my 94 ram 1500 has a very rough start, come to find out the fuel pump is not coming on when i turn the key to the on position, so the longer the truck sits the fuel pressure lets off and it wont start. i have replaced the relay sitll no luck, any suggestions? anyone know what wiring to follow/check?

 

welcome to DF... usually the fuel pump relay or power thru the relay is the issue. I'm not 100% sure about the pin outs on the relay but I can suggest downloading the manual and looking at the relay's there and start with that. you should be able to verify power on both sides of the relay when it's energized. unless it's not getting energized.

 

More commonly the fuel pump goes how many miles you have on the truck its not as bad as u think to replace the fuel pump and on a 94 its probly done the only part that sucks is u gotta drop the tank

 

dropping the tank is easy. the pump should turn on for 2 seconds prior to starting, if this is not happening then either the signal to the relay has a problem or the relay power to the pump is no good. if all that is good then the pump is probably on it's way out. if your at that point though your probably not starting your truck.

 

I would probably get a new pump anyway even if you don't need to right now, because later on down the road you will need to and there is no point in dropping the tank twice if you don't have to.

 

yea im not thinking its the physical relay because i have put in ones that i know work and still no 2sec cycle when i turn on the key, ive not yet checked to see if im getting a signal power, the fuel pump works fine once the truck is running, the truck has 175k on it more than likely the oem pump. not concerned with replacing it but im not about to go through all that hassle if thats not the prob....

 

and where can i download the manual? is it posted somewhere free, or am i better off buying the hardcopy?

NM i found it DUH..

 

ok well the relay is getting and sending 12v as needed though when i checked the plug to the fuel pump its only getting 2.5 volts?!?! am i missing somthing? i know its the right wire and it only gets it for the second or two its suppose to its just not the 12v it needs, though coming off the relay its 12v!

 

sounds like u have unwanted resistance somewhere in the line..
is it possible for you to trace the line??

it also could be a bad ground..

 

Are you sure you checked the right wire? It's possible you probed the wire for the fuel level sending unit. It also will havepower but much less voltage.