Hesitation on an incline

On to the next issue with my wife’s 1997 standard shift Subaru Outback… Pointed up an incline the car hesitates when starting from a full stop in 1st gear. I’ve experienced this in the very few times I’ve driven the car. My wife claims that it happens every time she is pointed up an incline when the car has 1/2 tank of gas or less.

I’ve run fuel injector cleaner through it and checked the air filter. I haven’t changed any fuel filters yet. The incline and gas level makes me think it may be something with the tank. Any thoughts?

It might be something with the tank. The fuel pump pickup might be toward the front of the tank such that when the car is pointed up a steep hill the fluid pool’s top surface is just on the brink of leaving the pump pickup dry. It’s possible that when the car is started the vibration raises the level just enough to get “over the hump”. Agitated (vibrating) fluids take up more space than fluids at rest.

The simple solution is to keep the tank over 1/2 full.

could this be a classic symtom of a slipping clutch?

Or perhaps even a “hillholder” feature? But if so I’d expect the symptom to be in evidence regardless of the gas level.

We have a few Subie guys here. Perhaps one of them can shed some light.

My wife is freaking out thinking it is the timing, meaning timing belt. The car is new-to-us and we don’t know if the timing belt has been replaced (141k miles, I would hope so), but I’m not familiar with timing manifesting by hesitating on an incline.

I really think that you and your wife have misplaced priorities. Rather than worrying about hesitation in one particular set of circumstances, you should both be worrying about the financial implications of a snapped timing belt on a car with an “interference” design engine.

An old timing belt will not manifest any symptoms until the milisecond after it snaps, at which time the engine of this car will emit a “clunk”, and the car will coast to a stop. Some valves will have collided with a couple of pistons, and you will then need ~$2k for engine repairs–over and above the cost of a new timing belt.

Right now you don’t know whether the timing belt has ever been replaced, but you “hope so”. For your sake, I hope so also, but I would not be as trusting. Unless you can afford the costs noted above (plus the possible safety implications of losing engine power, power steering, and power brake boost while cruising on the highway), I believe that you should have the timing belt, water pump, serpentine belt, and all belt tensioners replaced at the first opportune moment.

After you have squared that situation away, then you might want to pursue possible causes of the hesitation–which has nothing to do with the timing belt.