Cat D4 7U lacking power

My partner and I thought we had a pretty good addition to our low budget placer mining operation when we bought this 1956 Cat D4 7U with adjustable angle blade. After several months of replacing, changing, filling, inspecting etc I was able to get our D4 7U ready for a maiden run on grading our new "boat ramp" leading down to our now-dry pond. Though it smoked badly when a few months ago I first drove it down our 1 mile road to our equipment area, after changing oil and filter, fuel, fuel lines, fuel filters (all four) it has cleaned up and seems to burn relatively clean and smooth.

Confident that we had finally gotten the old girl ready for prime time I decided to head over and see what she could do. Initially she seemed to push the blade without too much effort on about a 15-20% downhill grade, but when I tried to back her up the decline I couldn't get enough power to get her to move more than a foot or two before she'd began and finally stall out. I had no problem with steering and clutch actions when on the flat and not pushing the blade.

I was under the impression that if you could fit an old D4 with climbing spikes it would climb trees. There was no sign of abnormal blow-by, and the exhaust remained somewhat white rather than the black smoke we get when under load. This leads me to believe that I have a fuel problem, maybe due to an unknown filter in the injector pump feed circuit or elsewhere.

The fellow that sold us the machine suggested installing an electric fuel pump between the tank and pump to make starting easier since we have to use starting fluid to keep from running the batteries down from cranking.

Hoping for some suggestions from those on this forum with greater insight. BTW, fresh fuel all the way to the top, and Standyne additive which we run on our other diesel equipment.

Thanks, -Tom F.

Could u get a good pic of the injection pump and filter set-up.??

Those old D4's might climb trees going forward , not the best going backwards . Combination of seemingly higher speed reverse and not overly powerful to start with . Crack the nuts on the injector lines once you have her going at the injector . Just to see if they are all flowing about the same . There is a little wheel at the top of the filter body , may be small jet to take a spanner depending on whats been fitted , open that to let out any air once its running , not too far open though , just enough to let the air and some diesel out . This is why the pony motors were good , as the cracking of the lines and air vet can be done easily .

thepumpguysc said:

Could u get a good pic of the injection pump and filter set-up.??

Click to expand...

I'll do that today because there's a lever on the side of the pump that must be pulled and latched in order to get fuel for starting. But it is always reset after running. Though I have the manuals for the machine I haven't a) identified the motor, and b) studied the fuel setup literature. I've just been too busy with other projects at the mine while trying to get ahead of the rains. But I WILL address these items today and tomorrow. Thanks! -Tom

epirbalex said:

Those old D4's might climb trees going forward , not the best going backwards . Combination of seemingly higher speed reverse and not overly powerful to start with . Crack the nuts on the injector lines once you have her going at the injector . Just to see if they are all flowing about the same . There is a little wheel at the top of the filter body , may be small jet to take a spanner depending on whats been fitted , open that to let out any air once its running , not too far open though , just enough to let the air and some diesel out . This is why the pony motors were good , as the cracking of the lines and air vet can be done easily .

Click to expand...

Yes, there is the knurled thumb wheel at the top of the filter can, and I DID bleed air both statically and while running. I'm pretty certain that the system is properly bled. Thanks, -Tom

Sounds like it could be a restricted fuel line, possibly a restricted fitting at the bottom of the tank. Is the shut-off valve at the bottom of the tank fully open? Sometimes crap builds up in the valve and won't allow full flow. DO NOT blow back through the valve- it will only push the crap back into the tank and it will likely come back to haunt you

What do you have for fuel pressure? should be 10 to 15 psi running.
Are you getting full rack travel?

Is it running fine on all four cylinders?
Crack injection lines at pump to check.

what is your fuel pressure it should have a gauge on the dash

TomA said:

Is it running fine on all four cylinders?
Crack injection lines at pump to check.

Click to expand...

Yes, no hesitation or stumble, just the stalling out under heavy load.

Old Magnet said:

What do you have for fuel pressure? should be 10 to 15 psi running.
Are you getting full rack travel?

Click to expand...

thepumpguysc said:

Could u get a good pic of the injection pump and filter set-up.??

Click to expand...

Here are shots of the governor and injector pump areas. I have no idea what motor this is since the manuals I got from Jen Sales included the D6 motor which doesn't resemble anything on our machine except for the general layout. The block casting number on the right side is this:

The injector pump and governor areas are next:



My attention was drawn to the governor where two of the top cover bolts are missing and some weld repair had been made at some time in the past:



And there is this lever on the top of the governor plate that must be pulled out and latched with the small swinging toggle stop. I'm guessing that's a stop lever but am mystified as to how it was originally configured. And it is always reset by the time we throttle down to off:



So my issue of lack of power may be related to the governor control of the fuel rack and not the fuel system itself? I'll figure this out somehow just as soon as I can identify the motor and get the correct manual for it.

-Tom

Dave Neubert said:

what is your fuel pressure it should have a gauge on the dash

Click to expand...

A damaged gauge prevents me from seeing fuel pressure without resorting to attaching an external pressure gauge, but see my latest post regarding the governor. Thank you! -Tom

I just see the last picture and the D4 serie 7u should have a d315 motor and with the picture motor it is a 3400 or 4400 and the control governor is't nice to see.