens several times on my 30 mile drive to work.

I am out of Ideas and $$$. I just want this truck to run the way it should. Sorry for the novel I just wrote. Any help or would be greatly appreciated. Thanks!

 

If it has the in tank fuel pump when the fuel level drops below the pump they heat up and become intermittant when they are going bad

 

Thanks sandhillmike.

Thats a good theory. I am unsure if the fuel pump is suspect or not. I remember the last time this happened it was half full. I'll keep an eye on the fuel gauge when this happens.

Anyway to test a pump?

 

The amount of fuel in the tank has become moot IF the fuel pump is going bad. I'm not qualified to say that it has, but that is sounding more and more like what the problem may be. Or a collapsing fuel line. I'm going to follow this thread with interest as I, too, own a '94. I just haven't encountered this problem... yet.

 

I'm far from an expert, but I've read a lot about EGR being big juju. Since there is hot exhaust working on the components things can go bad. I think that fordfuelinjection.com describes their functions.

I've also read a lot of service literature about fuel pumps. Apparently as they start to fail they take more current. The current waveform ( shown on a scope using a current probe) can also indicate problems -- from what I've read. There's a guy named Geff Bach(sp) who writes a lot of stuff for the online mag at autoinc.org. You can go through their archives is you're willing to dink around a little.

Finally, there's one that got my F150. The power wire to the PCM power relay was crappy. Caused intermittent problems. Since the distributor was in bad shape, I replaced it and the TFI before I figured that out. Doesn't hurt to wiggle a few wires to see if anything looks funny.

Just a few thoughts,

ford2go

 

I had symptoms similar to these, and it turned out to be a stripped wire from the Crank pos. sensor intermittently grounding out against the engine block whenever I sped up, hit a bump, etc. The only way I was able to find that was by paying around 50 bucks for a full diagnostic test on the truck.

It may or may not turn up anything, but you might consider that. Don't ask them to fix anything, (make SURE to ask this, otherwise they'll charge you 200 bucks for fixing a stripped wire or replacing a small gasket when you turn up again), and just get them to run a test on the entire truck. Ask for the results when you get back, (the actual physical results, not their interpretation), and they should point to whatever's wrong.

Of course, it could turn up nothing. Don't yell at us if it doesn't. Just keep in mind a car service place wants to make money, so make sure they only run the diahnostic tests and then tell you what's wrong.

 

Thanks to everyone who replied.

I will do some more checking around, but let me add this:

A few weeks ago I replaced the plug wires and plugs on the truck because it was giving these symtoms. Though, it wasn't happening as frequently. I checked the secondary resistence in the coil pack and it appeared to be good. Then I noticed that the plug wires didn't seem to seat properly into the coil pack. After I replaced them it ran much better and the symtoms seemed to be gone.

As for the plugs, they were Autolite copper cores and were in really good shape and showed no signs of abnormal wear. I replaced them with MC Platiums anyway. The code that I picked up for a lean condition in bank 1 really surprised me because the plugs showed NO signs of that condition. However, the Bank 1 exhaust manifold is white (instead of rusty) leading me to believe that there was a lean condition.

Now the truck seems to be giving these symtoms at lower speeds and lower gears (2nd) where I hadn't noticed it before. It is almost as if the power delivery is on an on/off switch that you feel as your driving down the road. It's not violent, but you can feel it.

I'm leaning on either a fuel pump on its way out or some electrical gremlin.

 

The one basic service item I don't see listed in your original post is an O2 sensor. A faulty signal will wreak havoc with the Air/Fuel mix, and will effect both fuel economy and drivability. I know it's an overused answer, but it sounds to me like it's one relatively cheap fix that, depending on the milage since it was last replaced, may simply be a good routine replacement. IIRC recommended service interval on O2's is about 50-60,000 miles. Just something to think about.

 

I have another question that I left out.

The truck has the factory air box on it. However, it does seal 100%.
1.) The bolts that fasten the two halves together do not tighen completely.
2.) The back side of the upper half where it is supposed to hinge on the bottom half is missing (top hinge piece is broken off). You can see the rubber portion of the air filter.

Since there are 2 vacuum ports on the upper half, will the air box not being sealed 100% cause any driveabilty/mileage issues?

 

My 87 ranger would drive just fine and intermittently just cut on and off. I found a bad ground to the EEC relay and the computer. Also the power wire to the EEC relay was bad. I just bypassed it with a switch and the problem seems to be fixed.