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1993 Ford Bronco

Question: Fuel pump problems

Question

leo beeloo, 5.8L V8, Venice, CA, September 03, 2010, 19:11

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This vehicle performs fine even when towing a 3,500 LBS trailer,on a flat road and an ambient temperature of 110 deg. f. however, when I go into the montains with an ambient temparature of over 100 deg. f. it will stall.
After cooling off for 30 minutes everything is fine again.
I have heat tested the vehicle on my driveway by covering the hood and blocking airflow to the radiator, running the engine in first gear with the wheels blocked, after reaching 190 deg, f. cooling water temp. and an under the hood temperature of 180 deg. f., using a heat gun heating up every component posible to their stress level, I was not able to stall the engine. the only item I have not tested under hot conditions is the fuel pump.
I strongly belief it is the fuel pump that causes the stall.
Question, if you agree what is the garantee that the stall will not happen with a new fuel pump.
Thanks,
Leo

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• Answer #1

  hollander62292 September 04, 2010, 05:40
  

   Technician

  if the fuel pump is not operating correctly it can cause the vehicle to stall, i would say that the chances of it not stalling again after replacing the fuel pump are pretty good.
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• Answer #2

  danielsreseda from Daniel's Automotive, September 10, 2010, 13:41
  

   Technician

  IS THERE ANY WAY YOU COULD HOOK UP A SAFE FUEL PRESSURE GAUGE( (NO LEAKS TO START A FIRE) TO SEE PRESSURE AT STALL?VEHICLES BEFORE 1996 ARE ABOUT A 100 TIMES MORE DIFFICULT TO DIAGNOSE AND THEREFORE A SOLID CLUE LIKE FUEL PRESSURE IS AN ABSOLUTE MUST.
  ALSO CHECK FUEL PUMP RELAY AND WIRING .REPORT BACK
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• Best Answer
  Visitor, September 10, 2010, 19:17

  The problem is this, when you drive slowly in first gear, most of the fuel is returned to to the reservoir. With 110 deg. F ambient the reservoir will reach this temperature.
  The returning fuel is heated by the engine and returns to the FDM reservoir which is quite small, at a certain point this heated fuel which now comes in contact with the hot pump, causes the fuel in the FDM reservoir to boil at which point you lose pressure and the engine stalls.
  A fuel cooler in the return line will help to avoid this critical boiling point and as long as your engine and transmission are not over heating, drive as fast as posible to gain as much cooling on the reservoir and returnline cooler.
  Hope this helps,
  Leendert
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