1999 Camry four cylinder. Occasionally on cold starts, runs a minute or so, dies then won’t start. When not starting, acts like low fuel pressure or bad fuel pump. Fires occasionally, but only rarely.
I replaced the fuel pump (decidedly not fun) pronounced it fixed, drove it myself for a week, handed it over to my wife. And it promptly died in the middle of the street after she backed out of the driveway.
So, I grounded the #@)*@$# thing and backed it up to the top of the driveway (so I could coast back down when it died) three times a day for a week. Finally, after 18 flawless starts, it took a long time to start one evening. Next morning, it took even longer to start and died in driveway. Can hear fuel pump running, but no start. OK, I can quit worrying about the (rather excessive IMO) electronics in the fuel pump circuit.
Set up the PC based OBD2 reader. No codes. Put a fuel pressure gauge on it. Once I got it started, Fuel pressure was 50psi. That’s fine. Still no codes, and all the sensors I can read with the computer seem reasonable. One odd thing. Once the car warmed up, the idle cycled between 700 and 1000 rpm every 6 six seconds. Can’t help thinking that if I were smarter, that would tell me a lot.
Next day, with all the test gear removed, it started fine, and idle did not cycle as it did the day before.
I guess I’m going to clean the idle air control and everything near it as they seem to be a problem on these cars. But if anyone has another idea, I’d sure love to hear it.
I would look for a vacuum leak somewhere. If you can’t find a cracked hose of fitting, try spraying carburetor of fuel injection cleaner all around the intake manifold gasket and throttle body gasket and look for a change in the idle.
If you feel the gas pedal sticking when trying to step on the gas, you may need a throttle body cleaning.
Check the TPS (throttle position sensor).
There should have been fuel pressure BEFORE the engine starts. Install fuel pressure gauge, turn ignition key to RUN (ON), and observe the fuel pressure. If there is no fuel pressure, turn the ignition key OFF, then RUN position, for two seconds, several times. There should be full fuel pressure, and it SHOULDN’T fall off. Results?
Thanks, I’ll check it, but probably not the problem. The MAP sensor readout looked OK (but what do I know) when I had the OBD2 readout gear hooked up. I figured that almost any vacuum leak would trigger a code of some sort.
Not on this vehicle. The fuel pump doesn’t start until the starter is engaged – by design apparently. But anyway, I did check the fuel pressure when I had the fuel pressure gauge installed (another not easy thing – no Schraeder valve) and it held fine for hours. I have the back seat out and can hear the fuel pump. Barring a failure of the simple mechanical fuel pressure regulator in the tank I’ve somewhat reluctantly concluded that this isn’t a fuel problem even though it acts like it is.
That’s an idea. It would make sense for the TPS to do strange things with the idle speed. And that alternating idle speed thing meets my threshold for strange. But can the TPS cause hard start and/or stalling?
When you get a good idle speed, unplug the throttle positioner. If the problem doesn’t come back, you will know which system is at fault. You may have to press the pedal down a little and hold it to start the car.