Hard starting 963

[George Goetzinger]

Got a 21z 963 with a 3304 in it. Started fine this morning ran a few hours and shut down to eat dinner. When I went to start it back after about 10 minutes all it would do is crank. No smoke or anything. Tried the primer pump and still nothing and of course I was all the way on the back side of my farm clearing trees with no tools or anything. Walked to my shop and got a can of starting fluid and went back. Gave her a little shot and she fired up. this is not the first time this has happened. Had this thing in the shop back in January and my dad replaced what he called check valves in or on the pump somewhere. He thought that was the problem but I guess not. The problem is kinda hit and miss, sometimes starts fine sometimes not. I believe it's starving for fuel but not sure where to start. Any suggestions on where to start?

 

[kshansen]

As always hard to trouble shoot from a distance but the "no smoke" while cranking would say it's not getting fuel so that would be the first place to start.

When you "tired primer pump" did it feel like it was building pressure?
Did you open the bleed valve while pumping to see if fuel was coming out?

I'm attaching a couple pages that give a brief description of the fuel system, might help some.

I believe the bleeder should be the red valve in this picture:

 

[George Goetzinger]

I did not try the bleeder. To be honest I didn't even know it had one on it. Also I didn't feel 100% confident in it. Previous owner said he also had this problem intermittently.

 

[DMiller]

If you do get air from the bleeder start looking for a raw rubbed fuel line from tank to transfer pump and may suspect the transfer pump, If I remember correct these use a standpipe system so may wish to pull it out and examine for a rust line as we used to see on heavy trucks that were kept at a low fuel level constantly. Does it have electric solenoid shut down? Have someone in cab cycle the switch while you watch it operate if does, these can also get sticky and not pull in as needed when hot, going back to the barn may have given it time to cool enough.

 

[farmerlund]

I had the same problem with a truck a few years ago. turned out it was the fuel filter. It had the wrong one on it when we bought it, so when we changed it we also put the wrong one on it. I finally used serial number and got filters from KW and behold they were a little different. Of course this was after trying about $200-300 of other things. Primer, check valves and so on.

 

[Welder Dave]

I'm not sure but see if there is a screen in the fuel line at the lift pump. On my 931B it was inside a longer hex fitting and removed with an allen key. Gave me fits until I finally figured out where it was. Got so bad machine would idle but speed it and it would die in 30 seconds. Took almost an hour to move it a 1/4 mile to get it back where I could look at it.

 

[George Goetzinger]

Lots of good points to start looking into thanks. Going to be a few days until i can get time to mess with it agin. Does anyone know if there is a vent on the fuel tank that could be stopped up pulling vacuum on the fuel or would that cause it to run poorly?just a thought I had while driving.

 

[kshansen]

Lots of good points to start looking into thanks. Going to be a few days until i can get time to mess with it agin. Does anyone know if there is a vent on the fuel tank that could be stopped up pulling vacuum on the fuel or would that cause it to run poorly?just a thought I had while driving.

Yes the fuel cap should have a vent in it. Depending on the machine and if it has had an updated cap there are two or maybe three versions.

If you remove the cap and look at it it should be obvious. Most of the old ones have a bolt on the under side that holds the parts of the cap together. This, if the original version would be an aluminum 3/8 inch bolt with a small hole thru the middle and there would be a couple foam filter like sponges under the plate the bolt holds on.

If the cap has been updated it may have a large headed plastic "bolt" holding the plate on. If the whole cap assembly has been updated it may be a lever operated cap with a separate filter/check valve that is held on by a couple small screws from the underside.

All the different caps are rebuildable with parts from Cat. I made this "cap Rebuild" a standard maintenance at least once a year or if machine was used in dirty conditions.

Easy way to tell if it is the cap would be tor remove it after running for a time and listen for air sucking in when cap is removed.

 

[George Goetzinger]

Got back out to the farm today to meet a surveying crew. Had a few minutes to messs with the 963. It appears mine has a return line in place of the bleeeder valve. I can pump the primer pump and hear what sounds like air moving in the pump and I can hear what I believe are the check valves moving. I have fuel at the filter inlet from the primer pump. But was still slow to start. I looked the filters numbers up when I got home and looks like I do have the wrong fuel filter on it. Next I'm going to clean primary filter and replace secondary with correct filter. Book calls for a 1P2299 and that crosses to a napa 3352 has a napa 3528 now. Think I'll check fuel pressure at the filter housing also. The fuel cap vent looked pretty clean but I believe I will take it apart just to be sure.