Fuel pressure problem, please help...
#11
10-17-2007, 05:54 AM
RE: Fuel pressure problem, please help...
I would suggest starting back at the top of the fuel tank
and checking to see that the plug back there has full voltage on the leads to the pump motor. I found it a lot easier to tilt up the cargo box bed of the pickup to get at this tight spot, rather than dropping the tank to the ground.
Then rig up an adapter to check fuel pressure back there where the special fitting connects to the fuel line running forward. You should have a minimum of 35 psi, with 39 psi typical of a new pump.
Off the top of my head I can remember at least 4 posts where Ram owners posted pictures of rubber and rust particles that came from the inside of their fuel lines, which apparently can break down inside...perhaps due to alcohol & water in gasoline. Considering that the fuel line is 13 years old, it should be a prime suspect.
When checking fuel pressure at the test port valve near the driver's side rear of the fuel rail, remember that there is a post inside that must be depressed by the correct adapter to get pressure (aka Shraeder valve)
Good luck.
and checking to see that the plug back there has full voltage on the leads to the pump motor. I found it a lot easier to tilt up the cargo box bed of the pickup to get at this tight spot, rather than dropping the tank to the ground.
Then rig up an adapter to check fuel pressure back there where the special fitting connects to the fuel line running forward. You should have a minimum of 35 psi, with 39 psi typical of a new pump.
Off the top of my head I can remember at least 4 posts where Ram owners posted pictures of rubber and rust particles that came from the inside of their fuel lines, which apparently can break down inside...perhaps due to alcohol & water in gasoline. Considering that the fuel line is 13 years old, it should be a prime suspect.
When checking fuel pressure at the test port valve near the driver's side rear of the fuel rail, remember that there is a post inside that must be depressed by the correct adapter to get pressure (aka Shraeder valve)
Good luck.
#12
10-17-2007, 02:21 PM
RE: Fuel pressure problem, please help...
Ok, here aremy suggestions:
1. My firstthought is the fuel pump. You said you replaced it but hear no sound from it. Some pumps are quiet so you may not hear it. Is it a factory or aftermarket?
2. Still at the pump, check for voltage. Is it present? If not start tracing wires. Or connect a battery to the wires for the pump and see if you can hear it then. If you can hear it and have no flow the problem is either a clogged filter on the pump (if there is one, I think there is) or a line has come loose from the pump (trust me it happens).
3. I was going to ask about fuel filter, but recently found out we don't have any on the trucks. So skip this one.
4. I don't have a diagram of the fuel system with me, but does the fuel line from the tank go to a pressure regulator? If so pull the line and check for flow there. If it is good there you know your pump works and the lines are clear. Then re-connect to the pressure regulator and check for pressure at the schrader valve (you should really get a pressure tester for this).
That is a few things I would check. I used to have a 95 Firebird Formula and I had the EXACT same problem. It drove me crazy. The pump was quiet and couldn't be heard, but I had no pressure. It turned out the pump kept blowing the feed hose off. I got to be an expert at pulling the pump and fixing it in 10 minutes. I eventually traded the car for my Ram.
Good luck.
1. My firstthought is the fuel pump. You said you replaced it but hear no sound from it. Some pumps are quiet so you may not hear it. Is it a factory or aftermarket?
2. Still at the pump, check for voltage. Is it present? If not start tracing wires. Or connect a battery to the wires for the pump and see if you can hear it then. If you can hear it and have no flow the problem is either a clogged filter on the pump (if there is one, I think there is) or a line has come loose from the pump (trust me it happens).
3. I was going to ask about fuel filter, but recently found out we don't have any on the trucks. So skip this one.
4. I don't have a diagram of the fuel system with me, but does the fuel line from the tank go to a pressure regulator? If so pull the line and check for flow there. If it is good there you know your pump works and the lines are clear. Then re-connect to the pressure regulator and check for pressure at the schrader valve (you should really get a pressure tester for this).
That is a few things I would check. I used to have a 95 Firebird Formula and I had the EXACT same problem. It drove me crazy. The pump was quiet and couldn't be heard, but I had no pressure. It turned out the pump kept blowing the feed hose off. I got to be an expert at pulling the pump and fixing it in 10 minutes. I eventually traded the car for my Ram.
Good luck.