Engine/Transmission (1994 - 1998) Hard Start...Now NO START

[GGill]

Morning Guys, a month ago or so I posted about a sudden hard starting problem and was advised to look into replacing the rubber fuel return and supply lines as well as the lift pump... all were overdue to be done, 125,000 on the truck.



Did that work... half day of fun Truck immediately ran much better and quieter, the old lift pump was making quite the clatter... all better.



A week ago started to loose "prime" again on the fuel system to the point where I have to manually prime the engine every time I start it up, and now it is to the point that it will stall if left to idle for more than 5 min. or so.



Air gets into the system so fast now that the engine cannot be re-started after it is shut down without using the primer on the lift pump.



Did the new lift pump fail already??? That seems plausible but unlikely.



Any ideas as to what I might have done wrong???



I do hear air bleeding from the vicinity of the injector pump when I prime it, but I have always heard that when I have primed it after replacing the fuel filter.



This sucks, as I thought I had the problem licked.



Thanks again, Greg

 

[Howard Durand]

Did you check or replace the overflow valve?

 

[GGill]

Hey Howard, No, I have not checked or replaced the overflow valve, in fact I forgot all about it.



I just assumed that if I did one repair and it seemed to "work" that the reaccurence must be related to the repair.



Do overflow valve failures exibit these types of symptoms?



Greg

 

[illflem]

A bad overflow valve doesn't allow air into the system which sounds like your problem. If you are losing prime rapidly you more than likely also have an obvious diesel leak also. There are lots of places that can allow air in - hose between fuel heater and lift pump, fuel heater itself and I've even seen the steel lines back to the tank spring leaks. I had one that sprung a leak right on top of the bell housing, very hard to see. Ended up replacing the line with fuel hose all the way from the injection pump to the tank.

I think the leak in the metal line may have been caused while replacing the return line, pushing the new hose on may have flexed the metal line enough to crack it where it's attached to the housing.

 

[Joe G.]

In addition to the above, you should check the fuel injector manifold return. That's the tube that goes to all the injectors. It attaches to the top of the fuel filter where the line from the lift pump is.

 

[GGill]

Thanks for the info Bill...



I was thinking the same thing regarding the existance of a fuel leak with the fast loss of prime, so I crawled under the truck (again) at lunch and found a small area on the bottom of the fuel cell damp w/diesel... fuel is running down from the top. No drops are hitting the ground yet however, time to drop the cell or raise the bed I guess.



Regarding the hose from the fuel heater to the lift pump, I had trouble aligning the elbow on the lift pump to the proper orientation towards the heater and still get it tight.



I was nice and tight at the 5 o'clock position, but I didn't have the "stones" to try to get it to the 9 o'clock position for fear of damage to either the lift pump or the elbow, so I wrapped it with a few layers of teflon tape.



Is there a better way to do this?



I'm not sure if diesel dissolves teflon, but it was the best I had at the time...

 

[Joe G.]

Use anti-sieze for thead sealant in the fuel system.

 

[GGill]

Thanks for the tip Joe, I forgot about anti-seize...



I was thinking I should "bite the bullet" and just get another elbow, I just can't seem to align it properly without something taking up some space in the theads. The factory had some kind of "pipe dope" like material there.



OR maybe I go with a foot-long piece of hose like a curly-cue pig tail to get to the other side of the lift pump



Then again maybe not...

 

[illflem]

I don't recommend Teflon tape with diesel but sometimes it's the only way the fill the space on a loose fitting. Any type of paste type pipe dope just doesn't have the body to fill gaps. Hate to break it off trying to get that one last turn out of it. Some lifelong plumbers have told me they like to use Teflon tape with a coating of pipe dope or anti-seize over the tape. I prefer to use Permatex #2 for diesel.



At least your problem is on the dirty side of the filter and if you need to take things apart to get them right any Teflon debris will get caught in the filter. That's the worst part with Teflon and filtered fuel, too hard to cleanup if things need to be taken apart. You have to remove the parts entirely so you can get at the tape debris with a wire brush and compressed air.