Long cranks, hard to start, intermittent codes P0352 and P0353 display

I wish you had come here before wasting so much money on the wrong parts. By now you've figured out replacing random parts is the least effective and most expensive way to diagnose this.

By far the most common cause of a long crank time is fuel pressure dropping off over a few hours or over night. It should hold for weeks. Dropping fuel pressure can be caused by a leaking fuel pressure regulator, a leaking check valve in the fuel pump, but by far it's more common to be caused by a leaking injector. It only has to leak a couple of tablespoons of gas to bleed the pressure to 0 psi.

When you try to start the engine, the Engine Computer runs the fuel pump for one second when you turn the ignition switch to "run", then the pump turns off until you start to crank the engine. That one second is supposed to be enough to get fuel pressure back up to 50 psi in case it bled down a little. That one second is not enough time if it bled down to 0 psi.

To add to the misery, once you start cranking the engine, the high current drawn by the starter motor draws the battery's voltage down to as low as ten volts. That low system voltage means the fuel pump is running slower than normal. Additionally, what little fuel is being supplied by the pump is being used up by the injectors faster than it can be supplied, so fuel pressure never builds up high enough for the fuel to atomize out of the injectors. (Liquid gas does not burn. It has to be in vapor form to burn, and high pressure is needed to make that occur). You're fighting low fuel volume. and low fuel pressure as long as you're cranking the engine.

The proper diagnosis is to remove the fuel injectors still connected to the fuel rail, flip it over, then turn the ignition switch on for at least one second. Then watch to see which injector(s) become wet at their nozzle. A far easier way to approach this is to simply turn the ignition switch to "run", wait at least one second, then turn it to "crank. That will give the pump time to run under full 12 volts to build some fuel pressure. If that doesn't help, turn the ignition switch to "run" for one second as before, then turn it back off after at least one second. Turn it to "run" a second time, wait one second, then crank the engine. That will give the pump two seconds which should be enough time to build sufficient pressure.

My daily driver is a '94 Grand Voyager with the same 3.3L engine. I'm in the habit of listening to the pump turn off after one second, then I crank the engine.

You can also verify this by connecting a fuel pressure gauge and watching what happens to fuel pressure over time. You can look at this article:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

to see how that is done. Most auto parts stores have tools to borrow or rent so you don't have to buy this expensive set. In my city, they make you buy the tool, then you get a full refund when you bring it back. If you choose to keep a tool, you can still return it, then they'll order you a brand new one.

We're going to need to connect a fuel pressure gauge to the test port on the fuel rail to see what's happening. An injector can't leak that fast. At a minimum, it will take a couple of minutes to bleed the pressure down to 0 psi.

I was involved with two vehicles that did lose fuel pressure almost instantly. One was on a brand new Intrepid on the showroom floor. It turned out to have a cut o-ring around the nozzle on the fuel pressure regulator, right from the factory that way. Ten cent part solved the problem. The second one was on a customer's Dynasty that was in for an oil change. I popped the regulator out and found a similar cut o-ring. With that knowledge, I was confident in my diagnosis, but the owner declined the repair. I guess he enjoyed the long crank time.

We can figure out if we're on the right track by watching how the pressure gauge reacts. If it starts out at 0 psi, jumps up to, . . . oh, . . . say 10 - 20 psi when you turn on the ignition switch, then falls right back down to 0 psi, try that again after using a hose pinch-off pliers to pinch the fuel return line. That's the smaller of the two fuel lines. If the regulator or its o-ring are leaking, pressure will hold once that return line is blocked.

If fuel pressure jumps up from 0 psi, then stays there for a good 20 - 30 seconds, turn the ignition switch back off, then to "run" a second time. Fuel pressure should pulse up higher, then stay there. It is possible that by turning the ignition switch to "run" just once, that may not be enough time to get the pressure high enough for the fuel to atomize out of the injectors.

One thing to be aware of is starting with the redesigned '96 models, the starter relay is controlled by the Engine Computer, and that will only allow operation of that relay three times. After that, it assumes the engine should be running, so it will not allow the starter relay to turn on for the fourth attempt. If you try to cycle the ignition switch too many times, it will stop working until you wait a little while.

If you find fuel pressure either has been holding at around 45 psi or higher, or it jumps there as soon as you turn on the ignition switch, the failure to run is not fuel pressure-related. For that we'll need a scanner to look at other things. Without a scanner, you can start the diagnosis by monitoring the automatic shutdown, (ASD) relay. An easy way to do that is to connect a test light to any wire in that circuit. You can use a voltmeter too, but most digital meters don't respond fast enough. Test lights can also be seen from inside the vehicle. Look for the wire that is the same color at every injector, and the ignition coil pack. That's usually a dark green / orange wire. You can also use either of the two smaller terminals on the back of the alternator. You will see the test light turn on for one second when you turn on the ignition switch, then it will turn back off. What's important is it must turn back on when the engine is rotating, (cranking or running). If it doesn't turn back on right away when you start cranking the engine, we'll need to look at the crankshaft position sensor and the camshaft position sensor. It's the signals from those two sensors that tell the computer it's time to turn on the ASD relay. That's also when the fuel pump will be running.

For the benefit of others researching this problem, if you need help using a test light, check out this article:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester