D8,46A fuel issues?

[americanson57]

I have a neighbor that approached me about a problem with his D-46A model.
They finally got the pony motor running and then they got the main running but
just only carry an idle but not long and no throttle response. All filters fresh everything service ready to go. Same as always ran the last time we used it a year and a half ago.
Any help would be appreciated

 

[Check Break]

I have a neighbor that approached me about a problem with his D-46A model.
They finally got the pony motor running and then they got the main running but
just only carry an idle but not long and no throttle response. All filters fresh everything service ready to go. Same as always ran the last time we used it a year and a half ago.
Any help would be appreciated

Do you still have air in the fuel system??? Compression release closed.

 

[americanson57]

Thanks for the response, but you know those famous words I assume. These are boys are pretty sure they know what they're doing.
Regardless those are a few common Sense points I'll ask because the first thing I know is I don't know.

 

[Delmer]

Is the injection pump rack free? I couldn't tell you how to access it, but look it up to find some pictures.

 

[Check Break]

Thanks for the response, but you know those famous words I assume. These are boys are pretty sure they know what they're doing.
Regardless those are a few common Sense points I'll ask because the first thing I know is I don't know.

I usually assume that if it was fine before I touched it, it's something I did. Could be the lift pump is weak. If they can regulate their shop air down to 4lbs, they can pressurize the fuel tank which will improve fuel delivery until she can build rpm.

 

[americanson57]

Is the injection pump rack free? I couldn't tell you how to access it, but look it up to find some pictures.

Delmer, thanks good question. Really do appreciate it,

 

[Delmer]

If one injection pump piston is sticking, from sitting, then that cylinder will be dead and it won't allow the rack to move out of idle.

 

[americanson57]

I usually assume that if it was fine before I touched it, it's something I did. Could be the lift pump is weak. If they can regulate their shop air down to 4lbs, they can pressurize the fuel tank which will improve fuel delivery until she can build rpm.

Some good advice, their problem is Doser is in back country about hour & half drive. Used for keeping watering holes open for cattle. Once I can gather enough good info we can put everything together so as to make trip productive.
Thanks

 

[americanson57]

If one injection pump piston is sticking, from sitting, then that cylinder will be dead and it won't allow the rack to move out of idle.

The sitting for year or so in back country and ramifications from that was my first concern. The issues concerning pump my first question.
From kens description saying fuel at injectors and wanting to idle but no throttle response.

 

[John C.]

Two things come to mind depending on the vintage of the machine. There is a strainer in that fuel system as I recall attached to the injection pump somewhere. The other concerns engine oil pressure being high enough. At some point in the production run there was a safety device in the pump that wouldn't let the fuel rack free until there was enough oil pressure.

 

[thepumpguysc]

If u can get a pic of the inj. pump and post it, we may be able to tell you how to access the rack..
There almost HAS TO have a skip..
If it runs at idle but no more rpm’s, that tells us the control rack is stuck.. but in order for it to pump at idle and no more, means 1 or more plungers are stuck in the up position .. or a broken plunger return spring..

 

[thepumpguysc]

Sorry.. I went straight to a stuck plunger..
Didn’t think about supply pump pressure.. but I think somewhere it states it has “good” pressure.??
If it was a pressure problem, it would bog down when the throttle was moved to full..(asking for more fuel) THEN running ok at low idle again..

 

[Bluox]

Check for oil pressure.
Pull the pin on the governor control arm where the throttle rod is hooked to it.
Start engine and see if it will idle up by hand moving the control arm.
If it does clean the throttle control ratchet out.
If it doesn't have someone who is familiar with that pump look at it.
Bad Bob

 

[americanson57]

Gentleman, much appreciated all for sure. Ken said parts manual available somewhere. Need to track it down so as to get my mind around all this good info. Will be looking for possible PDF or hard copy on service. But by all means if we can keep conversation ongoing this also would be appreciated. Last thing I would not want to do is go 1 1/2 hrs into back country and be ignorant on the matter.
Thanks

 

[old-iron-habit]

Pull the flat cover of the side of the injection pump. Nothing will fall out. Insure all six vertical plungers are free to move up and down. Take extreme care to not scratch the machined cylindrical surfaces. Use a plier with a good rag softener and be gentle. They usually are not stuck bad at all if stuck. The throttle pulls on a spring and the books will tell you to slam it all the way open when you give it fuel after the pony motor has warmed it up and then return it to half throttle. It's sounds like your throttle could be stuck. Not sure how familar the guys are with these old workhorses but remember that the idle speed is 600 RPM and the "fast idle" or wide open, no load, speed is only 900 or 950 RPM dependent on setup. It's all torque without much engine speed. That's one of the reasons why they are still working after 70 years. They will run fine even if the fuel pressure gauge is at the edge of the red. I do not believe you have a fuel supply to the pump issue.

 

[old-iron-habit]

Manuals are easily found on Ebay. You should have the Parts Manual, Operators Manual, Serviceman's Reference Manual, and the Engine Manual. If you don't find them one day, they will usually show up in a day or two. If you are a ACMOC member there is also a lot of 'legacy' manuals available to look at in the members only area. I would advise anyone with any old Cat to become a member. The retired mechanics there are a wealth of knowledge and very willing to help. Online only memberships are available very reasonable. Lots of knowledge, help, parts, and good comradeship abounds in the worldwide club.

 

[Bluox]

Pull the flat cover of the side of the injection pump. Nothing will fall out. Insure all six vertical plungers are free to move up and down. Take extreme care to not scratch the machined cylindrical surfaces. Use a plier with a good rag softener and be gentle. They usually are not stuck bad at all if stuck. The throttle pulls on a spring and the books will tell you to slam it all the way open when you give it fuel after the pony motor has warmed it up and then return it to half throttle. It's sounds like your throttle could be stuck. Not sure how familar the guys are with these old workhorses but remember that the idle speed is 600 RPM and the "fast idle" or wide open, no load, speed is only 900 or 950 RPM dependent on setup. It's all torque without much engine speed. That's one of the reasons why they are still working after 70 years. They will run fine even if the fuel pressure gauge is at the edge of the red. I do not believe you have a fuel supply to the pump issue.

If the motor runs the injectors are not stuck and a 342 high idle is somewhat over 1300 RPM.
If I caught someone with a pair of pliers in my injection pump they would be beat.
Bad Bob

 

[Delmer]

I don't work on Cats, but one injector sticking up will still run on the other cylinders, and won't let the rack move.

If it was a fuel starvation issue, on engines I've seen, they'd rev at least a little and have enough fuel in the pump to get some throttle response, but stumble with any load.

 

[56wrench]

The rack could be stuck in the housing which would let the engine run but not speed up. I had it happen once on a 3406 A block in a steiger tractor that had been sitting a few months. I removed the inj pump and the customer took it in for repair. According to the pump shop it was due to coolant contamination. It turned out that there was some coolant leaking internally and it gummed up the rack where it slides in the housing. I reinstalled it and after he brought it in to the dealership (with the rad cap loose) i proceeded to pull the piston/liner assemblies out and change the liner o-rings. It was still running years later when he finally retired

 

[Check Break]

You live in a great place. It's going to start cooling off which will soon complicate matters. Pony motor start helps after it freezes but she's not going to run with a low fuel issue. I haven't been up that way in fifteen years. Are you running ULSD. If so, you might have a biology problem. You'll see it in the fuel screen if you do. You're going to have to determine if you have fuel flow. Pull the fuel line and direct it at a bucket. If the tank shutoff valve is plugged, you'll know. (Did they open the valve fully after changing the filters.) If you have fuel flow from the tank, air it up with 4lbs. The last thing I'd worry about is the injection pump. There's no reason to look at the pump until you know you have fuel flowing from the tank, the filters are flowing fuel, the screen is open and the lift pump is making pressure. If she ran before you opened her up, she'll run again. There would have to be biology or water in the fuel for the pump to seize up in a year and a half. Look for simple problems first.