Cat 426 Engine Will Not Run

[Nige]

 

[Nige]

 

[Rocket Man]

This sounds suspicious from what you have said. From my experience, the return from the injection pump and injectors should return directly to the tank via its own line and not be connected to any filter head or any part of the suction line unless maybe that T has an integral check valve or pressure relief(or pressure maintaining) valve in the branch coming from the injection pump return which would allow return fuel back into the suction side. I've never seen it, but then i've never worked on any of the cat backhoes. Some manufacturers do strange stuff. I don't know what the purpose of that little short line is from that T to the banjo fitting on top of the filter head. Maybe its a constant-bleed feature or similar. Somebody should be able to tell you that has worked on these perkins engines. Its been a long time since i worked on a perkins with a cav pump so my memory is fuzzy.

Attached is a pic of that filter and line. First there is that little T (with the line removed that goes to front of pump) , you can see and when i turn on key fuel squirts of it. I took the banjo bolt out and turned key on and fuel squirts out as well, so i know that the fuel is coming from the filter direction and not thru the pump. I also logically think this is not right. There is no check valve in the small T or in the banjo bolt. I would really like to understand whether this is the way it is supposed to be or if it is a malfunction of some kind.

 

[Rocket Man]

View attachment 243811

Nige, that pretty much looks like mine. I was wondering about item #8 in the image as to whether that is a check valve or not? Kind of looks like a bolt? but also resembles a CV?

 

[Nige]

Sorry, missed an illustration.

 

[Rocket Man]

Sorry, missed an illustration.
View attachment 243813

Great, looks exactly like mine. The problem is there is pressurized fuel at the banjo bolt #19 into line # 9 which in turn forces fuel into line #20 that connects to the injector bleed off lines. Not sure that is what should be happening. It also pressurizes line #25 which goes to the front of the pump which has a check valve in it. While the pressured fuel from the pump won't overcome the CV , maybe is is stopping the natural flow of excess fuel FROM the pump back to the tank?

 

[Nige]

Quick question. Go back to the illustration in post #60. Is there any chance that O-Ring #9 is missing or you have two of them on there.? It's not unusual to find either of those scenarios.

If you mean #8 on the last illustration of the fuel injection lines it is listed as a "bolt", when obviously it is a pipe connector. However it is NOT listed as being a check valve.

 

[Rocket Man]

Quick question. Go back to the illustration in post #60. Is there any chance that O-Ring #9 is missing or you have two of them on there.? It's not unusual to find either of those scenarios.

If you mean #8 on the last illustration of the fuel injection lines it is listed as a "bolt", when obviously it is a pipe connector. However it is NOT listed as being a check valve.

I did look at post #60 and i just replaced that filter recently and have in the past. The first time i replaced it i found that the O ring goes on #9 fits over a protruded hollow shaft the mounting bolt goes thru. Well that shaft has a chuck out of the side of it. Looks like someone in the past either beat on it or it just broke off naturally. Not sure if that cause a problem BC the O ring seems to fit and sits firmly on the shaft past the broken part. Yes,m only one O ring there now. Could that be a problem?
Also, thanks for clarifying the item #8. My manual is not detailed enough to see that in detail.