I have a 1999 that has an intermittent stalling problem. The fuel pump failed 600 miles ago. The truck was towed and the fuel pump replaced with a new Delphi pump. Fuel filter was also replaced. Truck started right up and ran great.
A week ago I drove it about 20 miles. I parked it for lunch, came out and it started right up. Drove it 1.5 miles and it quit in the middle of the street while going 35-40mph. Coasted into a gas station. It was hard to restart. Had to let it sit 2-3 minutes. Once started, in died in about 30 seconds. It then started right back up. Drove it about three miles and it quit in a driveway. Started right back up. Drove it 1/2 mile and it quit in the middle of street going 25mph. Coasted to the side of the road. Hard to restart. Drove it about three miles home. Stalled at the top of my driveway. Started right back up and I parked it.
I got a fuel pressure tester. Once installed, I bled the line using the pop off valve. I then turned the ignition on for 10 seconds, turned ignition off and back on for 10 seconds 4-5 times. Pressure was 58psi. It dropped to 53psi over the course of about 4 minutes. It stayed at 53psi. I started over and got the same results three times. I started the truck and let idle for 90 minutes. The pressure held steady at 52psi.
I spoke to a Delphi engineer to get some specs on the pump itself. He confirmed the rail pressure should be 60psi max with the key on and engine off. Engine running it should be 54-55psi. He commented I'm a little low. With the pump dead headed, pressure should read 65-130psi measured at the filter.
He went on to say the electrical connections at the pump or relay can lower the pressure. He would not come right out and say it but he indicated there have been problems with the factory's pigtail wiring kit and the crimp on connectors included in the kit. Ideally, the pigtail should be soldered in.........but the instructions don't say that.
The two main culprits he called out were the electrical connections on the pigtail needed to support the 9.6 amp draw required for proper pressure and the fuel pressure regulator. To test, the first place to start was to dead head the pump. Here's the problem.
I get a zero reading when I deadhead the pump and no fuel flowing through the gauge pop off valve and hose. There is low pressure when the gauge is removed as it sprays some fuel. I got the same results with two gauges and four different fittings.
Next test, I left the key on and can hear the pump cycle up. I pressed the Schrader I mounted in front of the inbound side of the filter with a small screwdriver. A little fuel sprayed and it stopped. Remember, the key is on and the pump cycled up. I press this Schrader and I should get A LOT of fuel if that line has 65-130psi in it like Delphi says it should. And it should replenish since the pump is on.
Both pressure testers will read 58psi at the fuel rail (engine off; key on) when everything is hooked up. Both get a zero reading at the filter with the lines forward of the filter hanging open. It responds like there is a safety feature that senses the fuel is not going through all the lines and back to the tank and thus shuts the pump down and releases pressure into the tank as if the vehicle was in a collision and had broken fuel lines.
1) Does this truck have such a safety system to shutdown the fuel pump? That might explain why most forum posts suggest crimping the return line vs dead heading the pump. I'm hesitant to crimp a high pressure rubber line.
2) If it does have such a system, how do I bypass it so I can get a dead head reading?
3) If no such system, why am I getting virtually no pressure or flow at the filter with the key on? Remember, the pump registered a pressure of zero and no spray when the Schrader was held open.
I'm stumped. Suggestions on how to get a dead head reading on this pump?
Thanks for any help
A week ago I drove it about 20 miles. I parked it for lunch, came out and it started right up. Drove it 1.5 miles and it quit in the middle of the street while going 35-40mph. Coasted into a gas station. It was hard to restart. Had to let it sit 2-3 minutes. Once started, in died in about 30 seconds. It then started right back up. Drove it about three miles and it quit in a driveway. Started right back up. Drove it 1/2 mile and it quit in the middle of street going 25mph. Coasted to the side of the road. Hard to restart. Drove it about three miles home. Stalled at the top of my driveway. Started right back up and I parked it.
I got a fuel pressure tester. Once installed, I bled the line using the pop off valve. I then turned the ignition on for 10 seconds, turned ignition off and back on for 10 seconds 4-5 times. Pressure was 58psi. It dropped to 53psi over the course of about 4 minutes. It stayed at 53psi. I started over and got the same results three times. I started the truck and let idle for 90 minutes. The pressure held steady at 52psi.
I spoke to a Delphi engineer to get some specs on the pump itself. He confirmed the rail pressure should be 60psi max with the key on and engine off. Engine running it should be 54-55psi. He commented I'm a little low. With the pump dead headed, pressure should read 65-130psi measured at the filter.
He went on to say the electrical connections at the pump or relay can lower the pressure. He would not come right out and say it but he indicated there have been problems with the factory's pigtail wiring kit and the crimp on connectors included in the kit. Ideally, the pigtail should be soldered in.........but the instructions don't say that.
The two main culprits he called out were the electrical connections on the pigtail needed to support the 9.6 amp draw required for proper pressure and the fuel pressure regulator. To test, the first place to start was to dead head the pump. Here's the problem.
I get a zero reading when I deadhead the pump and no fuel flowing through the gauge pop off valve and hose. There is low pressure when the gauge is removed as it sprays some fuel. I got the same results with two gauges and four different fittings.
Next test, I left the key on and can hear the pump cycle up. I pressed the Schrader I mounted in front of the inbound side of the filter with a small screwdriver. A little fuel sprayed and it stopped. Remember, the key is on and the pump cycled up. I press this Schrader and I should get A LOT of fuel if that line has 65-130psi in it like Delphi says it should. And it should replenish since the pump is on.
Both pressure testers will read 58psi at the fuel rail (engine off; key on) when everything is hooked up. Both get a zero reading at the filter with the lines forward of the filter hanging open. It responds like there is a safety feature that senses the fuel is not going through all the lines and back to the tank and thus shuts the pump down and releases pressure into the tank as if the vehicle was in a collision and had broken fuel lines.
1) Does this truck have such a safety system to shutdown the fuel pump? That might explain why most forum posts suggest crimping the return line vs dead heading the pump. I'm hesitant to crimp a high pressure rubber line.
2) If it does have such a system, how do I bypass it so I can get a dead head reading?
3) If no such system, why am I getting virtually no pressure or flow at the filter with the key on? Remember, the pump registered a pressure of zero and no spray when the Schrader was held open.
I'm stumped. Suggestions on how to get a dead head reading on this pump?
Thanks for any help
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