Pontiac Repair: Fuel Pump, grand prix gtp, pontiac grand prix gtp

Question
2000 Pontiac Grand Prix, GTP, V6 3.8 L Supercharged.

2 fuel pumps have quit in traffic in two weeks.
The first one was 2 minutes after starting at 45 mph. Dealer replaced fuel pump module.
I drove it for a week putting about 150 miles on it in all types of speed and driving conditions. Then it died in traffic again, this time when coasting to a stop light.
I replaced the fuse, it started but the engine was really struggling then finally stalled. I had it towed to the dealer. It started for the dealer. They have had it for four days and can't find any problems with it. Unless something is fixed I have little confidence that it won't die in traffic again. Any suggestions?  

Answer
Norm,
 I assume the fuse was blown and it was the fuel pump circuit fuse. If theres anything else on it I would be wondering in that direction as well. I am out of the business due to a back injury so I don't have all the manuals handy. Since I don't know all the details I will just say this, if the fuse has blown once I would guess it has before and if so you have a wiring problem caused by some sort of movement or vibration which has caused the insulation to be damaged.The engine etc will twist in two directions along with anything connected to it so it takes the right twist to cause the damaged circuit to contact the frame or body of the car. Sure it wont happen in the shop because they don't drive as you do. I would have them run the engine and carefully move the harness assigned to that circuit in the engine area all the way to the fuel pump. These pumps don't fail like this, its the circuit which is at fault. I would have them test the amperage draw on the circuit and see if it stands up and make sure its tested for at least an hour. New volt meeter's have systems which will record the highest and lowest etc readings, so they don't have to sit there watching it. This not for a short to ground its for a damaged connection which will cause a blockage of current flow causing the circuit to draw too much power (amperage)when this draw/power/amperage becomes more than the fuse it blows to protect the circuit. If there is a bad connection causing a problem it will normally be discolored and maybe in the fuel tank connection itself. It could be overlooked. If its a bad connection a higher fuse value may cause the problem to go into remission for a while until the connection gets worse. If its a damaged wire shorting to ground the larger fuse wont change anything because the short normally will blow most any fuse. I would hold them to their word and it was a bad fuel pump and make sure they fix the car and give you a rental or small claims will reimburse you. With your documentation the dealer will get creamed in court and they know it. I also would go to the highest in command/owner. They found the pump to be at fault so now there on the hook and thats there business. I also would make a stink about the guy who is working on the car prove he has factory training in drive ability and is a tune up guy if not get a tune up guy on the job. Some shops have bumper to bumper techs and often they are not skilled in tune up as well most shops work on commission so the same guy gets the car back and theres no prevision for paying the best man for the job. Get the best guy or you will get the same result. If its under warranty I would surely keep the loan car until they find a problem for real.Remember a lot of thing's are covered for 5 years or 50,000 miles and some 7 years and or 70,000 miles (which ever comes first) That's the federal emission warranty.