1994 Ranger 4.0 V6 cranks but won't start. Tried all the normal things. Grasping for straws here. One weird clue.

[Josh B]

I doubt you hid a kill switch that you can't find.... You can only kill so many things on a ranger so if the fuel pump, ignition or whatever else you can wire a switch to would be obvious at the source, meaning you would see wires coming from something if there was a kill switch.

I scrolled through this thread earlier today and noticed a lot of contrast in the many differing remarks as to its cause, but my reply about the
air in the tires was not directed towards you sir , I'd only found it somewhat humorous about the wide ranging scope of the replies,which are all valid remarks

 

[BrightCalypsoGreen]

I'm kin

I doubt you hid a kill switch that you can't find.... You can only kill so many things on a ranger so if the fuel pump, ignition or whatever else you can wire a switch to would be obvious at the source, meaning you would see wires coming from something if there was a kill switch.

I'm kinda getting up there in the years so me thinking I did something or did not do something or not being able to remember where I put my keys or glasses from this morning is nothing compared to what I did when I parked the truck 2 years ago.

 

[BrightCalypsoGreen]

I scrolled through this thread earlier today and noticed a lot of contrast in the many differing remarks as to its cause, but my reply about the
air in the tires was not directed towards you sir , I'd only found it somewhat humorous about the wide ranging scope of the replies,which are all valid remarks

I laughed. no explanation needed. I got it.

 

[BrightCalypsoGreen]

Thanks for all the suggestions. I will be pulling plugs this weekend and chking that fuel regulator. I think that's going to turn out to be the issue. I did not know if it was normal for the fuel pressure to drain down so fast. So clearly that is something that I must address.

I'll update as I find whatever I find. ;-)

 

[BrightCalypsoGreen]

I think I have two problems.

#1 Ignition switch. My son (7YO) actually started the truck. LOL. he did because he did not know you are supposed to let the key go back to the run position. He held it in the start position. But the engine started right up and ran for 4-5 seconds before I realized what he was doing. I repeated it myself. I also found that as I turn the key there is a spot PAST the accessory position, PAST the run position, but before the start position that the radio turns on and the power windows work. I was able to start the engine, and slowly back off the key till a hair behind the start position and the engine would keep running but if I moved it just a tad more the engine would die. So I'm going to replace the ignition switch. The problem is the picture on Autozone is not a rotary looking switch. Anyone know how that thing works? I've seen this problem with old 1960's cars with rotary switches. Is the key cylinder different from the switch Autozone is selling?

#2. No leaking fuel out of the regulator. When I had it running for 10 or so seconds I had it unplugged the line from the regulator to the intake vacuum port and not a drop of fuel came out. However, my fuel pressure drops very low as soon as I turn off the engine. While running it was about 35psi. At the pump I measured 55psi. This system does have a return line so that might explain that. However after 30 seconds it's 0 psi at the rail. I think this might be normal tho. Unless there is a check or relief valve in the return line, then how does it hold pressure? When I had the pump out the return line had this little orange thing over the end, It provided a slit to allow the fuel back into the tank. AFAICT, that's the only restriction in that system.

I also tested and have spark on all 3 cylinders on the drivers side. Did not bother to check the other side as any engine will run with half the plugs firing.

Also fuses #6, #7 and #11 have zero power. Again i think that must be related to the ignition switch.

 

[Dirtman]

Pressure should stay for weeks... the fuel pressure regulator doesn't open until 30+ psi and with the injectors closed the system is sealed.

When you fix the ignition switch and get the truck running hold the gas pedal to the floor and try to start it. If it even attempts to fire, you've got a leaking fuel injector.

 

[BrightCalypsoGreen]

Pressure should stay for weeks... the fuel pressure regulator doesn't open until 30+ psi and with the injectors closed the system is sealed.

When you fix the ignition switch and get the truck running hold the gas pedal to the floor and try to start it. If it even attempts to fire, you've got a leaking fuel injector.

Thanks dirtman. Do I have to pull the manifold to get the injectors out? And how do I test them to find the one(s) leaking?

 

[Dirtman]

Pull the spark plugs. (If) one is leaking the offending cylinders plug will most likely be filthy and/or wet with fuel. Your not there yet though... get it running first.

 

[alwaysFlOoReD]

The key cylinder actuates a rod that goes down the steering column to the switch. The switch is what fubar. It may just need to be adjusted up or down so the switch corresponds to the key. There should be some adjustment if you loosen the bolts.

 

[BrightCalypsoGreen]

Okay, probably solved. (sorta) The issue was the ignition switch popped out of it's socket. It was only about 1/32" gap at the top but snug on the bottom (lower). That looked weird so I just pushed it down and I felt a little snap. Turned the key and it started right up like it has for 26 years. Runs smooth as silk.

Now, about the fuel pressure. With it running it's 30psi on the rail. As soon as I turned the key off it drops to zero w/in seconds. Everyone here said it should hold pressure. But also here on the forums I found a post that said the 90-94 does not use a return line but the pump is cycled on and off as needed. Does anyone know for sure if the 94 V6 4.0 MT has a return line for sure and should it be holding pressure?
Mine is a 94, not a 95, not a 2000, etc. It seems most comments and youtube videos are for either the '89 back or '95 forward. I could find very little info on the 90-94 4.0 MT.

I let it warm up and it idles just like it always has.

The truck does have some symptoms of a leaking injector:

The truck has always been very bad on mileage. (12mpg city/16+ highway) It has headers, a larger MAF, cold air intake (my own), a little box with two pots (idle and high speed) I use to "tune" it (due to he larger MAF) which by todays standards is hokey. I do have an A/F guage and O2 sensor but never installed them. I need to do that so I can make sure the tune is good (or at least better.)

The exhaust tip has always been black as night and sooty.

But it's been like this from the day I bought it 26 years ago.

But it's always started just fine.

I'm going to let it cool down and pull all the plugs and probably replace them. Now that I know it'll start I'll change the oil and filter as well.

 

[alwaysFlOoReD]

There isn't an idle adjustment nor a high speed adjustment. The IAC ( Idle Air Control) controls idle thru a metered vacuum leak. The TPS ( Throttle Position Sensor) has an "anti diesel screw" that a lot of people mistake for idle control. It is NOT. If you have adjusted the anti diesel screw you have introduced a vacuum leak that isn't accounted for and the computer will try to adjust fuel trims to " fix " it.it will think the engine is running lean and add more fuel. There is a way to adjust the TPS back to factory but I don't know it off hand. Its been talked about a couple times in the last few days so a search should find it.

 

[Dirtman]

Go to the junkyard and buy a factory intake and maf sensor. Problem solved.

 

[BrightCalypsoGreen]

There isn't an idle adjustment nor a high speed adjustment. The IAC ( Idle Air Control) controls idle thru a metered vacuum leak. The TPS ( Throttle Position Sensor) has an "anti diesel screw" that a lot of people mistake for idle control. It is NOT. If you have adjusted the anti diesel screw you have introduced a vacuum leak that isn't accounted for and the computer will try to adjust fuel trims to " fix " it.it will think the engine is running lean and add more fuel. There is a way to adjust the TPS back to factory but I don't know it off hand. Its been talked about a couple times in the last few days so a search should find it.

I have no idea what this post has to do with the thread.

 

[Josh B]

I have no idea what this post has to do with the thread.

He may well have been looking at two threads

 

[BrightCalypsoGreen]

Go to the junkyard and buy a factory intake and maf sensor. Problem solved.

I think you and the previous poster are replying to the wrong thread. These items have nothing to do with the thread.

The truck starts and runs great again. The only issue I'm having is the loss of fuel pressure after the engine turns off. Which I will be working on next. Thanks.