I just installed a new fuel pump in a 1993 Dakota 3.9 v6 LE. When I turn the key on the pump kicks on and should produce fuel to pressurize the line but no fuel comes out of the pump just bubbles of gas. I replaced the ASD relay but still no fuel pressure at all. Nothing comes out of the pump with no hoses attached but it's receiving power. I'm lacking a volt meter to test for a full 12v. If an ECM is bad it should still produce fuel even while cranking as you can here the pump run. Is it possible the new pump is bad? If it's not producing the full 12v could that be why? The only other idea I can come up with is disconnect the battery and see if a reset might help. It's just weird that the pumps running but no fuel. Any ideas would be helpful. Thanks.

 

Welcome to DF. Moving to the correct section so you can get some help.

 

Seeing bubbles would suggest to me that there was an air leak on the intake to the pump.

Also, don't discount a bad pump just because it's new.

 

Still no luck. Is there anything that tells the pump how much fuel to produce? I know the wire harness to the pump 3 of the are for the fuel gauge. I was just thinking maybe a sensor might be making the pump believe the truck is not trying to start so the pump engages but due to lack of the other half of information it doesn't know what to do. I would think the pump should produce fuel no matter what and pressure was regulated by the FPR. So as long as I have fuel in the tank and a good pump with a 12v current gas should be coming out. I will post the solution whenever I can figure it out.

 

I would want a wiring diagram to figure out what was happening. Early pumps had 3 wires going to them, 1 ground, 1 fuel level sender signal, and 1 that supplied the pump with 12 volts. The only other wires you need would be the power to the gauges & this didn't go back as far as the pump. Also, the early pumps had no regulator built in, it was in the fuel rail.

If you have more than 3 wires to the pump connector, I would definitely recommend getting a wiring diagram. Once you know what wire is ground and +12 for the pump, you can do some testing. Normally, the ECU provides a 1 or 2 second "turn on" voltage to the pump to build up the pressure for starting & this is not based on fuel flow or pressure, only on time. After the truck starts, the pump runs constantly. If you can hear the pump start for a second or two when you turn the key from OFF to ON, then that part is working correctly. If the pump provides bubbles, you have a leak somewhere on the intake to the pump (could even be the hose connection from the fuel rail). If the pump is submerged in fuel, you may have a crack or leak in the upper body of the pump. If you just get nothing, I'd suspect the pump is faulty. Knowing the +12 and ground, you can jump those to the pump from a good source (like the battery) and see how the pump operates on a continuous basis - if you get no fuel flow, return your new pump. Except for a little bit of ECU intervention, the fuel pumping system is stand-alone & not that hard to figure out once you have the right info to work from. If there's a service manual download available for your truck, I'd recommend getting that so you have the real info at your finger-tips and won't need to guess.

 

This is going to sound really dumb but after a ton of thinking I checked to see if the fuel/return connection on top of the pump might be clogged and sure enough it was. I will always check those type of things from now on. At least it was simple. Just a lot of work. Thanks for your help everybody.

 

Check your ground circuits too, I had the exact same issue, tried all the relays, fuses, and pulled the pump out twice, then just put in a ground bar (brass) and connected it to battery ground and all the ground wires to it, problem solved

 

With enough garbage going back to the pump to clog the intake, there'll probably be some in all the lines, fuel rail, etc. I'd put a new filter on soon - I know you said you put one on, but that one will pick up all the loose stuff that's still in the system & a fresh one will give your new pump and injectors a fighting chance. I would put some cleaner into the fuel also, to help clean any old build-up from the injectors (I use Sea Foam). It might also be a good idea to check the fuel pressures - I would recommend the normal idle pressure, the normal idle pressure with the vacuum off, and then do a leak-down test. If all those come out clean, you should be good to go.