1994 Ranger 4.0 Auto Truck is making me crazy.

[Wayne Ward]

Been decades since I turned a wrench on anything serious. Drove a 88 Ranger 2.9 5 speed GT for 20 years and loved that truck. Hardly any issues other then leaky valve covers and lifter tap . When my kids were needing a rig, I thought that a ranger would be great...and I still am thinking that. I purchased a purple 1994 4.0 Auto 4x4 with 113k on her 18 months ago. Blew the heads on her 9 months later and have put in a rebuild 4.0 in from Jaspers. Got her running again right off the bat but the idle was at 1500-2500. I cannot figure it out why..well I had to put that problem a side. While checking voltages on sensors and checking for vacuum leaks the spacer between the engine and tranny grenaded and the Flex plate came loose destroying the starter. Well it has been months of driveway work and I have her almost back together after going through the tranny and transfer case. Still have a couple things to do like add all the tranny and transfer case fluids which I am a bit confused about.

With all this work, the drive train is essentially all rebuilt. However I still have that blasted high RPM issue to deal with when I start her up again. A mechanic said it was probably my synchronizer. Well, I found the little bugger back where the old distributors would have been located. Great, but there is no sensor on it and this is a 4.0 OHV. I though all 4.0s had the sensor on top of the synchronizer in 1994. It just has the keeper on top of the synchr. No sensor. Does anyone have a picture of the same engine/s synchr.? I would think that it would not even run without that sensor if it was required

Prior to last problem with spacer
-I found no vacuum leaks
-no voltage issues
-no check engine lights

Suggestions please. This was intended for the kids while at school in Montana. I need to get this thing back on the road.

Thank you for your time,
WWWard

It has been fun working on this beast. I will have to find another after it is running.

 

[RonD]

Welcome to TRS

1994 4.0l Ranger didn't need a cam sensor unless it was sold in Calif., there is an oil pump drive under the cap
1995 and up required cam sensor for emissions, also an EGR Valve, you shouldn't have one of those either

After engine is warmed up and idling, unplug the IAC Valve's 2 wire connector, this will tell you if the Computer is setting the high idle or its something else

If idle drops then computer is setting the high idle

If idle stays high then could be IAC Valve is stuck open, remove and clean, also while its off, turn key on, look inside at the valve, plug in the 2 wire connector while you watch, should move about 3/8", not much, then unplug wires and it moves back, repeat until your are satisfied it works
IAC Valve can only be replace with Motorcraft or Hitachi brand, period, 3rd party brands will cause what you describe

Also check the Anti-Diesel screw on the throttle linkage, looks like an idle screw, but as we all know, "can't use an idle screw with fuel injection", so Ford renamed it
With IAC Valve unplugged turn it counter-clockwise to see if idle drops, keep going if it does, stop turning when engine is barely running, 500-550rpms
Plug IAC valve back in and see if idle goes up to about 700-750

If Anti-diesel screw doesn't drop idle turn it back to where it was.

Shut off engine
Remove TPS(throttle sensor)
Restart engine
You are checking if the TPS was holding open the throttle plate

Shut off engine
Open throttle wide and remove throttle cable(and cruise cable is so equipped)
Restart engine
See if idle dropped

PCV Valve is an often overlooked vacuum leak, as is brake booster
Block off each, one at a time and see

1994 4.0l does have two O2 sensors, one on each Bank, one of these will usually set a Lean code if there is a lower intake vacuum leak

 

[Wayne Ward]

RonD,
I am hoping to get the last bits taken care of today for a restart. I will look at all of this. A big thank you!
Wayne

 

[Wayne Ward]

Got her running for a bit. Even idled normally for a while, but then when back up to 1500 rpm. Did not get to run tests. Daughter forgot to hook up main power lead to alternator which drained the battery. Fixed problem that problem but it would not take a jump and this wire (white one in picture that I am pointing too) started smoking. It was part of a cluster of wires coming off of a component I don't know on driver side fender behind the fuse box. Need to trace wire now. uggggg Suggestions?? Should I run this as another thread? New to the forum.

 

[RonD]

Thats the starter relay, often called starter solenoid

Not a white wire its a Grey Fusible link for alternators B+ wire, B+ is the larger terminal on back of alternator, stud/nut terminal
Should have a black/orange stripe wire connected

You will need to open the harness up and find the end of that fusible link where it connects to the Black/orange stripe wire that goes to alternator

Fusible links are only 6" to 8" long, this one is a 12gauge fusible link

On that starter relay post is the Battery Positive cable, so thats the connection to recharge battery and also power the whole vehicle when engine is running

Starter relay post-------(fusible link)----(Splice to black/orange wire)---------------------alternator B+ terminal

 

[Wayne Ward]

My guess is the link is bad and that I will need to put in a new one? How would I check the relay...would there be something in the library on here?

Thank you

 

[RonD]

The starter relay is only used to activate the starter motor

That post is the 12volt connection between battery positive, alternator and the rest of the vehicle

That Relay does need to be Grounded, it's base bolted to the inner fender grounds it, to work, so you can activate starter motor using the key in START position

Yes, you will need to replace the fusible link
If B+ wire was not hooked up and its end shorted to ground that fusible link would blow, as shown in picture

 

[Wayne Ward]

Thank you...I think that is exactly what happened. Getting into it tomorrow after I pick up some new wire for the link. Also picked up a new locking cylinder because the key pulls out no matter what position the key is in.