BC 753 Shuts Off (Hydro Low?)

[Cannon]

Hi folks, 1st post - long time reader though.

1990's BC753, borrowed from a friend of a friend (random acts of kindness...) ten days ago, have used it 8+ hrs a day on annual leave since then. His care had been minimal, the first day I pressure washed the engine bay & that took 4 hrs! Minus when I lifted the cab today and it's a mess of mud as well I've got biiiiiggggg confusion(s).

Over the past 5 or so days, first thing in the morning she'd start-then die-then start-then idle-then die... I read posts on fuel bulbs, pump, etc and although the fuel bulb was collapsed, once things warmed up 45 to 60 degrees, I'd have no more start/die issues. So that's been isolated as NOT what I'm asking about.

1. Just below the Hydraulic Filter at 5 o'clock is a male/female plug. The yellow wire had worn in two (don't know if that started that way 10 days ago), but I spliced & reconnected. Now, here's the 'prob, just to the right of the ignition key, there's two idiot lights (there's no other lights/gauges/toggles there-gone before he bought). Once I reconnected the yellow wire, the transmission light now illuminates (lower of two idiot lights).
Q. Is this going to prevent the BC from starting?
Q. Am currently on an incline, nose up, is this preventing the BC from starting as a result of 'triggering a sensor?
Q. I know how to change oil (you-tube video) & drain hydraulic oil (nose of frame-w/o bucket on & arms secured) but what's remaining process? Is it all either motor or hydraulic oil? I THINK I'm missing out on hydrostatic issues.

Please advise. I've still 10lbs of work to put into a 5 lb bag (annual leave ends Sunday).


Other 'facts.
-Verry small oil moisture in engine bay, assume when I dealt with the before mentioned fuel bulb issue.
-Felling/pushing trees & full buckets of dirt-no issues.
-Drive controls are engaging (fwd/rev/turn)-no issues.
-No smoke (black/blue-white) or low compression issues.
-Have done a heck of allot of wire wiggling to ensure remaining connections are good-to no avail.
-Have, had to 'play with startup scenario of ensuring all lights to right rear of cab are 'green (illuminated), i.e.: ICBS. Routine start by ignition on, rops down, repositioning butt on seat, etc... to engage system. But I have success with turn ignition to on: 1)Click (assume fuel pump); then 2) Clunk (lower left side uhhh not totally familiar, but assume electric brake/drive assy)...

One thing I'm going to go do now, is (luckily) drag the
garden hose/pwasher out, lift the cab, pull off the access panels, and 'go to town cleaning in there... will be able to 'check back on any answers in about an hour....

AND if I teach myself in 2 hrs, I'll try a you-tube, or at least post pics.

(thanx Accurate Machinery, LLC for link to your article on
skid steer drive lines; & thanx dieselfuelonly for the you-tube video)

 

[jgl1962]

Hey,
As long as it's a keyed ignition and not a digital dash, Bobcats of that age will start regardless of low hyd oil or engine oil for that matter.

Quickly:

The 2 clicks you hear when you turn the key on/ start the machine are 1) the fuel shut off solenoid "turning on" the fuel flow.2 the parking brake solenoid releasing in the chain case basically directly under you.

I think you have a fuel delivery/ quality problem 4 things I can think of:

1: fuel pickup blocked intermittently with crap floating around in the tank. It will start run then suck up crap and quit, once the suction is gone the crap will fall off the pickup tube allowing the machine to run again until it happens again.
Pretty common in older machines that were likely filled with 5 gallon cans.

2:Fuel filter may be plugged ( I don't think you mentioned checking it) should be a drain on the bottom of it. open it up and see what runs out( water or crud) then that could be the problem.

3: Fuel shut of solenoid could be failing. They pull on the fuel shut of with one level of voltage and hold it on with another. On older machine these solenoids simply get tired and won't do one or both jobs. Its the deal with the wired mounted on the injector pump. You can get an idea if it's bad by trying to start it and going back around and feeling that solenoid if it's hot try this.Two people can fake it out to see if it's the problem. be VERY careful. One guy in machine turning starter and another physically hollding that linkage open(rod pushed into the solenoid) then see if it will stay running as long as you hold it on.

4: These machines have a mechanical lift pump to bring fuel to the injector pump. It looks like a miniature GM fuel pump bolted to the engine follow the fuel line from the filter. You can check that by disconnecting the line between it and the injector pump and cranking the starter should put out a consistant stream with some pressure behind it, if it just piddles thats a problem.

Probably didn't really help you as it's Sunday now. sorry you're leave got messes up. Easy for me to say but if you can afford it and assuming there's rental outlets near you, your leave time being as valuable as it is. I would consider renting for your projects so you don't have to go through this crap again.

They are good simple machines but sounds like this one needs some tlc.

Jim

 

[J_J]

Cannon,

Some system are designed to not start if the oil supply is low, whether it is the engine, or transmission. The light might just be a warning, or, is designed to keep the engine from starting if the fluid is low. Now, you said the nose was up. Can you turn the machine down hill and see if the light goes out. You said you pressure washed, you could have blasted something loose, or blasted some water in the fuel,or elsewhere where it should not go, but it probably has a fuel filter with water sensor. Is that one of the lights activated?

 

[Cannon]

Jim & J.J.

Ok! No worries on it being Sunday, I just appreciate the reply! Again crawled about for 3hrs, then I had to walk away, just walk away....

JIM. Re:
1) "Fuel Pickup Crap". 'k so how do I attempt to yank. I lifted the cab again ensure good connection(s). and saw the fuel cap housing leads to the 2" dia hose & 1/4" dia hose (assume venting). But I lose sight of the hoses so couldn't trace the remainder of the way back. Had recalled reading a post about it being a 'bear to access.

Q. Care to explain how to access the fuel tank?
Q. Would expect to have to purchase another pickup tube, anything else though?

2) Fuel Filter. Had bled off approx 2oz of water (no crud) 9 days ago. Have checked 2x since then with no more water.

Comment. I'll be off to 'stealership 2 morrow eve for a fuel filter....

3) Fuel Solenoid. I've seen it open/close. In fact I wanted to make sure it had free movement on the far vs the solenoid itself. Different times it's stalled -different positions. But can safely do self eval.

Q. Left 3"-Up 2" from Solenoid, there's a knob. Has been at 1/4 turn from fully backed out. What's it's purpose?

4) Mechanical Lift Pump (vs injector pump). Hmm, I describe above the 2" dia fuel hose disappears under the engine, but I think dealing with piddle amounts of fuel even leading prior to the primer bulb.. . Only note I can rehash from the first post is the bulb collapsing and my efforts to ensure all lines were clear.

J.J. Re:

'Tracking on the low oil supply... I assumed it was for the 'hydro-added approx 2 qts since starting. But engine oil has been good to go as well (so far).

Few 'idiot lights remain & thats "on". In fact that's the only one (plus the four light setup on the firewall). I've done a once-over on the connections either loose or .... Won't mind doing it again - today was a 3 gallons of water day due to the heat. Plus it'll give me a break on the f-fatigue.

General. IF someone were to describe or post a pic of how the devil to get at the fuel tank, I'd appreciate that, and tear into like no tomorrow!

'Copy on the needing TLC. But at least I have the wife to keep me sane. Really want to give the guy back the Bobcat in better shape than I found it. Kinda one of those long standing motto's along with 'pay it forward y'know?

 

[jgl1962]

Cannon,

I have been ASSuming that since you said 90's vintage 753 that it's a C or F model (rectangular headlights). If not let me know.

The knob is a bypass bleeder for the fuel system. If it runs completely out of fuel you use it to get the air out of the upper fuel system(beyond inj pump).

It should be turned all the way IN not 1/4 from full out. Could possibly be your problem turn it in and try it.

If the knob doesnt solve the problem, before you go chasing the pickup tube, try disconnecting the fuel line from the tank side of the bulb and stick a longer hose on it. put that hose in a can of fuel and see if it runs correctly.

If it doesn't and after you've verified the solenoid is working right (you can force that to stay where it should be with a zip tie if it turns out to be the culprit, you won't be able to shut it off until you cut it off though.

Fuel pickup tube is a little tough to get at. Raise and block loaders arms (if bucket is off block under the back of the machine), raise the cab. The fuel tank lives under the engine / pump assembly. probably need a light. you will be able to see it....sorry I can't recall it's exact location. 90 deg fitting coming out of top of tank through a grommet, disconnect the hose from the top and remove grommet etc (put it back in the same way.

 

[jgl1962]

Sorry to ignore the question on the wires from the hyd filter. It is the hyd pressure sensor. It won't keep the machine from starting if it's out of range and the light is on they also fail with age. Good idea for the owner to get a new one but it's not the root of your problem. And a new hyd filter is probably in order, it's a 500hr interval on them but lots never get changed.

 

[Cannon]

Update (2wks later).
Jgl1962-yes square headlights model. Thanks. Additionally, the local mom & pop carquest sold me the wrong Wix hydro filter, but I'd already manually filled it with fluid so my bust.

-Ive adjusted the bypass bleeder to all the way in. Verified the solenoid is working freely/correctly.

- Re: Your second recommendation of attaching an alternative fuel line to the feeder end of the bulb and operating? That works fine. (In fact I was all set to run a 10' length of fuel line, drilled with holes, and with a large screw attached at the end to weigh it down/keep in place inside a 5gal tank that I'd place..? on my lap? The fourteen year old talked me out of that one).

Review of efforts this past week when come home from work.
- Disconnected the fuel line leading from the tank to the primer bulb and blew air into the tank heard a 'pop-then fuel freely flows from the tank so reconnected to bulb and continued to operate. Results are still only about 1.5 gallons of operating time, then have to refill tank.
- Last night had to repeat the process. Where disconnecting the primer bulb, blowing air, etc Ive been able to blow air into the end of the line/into the tank and hear'gurgling inside the tank; and Ive been able to blow air into the tank and create a steady stream out the end of the fuel line. However, in the midst of all this I'm concerned about fuel line/fuel elbow inside the tank/fuel return/and screen replacement. So how do I go about this?

Re: Quote: Fuel pickup tube is a little tough to get at. Raise and block loaders arms (if bucket is off block under the back of the machine), raise the cab. The fuel tank lives under the engine / pump assembly. Probably need a light. You will be able to see it....sorry I can't recall its exact location. 90 deg fitting coming out of top of tank through a grommet, disconnect the hose from the top and remove grommet etc (put it back in the same way).

Am off to attempt getting at the fittings and pickup tube this rainy Sunday morning. Although, on my first attempt of at least accessing the tank was you'd see a 6'2" guy laying on a piece of plywood with my legs sticking out over the bob-tach. Ive traced the 2 fuel supply hose to under the engine, and that's where my efforts ended last week. This time I'll grease my arms up with Vaseline and bring a flashlight!!

Thank you for your guidance!

 

[majubamax]

im having the same problem it shut down then put air in the line thier didnt seem to be fuel in the tank nothing cane out of the line i then put fuel in and it came out of the line but it took very little fuel it ran fine after that could the tank be collapsed