Help! Truck randomly quits,,,it's throwing a code 543

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Apr 23, 2004 | 03:57 PM

user 2833083

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Help! Truck randomly quits,,,it's throwing a code 543

Well I need help. I've got a 1991 F150 4X4 four speed manual with a 300 I6. The other day I was backing a trailer up with the truck when it died, which is unusual. So I restarted the truck went about my business and then when I was driving down the road it died on me again. This time it took 2 to 3 seconds cranking before it fired up. This went on a few more times getting worse and worse before it finally died and wouldn't start back up. I managed to get close to my house so I left it where it was at. The next day it started fine and I drove it to my house. After changing the fuel filter I took it for a test drive. After a few miles it started the same thing over. I got it back to the house and pulled the codes. It gave me a code 543: "Fuel Pump Secondary Circuit Fault."

Can anybody help me out with this? The truck runs and idles perfectly fine right up until it suddenly dies.

Thanks for your help,
Morgan

Apr 23, 2004 | 06:37 PM

EPNCSU2006

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Joined: Nov 2002

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From: Concord, NC

Sounds like it is either time to buy a fuel pump, or a fuel pump relay. Test the relay before you replace it though. My truck did the exact same thing - I replaced the high pressure fuel pump (it did it on both tanks, but I think you have only high pressure in-tank pumps) and haven't had the problem again (knock on wood).

Apr 24, 2004 | 08:18 AM

user 2833083

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Thanks for your help. I don't believe that it is the fuel pump becuase it acts up on both the front and rear tanks, and like you said, this truck only has the two in-tank pumps. So that leaves the relay. Can anybody help me out with finding where it is located on my truck.

Thanks again

Apr 24, 2004 | 03:39 PM

user 2833083

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Well I replaced the fuel pump relay. It was out of its "holder" and had been bouncing around on top of the wheelwell. Problem seems to be fixed. If not, I'll be back.

May 6, 2004 | 11:09 PM

tefoley24

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Fuel pump relay F150 where is it?

Fuel pump relay F150 where is it? I guess thats a good thing to replace befor a rookie starts pulling Gas tanks. Thank you in advance for your replys.
Respectfully,
Tom Foley