Will not continue to run

130,000 MILES • 4.6L • V8 • 2WD • AUTOMATIC
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GLENN GILBERT
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My son was driving down the road the other day and the car just quit running. When he tried to start it he said it would run for a couple of seconds, backfire, and then shut off. He tried to pull the codes but no code showed up. Since I have not seen the car, this is a police interceptor, I told him it sounds like a crank sensor, but I may be wrong. The vehicle does not have a distributor, just coil packs. What would you think might be the problem?
May 5, 2018 at 9:20 PM
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ASEMASTER6371
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Good morning.

Yes, it could be, but the backfire is the key. If it was a crank sensor there would be no spark. A backfire is an indication of backfiring which requires spark. Also, it would code 335.

It sounds more like a failing fuel pump. Low or no fuel pressure will cause this and there is no code for fuel pump failure. You need to check the pressure. There should be a schraeder valve on the fuel rail.

Roy

May 6, 2018 at 12:10 AM
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GLENN GILBERT
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I spoke with my son in Florida and he said that the car is getting plenty of fuel, in fact when he depressed the schraeder valve it shot a stream of fuel six to seven inches in the air. Would that still be a faulty fuel pump? I was thinking that the timing chain might have slipped a tooth as he says when he gets it started for a second or two the car will shake very badly then shuts off.

Glenn
May 6, 2018 at 7:58 AM
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ASEMASTER6371
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Okay, just depressing the valve does not mean it has enough pressure to work. you need a gauge to verify the pressure.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

As far as the timing chain, very possible. You would need a compression test to very. You would have low compression if it is timing.

https://www.2carpros.com/articles/how-to-test-engine-compression

Roy
May 6, 2018 at 8:02 AM
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GLENN GILBERT
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What is the normal fuel pressure supposed to be on this vehicle? My son said that he is going to get a fuel pump tester but does not know what the normal pressure is supposed to be.

Thanks
May 6, 2018 at 8:16 PM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Okay, I attached a chart for the fuel pressure.

Roy

May 6, 2018 at 8:24 PM
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