• 1991 FORD F-250
  • 5.7L
  • V8
  • 2WD
  • 126,000 MILES
I purchased this truck about three years ago (really good price). I did not have the time or need to get it repaired and did not want to deal with ridiculous CA smog regulations. When I purchased it the check engine light was on. I did some troubleshooting and replaced the fuel filter, idle air control valve and throttle position sensor. This took care of the CEL (check engine light). I then tried to have it smogged and it failed because it was smoking (valve cover leaks). In July I purchased valve cover gaskets, plugs, wires, cap and rotor to clean things up and make it run better. It passed smog in September and my son started driving it. It ran well for about two months. One day my son was driving to work and the truck stalled (in neighborhood) and would not restart. I pushed it out of the road and went back to get it home a couple of days later. It started immediately, I drove it home (half a mile) and switched the fuel tanks a couple of times without issue. I hooked it up to my tester and it produced a code 67 for a neutral position switch problem. We replaced that and it started and drove great for a couple of days. Then it happened again. Driving around the neighborhood it stalled and would not start again. It took a few days to get back to it and again once it was started it drove home fine (again, only about an eighth of a mile). I again hooked up the tester to the truck and it returned a Code 11 (All Clear). I am thinking it is a fuel issue of some kind. Truck sat for a while (three years) so I am wondering if there might some junk in the fuel tank (s) that could be clogging things up. I do not think there is a pump problem because it does run after it sits for a couple of days. I appreciate any help you can give.
Do you
have the same problem?
Saturday, December 31st, 2016 AT 1:54 PM

1 Reply

First you need to look closely at exactly how it acts when it stalls. Forget things like the neutral safety switch. That is in the starter circuit and is done doing its thing once the engine is running.

Have you checked for spark when the engine does not start? Do not get hung up on the first thing you find missing, meaning fuel pressure or injector pulses.

If the engine loses power and dies gradually over a period of two or three seconds, or longer, a good suspect is the pickup screen in the fuel tank. They can collapse and block fuel flow, then stretch out again after a few minutes. The clue is they cause problems when the highest volume of fuel is being pumped, which is during coasting. You have the advantage of having two tanks and pumps, so this problem would not act up when running on the other tank.

If the stalling is instant, similar to switching the ignition switch off, the best suspect is the distributor pickup coil. That will cause loss of spark, and the fuel pump will be turned off. These often fail by becoming heat-sensitive, then they work again after they cool down for up to an hour. If only spark is missing, suspect the module on the side of the distributor. Those do not typically fail intermittently, but do not overlook the possibility.
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Saturday, December 31st, 2016 AT 4:04 PM

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