93 explorer sport starting issues

93 explorer sport starting issues --- resolution page 5!!!!

Greetings folks! New user here to the forums. I'm running into an absolutely frustrating problem with my wifes 93 Explorer Sport. Scenario is as follows:

Car will struggle to start when cranked. I have put in a new battery so I know it's not that. When you crank it just won't catch. Typically is a LOT worse when it is colder outside (mornings) but its not limited to cold morning starts. I have put a fuel pressure gague on the rail and I know I'm getting pressure. It's on the low side, but still should be more than enough. I will sometimes turn the key to run 3-4 times w/out cranking just to be sure the fuel system is primed and all that too. I have replaced the fuel pressure regulator up at the rail and have verified with my volt meter that the TPS and IAC valves are working properly and getting the correct voltage. I have cleaned all the contacts and tested the ECU/Fuel pump relays as well. When i am actually able to get the car started pulling either relay causes the car to die. The strange thing is that when I do get the car started about half the time it stutters and sputters and acts like it is going to die and the other half of the time it just hums along. Usually after i can get it started re-starting the car is not a problem unless it sits for a few hours. On the road it runs/idles fine as well. Power is good and gas milage is to be expected for an older car. I'm just pulling my hair out on this one because there's no rhyme or reason to when or why it sometimes takes forever to start, sometimes it'll just crank off w/out issue. (this morning I cranked it probably 12 times and on the 10th crank it acted like it was going to catch finally but died. I was reading somewhere that the ECU itself could be going bad but I'm not getting a CEL or anything like that either.

Mine will do this every so often, maybe 1 in 8 cranks it will catch but then act like it's running on 2 cylinders for a few seconds then either dies or goes to normal idle.

I don't know what causes it. It used to be that it did it all the time until I replaced the injectors and now it's a rare occurrence. Seems to me that replacing the ECT & IAT helped a fair amount too. But you can test those with a multimeter. When it acted that way every time I went to start it, I got in the habit of pulsing the gas pedal while cranking and that would make it fire up reliably each time. See if that works for you.

It does sound like yours is behaving worse than mine ever did but do check the ECT & IAT. Also do a KOER test. Aside from that, I'm kind of stumped. I've been thinking in the back of my mind to get ahold of another ICM to test. My gas mileage is on the poor side, a pinch above 14 where people seem to get 18 relatively easily. The engine also knocks with regular gas easily and this weird startup issue is intermittent. I've done all the tune-up items you can do. A lot of posts on here talk about the ICM failing silently and causing all sorts of issues. Maybe it's the magic bullet?

natenkiki2004 said:

Mine will do this every so often, maybe 1 in 8 cranks it will catch but then act like it's running on 2 cylinders for a few seconds then either dies or goes to normal idle.

I don't know what causes it. It used to be that it did it all the time until I replaced the injectors and now it's a rare occurrence. Seems to me that replacing the ECT & IAT helped a fair amount too. But you can test those with a multimeter. When it acted that way every time I went to start it, I got in the habit of pulsing the gas pedal while cranking and that would make it fire up reliably each time. See if that works for you.

It does sound like yours is behaving worse than mine ever did but do check the ECT & IAT. Also do a KOER test. Aside from that, I'm kind of stumped. I've been thinking in the back of my mind to get ahold of another ICM to test. My gas mileage is on the poor side, a pinch above 14 where people seem to get 18 relatively easily. The engine also knocks with regular gas easily and this weird startup issue is intermittent. I've done all the tune-up items you can do. A lot of posts on here talk about the ICM failing silently and causing all sorts of issues. Maybe it's the magic bullet?

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Interesting about the injectors. It does smell like its running really rich once i get the car running. Perhaps they are letting too much fuel through. I can try to replace the TPE and IAC sensors but since they tested within voltage range for function I don't think I need to. When you say ICM is that something like the ECU?? I'm half tempted to "borrow" the ECU out of my dad's 93 explorer and drop it in the sport to see if it makes any difference. However its an XLT and 4x4. Will that harm anything?

Test the ECT & IAT sensors, they're the 2-wire round ones on the driver's side of the engine. They measure engine & air temperature for fuel mixture, they'll drastically affect how the engine runs.

As for the ICM, they should all be the same as long as the connector fits. You should even be able to snag one off of a Mustang or F150 of the era. They just figure out the timing and spark for the ECM.

Running rich smell? First thing that comes to mind is fuel pressure regulator (FPR) --

I'd change the fuel filter first though, since that's easy and cheap.

If none of that did it, I'd suspect the pump at the tank. Check its connections.

Rhett said:

Running rich smell? First thing that comes to mind is fuel pressure regulator (FPR) --

I'd change the fuel filter first though, since that's easy and cheap.

If none of that did it, I'd suspect the pump at the tank. Check its connections.

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Aleady changed the regulator. That was one of the first things i changed.

Pressure is in the low acceptable range Or at least I think its acceptable when starting even when it's sat over night. 30 or so PSI on the guage. so I don't believe it is the fuel pump or regulator. Key on engine off it stays at 30 for quite some time and doesnt bleed off. It almost acts like its flooded especially since it smells rich at start. If my injectors are leaking into the cyls it could account for the hard to start problem.

natenkiki2004 said:

Test the ECT & IAT sensors, they're the 2-wire round ones on the driver's side of the engine. They measure engine & air temperature for fuel mixture, they'll drastically affect how the engine runs.

As for the ICM, they should all be the same as long as the connector fits. You should even be able to snag one off of a Mustang or F150 of the era. They just figure out the timing and spark for the ECM.

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Already did that as well. I've tested the throttle position sensor as well as the Idle air controller sensor with a volt meter and they test within spec. I cleaned out the IAC valve as well just to be sure. disconnecting the plug from teh IAC nearly kills the motor so I know its working properly.

Could the Mass air flow sensor be causing hard start issues though? This seems to be WORSE when cold and less bad when warm. I just went out at 430pm and its about 80something outside and it cranked over two times and fired right up. This morning at 730am at 60something degrees i cranked it 12 times and couldnt get it to catch.

Sorry but I gotta make sure; You've already tested the ECT & IAT sensors? They're the Engine Coolant Temperature and Intake Air Temperature sensors. Totally different than the Idle Air Control Valve and Throttle Position Sensor.

The ECT & IAT are known failures at the age our Explorers are.

natenkiki2004 said:

Sorry but I gotta make sure; You've already tested the ECT & IAT sensors? They're the Engine Coolant Temperature and Intake Air Temperature sensors. Totally different than the Idle Air Control Valve and Throttle Position Sensor.

The ECT & IAT are known failures at the age our Explorers are.

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No I havent tested those. sorry I misunderstood what you were asking. Is there a guide on how to test those?

If its related to temperature I would lean to the MAF or ECT. It sure does sound like an ignition problem. If it smells rich, it could be retarded timing. It sounds like your fuel system is fine, 30 psi is plenty. I would clean the MAF good, replace the coolant temp sensor, and if that doesn't work, look into the ICM.

SFCRangerDoc said:

No I havent tested those. sorry I misunderstood what you were asking. Is there a guide on how to test those?

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They're both 2-wire sensors, test the resistance of those two pins in the sensor and make sure the reading is close to what it should be:


When it's bad, you'll know it, it'll be tens of thousands of ohms off.

2stroke said:

If its related to temperature I would lean to the MAF or ECT. It sure does sound like an ignition problem. If it smells rich, it could be retarded timing. It sounds like your fuel system is fine, 30 psi is plenty. I would clean the MAF good, replace the coolant temp sensor, and if that doesn't work, look into the ICM.

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Thats the maddening thing with this. It sounds like so many things. I drove the car tonight, it started after two cranks...drove around for 30-40 mins...idles smooth as glass, runs good, etc. stopped for an hour at the gym and came out it fired right up no problem. But, I guarantee you tomorrow morning i'll go out after sitting all night and it will crank and crank and crank and then sputter start and run rough for the first half mile or so of driving and then be fine.

So this morning my wife went out and it fired on the first crank. It was just as cold as yesterday morning. ARRRRGH there is 0 consistency on this stupid problem. Hopefully will get to test those other two sensors this weekend.

SFCRangerDoc said:

So this morning my wife went out and it fired on the first crank. It was just as cold as yesterday morning. ARRRRGH there is 0 consistency on this stupid problem. Hopefully will get to test those other two sensors this weekend.

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That is so inconsistent. Are sure you don't have a wire shorting out somewhere?

Rhett said:

That is so inconsistent. Are sure you don't have a wire shorting out somewhere?

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It always could be...but i wouldnt even know where to begin looking for that...ugh

I currently have the coolant temp sensor and the air charge temp sensor on order from amazon. I guess 30 something bucks cant hurt to try. Next will be the MAF...then im once again out of ideas

A poor mans test is to unplug the sensors one by one. It might take a while, but it works. If the problem goes away, you found the problem.

SFCRangerDoc said:

It always could be...but i wouldnt even know where to begin looking for that...ugh

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I'd check
alt-to-batt positive terminal wire
fuel pump, all wires
batt-to-ground
starter wiring

Make sure the pos terminal to alt wire is securely tightened...there is a nut on the back of most alternators. I've had those work loose, and sometimes it would run great, other times, not so great. Same with the starter...wire was arc'ing, and sometimes it started great, other times, badly.

Rhett said:

I'd check
alt-to-batt positive terminal wire
fuel pump, all wires
batt-to-ground
starter wiring

Make sure the pos terminal to alt wire is securely tightened...there is a nut on the back of most alternators. I've had those work loose, and sometimes it would run great, other times, not so great. Same with the starter...wire was arc'ing, and sometimes it started great, other times, badly.

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Sounds like a plan. I'll put the car up on jacks and inspect the wires this weekend and report back. I would assume the fuel pump wires are up on the top of the tank, yes? How best to inspect those?

The problem with the battery to starter & ground wiring is that you can't really inspect them without cutting them open. They can be corroded and/or burnt inside and you wouldn't know unless the corrosion was so bad it was bulging the cable.

If the engine cranks over just fine, I'd leave the big cables for another day.

SFCRangerDoc said:

Sounds like a plan. I'll put the car up on jacks and inspect the wires this weekend and report back. I would assume the fuel pump wires are up on the top of the tank, yes? How best to inspect those?

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I agree with natenk above, I wouldn't get into cutting into wires just yet.

I would simply make sure the connections were securely fastened -- which is easy to do and fast.

Fuel pump area is a little tough to get to. If it were me I would not mess with it at this time, either. If your connections to your starter and alternator are secure, then you can start working toward those tougher areas. i would tighten the starter connections and the alternator nut...and see if that solves the problem.