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Intermittent Warm Start Problems

2003 Ford Focus automatic - 50K miles.

The car has been experiencing intermittent warm starting problems for about a year now in warmer (60F+) weather.

The car always starts fine in the morning, and has never stalled in traffic. However, the car will sometimes not start after running errands over a few hours (e.g. going from store to store with about a 10 minute drive in between, then parked for 1/2 hour.) When I come back out to start the car, it turns over, but then sputters out and stalls, unless I keep my foot on the accelerator. As soon as I take my foot off the gas it stalls. If I leave the car alone for an hour or two (or, the time it takes to get it towed somewhere,) it starts up just fine.

on two different occurances of the problem, y mechanic has replaced the fuel filter and coolant temperature sensor. He has checked for hose leaks, cleaned any corrosion off leads, checked spark plugs, etc., He is very hesitant to just start throwing parts at it, as am I.

No codes are turning up, and the car runs well (when it starts!) No check engine lights.

It’s kind of crazy-making (and, making me look more crazy than usual.) Any ideas? Thanks for any responses.

Does The Focus Have The 2.3L Engine ? When Warm And It “Acts Up” Does It Have To Crank Over For A Long Time Before The Engine Fires Up ? Does It Have To Crank Long When Cold ?


The fact that your foot on the accelerator will keep it running at these times suggests a flooding condition. You very well may have a leaky fuel pressure regulator or fuel injector dumping fuel into the motor when the car is off. Have the mechanic check these things.

no, it cranks up pretty much as “normal” warm or cold. it doesn’t take a long time before the engine fires up.

thank you for your response. I will definitely suggest both these things.

and yes, 2.3L

I have pretty much the same problem on my 2001 focus ZTS manual 93k miles. The problem happens rarely up here in Maine. To start it I have to give it gas, and it never starts on its own. I have to give it gas so it won’t stall as it runs, and I can use it when it happens but if I let it try and idle on its own with no gas it stalls. I’m pretty sure that the fuel gauge will under estimate how much gas I have when this happens. I remember maybe a year ago when it happened the check engine light was on for the mass air flow sensor. The MAF is not dirty, and the throttle body and idle air control have been cleaned. No CEL.

I think that in general when I start it, it seems like it takes a second for it to actually start once the starter is done cranking the engine. I’m in school for auto tech so I’m DIY although I haven’t taken engine performance yet and I’m no pro. I’ll check the regulator and injectors with a gauge. Do you know what else it could be?

in addition to what has been mentioned, Googling has turned up possibilities of:

  • crank position sensor, ignition module or the wiring between the two
  • air intake temp sensor
  • EGR
  • cracked hose
  • O2 Sensor or throttle position sensor (TPS)
  • leaking intake gasket
  • cold start valve
  • water in gasoline
  • vapour lock

the stalling hasn’t happened in a while for me. when it happens again, I’m going to suggest the fuel pressure regulator be replaced and the fuel injectors checked. the next thing I’m leaning towards is the IAC valve.

good luck!

Tell your mechanic to put a fuel pressure gauge on it, run it / drive it until it is fully warmed up, shut it down and watch what happens with the fuel pressure as it sits and then as it is restarted.

thank you. will do.

We had an intermittent warm start problem on a 03 windstar. I had the wife stop by the dealer every time she passed by as after 2 tows when they got to it it started right up. If we let it sit 45 minutes it would start fine. It failed to start at the dealer one time, they were on alert for the intermittent problem, and had done due diligence but could not replicate the problem. An analysis while in failure mode turned up a bad fuel pump that was replaced 3 years ago and no problems since.

thanks - it could be. it stalled once for me in traffic when it was new in 2003, and the fuel pump was replaced at that time.

it happened again yesterday. once towed, it started fine. the mechanic ran different tests, including checking the fuel pressure. everything checked out ok. the mechanic was about to give up yet again, but this time when the mechanic went to back it out of the bay, it wouldn’t start for him. a different mechanic came over to the car to help him. they honed in on the throttle position sensor (TPS) and ran some sort of test device on that. they ended up adjusting the TPS and the car was able to start right up with the adjustment. I’m afraid I don’t know of anymore technical details, or a better way to describe it. I do hope that does the trick though.

I have a similar issue and also have had instances where the car has started but when I have had to decelerate on the highway and I get below 35mph the lights in my dash all light up, my power steering goes out, and my car just turns off while I am driving. I have to throw it in neutral to restart and keep my foot on the gas to keep from stalling until I can get off the highway. Have had several problems with the Ford dealership where I purchased the vehicle and am looking for any information as to what the problem may be.

Replace the fuel pump.

Another thing to check out is the idle air control (IAC) valve - at idle and/or with your foot completely off of the gas pedal its job is to send the right amount air into the intake past the closed throttle plate. Various issues (wiring problem, carbon buildup) can have it stuck closed once in a while. The fact that keeping your foot on the gas will keep it going fits b/c your foot is doing the job of the IAC. (Your “gas” pedal is really an “air” pedal).

A fuel delivery problem is also perfectly plausible - a fuel pressure gauge would tell you about that.

Pretty perplexed, did you ever find a solution to this problem? You described exactly what my car has been doing for the last couple of years (and what it’s currently doing now). My mechanic hasn’t been able to figure it out.


The way we found our solution was to stop by by the shop, every pass by and they were on alert, as after being towed to the dealer twice it started right up. Wifey stopped by, no start, they jumped right on it and found a bad fuel pump, diagnosis in failure mode is the best answer.

Warm start problems (as opposed to no-crank problems which are caused by other issues) are usually something electrical, fuel pump, ignition module, crank position sensor most often. A shop might be able to set you up so you can test for spark yourself when it happens. If it is sparking ok, cranks fine, but it won’t start, might want to just take a flyer and replace the fuel pump after first verifying the fuel pump wiring and fuel pump relay look ok.