Engine/Transmission (1998.5 - 2002) transfer pump questions

[dodgeram1998.5]

what is the switching means for the pump to turn on and off. ? i mean there is not always 12 volts to the pump when i turn on the ignition or should i say the pump doesn't build pressure when the igniton switch is turned on . i am seeing my pump build pressure to 16 # then go to 5 ,4,3, # when driving then . if i restart the engine it will go to 16# . and most of the time stay there . i am getting some erractic readings and trying to find out what is going on or diagnose the erractics. ? this transfer pump is only about 15000 miles old/thanxs tdr

 

[Steve St.Laurent]

Depending on the programming you have in your ECM your pump will run up to about 5 seconds when you first turn the ignition key on. The ECM controls when the pump is running or not. When the starter is engaged it pulses power to the lift pump to supply a reduce fuel pressure to the engine. Once the engine is running it's providing full voltage to the pump continuously. Now, when the heater grids are cycling that voltage will vary somewhat which you can see by watching your voltage gauge on the dash - regardless that goes away at 25 mph or a few minutes. The eratic readings you are getting often happens when a lift pump is in the process of dying. I went through 4 lift pumps between 24,000 and 60,000 miles with one pump lasting less than 4,000 miles. Look into your options for upgrading the fuel delivery system there are a number of them out there. Personally I added a 7 psi carter pusher pump in addition to the factory lift pump and that went 90,000 miles before I had to replace one of the pumps - which was FAR FAR better than I ever got out of the straight factory setup.

 

[ntillm01]

What Steve said. The transfer pump 12 volt supply comes directly from the ECM, and it does the switching. If it's losing pressure while you are driving, I agree, it' starting to flake out and fail. Restarting probably just gives it a second surge of voltage to get it going again for a while.

 

[dodgeram1998.5]

thanx guys for the info ,i appreciate you all