I recently got my 1990 Ranger back after giving it to my cousin to use to get to school and around town. Unfortunately it doesn't seem like he was maintaining it very well because a lot is wrong with it. They recently replaced a leaking clutch cylinder and some brake lines but that appears to be the extent of the repairs they did. However, what I really need help on is this high idle and fuel consumption issue. I will list all the issues as well as what I have done because there may be something systematic I am not seeing. Thank you for you time!
The following are the problems that I have encountered: high idle (revs high then stabilizes at 1400 - 1200), leaking oil pan gasket, can smell fuel when idling, broken coolant temp gauge, low power in high gears and it seems to be running hot. I have not gotten any codes read off of it because I don't want to drive it to a auto parts place in this condition.
I replaced the EGR valve which was rusted and filled with carbon deposits, I cleaned the throttle body and the plenum which were both full of greasy carbon, replaced the spark plugs and spark plug wires, replaced the air temperature sensor, coolant temperature sensor and sender, replaced brittle vacuum tubes, replaced air filter and cleaned the MAF sensor. The PCV valve rattles so I didn't replace that. I have checked for vacuum leaks in all the usual spots and found none. I disconnected the battery and let it sit overnight but the idle still sits at 1200. To be honest it almost seems worse after all the work I put into it.
Any help would be appreciated! I don't know how I am going to replace the oil pan gasket and want to get this figured out before I spend money on pulling out the engine. I am starting to wonder if maybe it is a fuel related issue rather than vacuum but I am no expert.

Start the truck up.. give it a few minutes to get at least warm and oil pressure going. really should wait until the fan comes on indicating operating temperature but in this case.. as long as its warm enough to be out of closed loop you should be fine.

While the engine is running. Unplug the TPS sensor on the the T/B (Throttle Body), pay attention to the RPMs. Do they drop? Stay the same? - Take note, plug back in.

A little further down on the I/M (Intake Manifold), you'll find the IAC (Idle Air Control-valve). Repeat above procedure. Take note, plug back in.

Which sensor(s) dropped the RPM's if either or both? Which ever one brings the RPM's down SHOULD be the culprit and if both, well then you're in double jeopardy possibly of both parts needing replacement.

I would also say to dbl check the inlet pipe, make sure the rubber seal is in good condition and not torn. Had one that was torn once that made the T/B gag on a chunk of rubber like a porn star and it kept the throttle plate from closing all the way running idle and RPM's up. The low power has me believe it may be the TPS because usually with IAC once any RPM is seen it acts right generally not laggy.

Your fuel smell could likely be the purge canister plugged or needing replacement, my 93 has that issue and on hotter days over 3 digits its worse. But just for shits and giggles check the vacuum line to the FPR (fuel Pressure regulator) make sure its not getting fuel in it and you should check the fuel pressure while your at it.

Coolant temp gauge is an easy but fast swapping of the sensor.. and MAY be a false indicator of high engine temps too (?).

others may be able to elaborate

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Thank you so much for your reply. I'll do everything you recommend when it stops raining everyday here. I may have gotten focused on phantom vacuum leaks and failed to think about the main sensors.

I'll need to fix the oil leak before I idle it for any extended period of time though. After I worked on it today I drove it up the street and back to warm it up and when I parked it I could smell hot oil and heard liquid pouring onto the driveway. I turned off the truck and looked under and there was a good amount of oil flowing from the drivers side of the oil pan. If it's the gasket I believe I will be sidelining this project until I can afford to have a mechanic pull the engine.

As far as the coolant gauge I actually replaced both the coolant sensor and sender because the gauge doesn't move at all and it still doesn't work. I may have to pull the instrument cluster to see if the gauge contacts are corroded (the other gauges work fine but there is a leak in the cab and rust under the dashboard). Thanks for your guidance, it helps to have someone point me in the right direction.

let us know what you come up with or against...

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Update: After calling mechanics today in regards to my oil gasket and drying my tears I degreased my oil pan in the hopes of pinpointing exactly where my leak was coming from while I tested the sensors you instructed me to. You mentioned waiting for the fan to come on after idling and that stood out to me because the fan comes on immediately at start up and never shuts off. I vaguely understand what the closed loop is but I am not entirely sure what that looks or sounds like to be honest.

After idling the vehicle for 3 minutes I pulled the TP sensor and saw no change in idle. I replaced the sensor, waited a couple seconds and pulled the IAC sensor and saw no change in idle. Sufficiently confused I took the car up the road and back (just like yesterday) and expected to find the oil pan leaking again but instead I saw no oil whatsoever. The engine still smelled hot so I squeezed the upper radiator hose which was hot but not firm and the lower radiator hose which was cool and felt like there was nothing in it at all.

I know I am throwing a lot out there but I am at a total loss. I am not sure what to try next but I am open to any other suggestions. I can take pictures of the engine and post them tomorrow if anybody thinks that may be helpful in figuring this out.

Pics arent exactly necessary yet.. OHV is pretty basic from 93-97 with only a couple minor things 95-97.

If the truck was running for a bit, driven, and then you checked the lower hose and it was still cold to the touch id say you have a stuck or bad T-Stat. That could be the hot issue. For ease of access and a $9 part would likely be in your best interest to swap it anyway IMO. I don't like throwing parts at a vehicle until it fixes itself but that's just a simple pre maintenance item to me.

Outside of that, Fords in General have always seemed to run hot to me and I've had a lil bit of everything from Domestics to imports, even high-lines.. And my 01' Bimmer 328 coupe, 08' 550 Sedan both ran hot too..
and my 93 is a little less now but still seems like under hood pressures holds all that heat in.

Anyway for now, I'd swap the T-Stat and do a flush in the system and replace with fresh 50/50 pre mixed coolant. and lets remove one issue at least in a move forward.. Dont forget to check the clutch fan too

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That sounds like a good plan. Any idea regarding the idle not changing when I pull either of the sensors?

Start the engine and feel the temperature of the upper radiator hose. It should stay cold until the engine warms a bit, and then get hot quickly when the thermostat opens. If it slowly warms, the thermostat is leaking coolant, allowing it to flow when it should be restricted.
I would check the fuel pressure and regulator. A failed regulator can cause too high pressure, which will lead to too much fuel being fed to the engine.
I would also check the ribbed air tube from the MAF to the throttle body. The ribs can crack and allow air in that is unmetered.
Also, I would check the hard throttle stop on the throttle body. If you cousin had a friend 'mechanic' try to help, they could have turned the hard stop in to raise the idle. The stop should make the engine run at ~500 rpm(I think) when the IAC is disconnected, engine warmed up @ idle. It should come close to stalling it is running so slow.
tom

I don't have a fuel pressure gauge so I am not sure I can check the fuel pressure; however everything I have pulled out of that engine has been covered in either rust or grease and carbon so should I just go ahead and replace the regulator just to be sure? My day off is tomorrow so I plan on replacing the thermostat and doing some more troubleshooting if the weather permits.
I just fiddled with the hard idle screw and it was turned In quite a ways, I loosened it and the idle got down to about 700. However after taking it up the road and back and shutting her off for a second she won't start back up. She is hot, and the upper radiator hose is doing exactly what you said so I will replace it and flush the system tomorrow. I loosened the screw until it was practically flush so it wasn't affecting the throttle at all. I checked the air intake ridges as well and they all are solid. When I try to start I just get a grinding noise, it doesn't turn. Over at all. Thanks for the help guys!

Any auto parts store in town, especially the "Big Box" stores rents tools. You can rent a pressure test kit for $XX.xx and you get your money back when you bring it back. Virtually FREE minus gas money and time.

I think you'll see an improvement once you get the T-stat replaced. Check your hose while your at it before you go.. never hurts to make one trip

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When you first start the engine, the IAC should bump the idle to around 1100-1200 rpms. If it does not, either the IAC does not work, or the temperature senders are not telling the computer the engine, coolant, etc are cold.
If you have A/C, and it works, when you turn it on, the compressor load should be compensated by the IAC, again, bumping the idle.
If it does not, the IAC is suspect. Power steering may have a PSPS switch that again, bumps the idle when turning the steering wheel at low rpms.
The hard stop idle should be screwed out just a bit so the throttle plate is very close to completely closed.
If it won't start, put your foot on the gas pedal, and open the throttle just a tiny bit. Try starting with the throttle in that position. If the throttle is closed, and the IAC dysfunctional, you'll get no gas... and it won't start.
tom

Alright, so here we go with my findings. I did a fuel pressure test and when with the engine on the fuel pressure is 30 psi, when I remove the vacuum line to the FPR it goes up to 40 psi. The fuel pressure with the ignition on, engine off was 20 psi at first but I don't think it was tight enough (lots of fuel leaking from the gauge) so I put Teflon tape on it and it was 35 psi ignition on, engine off. I replaced the thermostat and discovered that the pigtail to the coolant temp sender was broken so I will replace that. It didn't seem hot at all even after 15 minutes of idling. (I stuck my multimeter in the plug for the coolant temperature sensor and it was getting voltage so I don't think that is an issue.)

I turned the hard idle screw in where it was originally (too far) and I got it to start, so I turned it back in until it was barely touching the plate. I cleaned the IAC with carb cleaner and put it back and while I was idling it this morning (doing a radiator flush) I pulled the cable to it and but it still had no effect on the idle. I had an issue with dieseling when I shut it off this afternoon and I couldn't get it to quit so I pulled the battery cable thinking it might help - it didn't but it stopped eventually. However, when I was doing the fuel pressure test a couple minutes ago I pulled the IAC just to see and sure enough it dropped the idle and nearly stalled out. Maybe pulling the battery cable let it relearn things? I don't know.

SO - I have a new IAC waiting for me at the parts store as well as a new pigtail for the sender. I am not sure what exactly the fuel pressure readings mean so if you have any idea it would be greatly appreciated. I feel like you guys are on the right track, just not sure what to do next. I put the new pigtail on but it wasn't an exact fit, I forced it on the sender and I still got nothing on the gauge. Im gonna ground it tomorrow and check again in case the connection I made wasn't crimped enough, the only other thing I can think is that maybe the sender somehow isn't grounded which doesn't seem likely.

Fuel pressure seems about right. If you pull the vacuum line with the engine idling, the pressure should bump up.
If you ground the gauge sender wire, the one on the drivers side of the block above and rearward of the oil filter, the gauge should peg at HOT immediately.
If it does not, either the gauge or the voltage regulator on the back side of the cluster is defective. The fuel gauge uses the same regulator, so if it works, the likely problem is the gauge.
The hard idle should be just enough that a hot engine MAY idle at ~500 rpm, but will want to stumble & die. The IAC should control the idle to ~750 rpm when hot in neutral.(manual transmission) It should bump for cold engine.
tom

Thank you both for your help, it is definitely improved from where it was. The gauge is fine, I grounded the original pig tail but the elbow was cracked so I had to press the metal together. The sender is new but the last one was corroded around the threads so when I drain the radiator flush again I'll scrub the hole (is there a technical word for that? Lol) and hopefully it will work. It is such a pain to get to though.

I will replace the IAC since I have a new one and then will go from there. I'm not off until Saturday so Ill get a break from this headache. Thanks again!

Good to hear and thanks to Tom for chiming in..

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