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I'm trying to diagnose why my car doesn't start. Hope you guys will share some ideas for what to test.

First of all, the car started when towed by another car and holds idle, but as soon I press the gas pedal it dies. My first thought was that it's not receiving adequate fuel and indeed the pressure was too low. So I have changed the fuel pump. Afterwards, I checked the spark plugs. The pins were black and they had a weak spark so I changed them also. Then I started my car from pushing again and was able to actually drive it, but the same problem holds: when gas is pressed, the engine tries to die out, unless I press it VERY gently. Then it can actually rev up quite nice.

I also removed the tail pipe, thinking that the catalytic converter could be clogged and causing too much backpressure.

When the engine started the smoke wasn't black, but spew some flames, so it's indicating that it may be running too rich.

Starter turns over the engine.

Maybe you will have some ideas what to check and cross out next. Today, I'm planning to check the injectors for shorts and leaks. Thanks!

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    Did you check the fuel pressure after replacing the fuel pump?
    – tlhIngan
    Jun 6, 2017 at 6:15
  • I'm wondering if the timing belt slipped. You state there are flames coming out the tail pipe. This could indicate an early opening of the exhaust valve. This is really a SWAG out in the breeze, but it might be worth checking your valve timing, especially before you spend the money to replace anything else.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 6, 2017 at 14:21
  • If you haven't done so, change the fuel filters.
    – Steve Matthews
    Oct 4, 2017 at 12:50
  • Clogged air intake? More gas = more air needed to combust.
    – Spivonious
    Apr 2, 2018 at 19:33
  • Timing belt slipped makes sense. Another thought is the V6 Probes have two crank sensors. If the one on the bottom is damaged, the car will run but is very hard to start.
    – edt11x
    2 days ago

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Honestly, this could be so many possible problems. Do you have a CEL on? You'd have to use an obd1 reader to check for codes and auto parts stores don't test for vehicles pre-1996. Firstly, I second confirming that your fuel pressure is normalized after swapping the pump and address accordingly. The weak spark still bothers me. If your plugs were that bad, I wonder how old everything else is. I'd start checking your distributor cap and rotor, test your ignition coil and wires. I'm not sure if you changed those with the plugs but if I were you, I would. In addition to checking the ignition system and confirming the fuel system is good, you'll want to carefully inspect all vacuum lines. Check the PCV valve as well. Try to listen carefully for air leaks. Hopefully you've taken a look at the air filter as well. If all seems good with all of that, you will want to have a compression test done on the cylinders. By the way, if it idles without dying, you should let it idle until completely warmed up and see if the problem gets a little better. Your o2 sensors will respond better to adjustments after it's warmed up, so that might point to a bad sensor somewhere. (I'd try to check or replace your pre-cat o2 sensor anyway- who knows how long it's been.) Let us know what you find and good luck.

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