Q: I have a situation occurring in my '87 Ford F-150. The engine has shut down three times while driving. It eventually restarts, but one time it took about 15 minutes. The 5.0L V-8 EFI runs great except for this quirk. The ignition module and the ignition switch on the bottom of the column have been replaced. I even had a light installed under the dash to show if the fuel pump has electricity. What else could be causing this problem?
| 03z 1987 Ford F 150
A: The possibilities are numerous and may require a qualified technician to narrow down the cause. It's often a good idea to let the tech drive the vehicle for a few days. When the engine quits, he can jump out to check for fuel pressure, ignition spark, fuel-injector pulse from the electronic-control assembly, etc. Off the top of my head, and going by your description of the problem, I'd be looking closely at the fuel pressure. The lightbulb showing there's power to the pump doesn't tell the whole story. The pressure and volume should be properly tested using the correct Ford service procedure in order to eliminate a weak pump, faulty pressure regulator, or fuel-line obstruction as possible causes. Your 5.0L should be reading 35-45 psi on the fuel-pressure gauge with the key on/engine off, 27-37 psi with the engine running, 40-45 psi with engine running and vacuum hose disconnected from the fuel-pressure regulator, while at the same time being able to pump out 5.6 oz of fuel in 10 sec. A little secret I've learned is to momentarily kink the fuel-return line while observing the fuel-pressure-gauge reading. This will shoot the pressure up to the pump's maximum, which is way above specifications. If it doesn't, you may still have a weak pump even though the initial readings looked good.
How To Reach Alex
If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at trucktrend@sourceinterlink.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.
Can't wait for help with a problem you're having with your Truck or SUV? Ask the expert we trust here at Truck Trend Garage—visit Alex Steele at www.RealWorldAutomotive.com.
