First off, I'd like to say Hello. I didn't see an introduction section, so hopefully this is alright. I've inherited a 94 Explorer with the 6 cylinder motor that has an issue that is driving me crazy.

On occasion when the motor is hot and I try to crank it up to go again is when I get the problem. Like when you drive to a restaurant, eat and then come out and try to leave.

The motor will crank no problem, but then will idle extremely rough at 500rpms and under. Pushing the gas pedal has no effect, and after about the 30 seconds it dies. Try to crank it again and the exact same thing happens. When I get out and walk around the vehicle the smell of gas is in the air. Just my simple minded idea, but it seems to me that it's choking it's self out. Let the motor sit 2hrs or so and return and it cranks up just like it should.

Now this only happens maybe once per week so it's a rare problem, but really annoying. I have taken it to my mechanic several times and he is so busy he doesn't have time now to really explore the issue. Last week he put a new fuel filter in and told me to bring it back if it happened again, and tonight I got stranded. I am planning to try a new mechanic later this week.

On another note, gas mileage has dropped from about 17mpg's last fall to 15.5 on my last few tanks. Is this normal for my model explorer? That seems like an indication of a problem to me and I hope this vehicle will get better than that.

Thanks for the help and sorry for the long first post, I am a little bewildered at the moment.

ETA: No check engine light

 

The first thing I would do is pull the codes - ask the computer what it thinks is going on. You can borrow a code reader for free (in their parking lot) at some auto parts stores (Checker/O'Reilly's at least, possibly also Auto Zone).

The computer may or may not know about the situation, but you shouldn't be smelling gas and the sudden drop in MPG is an indication that something's up.

BTW "crank" means turn the key, the starter motor turns, connects with the engine, and rotates the engine. Nothing more.

With any luck, the engine then starts.

 

ctubutis,

I have tried to get the codes read at the local autozone in the past but they say my explorer is older than they can use the handheld scanner on. I have been told to get one of the blinking scanners from autozone, but I never knew how well that would work.

 

You need an OBDI (on-board diagnostics version 1) do you have a Checker/O'Reilley's near you?

If you're inclined, here are instructions for doing it yourself:

Ford Fuel Injection » How To Run a Self-Test
Ford Ranger/Bronco II EEC-IV Testing

 

An ODBI code reader is not very expensive and is the most handy tool in your toolbox when you own a 94 Explorer. I own a 94 Explorer and had a lot of problems which I chased for two years. Changed out every possible engine control item. Cleaned every wire connection associated with engine control. Measured every voltage associated with engine control.

After changing the fuel filter and fuel pump I still had to prime the fuel system at times - key on and off for at least 3 seconds each time sometimes up to 8 times. It would also start with a low, rough 500 rpm idle, IAC not working, and exhaust would smell very rich.

You can read my solution to the many problems I experienced at this post:
New Life For An Old Explorer

 

One of the first things I like to recommend for hard warm starts like yours is to check the fuel pressure regulator. There's a diaphragm inside the regulator that often develops leaks, which then allows unmetered gasoline into the intake, effectively flooding the engine. To check, next time it is hard to start, pulll the vacuum line off of the FPR and check for gasoline. Any gasoline in the vacuum line means the FPR is bad. If that test proved negative, I'd probably put a fuel pressure gauge on it and see if the FPR was stuck closed, causing the fuel pressure to be too high (obviously tested when it is hard to start).

 

When was the last time this engine enjoyed a full tune up?????

 

Before this most recent visit to the shop, I couldn't tell you. I have been driving it since last august and slowly working on changing fluids, filters and what not myself. I had a different shop take a shot at finding the warm start issue and while it was there they did a partial "tune up".

I bought new spark plugs and wires to install tonight when I pick it up. Also picked up haynes repair manual to help me do other maintenance I wasn't sure about. This explorer has seen so many mechanic's, I decided they don't know much more than me.

This most recent mechanic told me he couldn't work on it until it messed up which I understand, but he said to look into the idle control on top of the motor. Any one know if that could be a possible cause?

mrshorty,

Thanks for the tip. Now I just need to drive it and wait til it has an issue. I checked at auto zone and a new FPR is only $100 so if that's the problem I would be happy.

 

The Idle Air Control (IAC) servo is a valve that allows air to bypass the throttle plate. Since you mention in your first post that when it has the low, rough idle, pressing the throttle doesn't have an effect, I doubt the IAC is the issue as it would be doing the same thing as a functioning IAC.

I'd normally suggest checking things like the engine coolant temperature (ECT) sensor and for vacuum leaks, but since it seems so intermittent, an ECT sensor doesn't seem a likely candidate. Any chance one of the shops you frequent has a OBD-I scan tool that will allow you to monitor sensor datastream? Ford didn't have the best datastream capabilities in the OBD-I years, but at least by 1995 datastream was available. It may have been in 1994 as well.

-Rod

 

Shorod, If the FPR doesn't fix the problem I will ask the local mechanics about the obd 1 datastream. Just curious what that is? I haven't heard of datastream before.

The more I think about it and read on the FPR, I am feeling like that is where my issue is. Problem is, I haven't had the idle issue since picking my explorer up from the mechanics this week end and I am planning to replace plugs and wires this week. I am thinking while I am replacing plugs and wires I could swap the FPR out without to much trouble.

Would it be pointless to swap that out until I am able to pull the vaccuum hose and check for gas, or being 15+ yrs old is the FPR something that should be swapped? Out of curiousity, what color should my FPR be from the factory? The one I have on it now is what I would call a black color, and the ones I have seen for sale online are all a silver or bronze color.

 

The simple visual check for a ruptured FPR is always backed up with a full fuel pressure test with a gauge connected to the fuel rail..10 min and you know for sure....Philip

 

The datastream feature of the scan tool allows you to monitor sensor values realtime. Depending on what values were available for your 1994, you may be able to monitor what the oxygen sensor values are, the battery voltage, spark timing, etc. Maybe one or more of the values will stand out as being out of expected range and point towards a likely issue.

As for the color of the FPR, I cannot speak to that. If the FPR is inexpensive enough, it may be worth changing it as preventive maintenance even if the original isn't bad. The color is probably just a difference in who manufactured the one you are purchasing, but sometimes Ford will improve a design and suggest one style over another for reliability reasons. You'd probably need to check for Technical Service Bulletins on your truck to know if that's the case here.

-Rod

 

Idle issue happened again yesterday and today.

Pulled the vaccuum line off of the FPR both times and no gas was present. Stopped by advanced auto tonight to get a fuel pressure tester kit, but they were out of stock. When this happens again I'll get a pressure reading.

Talked to another mechanic last night who said he would be willing to bet it's a stuck/ leaky fuel injector. Said everything I described could be symptoms of a fuel injector acting up. Any possibility to this, and will checking the fuel pressure indicate a problem with an injector?

Thanks

 

If you perform the fuel pressure system test correctly you should determine if you have a leaky injector......as the leakdown is part and parcel of the procedure.... Philip