Question

96 Ford Explorer Sputters to death

Hello, first time poster so please forgive any rules I may have missed.

My 96 Ford Explorer, 4.0L 6 cylinder engine with 238,000 miles on it. Been at least 75,000 miles since last tune up.

The issue: Sometimes (not all the time, but with increasing frequency) when I go to start my car, then engine will turn over then immediately begin to sputter to death. I was countering this by pushing on the accelerator just after it turns over, and this seems to be the only trick to make it start revving. However sometimes this doesn't work and it just prolongs the pathetic sputtering. I've been told that pumping the pedal a couple times before turning the ignition can help, and it did for a few days, but then it stopped working.

My theories: I was hoping it would be a cheap fix, so I replaced the fuel filter. The issue continued. My thoughts are that it's either a fuel pump issue, which is a bit out of my experience level, but I have friends to help me with. Or it might be a bunch of toasted spark plugs, as they haven't been changed in a long time.

Please keep in mind that it will still start most times. Especially when it's cold. For example I left to go shopping after not driving all day last night and it started just fine. Drove a mile to the store, did my half hour of shopping, then I went to leave and it wouldn't start. It would turn over almost every time, but then just sputter to death right away. Pumping the gas wouldn't help, just prolonged the sputtering. I let it sit for about 40 minutes while I tried to clean out the intake filter and look for any loose wires or plugs, then I tried one last time and it grabbed and revved and I got it home.

Any other thoughts would be greatly appreciated. I don't have a ton of funds so I really don't want to replace anything that won't solve the issue. If you have any questions, I'll do my best to answer them quickly. Thank you!

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Answer
Mileage, age are not going to be kind here.

It's definitely gone pretty far but if this was mine I'd have it down to my favorite mechanic for him to give me a diagnosis. There are simple DIY items that I'd look at such as just go ahead and replace the fuel and air filters while looking over all the vacuum lines to see what shape they are in. At this age you are likely to see deterioration or out right cracked lines.

Remember I'm not there so I will never claim any idea is "it."

There are also some models that a carb/inject system is failing but I like to start with simple DIY items first then move to fuel pressure checks and more.

The pump action does make me thing vacuum lines, fuel filter and delivery issues.

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No mechanic on hand

All of my friends are pseudo-mechanics. They know a bit but aren't professionals. Unfortunately my current financial situation makes it so professional diagnosis isn't really an option. I'm just looking for as many opinions as I can gather before making a decision on what to do.

Thank you for responding. When you say delivery issues, do you mean fuel pump issues? Or somewhere along the fuel line? Or both? >.<

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Remember I'm not there.

So these are just guesses with what clues we have. The age gives my pause over areas like vacuum lines, filters and fuel delivery. The fuel pressure test is how most fuel pump issues are discovered. It's cheap compared to replacing parts.

The fuel filter has a funny story. More than once I have handed out the old advice about just replace it and later find out they didn't, spent hundreds on diagnosis and it was the filter. It's one cheap part and I think there are videos on it after so many miles. It's funny to mechanics since they won't test, check or such a part. We know if the answer is "never or don't know" we change it. That's a lot of miles and there are things that just need doing. Your choice of course.

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Answer
Poor starting

Hi, T-tech; A couple of things I caught in your symptoms; a. Starts good when cold; b. Seems to be able to keep running by holding the throttle open; Okay. We are dealing with a fuel injected engine, here.
Fuel injection depends on the various sensors, air temp and volume, engine temp, ect. There is no choke with fuel inj., so it depends on the coolant temp sensor to "tell" the computer that "I'm cold, give me lots of fuel", which it does. Conversely, when the engine is warm, the sensor tells the computer "just a little fuel, I'm already warm". Fuel pressure is a constant, so when you push on the 'gas' pedal, all that does is increase the air flow into the engine. So, you can pump the daylights out of the pedal, and it won't help in the least. (totally different than a carbureted engine). Back to the sensor; The whole problem could be this dreaded sensor. When the coolant temp. sensors go bad, they will usually revert to -41F. That works great...in you are in Fairbanks in February. LOL. When this happens, trying to start a warm engine causes it to get too much fuel and flood. Holding the throttle open, helps to compensate by giving the engine more...you guessed it...AIR.
With that said....With 75K on the plugs, yes, I'd recommend replacing them (normal maintenance). I'd also want to check fuel pressure. (most parts stores will rent a fuel pressure test kit). Also, as regular maintenance, I'd clean the MAP sensor, IAC motor, and throttle body. All three are very easy, and I'm sure there are YouTube videos you can watch, if your friends don't already know.
Good luck. If you have any further questions, I'll be here. Happy
Loren

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Sensors?

I ran the codes today and they said i need to fix an O2 sensor and that something is up with my catalytic converter. Does that tell you any more?

I'll look into cleaning all of those parts and I'll try to replace the plugs tomorrow. Which sensor are you talking about though? Specifically the coolant temp sensor? Or could it be any of them?

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Sensors

Hi, T-Tech; My main concern is the coolant temp sensor (CTS). Neither the Oxygen or Catalyst sensors would cause this particular problem. Neither of those come into effect until the engine is running, but don't ignore them. You could have an Oxygen sensor that is lying to the computer, telling it that the engine is too lean or too rich and that the Catalytic converter is not doing it's job.
The upstream O2 sensor looks at the downstream O2 sensor (via computer). If both are reading the same value, the catalyst is dead. Although very rare, I have seen a completely plugged catalytic converter keep an engine from starting, but there would have been 'signs' prior to that, usually. A poorly running engine can 'kill' a catalytic converter.
Fords are very persnickety regarding fuel delivery. The MAP (manifold absolute pressure) sensors get dirty and should be cleaned at every tune up. Easy to remove. There is a spray cleaner you can buy at any parts store. The IAC (idle air control) motor is also easy to remove and clean. When you do, make sure the passageways are clean, also. Being a computer dinosaur, I can't figure out how to post pics of these parts. aaaarrrrrggghhh. Several of the moderators have tried to explain it to me, but....
If you need any help, or more info, don't hesitate to ask.
Loren

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Same problem with my 96 Explorer

I replaced the fuel pump & filter...all O2 sensors and the Maf. Still sputtering after it's warmed up to the point of power loss (anything under 40mph) I can force it to go if I slam down the accelerator but it feels like a bucking bronco. It's not consistent and doesn't happen every single drive so I'm at a loss. It's not throwing any codes even when running rough. My guess is the injectors but I'm going the cheap route first and replacing the plugs and wires (been about 8 years since it was last done) this weekend (thanks dad for teaching this woman basic car repair) Temp stays in the mid range according to my gauge when driving. I'm chasing a ghost in this car at this point. Any other suggestions?

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