Happy New 955L Owner With Questions

[leadfarmer]

I will do the injector test tonight, and throw the hand pump on the shelf for a spare if I don't need it. Maybe I will hold off a day and pick up the hand pump tomorrow. I also ordered a new drain valve for the injection pump since the stem leaks when I open it, and it is cheap.

I guess I'm struggling a little to understand some things. This is basically the first diesel I've worked on, aside from oil changes and basic maintenance.

For this test, am I loosening the 4 injector line connections at the top of the pump or at the injectors?

If the injector capsule (in the head) is failed, how does that create foamy fuel in the pump?

Just to reiterate the symptoms, the machine runs good when I prime it and start it for about 10 minutes of normal heavy use, then I have the bog down issue, foamy fuel comes out of the IP drain when I hand prime it (machine off), OR I can idle for 5 minutes or so, either way lets me run for another 10 minutes until another bog down.

 

[Nige]

For this test, am I loosening the 4 injector line connections at the top of the pump or at the injectors?

You are loosening the line at the fuel injection pump end.


TCT's procedure repeated here - "By the sound of things you have a failed injector capsule, to test this point start the engine up and run it at low idle and undo each injector fuel line at the pump, look for a line that blows bubbly fuel out and makes the most fuss. tctractors." So basically not only look for bubbly fuel but listen to the engine note as well. If TCT is correct when you loosen one of the four lines the change in engine note will be different to the change you hear from the other three cylinders.

 

[leadfarmer]

Roger that!

I wish I could remember exactly why I changed the hand primer pump in 2020. I went back to page 7 or so of this thread when I had a fuel contamination issue with a clogged filter, but I think the hand pump piece wouldn't tighten down and that is why I replaced it. Either way I didn't record it here.

 

[tctractors]

I seem to speak in a non English script often so lets start again, how does this sound your hand primer pump is what we might call a lift pump or bleed pump, anyhow it is not uncommon for the injector capsule on the P.C. engine to fail and let cylinder pressure back through to the injector pump, this will show up as foaming out of the fuel line to the duff injector capsule, you can test it many ways so if you need I can post a bit more on it, the injectors are set very low pressure only a few 100 psi over cylinder compression pressure, so making things easy you can slacken the lines on the pump or at the top of the injectors its your shout, with the engine running at low idle or mid speed take your 3/4 A.F. to the line hex and see if you can spot a change with the fuel leaking out, the frothy one is the duff one. tctractors

 

[leadfarmer]

AH, now I understand what could be happening. I appreciate you taking the time to spell that out. I didn't know cylinder pressure could enter the IP through the injector.

 

[charles walton]

I wonder what the cat shop charges for that? Hmmm. Should I also have injectors cleaned/tested or anything if I have the pump off?

I would defintely rule out the injectors first,and then find a good fuel system shop,CAT will drag you over the coals because they will replace EVERYTHING and it probably does not need all of the parts you will pay for.

 

[leadfarmer]

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.

 

[leadfarmer]

Attached is a picture of the bubbly fuel that came out of the IP drain while at low idle. Not sure if this is normal or not.

at that point I decided to take out my frustrations on the loader arm safety lock. Its been frozen in place since I got it and shame on me for not fixing it sooner, but I always sat the bucket on something for safety, etc. well its fixed now. It took a lot of muscle and a porta power, chain hoist, pry bars, kroil, hammers… the usual party supplies. So at least I got that done.

 

[leadfarmer]

When I first did the injector test I thought the 4th line sounded different. Then I set up the camera to make that video. That time I thought the third line sounded different. Either way, the difference in sound wasn't significant, just a slight difference.

 

[361brock]

There is a plug on the injection pump to insert a pressure gauge, should be about 32psi, once that pressure drops to 20 or below the machine will begin to stumble be hard to start or quit. I would be looking at transfer pump if you have established the tank and lines including if you have one of those basket strainers is all clear.

 

[leadfarmer]

Maybe I will replace the rubber hose that is part of the line from the tank to to the filter. Just to rule that out, and it costs nothing. It's probably older than I am.

 

[tctractors]

The cylinder that shows the least change to the running of the engine is the duff cylinder, sad to say as you opened No1 fuel line a big hand was in the way to see how powerful the fuel pumped out, an easy thing to try and cheap enough would be to invest in a rocker cover gasket and a set of new capsules and seals, pull off the hood and wash off the engine then run a valve set and fit the new injector tips, if you had the injector pump rebuilt you would be fitting new tips anyhow, the sleeve metering pump was never the most robust fuel system CAT built, the fuel elements jamb up with the first excuse they find, as for your thinking that it could be sucking air well it often shows up as a leak when the engine is not running, another way of testing the injectors in place is to remove the fuel lines after first turning the tank tap off, with the throttle shut off squirt a drop of oil into the top of the injectors and spin the engine over to see if the oil blows away. tctractors

 

[leadfarmer]

No 1 shot fuel out with good enthusiasm when cracked.

 

[fest777]

i think its your number 2 cylinder, 2nd one back from front, could not hear much of a change in engine pitch when you opened line, i know it can be hard too tell when your right up in close to the engine when running, other than that motor sounds good, cant hear the pc rattle 3304's are noted for that canny pinging sound

 

[leadfarmer]

Well I think I'm still going to replace the hand pump and rubber fuel hose before anything else, just for the piece of mind, knowing I tried the "cheap stuff" first.

If anyone wants to start educating me on how to replace an injector capsule feel free. This is all new territory for me.

 

[fest777]

really easy- remove line on top of valve or injector- unscrew cap/nut around 7/8" then pull injector out, there is an adapter tube that attaches to caps it is hand tight reinsert new assembly and torque nut,clean pc chamber adapter bore with round wire brush

 

[leadfarmer]

So there is no calibration or setting injector height or anything like that? Easy part swapper job?

 

[361brock]

If this is a 13x machine it doesn't have pre-combustion chambers

 

[Nige]

So there is no calibration or setting injector height or anything like that? Easy part swapper job?

Once you've figured out what is the correct Part Number for the injector valve, pretty much.

If this is a 13x machine it doesn't have pre-combustion chambers

From his signature line it's a late 85J.

 

[leadfarmer]

Yes, 85J model with a 3304 engine.

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.

Tonight I'm going to change the primer pump and suction side fuel hose, maybe remove the entire filter housing while I'm at it and just check it for any blockage on the outlet side, the only place I didnt have fuel free flowing. Then tomorrow I plan to use the machine to push a couple of fence posts into the ground. We will see how she runs.