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themickel

Engine Starts Just Fine, But Sputters And Dies Eventually

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I was driving my 2000 Corolla on the freeway today when the engine started sputtering. It would go away, then come back, go away, and then finally the engine just shut off (while driving 50mph). The dashboard lights came on and the power steering/brakes went out. Pulled to the side and restarted it. Engine kicked on just fine, though it would die again as soon as the accelarator was pressed.

 

After 15 minutes it would drive again for a mile or so (was able to park it), but then the engine would shut off again. Will still start, but the engine dies before long.

 

Does anybody have an idea what is happening here? From what I've read, the possible culprit can be anything from spark plugs, MAF, ECM, or a clogged fuel injector. I'm hoping someone has had a similar experience and can possibly help narrow the field.

 

One other thing: about two weeks ago I filled up the gas tank and the same thing happened. After a 30 minute rest, it worked just fine again (until now). I'm assuming this is related.

 

Thanks for your help.

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Could be any of those listed. Hard to narrow down from this point, as you need to do a bit more diagnostic work to try and shorten that list.

 

Given the things that you saw in your post - this is definitely leaning toward the electrical side / possible ECM failure. Really need to car hooked to a Toyota Techstream tool and have it run all the checks on the ECM. Then do a driving test with data logger to see what the real-time sensor values are.

 

In the mean-time - things you should check first:

 

- Condition of the battery, battery cables, and chassis ground points. This engine is known to be extremely sensitive to electrical noise. Bad chassis grounds, poor connections to the battery, weak battery, etc. can all cause weird electrical issues - including those that might appear to be an ECM failure. Wouldn't be a bad idea to get the battery load tested - if it is more than 5-7 years old, might be time to just replace it.

 

- Check the conditions of the spark plugs, ie, read the plugs. Spark plugs are one of the quickest way to judge engine health. Depending on how the plugs come out - wet, dry, lots of deposits, color of deposits, physical damage, plug well full of water or oil, etc. - that would tell you a lot on what was happening. If in doubt and/or you have more than 100K miles on these plugs - just replace them with like plugs (Denso or NGK Iridium plugs).

 

- Do a quick visual inspection. Note anything that is leaking, fluid levels that are too low / too high, obviously damaged hoses, wiring, etc. If there is something obviously damaged or missing - that would help direct your initial diagnostic efforts.

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Okay, quick update:


I've checked the MAF, spark plugs, EFI relay, battery cables, fuel filter, fuel injectors, and used gas treatment. Have also done the visual inspection. None of these have done the trick.


My next step is to check the fuel pump, as I don't hear it activating when I turn the key to the "on" position. I'll first make sure it's getting electricity. If it is, it seems likely that the pump is bad.


Any other advice/anything I'm missing? Thanks for your time.

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I forgot to mention - before you get too far down the road buy parts / swapping parts in - I'd do a compression test first. Just to make sure that the engine has good compression. If compression is dead or low in any particular cylinder(s) - all this diagnostic work would be just wasted time.

 

As for the pump noise - this generation has a returnless fuel system - basically, pumps fuel only on demand. So there will not be that tell-tale "cycling noise" that you get with the older fuel injected setups.

 

But you can still diagnose it like the older ones. First thing I would check is for power running to the pump when the ignition is ON. Just pull up on the rear passenger lower seat cushion (just friction clips in the front), and the lower seat will pop right out, you'll see the wiring running right behind the driver's seat to an access panel on the floor. Just disconnect the connector, use a multimeter to check for voltage - I'd cycle the ignition on and off just to rule out an intermittent issue with the switch.

 

If that show good voltage - it is possible that the fuel pump itself might be dead or dying. These fully immersed fuel pumps generally do not go bad, unless you have a habit of running the tank as low as possible between fillups, or if you drive in a way where the fuel will slosh away from the fuel pickup (ie, autocross, SOLO cone bashing, etc.)

 

Fuel filter is actually inside the fuel pump assembly. Debris is usually stopped by the exterior "sock" filter on the fuel pickup. A feature of the returnless fuel setup is that it only filters fuel that will be used - so the fuel filter itself actually sees very little utilization, compared to other setups. Back-cycling feature also flushes out contaminants that would clog other filters - made to last the life of the car, unless you suspect the tank with something other than unleaded fuel (like diesel) or fuel that was heavily contaminated with water, etc.

 

Great job so far - given all the steps you've done so far - you've pretty much got it narrowed down to potentially the ECM or fuel pump. Hopefully, it will be a case of a bad fuel pump, unusual for this generation, but not unheard of. If pump checks out - leaves the most expensive item on your list. The ECM is a little trickier - might be worthwhile to check on Ebay or your local pick-and-pull to see if you can get your hands on a cheap ECM. I've seen then go for under a $100 - dealership will ding you for about $1800 if you go that route.

If the ECM doesn't do the trick - then you are left with back-tracing the wiring, possible bad crank / camshaft / TPS sensors, etc. Possible VVT-I system failure (timing locked to something funky).

Edited by fishexpo101

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Great advice. Thanks, Fishexpo101.

 

I did the electrical test yesterday and found that the pump is getting power. I have a new pump ordered, but in the meantime I'll go ahead and do a compression test.

 

Like you said, if these don't work the next culprit is probably the ECM. I know they're expensive, but at this point I'd be ecstatic just to know what the problem is.

 

I'll post an update later.

 

Thanks again!

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UPDATE:

 

Installed a new gas pump today. While replacing it, I noticed there was a tear in the casing of the fuel pump connector wiring. It was about 1/4 long and the wire was exposed. It was apparent that it had been there for a while.

 

Anyways, I sealed it up with a heat shrunk butt splice, put in the new pump, and so far the engine sounds great. Took it out on the highway and it appears to be running smoothly once more.

 

But now I'm wondering--was the problem the tear in the wiring case or the fuel pump?

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Great to hear that is up and running. As for your question - entirely possibly that it could be both.

 

Hard to say with electrical components/wiring - exposed wiring is always a bad thing and can cause you all sorts of headaches.

 

How it affected the pump? Harder to say. It was designed to for a certain duty cycle - depending on how the wire shorted, if it actually shorted out on anything. There is a chance that the original pump is still good - but since it is working now, I'd just stick with the new pump and keep the old pump as a spare.

 

I'd just make sure that the repaired wiring has plenty of strain relief and not actually touching anything. Pretty easy to check on the wire condition - so might be worthwhile to check on it from time to time - just make sure it doesn't pull from the splice or other sections of the insulation peels off.

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