Sometimes she starts then at others she cranks but no fire cycle the key & maybe the next try she'll fire but it might take up to 6 tries before starting, do I have a bad fuel shutoff or is it the relay ?

 

You most likely have a rotted hose leaking air. By far the most common is the return line in red below. 2' of 5/16" diesel rated hose will do it.
Not all fuel hose is diesel rated, don't let the counter guy tell you otherwise.



Never replace the shutdown solenoid. They are probably the most needlessly replaced item on a 12 valve, expensive too. They are very stout and will easily last the life of the truck.
Problem is almost always a corroded blue wire at the battery or a failing relay on the firewall. Also if the rubber boot on the solenoid is missing or torn gunk or rust can cause the solenoid to bind. Remove, clean it up and replace the boot.
Relay and boots available here http://www.fostertruck.com/dodge/default.htm

 

Thanks Bill for the pic would that be the red highlited hose in said pic ?

 

If it is the fuel shut off [ either the solenoid or relay ] , turn the key to the run position , go under hood and lift the linkage straight up , it will take a little effort / not a lot [ unless there is a dirty piston/cylinder - ripped boot , the solenoid has a piston inside that is lifted by magnet ] , also the linkage can stick .
If it lifts and stays up , then go turn the key the rest of the way to start , if this makes it start all the time , then you just need a 70 amp relay that puts power to the solenoid .
If not then , disconnect the solenoid electrical connector , try jumping one wire to ground & other to battery positive , 3 things may happen , lots of sparks [ it will some anyway , because its pulling 70 amps ] heat up jumper wires =this means an internal short , need new solenoid .
Nothing at all , open circuit , solenoid bad .
Next it may lift = solenoid is good , hold circuit is bad , possible relay .
It could be a lot of other things also , but more info / testing , when it does start , fuel pressure test .

 

Yes.
Wish it was as easy to get to as the picture. Remove the filter for better access and prepare to earn scars getting at the other end. Buy some new hose clamps, most times the old ones aren't reusable.

 

Is the relay the one in the box under the hood marked "Fuel System" ?

 

I'm going to assume we are talking about the FSOR = fuel shyt off relay ,
I think on your truck it is under the hood at the top of the firewall just off center on the drivers side , one way to be sure , is look at the markings on it , I think its the only one in the hole truck , that is rated for 70 amps .

 

On some years the above relay is a double. Smaller relay is for the fuel heater. The two relays can be seperated so only one need be replaced.
Get a new relay here http://www.fostertruck.com/dodge/default.htm

 

Thanks guys I tend to think that the relay's my problem as most of the time she starts fine.

 

Be sure to check the blue wire at the driver's side battery for corrosion first. It may be corroded under the insulation where you can't see it.

 

Shorthair, mine is doing the same thing,at least sometimes. When we got our first cold snap here it started doing what yours is doing. Occasionally I could cycle the key and it would pull in, but not always. It would always hold, whether it pulled in or I manually raised the arm. I cut off and replaced the ring terminal and the last six inches or so of the blue wire(which is now brn) and it worked fine until it got colder. I'm thinking that the wire is corroded up in the loom somewhere. You might have the same problem, which is cheaper than throwing parts at it just yet.

 

How does the return line cause hard starts? I have always heard this, but the return, the way i see it, should just be dumping into the tank and it shouldnt matter if it has air in it. As long as the supply line stays primed up.

And I would think the overflow valve would keep any air that was in the return from getting into the pump?

My truck has been starting hard, and i replaced the 5/16 supply line tonight. Ill try it and see how it does tomorrow, but im afraid the return may be the cause of my problems, and they sure are aggrovating to get to.

 

It's like the picking up water with your finger over the end of a straw trick.
If your return line has a leak that lets air in it also lets fuel out into the the tank. Eventually enough air has entered to air lock the the injection pump. Injection lines get full of air which compresses easier than fuel not allowing enough pressure to build to pop open the injectors to let the air out.
How long it takes for this to happen depends on the severity of the leak. Could be a few hours or even a few days parked for it to happen.

 

Don't forget the fuel heater. If it's an original; they tend to melt the contact points which causes a leak on the vacuum side of the lift pump. You can slobber some grease onto the power plug of the heater then plug it back in. Or you can pressurize the fuel tank to about 3-5 psi and see if it drips. I've replaced both of mine and a few more a my buddies fleet. You can also delete the fuel heater and rid yourself of the problem if it doesn't get too cold where you are. The whole fuel heater system is a marginal design, really needs bigger wires too. cd

 

Weather hasn't been conductive to working on it & a fall at work has had me off my feet but so far when I start it I turn the key to run wait 5 seconds or so turn it off then it will start as normal about 90% of the time.


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