First off, Happy New Year!! So the other day I went down to continue pushing brush with the 941B (80H6907) and could not get it started. It has been sitting for a couple of weeks and we've had some cold nights (teens/20's) so I thought maybe the glo-plugs needed a bit more time to warm. The machine will crank and I get a little exhaust coming out the pipe but noticed the fuel pressure was in the red/green area of the gauge. In the past (after running it out of fuel once and changing the fuel filter) it wouldn't start until I bled the line and built up pressure into the "green" with the primer pump on top of the filter. I tried this same method of bleeding and priming and could not get the pressure beyond the red/green and the primer pump didn't seem to have much resistance as it did when I've done this in the past. Thinking maybe there was some water in the filter that froze up I put a new filter on, bled the line but still not sufficient pressure. Pulled the primer plunger to see if anything noticeable was wrong, seemed to "sputter" when I pumped the plunger. Put the plunger back on and kept pumping, and bleeding the line. Would seem after a few pumps I'd crack the bleeder valve and get some air, did that a bunch of times (about 2 gals of fuel in the catch can). So I'm kind of stumped. Could the primer plunger be bad (the rubber collar did come off, cracked I'm sure from age)? Is there somewhere else I should be looking to see where air is getting into the system. Also, pulled the batteries and charged them since I'd been cranking it so much.
Have you checked and cleaned the primary filter yet? I think you should have one like this. Any water will gather in the bottom of the canister.
Where would this primary filter be located? I don't believe I've seen anything that resembles the one you've shown. There is I believe a filter under the tank, mounted on the side of the machine, that the fuel lines go into/out of but it looks more like a square box about 3"x5"x2" with a metal bracket of some sort and a petcock on the bottom of it. Could that be the primary filter?
941B only has the one main filter. Check the plunger on the transfer pump bypass valve, either for crap preventing seating or deteriorated plunger not properly seating.
If the fuel pump is compact(old scroll) it would have a small sediment bowl under the drive housing near the transfer pump. The bowl is steel not glass, empty out and clean the screen/element. Later Bob
I was looking on SIS and it looks like this may be a sleeve metering pump system. Does the pump look like this? If that is what it has there is a check valve under the side cover, not sure but could that be the problem? It is circled in red in this next picture:
I've never had that little button that Kshansen circled ever give me problems with priming it up,, especially if you've pump the two gallons that are in your catch can thru the button. The button gives me problems when the machine sits and then the fuel drains back, but the primer pump always starts its..... I'd be leaning to what Bob said about the little metal can type filter... I would also blow some air back to the tank to make sure your problem isn't from the filters to the tank.
Does the thing you see look like this? When I look up your serial number they list optional primary filters like the first one I showed or like this one. It would be a good idea to have a water separator somewhere before the pump.
Next hole over to check the transfer pump relief valve. (Cross section D-D)
Yes, this looks very similar to what is located in the rear of the machine, under the fuel tank mounted on the side. I'm assuming this is the primary filter. Is this a water separator or just a filter? If just a filter then should there be a water separator on the machine that was taken off, or is there a way to add a water sepator
If you have a filter like Mobile Tech posted, it is a filter water separator... There is a drain on it to get rid of water. They are serviceable from any good parts store.
Forgot about that one! Been a few years since I had the side off a Sleeve metering pump. Also isn't there a check valve disk of some kind in the channel bolted to the inside of the side cover of some of those pumps?
Thanks guys, I'll head down to the farm and see what I come up with. I appreciate all the input/replies since I'm pretty much a novice when it comes to heavy equipment and I've learned quite a bit from the sage advice.
Yes that is a water separator. The metal clip on it just unhooks if you pull out on the top tab while pushing in at the middle. You can buy this filter at most parts stores.
Yes, lots of different configurations for these pumps. The check valve you circled in red is actually for the hand priming pump circuit.
So went down and worked on the machine today, and first thing I did was drain the water separator. What came out looked like iced tea, brownish/waterish. Drained it until got nothing but red diesel and the sight glass looked at lot better (see photo/primary). Still same issue with not generating pressure with the primer/plunger. Seems like the primer/plunger is actually injecting air into the system. Pulled the primer/plunger and noticed some gunk on the gasket around the two inner openings. Also noticed the shaft of the plunger was "wet" after a few pumps which I wouldn't think it should be. To test my theory of the primer/plunger injecting air into the system I put about two inches of diesel in the bottom of a five gallon bucket and put the primer/plunger in and gave it a few pumps. I figured if the pump is working correctly then there should be no air bubbles in the diesel after a few pumps, but that wasn't the case. As I pumped there were air bubbles forming in the diesel. So I'm thinking maybe a combination of an old worn out gasket along with a bad primer/plunger might be the culprit. The parts manual I have doesn't show the primer/plunger so would anybody be able to tell me the part number for this thing (see photo/primer) so I can start a search.
Pump should be a 4w0788 with a 1p0436 gasket.
Those pumps are know to give problems. And while you are picking up the pump and gasket Mobiltech gives the numbers for don't forget the primary filter/water separator! Part Number 6N7617. A couple optional numbers for the same filter, NAPA-3369 and Baldwin-BF912 If this helps any this is the picture of the lines with the filter. numbers are a bit hard to read.
Thanks Mobiltech, I did a quick search and found them (not too expensive either)
This may have nothing to do with it at all , I had a similar problem on a 3208 truck engine. It had the same type water separator on it. When it was low on fuel , it would suck air between the base and the separator. Found out the base was slightly warped. Changed it over to a spin on style filter separator and than cured my problem. Like I said , this may have no bearing on your issue.
Still insufficient pressure on the 941. Changed the primer pump (part #4w0788), gasket and the primary filter/water separator and still can't build the fuel pressure beyond the middle of the gauge (overlapping area of green/red). Do get a little more resistance on the new primer pump than the old one but not enough to get the pressure into the green. Still getting a slight amount of air bubbles in the tube going to the catch can when I crack the bleeder valve, not as much as with the old primer pump. Also, do get a slight "clicking" noise in the area of the bleeder valve while I'm pumping the heck out of the primer pump. I'm a bit disappointed, I thought for sure it was the primer pump. So now I'm a little stumped. The neighbor suggested cracking the nuts at the injectors to release any trapped air, it looks like I can get to two out of the four relatively easy but the other two look pretty tough. So....I'm open to any suggestions.
Get a gasket, valve and spring and change them. The valve under the side plate of the pump, lower front corner. Might just be dirt under the valve but best have a valve when you have it apart. Sect DD post #9 Later Bob
Thanks Bob. I went down and pulled the plate off and pulled the valve and spring (see pictures). I'll swing by the CAT dealer and pick up a new one. I do have some questions though. Should there be an "o" ring on the valve? Also, does the spring simply rest in the recess of the plate? There were a couple of holes there that almost looked like there should be a cover over the valve and spring.
No everything is there and doesn't look too bad unless some dirt fell off. Install with flutes inward. Fuel pressure measured at the pipe plug in the plate should be 20 to 30 Psi running. Later Bob
Thanks Bob. In a way I was hoping there was something wrong with the valve, seemed like an easy fix to the problem. So now I'm stumped (again).
What fuel pressure do you have when running? Is any fuel leaking out the bleed holes of the pump when you are pumping? Later Bob
Not really sure of the exact pressure when running, I've never put a gauge on it but the gauge on the dash shows it pretty much pegged in the green (when it has been running in the past). I haven't noticed any fuel leaking anywhere when I'm pumping the primer pump.
I am thinking you may not have any problem at all. If the gauge stays in the green when you work hard it's good. The gauge is really only to tell you when to change the filter. It reads pressure after the filter, the dirtier the filter the more the pressure drop. Later Bob
Thanks Bob. It doesn't seem to be a problem with pressure once it is running, the problem is I can't get the pressure high enough for it to start. Only slight ressitance on the pimer pump. In the past (when I've run it out of fuel once and then when I changed the filter) I couldn't get it to start until I bled the air and primed it (a lot of resistence on the primer pump) and got the pressure well into the green area.
You should be able to change the filter, open the tap on the side plate, pump the fuel through until the air is all out, close the tap and crank it up. Will that get it started or do you need quick start? Just noticed another thing, look at the check valve beside the relief valve, the rubber flaps sometimes break up. Later Bob
In the past that was the scenario, change the filter, crack the bleeder until all the air it out which would build the pressure then crank it up. Not so this time, seems like no matter how much I pump the primer pump I'm still getting air when I crack the bleeder, even after pumping about 2 gals of fuel into a catch can. It would seem somewhere air is getting into the system, or is locked in. When you say "quick start" are you speaking of ether? I've read a few posts here and one school of thought says it's OK and the other strongly advises against using it, big risk of explosive type reaction. I'd really have to think about taking that risk. As for the valve beside the relief valve I looked at it and it appeared to be OK, i.e. the rubber flaps looked like they were intact. I wasn't sure how the thing came out so I didn't dork around with it. Is there a special tool needed to remove it?
Every once in a while I will have problems getting one to prime up also,,,, I use ether to get it started. Once she starts on ether, it then functions ok on all subsequent start ups.... the ether deal with have to be your decision,,, but I wouldn't hesitate.
Not sure if this has been mentioned or tried, but how about hooking a hose to the filter head that has the spinon filter on it and put the other end in a bucket of fresh fuel oil and see if that lets you prime the system and start. That would eliminate everything back to the tank. If that works then you know where to start looking.
I am far from being an authority on the matter but I will contribute my 2 cents worth. If you are afraid of the idea of using the ether then try this little trick. Soak a rag in gasoline, ring it out good and then drape it in the path of the intake so the engine can get a whiff of the gasoline fumes when you crank the engine. She is going to start, so be sure and secure your gas rag so it doesn't get sucked into the intake. If it's not pumping diesel fuel the engine will quit after the gasoline fumes are used up. As far as priming the fuel system and expelling the air from the system. After I ran my Cat out of fuel and did a filter change I could not get the air expelled from the system no matter how much I bled the system. I finally took my shop compressor airline with an air blower on it and removed the cap from the fuel tank, wrapped a shop rag around the blower to get a seal and put a small amount of air pressure on the tank. While I held the pressure on the tank my brother bled the fuel system and the old gal fired right up. Do this at your own risk and with a little caution. Any more than about three pounds of pressure inside the fuel tank might burst the tank at a welded seam. You can also blow out a filter o-ring using too much pressure. A lot of pressure can blow a seal somewhere in the system. If you have an air pressure regulator hooked up, set the regulator on two or three lbs. to pressurize the tank. If you decide to try anything posted here you would be better off if you first pressurized the system and bleed the air. Remove the pressure from the tank and replace your fuel cap. Then try to start the engine. If it refuses, then introduce the gas fumes on the intake gasoline rag. It should run long enough on the gasoline fumes to expel any remaining air and pick up the prime. Nothing said here will fix your transfer pump problem but it stands a good chance of getting your engine started despite the pump malfunction, provided that your system is not getting air from an unknown source. My Cat 951 C does not even have a manual fuel pump, someone removed it prior to my ownership. I just won't run it out of fuel again and make sure that I am close to an air supply when I service the fuel system in the future. good luck and let us know how it goes!
Thanks guys for all the good ideas. I ordered a new gasket and if it comes in I'll head down to the farm this weekend and try your suggestions. Keeping my fingers crossed.
So I finally got a new filter (second try) and put that on along with a new valve (from post #9) and pretty much the same issue as before, using the primer pump can only get the pressure about half way up the gauge. Tried the trick kshansen mentions in post #33, attached a 5 gal bucket of fuel to the intake side of the filter/primer pump. Still pretty much the same so I'm thinking that might rule out any issues from the filter back to the tank. The neighbor stopped over and I had him pump the primer while I sat in the seat and tried cranking it over, the gauge would bounce into the green (about 3/4 of the gauge) on each of the downstrokes of the primer pump while the engine turned over (no smoke from the exhaust). At a loss. Next option will be to try what Nitelite has suggested about putting some pressure on it. Any other opinions/suggestions are welcomed.
I have a 96 963b with the same fuel issue, Replaced the filters twice new primer hand pump and the same issue could only keep it running if I continued to pump the primer, Not sure if thats your issue but we ordered a hight quality 24V electric fuel pump pre set at 28lbs of pressure and its adjustable, tied into the key when you start up. it was about $500 marine commercial application and she runs like a dream now. other than blew a hydraulic hose that I am dealing with now.
Thanks Mike, I may have to go that route. I'm going to give Nitelite's suggestion about some air pressure a go and see what happens. I feel for you on the blown hydraulic hose. I blew the one to the lift cylinder last summer, wasn't all that bad to replace other than bending it into place and connecting it - those hoses don't give much
I have a 941B in VA too. I had to give mine a shot of ether back when it was cold there to get it going. It doesn't normally need it though. I've been researching to see if I could put a root rake on my track loader and had read that you had one made for yours. I'm wondering where in VA you had that done and how its worked out? I'm clearing young saplings and trying to leave as much topsoil as possible.
KennyR, I gave it a couple of shots of ether the other day when the weather was a little bit warmer. Still same issue, would cough a bit - blow a little white'ish smoke but would not catch. Too cold this weekend to work on it. As for a root rake yes I did buy and install a root rake on the 941B to clear 27 acres of saplings/small trees (1inch to 4 inch diameter pines, oaks, poplars (which I hate because of the roots)) see attached. The farm is located in Spotsylvania County. Once I get the bad boy running you're more than welcome to swing by some weekend and see it in action. Shoot me an email and I'll give you the specifics on where I got the rake, install and directions to the farm
Thanks for the info. My machine looks just like yours except the sweeps and the rake. Was that rake completely fabbed from scratch or did you start with a dozer root rake? I was curious because it almost looks like a D6 size rake for the bottom portion. How good of a job does it do? Does the small stuff slip through or does it catch the saplings? What about stumps? I'm clearing 1 to 4 inch stuff as well with the occasional stump. Land was logged 10 years ago or so. And does it put to much weight out on the nose? I'm in western VA so I have a lot of hills. Thanks, sorry for the hundred questions, but that's what I had in mind to do on my machine.
I use a rubber pipe test cap with a tire valve glued into it to prime all my old cats. I do not put a clamp on it but simply hand push it on the fuel tank threads. It will hold well on the tank threads but will blow off if you overpressure avoiding damage. I set my compressor regulator low (3 to 5 PSI)and it makes bleeding simple. Just start closest to the tank and work your way all the way thru the system. Keep the pressure on for a few minutes and look close as it will often drip and show a leak where the system was sucking air, as it will leak out when pressurized from the tank. Good luck.
Thanks old-iron. I bought a Schrader (tire) valve the other day from the plumbing supply place and was looking for a cap, and I like your idea. Probably look to do this next weekend when the weather is predicted to be a little nicer.
Well the weather has finally gotten bearable so I was able to get someone out to look at the ol' gal. The gent tells me it was "air locked", he cracked open the lines on top of the pump and was able to get it started. I went down today and it cranked right up so we're back in business. Thanks again for all the suggestions/help - I do appreciate it.