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Cat 426 Engine Will Not Run

T

thepumpguysc

Senior Member
Joined
Mar 18, 2010
Messages
7,538
Location
Sunny South Carolina
Occupation
Master Inj.Pump rebuilder
2 things>>
1– do u know there is a plastic filter screen IN THE PUMP.?
It’s under the large inlet nut, 15/16”
Let me know if you knew that and have checked/cleaned it..
2– the filter ur running.. on that type of filter and head, U HAVE TO put the oring UP IN THE FILTER HEAD... NOT “ON” THE FILTER.!!
It looks like it goes ON the filter but it doesn’t.. it WILL choke off the fuel..
It’ll start and run until it depletes the fuel and then shut down.. and then u have to wait until it fills ..
Take the filter back down and SEE where the oring is..
Let us know about the filter in the pump inlet.. it requires instructions to remove... or bad things will happen..
 
R

Rocket Man

Well-Known Member
Joined
Dec 10, 2020
Messages
199
Location
El Paso Texas
thepumpguysc said:
2 things>>
1– do u know there is a plastic filter screen IN THE PUMP.?
It’s under the large inlet nut, 15/16”
Let me know if you knew that and have checked/cleaned it..
2– the filter ur running.. on that type of filter and head, U HAVE TO put the oring UP IN THE FILTER HEAD... NOT “ON” THE FILTER.!!
It looks like it goes ON the filter but it doesn’t.. it WILL choke off the fuel..
It’ll start and run until it depletes the fuel and then shut down.. and then u have to wait until it fills ..
Take the filter back down and SEE where the oring is..
Let us know about the filter in the pump inlet.. it requires instructions to remove... or bad things will happen..
Click to expand...
Yes to the plastic filter in the pump. Pulled it and was clean as a whistle. That secondary filter is a PITA and yes that o ring at the top goes in first. I get a good flow of fuel from the input line at the rear of the pump, so fuel is there for the pump. Pump is failing somehow. Its at the shop now and i will know results on Monday. Will share what the problem was.
 
R

Rocket Man

Well-Known Member
Joined
Dec 10, 2020
Messages
199
Location
El Paso Texas
I got the pump back from the shop today. My reason for posting today is to bring you all up to date on the possible problem with my Cat 426 backhoes issue. Hopefully no one ever has this exact problem, but in case they do, you can see what the potential problem is.
It turns out the pump works just fine on a test machine. He showed me a video of the test which included the pump mounted on the machine and the resultant pressure it generated along with a visual on the clear hoses attached to it.
The rebuilder and i had a long conversation where i explained to him that the machine ran fine until it got hot and then it just quit running.
His answer? It could be the pump head is bad! That was his only explanation. He could not duplicate what happened when the pump was on my tractor because the bench test would not heat up the pump to the degree that the tractor would. There are two ways to test his theory: 1) replace it with another pump 2) replace the head on the existing pump.
He says that it would be cheaper to just get another pump.
So there we have it.
 
R

Rocket Man

Well-Known Member
Joined
Dec 10, 2020
Messages
199
Location
El Paso Texas
I was able to get the pump back on today but bad news, it is worse now than it was before. It looks like they took it apart and put it back together wrong as fuel is pouring out of the head and around the seals. No start of course and no fuel to 2 of the cylinders. The first and last cylinders are getting fuel. Yes, i did bleed the air from ALL of them. Got a feeling that i am in a town where professional service does not exist.
So why don't i take it back you say? Well, first off there was no charge just to check it out and second, if i get the same treatment as before, who knows what i will end up with. So, i am going to cut my losses and just get things done elsewhere.
Tomorrow i will order a new one from somewhere in the East. Not impressed with what is available here.
It looks like i will actually never know what the original problem was.
 
Vetech63

Vetech63

Senior Member
Joined
Aug 10, 2016
Messages
6,440
Location
Oklahoma
Rocket Man said:
I was able to get the pump back on today but bad news, it is worse now than it was before. It looks like they took it apart and put it back together wrong as fuel is pouring out of the head and around the seals. No start of course and no fuel to 2 of the cylinders. The first and last cylinders are getting fuel. Yes, i did bleed the air from ALL of them. Got a feeling that i am in a town where professional service does not exist.
So why don't i take it back you say? Well, first off there was no charge just to check it out and second, if i get the same treatment as before, who knows what i will end up with. So, i am going to cut my losses and just get things done elsewhere.
Tomorrow i will order a new one from somewhere in the East. Not impressed with what is available here.
It looks like i will actually never know what the original problem was.
Click to expand...
Is this a professional rebuild shop? Or just someone thats says they can rebuild one? There is a HUGE difference there.
 
R

Rocket Man

Well-Known Member
Joined
Dec 10, 2020
Messages
199
Location
El Paso Texas
Vetech63 said:
Is this a professional rebuild shop? Or just someone thats says they can rebuild one? There is a HUGE difference there.
Click to expand...
They are a "Rebuilder" of injector pumps, and the only one in town i can find. The guy who "checked it out" and made video, well serious doubt about that too.
Yes, its all about where i am, not about this site at all. I have had great success with all my questions and participation is excellent. It seems that there are many more shops and retailers of equipment in the East than here. When i was looking for a backhoe to buy the most machines i found were there, much too far to ship to West Texas.
 
D

Delmer

Senior Member
Joined
Jan 3, 2013
Messages
8,891
Location
WI
Thepumpguy can handle most pumps, that is not a complicated pump as pumps go. you could also get a used one, don't know what thepumpguy would say about that? You have a fixer upper, that probably sat for a while, this is just another kink to work out, I wouldn't get mad at the pump shop that rebuilt yours until you get this resolved and know what the issue was.

Since you have had several issues with this machine, does the engine make any smoke as it's slowing down? Can you tee into the line before the injection pump and hook up a pressure/vacuum gauge to see if the pressure drops/vacuum builds as it slows down and shuts off? Good fuel pressure, and a clear return to the tank eliminates anything outside of the pump, that should have been done before the first rebuild.
 
R

Rocket Man

Well-Known Member
Joined
Dec 10, 2020
Messages
199
Location
El Paso Texas
Delmer said:
Thepumpguy can handle most pumps, that is not a complicated pump as pumps go. you could also get a used one, don't know what thepumpguy would say about that? You have a fixer upper, that probably sat for a while, this is just another kink to work out, I wouldn't get mad at the pump shop that rebuilt yours until you get this resolved and know what the issue was.

Since you have had several issues with this machine, does the engine make any smoke as it's slowing down? Can you tee into the line before the injection pump and hook up a pressure/vacuum gauge to see if the pressure drops/vacuum builds as it slows down and shuts off? Good fuel pressure, and a clear return to the tank eliminates anything outside of the pump, that should have been done before the first rebuild.
Click to expand...
Yes i have done just about everything that has been mentioned except what you have suggested about the pressure test. The return line thing you mentioned triggered something i did not understand about all the tests i did. When testing to make sure i had a good return i could hear the fuel dumping back into the tank. Key on motor dead. (electric pump)
So, I went back over my notes on all i have done just to see of maybe i did miss something and the one thing i saw that just stood out that seemed odd was the return line test. I took the lines loose from the "T" at the top of secondary and removed the T. I turned on key and fuel shot out of the top of the filter housing where the T was. I thought that was normal. But,,
Now that i think about it it might be more ODD than normal? Reasoning that the return line originates at the front of the pump where the check valve is AND from the injectors too, i would guess that the fuel returning from the pump and the injectors would enter the return line unencumbered and then return to the tank. But if there is high pressure fuel coming out of the filter top into the T , it would seem that the fuel entering the T would overcome the fuel from the pump and injectors and block it from going back to the tank??
Any thoughts on this would be appreciated.
 
5

56wrench

Senior Member
Joined
Dec 4, 2016
Messages
2,119
Location
alberta
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.
 
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