Recently my truck has started acting up. Instead of firing right up it has to crank a while and when it starts it idles at between 550-650. I know the heater grids can make it idle a little low at first but it does it when it's hot out and the truck is warmed up too. What seems strange to me is a little while down the road if I come to a stop it will idle normally. This doesnt seem to change if the water temp is hot or cold. I've tried pinching off the return line to check the overflow valve and it makes no difference. I'm thinking maybe I have a leak letting air into the fuel supply or my lift pump is going out? Looking or opinions. I'm stumped

 

I'd start by turning up the idle to spec after the engine is warmed up.
Instructions> http://dodgeram.org/tech/dsl/adjustm...d_Gen-Idle.htm

 

Get yerself a new overflow valve for the pump. My truck does the same thing, just not long to crank b4 it starts. Streetched the spring, and its better, but still ordered an overflow valve. And follow infidel's advice, (note the post count??)

 

My 95 was doing the same thing at 140k. It started cranking longer and longer until it just did not want to start.What the problem was, was a 5/16 fuel line. This line was totally inaccessible. The factory goodyear hose cracked lengthwise along the hose. The crack could not be seen unless the hose was squeezed. The fuel system pressure would bleed off. This hose comes off of the steel line from the tank. It attatches to a nipple on the back of the injection pump. This sucker is deep, right against the block, right under the intake. It took two people to change. One working from the bottom and one working through a hole cut in the drivers wheel well. Changing that hose solved the starting problem, and the idling problems I was having (shutting off while in gear).

 

Changed out my overflow valve yeterday, while it certainly made a big difference for the truck all the way around, I still have a very low idle for about 10 second on the first start of the day. Noticed this morning it had a little bit of a miss to it as well.
Gotta be a fuel line.