Trouble starting, hesitation, and stalling


I have a 1991 Toyota Camry that has 100K miles and has been a great car with no major problems (and very few minor ones) until recently. A few months ago it started occasionally having trouble starting, always after I had not driven the car for at least a day. The engine would crank, but would feel as though it wasn’t getting gas. On the mornings it had trouble starting, it would then also sometimes hesitate, meaning that when I pushed on the gas pedal at low speeds, it would be as if I had shut off the gas rather than given it more. Over time this problem has gotten worse, so that it has trouble starting more often, and the hesitation also occurs more often, and is more pronounced, so that it has begun to stall at stops. It doesn’t stall as I come to a stop, just after I press on the gas pedal to leave from a stop. The check engine light comes on when it stalls, of course, but doesn’t stay on so, apparently, there is never a code written to the computer. Also, as this is intermittant, it (of course) never happens during the (now numerous) visits to the mechanic. Lately, a couple of times it has felt like it happened at high speeds, losing power briefly and feeling as though the gas is not being fed continuously to the engine.

Before all this started happening, I had put in a new distributor cap and wires. They have wet these down to see if they are bad, but without any effect. I have also used a fuel system cleaner, which seemed to help for a while, but then the problems started up again. Advancing the timing also didn’t help. I drove with the EGR valve disconnected for a few days, but that didn’t help either. And finally, I had the coolant temperature sensor replaced with a new one, but the problem is still there.


[b]Has the fuel pressure been tested? Because you describe the symtoms of a weak fuel pump.



Take a look at the adjustment and operation of the Throttle Position Sensor (TPS) and the Manifold Absolute Pressure (MAP) sensor. These and the Coolant Temperature Sensor (CTS) are the key sensors that the computer looks at in open loop operation which occurs during startup, acceleration, and full throttle operation.

Its too bad that the mechanics scanner cannot read the engine data because that would give a window into the operation of the sensors without having to unplug, back probe, etc., to measure everything.

Let us know what the outcome is and what the mechanic finally replaces to fix the problem.



The fuel pressure hasn’t been tested, I’ll ask about it. But for that to be helpful, wouldn’t the car have to act up while it’s in the shop? It never has.