Dodge ram fuel pump problem

[mongofix22]

Hi, everyone I have a dodge ram 1500 4x4 5.2 when wet or sitting for several days the engine will crank but not start,When key is released from start to ignition the engine will run roughly for several seconds, backfire , with exaust coming up through the intake and throdle body. what is this and how do I fix it

[carriedi]

what year is your truck?

Check for spark during crank. You may have no spark when cranking but are powering up the coil. Releasing the key from crank momentarily cycles the coil and send a spark. You should see if you have a fuel pressure problem. Cycle the key three or four times. The fuel pump should pressure up to 44 to 54 psi on a single key cycle. If the fuel pump is weak, cycling the fuel pump several times may pump up the pressure and allow the vehicle to start. It won't run good but it gives you a clue on what to do next.

Any no start, check your basics. Spark, fuel pressure, injector pulse. Once you see what you have and what's missing it will tell you what to look at next. (most of the time. there are always exceptions)

[mongofix22]

truck is a 2001 and I hit the gas pedal a lot to get it to start but even that doesn't work

[carriedi]

Cycling the key lets the fuel pump do the prestart prime of the fuel system. if you do it a few times with a weak pump each time you cycle the key the pressure will increase and possibly get high enough to start (not always though, it is just a place to start with) Pumping the pedal on a carburetor makes the accelerator pump prime the intake with a stream of fuel for each pump. There is no accelerator pump on a fuel injected vehicle. On a cold start the computer looks at the coolant temp sensor and allows more fuel just like the choke did on carb cars. But a carb has a fuel bowl to draw fuel from. Fuel injection has no bowl of additional fuel to draw from. Fuel injection needs pressure to push fuel out the injector nozzle while the computer opens the injector.

did you check the fuel pressure, spark and injector pulse? that it the beginning of any no start condition. See if you have the basics and go from there. If you have spark and injector pulse but poor fuel pressure the vehicle may want to start but hasn't enough fuel to stay running. If you have no spark out of the coil you may want to check the signal that is sent to the coil. If you have spark but no fuel injection pulse you may want to look at the signal to the computer for injector pulse.

[wellsy]

Hi, I know this is an old post but my 2001 dodge ram 1500 is doing the exact same thing. what did your problem turn out to be. Thanks

[huisengaron]

1997 dodge ram 1500 fuel pump works directly off battery but not off tank connector. battery voltage is 14.5, connector voltage is 8.5. what should I check next?

[carriedi]

you might try switching your fuel pump relay with another like relay. there could be built up resistance in the relay contacts. If you get good voltage with another relay replace the relay. If you still have reduced voltage with another relay check the voltage at the fuse. Fuse #8 in the power distribution center a 20A fuse should be hot all the time.

power goes from the battery to the power distribution center. to the fuse #8 then through a red and white wire to the relay. Goes through the relay then out on a dark green/black wire to the fuel pump. you should be able to trace voltage back to where you have the voltage loss from there