Here’s my problem: My 2002 Focus SE (Wagon) with the Zetec engine will not run when weather is cold—20 degrees or colder. It will start just fine but will not keep running. This is a cold weather only issue.
EXAMPLE 1: When I park outside and car sits in cold overnight, it will start in morning, run 4-5 seconds like normal, then die. I start it again and same thing: the car runs for 4-5 seconds then dies. I can do this over and over. It seems like or acts like fuel supply is being cutoff in this warm-up/idle cycle.
EXAMPLE 2: Three weeks ago I had car in garage during zero-degree cold spell. I started car in garage, let it warm up and get good and hot for 20 minutes, then headed out. Less than 15 minutes on the road, traveling through zero-degree weather the car kept trying to die on me and eventually did. It would immediately start but would not keep running. Again, it was as if fuel to engine being cutoff.
Some part or component does not function properly in the severe cold, 20 degrees or colder. Does anyone have any ideas? Electrical or mechanical? Has anyone seen this with their Focus or Ford? I’ve replaced the fuel regulator and nothing else. I thought I would pick all of your brains before becoming a parts changer!
Tests need to be made to see if spark vs fuel are missing.
No fuel could be no power to fuel pump or the pump itself.
Listen to hear fuel pump running. Measure for power with a voltmeter. Measure for fuel pressure with a gauge.
No spark could be faulty crank position sensor.
Check for spark at a coil output. Check CPS with a multimeter.
If you can’t DIY you’ll have to leave the car at a shop overnight for them to troubleshoot on a cold morning.
On some cars the electric fuel pump shuts off if there’s a no-oil-pressure signal. Is there enough oil in the engine? Is there an oil pressure warning light?
In any case there is probably an oil pressure sending unit screwed into the engine, near the oil filter. That, or its wire, may be the problem. An OP sending unit is simple and cheap and easy to replace.
Suggest to focus on getting a proper diagnosis, and not engage in wishful-thinking parts swapping. The parts-swapping method used to work pretty good in the past days of carbureted engines, but when cars became fuel-injected rolling computers in the 80’s, it’s very easy to run out of money before running out of ideas what part to replace next. Unless you just enjoy the process of replacing parts of course.
As mentioned above, determining whether the stall (when cold) is fuel or spark related is the first priority. My guess this is an air/fuel ratio problem, either not enough fuel, or too much air in the intake mixture. Ideas for initial shop testing, performed when this problem is occurring
Quick check of maintenance-related fluid levels and fluid quality.
Are there any engine or transmission diagnostic codes stored in computer memory?
Is there a spark at spark plug?
Is throttle-body idle air control function working as expected?
Is the battery/charging system working correctly?
Does drivetrain computer know the correct coolant & ambient temperature?
Does fuel-trim data indicate a too lean or too rich condition?
Is fuel-rail pressure correct?
Is vacuum system leak-free?
Are the normal tune-up related parts in good condition? Spark plugs, engine air filter, etc.
Is intake manifold vacuum correct?
Is spark timing correct?
For these tests, seek out a shop having access to a pro-level Ford scan tool.
Disclaimer: I’m just a driveway diy’er & not a Ford Focus expert. The fastest way to get your car fixed is to take it to a well-recommended qualified shop, tell them the symptoms, and let the pro’s there diagnose and fix the problem(s) for you.
Interesting thought. Thanks for the intelligent reply. There is plenty of oil in the engine, and the check-engine light is not on. The computer is not recording any DTC/OBD codes either, so I don’t have any clues there. I will look into your oil pressure suggestion. Thanks again.