1999 Ford F-150 Fuel System

Tiny
NWILLEY
  • MEMBER
  • 1999 FORD F-150
  • 6 CYL
  • 4WD
  • MANUAL
  • 78,000 MILES
My truck does not start when it is hot outside, especially when parked in the sun. If it's cool it starts fine and I can drive it and there is no issue. If its hot (80's) and I park in the shade it will start and run fine - if in the sun won't start. If its 100 it won't start at all. I found that when it doesn't start the fuel pump never buzzes when the ignision is turned on but engine is not running. So I checked the voltage at the plug on the frame rail at the fuel tank. When its cool and I turn the key to on (engines not running) it shots up to about 12 to 13 volts. When hot it only goes up to 7 or 8 volts. In the fuse box under the hood there are several relays that look the same. So I switched the air suspension (which I do not have) with the fuel pump relay this did not change anything.
I have tried starter flued when it will not start - it runs briefly then dies.
Also there has been times when the truck is parked in the sun and its in the seventies and I spray the truck with water to cool it down and it starts. If its realy warm out this does not work though. What should I try next? I have been trying to figure this out for a long time.
Thank you in advance!
Neil Willey
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Thursday, May 7th, 2009 AT 4:10 PM

3 Replies

Tiny
MERLIN2021
  • EXPERT
Read this it may pertain to you, since the refineries are producing winter blend fuels still.
1989-99 F-150, F-250 LD, Ranger 1991-99 Explorer 1992-99 Econoline 1993-99 Villager 1995-99 Windstar 1997-99 Expedition, Mountaineer 1998-99 Navigator 1999 Super Duty F Series Medium/Heavy Truck: 1990-97 F-700 ISSUE Some vehicles using winter blend fuels may exhibit a stall on start up and a no restart, hard start condition or a no start condition in unseasonably hot weather (greater than 27 C/80 F). These concerns may be related to fuel volatility from winter blend fuels during winter-spring and autumn -winter transitions and may result in a fuel pump vapor lock condition. This condition may appear to be a fuel pump failure but may be caused by winter blend fuel. ACTION Refer to the following text for further information. NOTE: Fuel tank additives will not resolve these concerns because vapor forms from cavitation within the fuel pump. Filling the tank to full may be effective. Advise customer to use the recommended octane grade per owner manual and not a higher grade. Explain to the customer that this concern may be due to a low tank level of winter blend fuel combined with unseasonably warm weather. Advise customer that filling the fuel tank to full may be effective in resolving this concern. Also, advise customer to use the recommended octane grade per their Owner Manual and not a higher grade. BACKGROUND Gasolines are seasonally adjusted, meaning they have higher volatility (vaporize easier) in the winter and lower volatility in the summer. Government mandates to improve air quality have resulted in significant changes to gasolines, such as the mandatory use of oxygenates (ethanol, methyl tertiary butyl ether (MTBE), and others) in the winter or the reduction of Reid Vapor Pressure (RVP) in the summer. The addition of oxygenates (especially ethanol) increases volatility while the reduction of RVP reduces volatility. Gasoline distribution practices often do not allow branded marketers to have much control over their gasoline's volatility other than RVP. Oxygenate (e.G, ethanol, MTBE) use is more dependent on local gasoline markets, rather than specific marketers practice. Therefore, it is difficult to recommend specific brands to avoid volatility related complaints.
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Thursday, May 7th, 2009 AT 4:31 PM
Tiny
NWILLEY
  • MEMBER
Thank you for the information Merlin 20221,
This actually has been going on for a little over a year and it doesn't seem to matter what time of the year it is - only if the tempture is high. I live in Tucson AZ so I am not sure if they would do that with the gas here?
Again thank you for your time.
-Neil
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Friday, May 8th, 2009 AT 1:59 PM
Tiny
MERLIN2021
  • EXPERT
Try filling it all the way up, if it relieves the symtom, the fuel pump may be cavitating like the TSB stated. The other thing is between the radiator and the a/c condenser a lot of road dirt and grime accumulate, making a blow gun with a piece of 5/16th brake line cut the end and crimp it, then cut a slot in the side of it about an inch from the end, screw the other end into the blow gun, then blow firts towards the engine to clean the radiator, then away from the engine to clean the condenser. When these clog with dirt, the fuel can boil in the fuel rail before it reaches the injectors. The ECT can play a part in this too, giving wrong info to the PCM. Also check the fuel pump prssure.
http://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm
Go here and checkout our video.
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Saturday, May 9th, 2009 AT 8:06 AM

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