More car trouble

[shooter76blue]

I think the thing that plugs into the top you are talking about is the PVC valve. Those have given me fits in the past...

[seamusTX]

A mechanic can test the fuel pressure and tell if the pump is bad without replacing it blindly.

You might even be able to rent the gauge at Auto Zone.

You need three ingredients to start a gasoline engine: fuel, spark, and compression.

The fact the starter fluid works confirms that you have spark

You could be lacking fuel because of dirty injectors or because the engine computer is missing a signal from something like the engine speed sensor. It is usually possible to read out the engine codes without the machine that shops use. It often requires something like turning the key from Off to Ignition twice quickly. You can find it on the web somewhere.

You could be lacking compression because the valves or rings are worn out.

I have found that a good mechanic can get to the root of these problems and save money compared to replacing parts that have nothing wrong with them. I've certainly made that mistake many times.

- Jim

[mr.72]

I had a Mazda 626 with similar mileage and it did the same thing, although I never tried starter fluid. I don't think that's usually necessary in a fuel injected car. In my car's case, it was the ignition module. In fact there is a pretty funny story that accompanies this particular car debacle but I'll leave that for later. However one symptom that would happen with this car that you don't describe is that it would die right out of the blue while it was running.

Also my Miata has had problems with the coil packs going out. Miatas have one coil per cylinder so it is not a binary run or no-run issue, but I would guess an MX-6 only has one coil. Ignition coils can be intermittent as well as the ignition module. In my Miata they are all one piece anyway (2 coils + two ignition modules in one unit, runs two cylinders, and costs $600 to replace).

Jim is right, if you have fuel, fire, and compression, it will run, in most cases. Unfortunately with modern cars, you have a fourth element, "computer", which may decide not to run the car for some reason. A gross vacuum leak in my H2O VWs would cause the computer to shut off the fuel (like if you pull a vacuum hose while the car is running, it dies instantly and won't restart). So there may be some failure mode that is not so easy to diagnose.

I wouldn't figure dirty fuel injectors are your problem, since the odds of 4 or 6 all going bad, intermittently, and synchronously, are pretty much zero. Likewise a compression failure is not going to kill the whole engine all at one time unless you broke the timing belt or something, or unless it's a rotary. You need to be looking for something that affects the whole engine all at once. Does the car have a distributor? If so, cap, rotor, coil wire. If not, ignition module, ignition coil. Does it have a fuel rail? If so, you may have bulk fuel failure like fuel pump or filter clogging. Could be an electrical connection to the fuel pump, and not necessarily the pump itself (corroded wiring, cracked insulator, bad connector, etc.). With 200K+ miles all of these things are suspect. MAF/MAP or whatever air flow sensor? throttle position sensor? coolant temp sensor? all of these things can cause the car to not start (car thinks the throttle is off, car thinks the engine is hot and doesn't apply start-up enrichment, car thinks there is no air so it injects no fuel, etc.).

[lunchbox]

sounds like you have an ether baby

[WarHawk-AVG]

What code does your car throw?

[Fangs]

I used to have a 1987 Toyota Supra with almost 200k miles on it. It would start / not start at its whim, hot or cold, sitting all night or just turned off at the gas station. I took it to four places, each of them claimed to fix it, only to have the problem start again as soon as I got it back.

I mentioned that it might be the starter to each place. They each dismissed it because it sounded like it was working just fine, but the engine didn't catch.

After blowing $100+ at each place, I finally followed the wires from the battery to the starter and GUESS WHAT?!

The bolt attaching the wire to the battery was loose, and covered in oil and dirt. So I cleaned it off and tightened it, and never had that problem again.


EVERYONE I talked to said if the starter's turning, then it's not the problem. They were all wrong. Not saying this is your problem, but it's close enough that you might want to check it.

[mr.72]

EVERYONE I talked to said if the starter's turning, then it's not the problem. They were all wrong. Not saying this is your problem, but it's close enough that you might want to check it.

No, they were not wrong.

Whatever the cable you traced down might well have been the problem, but if that was the wire supplying power to the starter, then it wasn't causing the starter to not turn.

However, you might be surprised how much bad wiring connections, loose or corroded connections, or corrosion that has run up inside the insulation on the battery cables can muck with the whole works of a car. Bad ground to the engine may cause it to never fire the spark plugs! I have seen problems like this a hundred times!

But if the starter is turning, then the starter is not the problem. If the cable that goes from the starter to some other thing happens to supply power or ground to that other thing, then tightening that connection may very well fix that other thing.

[flb_78]

I would put a fuel pressure gauge on it. The fuel pump is an electric motor. It may have a worn armature in it and if it stops on just right, it won't spin up. I had a Pontiac that the fuel pump went weak in. Supposed to have 8psi pressure but I only had 2 psi. That made for some fun driving times!!!!


Sometimes, when it's the fuel pump, you can hit the gas tank and jar the pump and it will start working again.

I could be the fuel pump relay as well. Too many variables to guess over the interwebz without seeing it in person.

[bdickens]

If you haven't already, STOP USING THE STARTING FLUID NOW! Never, ever use that stuff. It's a bomb waiting to explode. Ether is supposed to only be a cold-start aid for big diesel engines.

I really suggest taking it to a pro. You'll spend more up front, but end up spending less in the long run by replacing only the part that's bad. Swaptronics gets very expensive very fast, as you can already attest to.

I wish I could be more help, but without the car in front of me I'm only guessing.

[FlynJay]

You definitely have a fuel delivery problem. There really isn't that much between the fuel tank and the engine. But it could be an electrical problem with the fuel pump.

I agree to check the fuel pressure, but since you can't reliably repeat the problem you are going to have a hard time diagnosing the problem.

The car runs fine after it is started? If so that lends me to question the fuel pump relay.

Another thought - When you turn the key to the run position (before starting, when all the electrics come alive) do you hear the fuel pump firing up? My thought is that the pump is not priming the system and is only running when the engine is already on.

You need to look at the wiring diagram for your car, try to determine the electrical path for the fuel pump, there may be a bypass that keeps the pump running when the engine is on but is not there during starting.

Several engines have a fuel pump shutoff that is wired through a oil pressure sensor so that the fuel flow will stop if the oil pressure drops off.

Just a few thoughts. I would definitely stop randomly replacing parts. For every suspected bad part there is some sort of way to double check and get some confirmation that it is causing the problem.