92 Air in fuel

[andrewleach]

Hi guys,

My brother took over my 92" Ram 350 about a week ago, it had been running great for me. Two days ago my brother was in a drive through idling when the truck started running crummy an croaked! He promptly called me, when I got there the truck wouldn't start, so I bled the injectors. It fired right up and appears to be running fine since. But now we are paranoid, how does a truck that is running suddenly get a big slug of air and croak and then run fine later? This truck had a new injection pump 20,000mi ago and a new transfer pump 40,000mi ago. Any ideas?

Thanks,

Andy

 

[JLEONARD]

as a first wave I would put a wrench to every fitting that would have been removed for either of the jobs you mentioned... you never know, someone may have forgotten to tighten one of them correctly. Then check the fuel filter and make sure it is tight.

Jay

 

[andrewleach]

We were gone for the weekend so I'm just getting back to this project. I do'nt think it is a loose fitting because it ran fine for 20,000miles after the new parts were installed, and it is a very intermittent problem. The problem is definitely still there though. My brother says that several times now it has started to run rough at idle, so he revved the engine up a bit to keep it running and the problem would go away again. Personally I am beginning to wonder if the new fuel pump is going bad already.

Thanks,

Andy

 

[PWall]

I am new at working on them but i have had a 93 for six years and mine has been doing the same thing. Just recently, I have replaced the fuel pump and the porblem became worse. I finally took it to a dealer and spent a fortune on ..... A Fuel pump . and the problem came back... The mechanics (4 ) of them said that it was most likely an injector bleeding back some how. They ran pressure checks and vac checks on everything and all came out good. I got my truck back and did not make it thirty miles before it done it again

I am at a loss... My next step is to replace the injectors ( all 6) to see if that is the problem. If not next is injector pump

 

[BushWakr - RIP]

I suspect either the lift pump is going out on you, or... ... ... ..... mmmmm... . the injection pump is trying to tell you something.

I assume the filter is fresh, there's no sign of water or bad fuel when you bleed some off, you haven't had any significant change in mileage,smoke, performance or other telltale symptoms right. . ???



pb. .

 

[RWWinslow]

Check the rubber fuel line going to the lift pump from the steel fuel line. Change it if it looks 'tired' or if there is any evidence of fuel leakage (dust, dampness, etc. ). Make sure that you use marine grade fuel line or fuel line rated for all types of fuel and fuel injection service. If you use regular gas line it will suck air. Also, check your rubber fuel lines where they come out of the fuel tank and attach to the metal fuel lines that run along the rail.



Mine recently started idling rough when warm - checked the rubber fuel line going to the transfer pump and it was damp under the hose clamp. Could not get quality fuel line so I used generic fuel line and it was an improvement but still sucked some air. Finally got injector service / multi-fuel grade fuel line and new hose clamps - purrs like a kitten.



Oh, by the way, my problems started after I changed the lift pump. I have worked on Cummins marine diesels and also have an 8. 3L Cummins in a small Ftliner and have noticed that they are all very sensitive to any small amount of air entrained in the fuel.



This is a relatively easy and cheap check / fix.