Happy New 955L Owner With Questions

[AllDodge]

Cost me about $1700 to have the D3 pump rebuilt in 2014, sure it will cost more now.

Just thinking like if one went bad, might not be long before another does

Edit: looks like CAT wants 10K for it

 

[Nige]

Well, I guess I'll look up the part number for those in my catalog and see how much they cost, but I should probably get them out and check them for numbers before ordering.

i think that might be your best bet.

Looking back through the thread I recalled that the engine in your loader is a transplant (or at the very least the cylinder block is) that originally came from a 4B-prefix 3304 Industrial engine. So based on that who knows for certain how anything in the engine, including the injection system, is configured compared to what (per the parts manual) ought to be in the original 78P-prefix 3304 engine installed in 85J10466 by the factory.? IMO this is the dilemma any owner faces with a transplant engine if he wasn't there when it was assembled.

 

[leadfarmer]

Its a 3304PC, SN 78P28005, 4N3974

 

[Nige]

Its a 3304PC, SN 78P28005, 4N3974

Sorry, my mistake. Someone else posted a photo of an engine S/No plate earlier in your thread that I thought was yours.

 

[Bluox]

If I'm still allowed to post real information .
Original part number 7S9891 valve service group 4 of each.
Make sure you get real fuel hose .
Next time it acts up pull the hose off the filter to check for floaters in the tank.
I've found when a nozzle check valve goes bad with the motor running and you loosen the fuel line on that nozzle the engine will run better.
Good luck
Banished Bob

 

[charles walton]

I loaded some shale in my dump truck after work. When I load the truck I shut down, go dump, restart the crawler etc. i cut my work short because the 4th time I restarted it the crawler really sounded like it was missing on one cylinder and after idling for a minute it cleared up. So then I drove the crawler about 1/4 mile to my garage. When I keep the throttle under wide open, working it or driving it, I never had the bog down issue. I just got nervous because restarting was more getting more difficult.

I did not change any parts yet.

So I did the test cracking each injector line at low idle. I had bubbly fuel at each line, pictures attached. I think the 3rd and 4th lines sounded a little different, but I made a video so your more experienced ears can check it out. I uploaded the video to my google drive here:

https://drive.google.com/file/d/150SB94I7S0nvpV8KMNRMXLBnzZAiYGcr/view?usp=drivesdk

I also sprayed starter fluid around everything while it was idling and nothing happened.

I would be willing to bet that you need some work on the IP, your symptoms of air in all the lines is EXACTLY what mine was doing,but you should replace the nozzles,or capsules, first just keep the old ones for spares in case you get in a bind and need one quick, yours are probably still good. I will try to check and see if the fellow that I know down in Ga. is still alive and doing work. He charged me $800 to go through my pump and it was running like a champ when he got through with it. I'm sure it has increased in price now and the price varies on what he actually replaces.

 

[leadfarmer]

No updates, rain has been relentless and I've been tackling some other things.

Looks like the injector capsule 7S9891 is now 8N8796.

What's involved in rebuilding an IP? Sounds like something the average DIY guy doesn't attempt.

 

[Welder Dave]

Definately not something even remotely close to DIY. Send it to the pumpguysc.

 

[sawmilleng]

I'm scratching my head here--am I missing something?

1. You are getting bubbly fuel at the IP overflow.
2. No real changes to the engine when you loosen the injector lines
3. AND you are still NOT SURE that you are getting pure fuel to the IP, without air.
4---and we are now off chasing parts in the injectors????

Why not take off the fuel line to the injector pump and attach a hose to it, then:
A. See what happens when you hold the fuel above the IP and allow it to gravity feed into the pump, (no more bubbly fuel?) & (how does it run when working?)
B. Put the fuel below the pump and force the IP transfer pump to suck fuel into the pump. (back to bubbly fuel?) & (how does it run when working?)

Those two tests will cost you nothing but some time and will tell you if you have a bad transfer pump inside the IP or air coming in from somewhere upstream in the fuel line from the filter/priming pump/fuel tank.

I must be cheap or something...nobody is going to reimburse you if you have the injection pump rebuilt and find out that nothing changes! The two tests I have suggested will likely allow you to make the decision on rebuilding the pump with some certainty, although it may only be the transfer pump inside the IJ that is bad. However, a decent shop with test equipment should be able to tell you if the transfer pump is bad and be able to document your injector pump performance to see if it is acceptable without rebuild.

 

[charles walton]

No updates, rain has been relentless and I've been tackling some other things.

Looks like the injector capsule 7S9891 is now 8N8796.

What's involved in rebuilding an IP? Sounds like something the average DIY guy doesn't attempt.

You're correct,all that I know is that if you do it wrong the engine can run away and the parts are not easy to get.

 

[leadfarmer]

I'm scratching my head here--am I missing something?

1. You are getting bubbly fuel at the IP overflow.
2. No real changes to the engine when you loosen the injector lines
3. AND you are still NOT SURE that you are getting pure fuel to the IP, without air.
4---and we are now off chasing parts in the injectors????

Why not take off the fuel line to the injector pump and attach a hose to it, then:
A. See what happens when you hold the fuel above the IP and allow it to gravity feed into the pump, (no more bubbly fuel?) & (how does it run when working?)
B. Put the fuel below the pump and force the IP transfer pump to suck fuel into the pump. (back to bubbly fuel?) & (how does it run when working?)

Those two tests will cost you nothing but some time and will tell you if you have a bad transfer pump inside the IP or air coming in from somewhere upstream in the fuel line from the filter/priming pump/fuel tank.

I must be cheap or something...nobody is going to reimburse you if you have the injection pump rebuilt and find out that nothing changes! The two tests I have suggested will likely allow you to make the decision on rebuilding the pump with some certainty, although it may only be the transfer pump inside the IJ that is bad. However, a decent shop with test equipment should be able to tell you if the transfer pump is bad and be able to document your injector pump performance to see if it is acceptable without rebuild.

Well I appreciate you summarizing it and those suggestions. I was planning on doing some more work on the "suction side" of things before going after inspectors and the IP. I'm grateful for everyone posting all the information though, I have a lot to learn, and yes, I'm very thrifty in general. I was going to replace the hose and primer pump next. I think I can rig up the fuel can as you described, the only problem is the issue was manifesting after 10 minutes of running, so I will have to figure out how to pull that that alternative fuel source test.

Regarding a shop testing the lift pump and IP, would that be a Cat shop or someone independent? If independent, how do I even go about finding someone like that? Everyone local I know either has a new machine or an old machine that never needs a thing, so my local networking hasn't turned up much.

 

[tctractors]

I would just like to bring a small detail forward, the fuel tank bottom is I feel higher than the top of the injector pump and with a full tank of fuel is a good foot + higher than the top of the injectors, so the fuel feed involves no sucking, there is control valves (Check Valves) in the sleeve type pump that could be an issue but often on a fuel system of this type if it can suck air it can also leak fuel. tctractors

 

[leadfarmer]

Correct, the fuel supply is higher than the pump, and I never did find a lift pump in the parts book.

 

[AllDodge]

I don't remember a separate lift pump on mine either.

 

[Bluox]

Cliff notes
Trouble shooting KISS keep it simple.
Homeowners shot gun method replace the most expensive and work back to plugged filter.
My son holds the record for floaters came back from 3 weeks off other shift spent 30K on fuel system parts still won't run.
He spent 30 minutes fishing a sandwich bag out of the fuel tank runs again.
Put end of new hose on fuel shutoff valve.
Put other end in bucket and turn fuel on .
See if fuel flow is steady for 3 or 4 gallons.
if not check tank for floaters.
If good hook hose to filter and see if fuel will flow thru filter.
make sure tank is at least half full.
The fuel transfer pump is inside the injection pump.
Good luck
Bad Bob

 

[361brock]

I installed electric inline fuel pump before IP to solve my mechanical lift pump issue. Turn key on and fuel is flowing. If still doesn't run good then you can look else where. Cheap transfer pump diagnostic.

 

[sawmilleng]

There's a lift pump inside the injector pump body, as others have noted. And for those who are implying a lift pump isn't needed seem to forget that these machines get into some gawdawful places where she might be nearly standing on end---in other words, the tank may be FEET below the injector pump.

361 Brock also mentions a simple test by using an electric pump. I had forgotten about that kind of fix--my forwarder has a Perkins diesel where the lift pump is a simple diaphragm pump run off the camshaft. The previous owner had trouble with getting fuel and did the same- an electric pump in front of the OEM pump. Been running it that way for years.

YMMV.

Jon.

PS:. Where's PumpGuySC? I'm sure he would have some words of wisdom.

 

[361brock]

The only down side of fitting an inline electric pump before a diaphragm transfer pump is if the diaphragm fails the fuel could pass into the crankcase where the cam drives that pump. Not real sure that can happen, just my thinking possible. I still would try it.

 

[charles walton]

Well I appreciate you summarizing it and those suggestions. I was planning on doing some more work on the "suction side" of things before going after inspectors and the IP. I'm grateful for everyone posting all the information though, I have a lot to learn, and yes, I'm very thrifty in general. I was going to replace the hose and primer pump next. I think I can rig up the fuel can as you described, the only problem is the issue was manifesting after 10 minutes of running, so I will have to figure out how to pull that that alternative fuel source test.

Regarding a shop testing the lift pump and IP, would that be a Cat shop or someone independent? If independent, how do I even go about finding someone like that? Everyone local I know either has a new machine or an old machine that never needs a thing, so my local networking hasn't turned up much.

Talk to some local loggers or anyone running older CAT machines,someone should know of a private fuel system guy,CAT will want more than you could imagine to fix your pump.

 

[thepumpguysc]

I was lead to this topic by a concerned member..(lol)
I’m gonna need some time to read thru the postings but I’ll back..