My car cranks but won't start until I press on the gas pedal

Maintenance/Repairs
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1

I have a 2001 volvo s40 1.9T. In the morning my car start up fine every morning. After it’s driven for 10 minutes then I turn off the engine. When I restart, it won’t start back up until I press on the gas pedal. Can someone help to give me some reasons to what might be the issue ? Thank you.

2

The problem might be with the Idle Air Control circuit.

In this circuit is a device called the Idle Air Control valve.

https://www.rockauto.com/en/moreinfo.php?pk=1354978&cc=1431484&jsn=351

This device controls the engine idle speed under all conditions by allowing air past the closed throttle plate on the throttle body.

So when the engine is started cold, the IAC valve moves to a certain position so the engine is at a higher RPM. Once the engine is warmed up and restarted, the IAC valve moves to a different position so the RPM’s are lower.

When you step on the accelerator, you open the throttle plate on the throttle body, which allows air into the engine and the engine starts.

Sometimes removing the IAC valve and cleaning it solves this problem. Other times replacing the IAC valve solves the problem.

Tester

3

Tester’s scenario is definitely a possibility.

Another is that a leaking injector makes the mixture too rich to ignite… Pressing the accelerator pedal admits a rush of air to the mixture, leaning it out enough to allow it to ignite.

Why this happens soon after the engine has been run, and not first thing in the morning, I don’t know.

1 Like
4

As long as you have figured out how to start it, why is it a problem?

5

When the engine is cold it needs extra gas to start. When the engine is warm, it won’t start if the mixture is too rich. It will act flooded. So if an injector were leaking, the symptom might well show up only when the engine was warm.

6

lol … that’s how I’d treat this problem , but I suppose not everyone is as flexible about work-a-rounds to avoid actually fixing the problem outright … lol … this from somebody who’s currently dangling bunch of led’s from the car’s ceiling as an alternative to repairing the dome light!

1 Like
7

If a workaround starting procedure works, and the underlying cause is not intermittent or getting worse, then there’s no harm in the driver going on using the workaround technique.

Problem moves to the foreground when someone else (spouse, child, friend) tries to start the car and does not know the workaround technique or recognize the need to try it.

My 1999 Honda sometimes needs a “key dance” [On-Off-On-Off before turning the key to Start in order to pressurize the fuel system especially when the tank is low]. If I ever sell it I will inform the new owner. In the mean time I hope my wife will remember this if she ever faces this rare starting problem…