Bobcat 743 Kubota 1702-BA engine injector question

[k4shf]

Hey folks! New kid on the block (well, at least here). Son obtained a Bobcat 743....I think he paid a bit too much but he got a great heavy trailer with it that makes up for it.....so, has some issues that need addressed.

This thing is HARD to start (understatement). Replaced 3 glow plugs but over past 3 days, I have been unable to get it to fire. (even squirting WD-40 or oil/diesel mix straight into intake). No ether, not with glow plugs....

It appears to me that the lines from the injector pump to the top of the injectors (high pressure) may bleed when not running (top of pump all gummy)....it has ran within last two months but I've spent past 3 days trying to start.

I'm an electronics geek, not a mechanic so bear with me. I cracked open a line and had air bubbles which leads me to believe the high pressure rail/fuel line needs bled...air in line, not enough oomph to pop injector AND atomize fuel well enough to fire (my theory, as I said, not mechanic).

The top of the injector pump is all gummy...I was unable to view it when running so don't know if those lines actually leak under pressure but they do appear to be bleeding down when not running.

I'm trying to not have my local Bobcat dealer retire early but don't know any good diesel mechanics. Willing to replace these lines or get the parts to redo the ends (don't know if the lines are flared so may need to do the whole lines). I'm willing to toss a few $$ towards doing this more minor work....has 5k hours which is a bit high but not needed for serious day to day operation so I don't think serious work required.

I have gray smoke but no attempt to fire. Had to replace the fuel shutoff cable (the old one was just plain froze up) and you'd question my sanity if you knew what I had to pay for a replacement....didn't have any baling wire handy though (do they still even make baling wire?)

Don't have manual on that engine and not diesel smart, just observing what I see. These do tend to have hard start issues but they are a solid and simple machine (pre-electronics everything).

Will bleed the lines today (friend coming over to handle the starter....I don't have a remote cranking cable...could make one but too lazy...and he works cheap.

Sorry so long winded, brevity is not my strong suit (I don't get out much).

Any suggestions are more than welcome. I can leave the glowplugs off and use ether but prefer to not if I can get away with it. Murphy lives with me so I'd disconnect the wire to the plugs anyway....

Just wondering if I'm out in left field or if this is feasible possibility that those lines are bleeding down when no pressure.

Thanks for all comments, advice, solutions....

Tim

 

[MSM]

I would do a compression test on it.
Pressure should be in the 350# range.
If it is low, squirt some oil in each
cylinder and retest. If the
compression comes up you have a ring
problem. Kubota engines do not like
ether. It usually breaks the top
ring. If you have smoke from the
exhaust when cranking, you are
getting fuel, just not enough
compression to fire. Another thing
that will make for hard starting is a
worn injection pump not building
enough pressure to atomize the fuel.
This usually happens from poor fuel
system maintenance, dirty fuel or
water has worn the injection pump.

 

[JoeM(GA)]

just so you know, almost all Kubota engines like the 1702 were pretty much self bleeding, there should be a fitting like this
at your injection pump where you can loosen, not remove the center bolt a half turn or so and then you can wind the starter over until it cranks, fuel and air will be coming out this bolt, and engine will run rough until you re-tighten this bolt. Some were even a knurled
knob to make it easier.

 

[k4shf]

Wow! That would sure make life a whole lot simpler....last guy had this a year, don't think he EVER did anything....so I have all new filters to go in, going to replace all fluids....

Quick opinion please...I'm not sure what all is in fuel tank...I did put in 4 gallons of fresh diesel but going to replace the filter, was thinking of just draining the whole tank and then fill with fresh. This is going to be sitting a lot, figure more fuel, less room for water to collect...was gonna add in stabil for diesel. I'm not going to be able to run it enough to run more than a cup of diesel (providing I get it started) so do you think wise to just drain and start afresh? Going to also replace filter and hydraulic/hydrostatic oil (trying to figure out where to discard the old oil...not sure how well it burns....maybe mixed with diesel? Find somebody clearing land and help with their brush pile? Oh, is one of the screws on top of filter also a bleed screw? And even if I bleed at injector pump, won't there still be air in lines? You can tell me if it's a stupid question....I've asked plenty in my life....and I have a good sense of humor.

Thanks for the info!

Tim

 

[k4shf]

My limited knowledge and advice of others, hot glow plugs and ether....gonna make things happen that you really don't want.

Has a few over 5k hours on it (but lot of wiring somehow burned up so who knows if the hour meter is correct). Kid did quick and dirty wiring so glow plugs will come on and it will crank. No warning lights, no gauges.....if I could find correct color wires I would rebuild the harness. Big red wire was almost crystalized (burnt one of those new style fuse holders in half). He only replaced the cab part, not the rest. Today's kids....27 he should know better. That wire will get replaced.

Last owner had it a year to clean up hurricane damage from last year (maybe he wishes he kept it). Found a contractor sticker from before that, no idea what, not local. So who knows what the maintenance history is.

With 5k hours, I don't doubt that could need ring job....beyond me. Would replace the whole thing.....

Thanks for that info.....I need to get a compression gauge.....Amazon has a universal set for about every imaginable injector hole, think around $80....be a one time use....maybe see if I can rent one.

Starter solenoid, need to ground one side to engage or give it 12 volt? I can find out if I got out and measure, but taking meds at moment, half asleep..

Manual for engine itself almost $190.....I like having reference but I like having $$....

Thanks for your advice....oh, if there is air in those fuel lines, that could keep the injector from fully opening and just dribble fuel in....would that keep from firing? Would think I'd get something though with the WD-40.....also mixed diesel with 30 weight oil and squirted direct into intake, about 50/50....read that use gas instead of oil....safe? I prefer to not have big boom....

Seems like diesels are so straight forward they should be simple...until they don't start. Fortunate, this is old so not all the fancy crap that you can't troubleshoot.....

Sitting on slope by house, want to move it into backyard where it is flat before I do anything major. When cranking the wheels are turning....and it has a severe pull to the right....linkage/bushing or bolt fell out of hydrostatic pump from what I've read....old, bad joints (me...and the rig) so flat ground preferred.

If I had neighbor come tow it 50 feet, books says max 20 feet...I gonna break something serious? Worst case to do that....

Can I pull glow plugs and squirt in some oil rather than pull injectors just in case ring issue? (prior to me getting a gauge)

And, thanks again for info. Sorry long winded, don't get out much any more.

Tim

 

[jfreed]

Not saying this is the issue. but is there a primer "bulb" similar to an outboard motor gas tank on that machine? our 753 has it and it's been a life saver when dad runs out of fuel. thankfully not often

 

[k4shf]

Did that....never got it completely tight and can barely reach it....but thanks!

Think I'm gonna drain the fuel tank, replace the filter and bleed as I move along. Condensation in fuel is an issue in this climate.... and if I do it all from the beginning, then I'll know it's all good and I'll find anything along the way. I touched the return fuel hose from the injectors yesterday and immediately, just like changing diaper on a little boy....nice squirt. Cut back, put back on, another squirt...plugged holes (piece of broke fishing pole on injector pump end and small piece of hose that wasn't leaking on other with vise grips). Got chunk of new hose and managed to not even lose the darn little fine clamps.....amazing.

 

[jm.old]

MY best bet , you replaced the glow plugs , when in fact you should have replaced the glow plug
relay, that is what always goes bad. If you get power to the end of the glow plug strip the thing is
probably going to start. Grey smoke is fuel ,but like you said just needs a little help.

 

[k4shf]

(quoted from post at 09:08:43 09/04/19) MY best bet , you replaced the glow plugs , when in fact you should have replaced the glow plug
relay, that is what always goes bad. If you get power to the end of the glow plug strip the thing is
probably going to start. Grey smoke is fuel ,but like you said just needs a little help.

Three glow plugs measured bad, replaced. They do have juice to them when switched on...but, it seemed to climb slow....but had cheap clips on meter leads....going to verify next time I fiddle faddle with it.

Had to stop, back/hip....munching pain med and napping with dogs.

Thanks for the input, seems like I'm at least checking the right places. I already dumped over 4 gallons of fresh fuel in....going to fill up rest of way, replace filter. The stuff in the return line from injectors was fuel, not water. Gonna add some stabil for diesel...then replace filter (will the squeeze bulb fill the filter so I get fuel out of the bleed on top?) I can barely reach....but figure do that, then step along the fuel line, bleed any air from each point. Even with the bleed at the injector pump, I'll crack lines at each injector while cranking until no air....THEN, if it don't want to fire, I'll pull each injector, squirt some 30 weight in each cylinder just in case the compression ring is running dry or is tired. If that don't work, I'll get tow truck and go toss in river....

 

[AJ.]

Fill it bleed it, stop in run position crack the injector line nuts a couple of turns,full throttle crank the engine over till fuel spurts out of the unions,tighten them up heat and start,no start and you know the glow plugs are working there is a possible cause that I came across some time back,the injectors were fitted with filters and they had blocked,we had fuel going to the injectors but not through them,Diesel Tech may have come across the problem and what can be done I just fitted an exchange set.
AJ

 

[k4shf]

(quoted from post at 17:37:01 09/05/19) Fill it bleed it, stop in run position crack the injector line nuts a couple of turns,full throttle crank the engine over till fuel spurts out of the unions,tighten them up heat and start,no start and you know the glow plugs are working there is a possible cause that I came across some time back,the injectors were fitted with filters and they had blocked,we had fuel going to the injectors but not through them,Diesel Tech may have come across the problem and what can be done I just fitted an exchange set.
AJ

Since I do have smoke, at least some fuel is getting through but it could be drips....once this hurricane is passed by, I'll go ahead and fill the fuel, change filter, bleed, then go to injector pump and bleed, then loosen each line to injector and bleed each one. If still no fire, I'll pull injectors, squirt some engine oil into each cyclinder, then put injectors back and try again. If all that don't work, maybe I'll go play on the freeway. Good point on opening throttle all the way, hadn't thought of that. I'll sure be glad when this thing finally fires....not a question of IF, just a question of WHEN. Lots of good help on here. Thanks for taking the time to respond.

 

[AJ.]

You started by saying it's hard to start, answer this question has the engine started since you bought the machine,has it been running and stopped? or did it not start since you got it, if so it is likely why it will not start now is the injector pump rack is stuck in the stop position,this can happen if the stop was left pulled out while it was parked.
AJ

 

[k4shf]

(quoted from post at 18:44:36 09/05/19) You started by saying it's hard to start, answer this question has the engine started since you bought the machine,has it been running and stopped? or did it not start since you got it, if so it is likely why it will not start now is the injector pump rack is stuck in the stop position,this can happen if the stop was left pulled out while it was parked.
AJ

The engine has ran within the last 6 weeks and I just changed the cable for that fuel cutoff as it was pretty much frozen. When disconnected, it is spring loaded and goes to the "on" position. I did replace with a genuine bobcat replacement (sorry, won't do that again, 3 figure pricing for it). When cable is removed, it spring towards the rear, cable needs to be pulled to bring it forward to kill it

Between hurricane rains and pain meds for bad back, haven't looked at for two days. Will get more fuel tomorrow (prop can on tire and use a d cell pump to make life easy). Then filter swap and bleed as I go. I did get the proper wrenches for the nuts so I don't round them off. I'm going to clean top of injector pump and then once it runs, be able to see what is leaking to gummy up top of the assembly. I'm going to give all those nuts a slight nudge before I move to injectors....and crack each open.

Thanks for the comment, it all helps!

 

[AJ.]

It would make it easier for us to try and diagnose the problem if we knew did the engine stop when it last ran on its own and will not start since or did you/someone else stop the engine and it will not start since,you may often see on here where machines that were standing have rodents move in and block air cleaners etc,hope you get over the storm ok.
AJ

 

[k4shf]

The bobcat was parked and the fuel cutoff cable was pulled as per normal. I had opened the air intake (pulled filter) to squirt a mix of diesel and 30# directly in. The filter looks to beyond it's normal life but I am unable to push the button to see how restrictive it is, since I do have a complete set of filters, I will be putting in a new on. The return fuel line from the injectors had sprung a pinhole leak and I had to replace it but it was good diesel (I had added about 4 gallons) and didn't appear to have any water issues. Weather permitting today, I'll finish filling the tank and adding some stabil for diesel to help reduce condensation issues. I'll be changing the fuel filter at that time, then bleeding the system starting at the filter and working my way forward. I will crack the joints at the injectors and make sure I have pure fuel with no air bubbles today (weather permitting). If no fire then, I'll pull injectors and squirt some 30# into each cyclinder just in case the top ring isn't sealing.

 

[AJ.]

There is a big difference in the symptoms between an engine running and then cutting out of it's own accord and an engine that has been stopped by the stop control,if the engine ran then you know that basically it's ok,but if the engine stopped of it's own accord it can be caused by a range of things,no fuel,no oil,no air etc,an after thought make sure none of the controls are engaged that could be loading the engine too much for it to fire up.
AJ

 

[k4shf]

(quoted from post at 07:42:50 09/06/19) There is a big difference in the symptoms between an engine running and then cutting out of it's own accord and an engine that has been stopped by the stop control,if the engine ran then you know that basically it's ok,but if the engine stopped of it's own accord it can be caused by a range of things,no fuel,no oil,no air etc,an after thought make sure none of the controls are engaged that could be loading the engine too much for it to fire up.
AJ

Very true....but I dd claim it as a starting issue and not as a suddenly stopped issue. The first day I was trying it would barely turn over with good battery (fully charged and tests fine) but it was trying to move while cranking. I think the tires may still be trying to turn and it my be sitting on it's belly now but it spins at what I would assume normal speed now. I originally had to jump with my truck but have been able to skip that as of late. Means I made progress somewhere, when it fires up, then I'll be happy. I'm pretty sure after I bleed everything its gonna go....but it makes me wonder why it seems to be getting air in lines while sitting. Top of injector pump is all oily, I don't know if perhaps without pressure, the lines are somehow bleeding down onto the top of the pump. I didn't get a chance to look when it was running. I got a can of brakekleen and a handful of rags, will clean it all up after I get through bleeding. Apparently my hip is about to give up the ghost on me....all this clamoring around has not helped it. Plus sitting on a slope....be glad when I have it moved onto a flat area, get it up sitting with wheels on double 2x12s. Has hard rubber tires currently, definitely got their money's worth out of them but have new wheels and pneumatic tires to go on....but only once I have it on flat ground.

 

[AJ.]

If the wheels are trying to drive the machine is in gear,was a guy over on the Case forum a couple of years back with a fairly new Case 580 backhoe,he changed the bucket getting ready for the morning and while doing so he lifted up the jack leg and stalled the engine,went away came back in the morning no start,change filters etc no start,injector pump off and reconditioned still no start,what was wrong the jack lever had stuck in the up position and would not let the engine fire up,cost him a fortune,I am taking it that you did not have the engine started at all.
AJ

 

[k4shf]

(quoted from post at 13:25:18 09/06/19) If the wheels are trying to drive the machine is in gear,was a guy over on the Case forum a couple of years back with a fairly new Case 580 backhoe,he changed the bucket getting ready for the morning and while doing so he lifted up the jack leg and stalled the engine,went away came back in the morning no start,change filters etc no start,injector pump off and reconditioned still no start,what was wrong the jack lever had stuck in the up position and would not let the engine fire up,cost him a fortune,I am taking it that you did not have the engine started at all.
AJ

The engine ran less than 6 weeks ago. Had to drive onto trailer, then off trailer to park. So, this is a "hard to start" issue, not a "won't start". Throughout the entire thread I've pretty much given the whole story....we initially used ether (when glow plugs were non-functional). Since they now work, I'm staying away from the ether...seems some folks will leave them on for a full minute....book says at these temperatures (well above 40) should only need 20 seconds. ...but, from what I read, as these things age, they tend to get harder to start.

That could be due to compression decreasing over time, injectors getting dirty, spraying poor pattern....but I seem to have air in fuel lines. I'm scratching head trying to figure out why as it has not be opened.

For now, it is parked on very unlevel ground. Very hard on replaced knees and hip that appears to want to get replaced. Not a spring chicken so trying to do minimum until I can get it on level ground, get new wheels/tires on. If continues to be issue, I may get injectors rebuilt or replaced if I can find a decent price. And I'll have to check the compression...if it needs ring job, then probably needs total rebuild....maybe better just replace....won't be my call but rings are beyond me....I'm an electronics geek, not a mechanic. If my older brother lived here instead of west coast, would drag it into his shop, pull engine and redo from bottom up.....he has that talent, I don't.

 

[jfreed]

In our experience,3 out of 4 glow plugs tested BAD. After replacing all 4 of them, no more cold weather starting issues. '99 753

 

[k4shf]

(quoted from post at 19:25:00 09/06/19) In our experience,3 out of 4 glow plugs tested BAD. After replacing all 4 of them, no more cold weather starting issues. '99 753

Clips on meter leads are a bit on small size...thought I was able to measure volts on the plugs the other day. Got a little bit bigger clips today, ran negative direct to battery. No juice. Don't hear relay click. So, either the energizing coil is open or the signal isn't getting to the relay to energize it. Since a lot of the wire was burned, it could be possible there is no juice on the wire. A new wiring harness from Bobcat is just under $300....I have not been able to find one anywhere else...nothing on ebay....nada. And this is literally a small handful of wires. I could rebuild but some of the connectors appear to be specific for this application.

I'll have to do some wire chasing to determine what the actual issue is. Can someone give me a quick idea of where that relay is? Physical size? I lost nearly half of my peripheral vision just before Christmas....it's not coming back...and trust me, it does not make things easy....enough sniveling....need to go look at wiring diagram in the manual....

I can do a temporary jumper once I find it. The plugs measure around 4 ohms so each should draw about 3 amps....all 4 would mean it draws around 12 or 13....I got wire that will handle that. Just gotta find where it is.....

Tim
:?: :?: :?: :?:

 

[Jim.ME]

Looking under the air cleaner, towards the back of the engine, there maybe two solenoids mounted back to back. One would be for the starter and the other is for the glow plugs. There should be a wire from the glow plug solenoid to the glow plug at the back of the engine(nearest the operator) to the glow plug solenoid.

 

[k4shf]

(quoted from post at 20:40:38 09/07/19) Looking under the air cleaner, towards the back of the engine, there maybe two solenoids mounted back to back. One would be for the starter and the other is for the glow plugs. There should be a wire from the glow plug solenoid to the glow plug at the back of the engine(nearest the operator) to the glow plug solenoid.

Thanks! I figured worst case was to just grab wire and follow it. Of course, that glow plug is the hardest to get at <smile>. I know where the starter solenoid is...so this one should be easy. (famous last words). But, I should be able to connect a clip lead to it and perhaps hear it...while hooking the meter to one and seeing if I have voltage. I can also verify current with the clamp on meter. Thanks again!

Tim

 

[jfreed]

It's not the volts going to them, it's the OHM's in them, you have to disconnect the power strip and ohm them out. Seems like 2-4 ohms ??

 

[k4shf]

(quoted from post at 18:57:34 09/08/19) It's not the volts going to them, it's the OHM's in them, you have to disconnect the power strip and ohm them out. Seems like 2-4 ohms ??

Yes, we had replaced 3 after resistance testing. Have wire traced to relay now....have to get holes burned in eyeballs on Monday, then when the vision clears up I can get back at it.


Tim