My 01 2500 started to crank longer to start and within a couple of days I had to bleed the return line to get it started every time. I checked all the fittings and put in a new filter and o ring. I cant find any leaks. Its still getting air.
About 6 months ago it was also cranking longer before starting so I changed the filter and put a new lift pump (stock) on. It was starting fine after that.
Im wondering if the lift pump I put on is a problem but I am not getting air out of the supply line, just the return line.
I went thru the forum this morning and got a lot of good info on changing and relocating the lift pump and will be doing so as funds allow. I also ordered a fuel pressure gauge.
Any ideas on where I could be sucking air? thanks

 

The rubber lines can suck in air and never leak a drop. The fuel heater can let air in around a plug that got too hot. A hard line can have a crack in it at a weld on the brackets. Lots of places to pull air from.

http://www.cumminsforum.com/forum/94...m-writeup.html

 

When is it cranking longer? All the time, only when the engine is hot, or only when the engine is cold?

 

Check you rubber hoses. I had the same problem on my Mule and finally replaced therubber hoses and fixed it up.

 

huh??
I'm not sure why you should worry about air the return line..it goes back to the tank.
not the any of the tank to engine stream.

what's you fuel pressure? and during cranking? too high is know to cause hard starting

-dkenny

 

re checked the fuel filter lid and seal, changed the rubber hoses, bled the system, started the truck, let it run for awile, shut it down, let it sit 20 min and it doesnt start again.
On the long cranking over time, it did that hot or cold. So it was getting some air in the system but still starting. Now it is getting air in the system and will not start until I have bled the air out of the return line on the injector pump.
When I crank the engine, engaging the lifter pump I get fuel at the supply line on the injector pump. If I crack the injectors, I get no fuel. If I crack the return line at the injector pump, I get air bubbles and when I start getting fuel the truck starts.

 

Air in the system doesn't travel downhill to the tank, it goes to the highest point, the injection pump.
In the pump it causes an airlock that causes hard starting.
Most air leaks don't leak fuel so just looking for a leak rarely works.
Best way is to pressurize the fuel tank with air, 10 psi max, then go hunting.

 

Ok, how do I pressurize the fuel Tank? I assume I disconnect the fuel line before the injector pump and plug it. What about the return line?

 

The most common places for return line leaks are the injector o-rings (very common when changing injectors), the banjo bolt on the back of the head, and the T fitting just below the banjo. Now if you live in a high corrosive area where they salt or treat icy roads then OEM metal fuel lines can develop small cracks or pin holes. One of the best way to identify leaks is with baby powder.

 

An air blow gun wrapped in a rag blowing in the fuel tank fill is the simplest but it takes one person to blow and another to look for leaks.
If you want to get fancy you can drill and tap an old fuel cap for an air chuck. Then it becomes a one person operation.

 

And hopefully the fuel tank vent is working properly.

 

Im leaning towards a weak lifter pump as the problem. When the pump stops cycleing, I hear what sounds like fuel settling in the pump. If it is it could be losing prime and sucking air back thru the return line into the inj pump. ??? hypothesis. Anyway, I am waiting for the pressure gauge I ordered so I can test the pressure. This should tell me if the lifter pump is good or not. If the lifter pump is good, then I am back to looking for leaks. Ok, so I was thinking about how a shop has a machine that puts smoke thru the fuel line to find leaks. That got me to thinking about how a aerosol can could be made for the backyard mechanic. Im not an engineer but it seems like it woul not be too hard to figure out. Anybody ever runacross such a thing? Just thinking out loud. Thanks

 

Hearing what you're thinking out loud..... Just remember that if there is zero leaks in the fuel system then it would be impossible for fuel to "run" or flow out of either fuel line. But saying that, this doesn't mean that the fuel system will retain fuel pressure when the engine is off. Pressure will always bleed down. It just means that the prime will remain and there will always be fuel in the lines. And I'd be really cautious about putting anything foreign in the fuel lines.

 

Heres where Im at. Replaced the supply and return lines with fuel hose and hose clamps. Also replaced the T fitting with a one piece fitting, had to cut the line out of the back of the head and put a section of fuel hose there as well. Did another new o ring on the fuel filter, also ran a test bypassing the fuel filter cannister to rule that out.
I bled it and got it running, let it run. I have a section of clear tube on the return line between the inj pump and the T fitting. When the truck is running, I see tiny tiny bubbles running thru the line in the direction of the flow. When I turn the truck off, after several minutes I start getting large air bubbles coming back from the tank side of the return line. Clamping the line shut on the supply side stops the air bubbles. This tells me the fuel is bleeding down and pulling air back in, which I thought replacing the return line would fix.
The truck starts harder the longer it sits between when it is running.
The lift pump pressure is around 14 psi.
I can not find any fuel leaks, but I have not tried pressurizing the tank, have not figured out how to do by myself yet.
Im thinking banjo bolts and crush washers are the next step. ?????
Im liking my 93 W350 better every day.

 

I also like vehicles that don't have any problems.

Where in the supply line did you pinch it? Before or after the lift pump?