753G starting and running issues from a newb.

[Vintagecarlover]

Morn all! Recently purchased a 753g bobcat from water works Dept, city of Atlanta. Was told machine is good with only 239 hours but because of newer machines this ones sat unused with a flat tire. 239 hours with full exposure to weather. Brought it home and when I unloaded it, dumped a few gallons of fluid from spool valve seals being bad. Fixed that with new seals (thx tazza) and found out that turning machine off at key didn't work but found the fuel shut off on injector pump worked great. I think not shutting off at key may be part of the reason I'm typing this now. Machine always starts fast with or without waiting for glow plug count down, really fast and good compression. Unit started shutting off immediately after start. Found out solenoid on injection pump shutting machine off. i put a strap on solenoid arm holding it open and mache run. Yesterday with strap on solenoid, machine cut off and made no difference if solenoid was open or closed. Also notice glow plug count down wasn't initiating like it normally did. Somehow this is tied in to no start. My issue is definitely fuel starvation related but as I said yesterday it didn't matter where solenoid rod was in or out. That was a first. Love this machine and need it running asap. Thx for any and all help in advance. Ps. I didn't see if solanoid was getting any power at all yet. Since I had panel where relays are was moved out of the way to do spool valve I thought something wasn't plugged in and did check the plugs as best I could. What and how to check or replace next. This is a real time fix. Thx. I can post my cell if that's okay?

 

[reaperman]

The fuel shut off and glow plugs are both connected to relays. I'd swap a relay that you know is good, like from the headlights with the one from the fuel shut off to test. And the same with the glow plug relay. Relays aren't like a blown fuse, they can work intermittently when they are getting bad and confuse us in the process.

 

[Vintagecarlover]

The fuel shut off and glow plugs are both connected to relays. I'd swap a relay that you know is good, like from the headlights with the one from the fuel shut off to test. And the same with the glow plug relay. Relays aren't like a blown fuse, they can work intermittently when they are getting bad and confuse us in the process.

Is "not turning off with key" also tied into same systems?

 

[Tazza]

Is "not turning off with key" also tied into same systems?

Not turning off could be a sticky solenoid too, is it nice and easy to move and returns to off when you let it go? I worked on a machine that had rusty linkages and refused to turn off with the key.
The shutting down, is it sudden or is it like it ran out of fuel?
I'd change the filter and bleed the system. If it still does it, you may need to clean the pickup tube screen in the fuel tank. The pickup tube may even be cracked allowing in air.
When you have a restriction, generally the primer bulb is sucked flat and the engine will bog down, then die.

 

[Vintagecarlover]

Not turning off could be a sticky solenoid too, is it nice and easy to move and returns to off when you let it go? I worked on a machine that had rusty linkages and refused to turn off with the key.
The shutting down, is it sudden or is it like it ran out of fuel?
I'd change the filter and bleed the system. If it still does it, you may need to clean the pickup tube screen in the fuel tank. The pickup tube may even be cracked allowing in air.
When you have a restriction, generally the primer bulb is sucked flat and the engine will bog down, then die.

Tazza. Ordered an eBay fuel solenoid today. Shut off is immediate. Also other new symptoms are no count down for glow plugs, recently turn key and no starter turning. Messed with key and once it turned engine but didn't fire and then went right back to no starter turning at all. Finally got code 13-07. Didn't see any pinched wires. If I don't see the count down I know I it won't start but today I saw glow plug countdown and still didn't start.

 

[Vintagecarlover]

Tazza. Ordered an eBay fuel solenoid today. Shut off is immediate. Also other new symptoms are no count down for glow plugs, recently turn key and no starter turning. Messed with key and once it turned engine but didn't fire and then went right back to no starter turning at all. Finally got code 13-07. Didn't see any pinched wires. If I don't see the count down I know I it won't start but today I saw glow plug countdown and still didn't start.

Didn't have test light but next trip I will have one. Relays are clicking when ignition turned.

 

[reaperman]

Didn't have test light but next trip I will have one. Relays are clicking when ignition turned.

There is also a 30 amp fuse labeled fuel shutoff. Did you check to see if that was blown or swap the relay yet. From what I remember a older 753's like a F and C series did "click" when the key was turned on. The click would be the fuel solenoid opening. With the G series, no click is audible. I have a 753G also. The only noise I hear when turning the key is the instrument panel coming to life.

 

[rodbuilder]

Put a can of Seafoam in the fuel tank. that will help in cleaning out your fuel system. If you find that the fuel shutoff is bad MY suggestion is to put a manual one on it. They NEVER fail and will last a lifetime. Go to NAPA and tell the man you need a Morse-type cable with the big red knob on it - like they use for a PTO cable on a dump truck. Those things are Teflon-lined and have a really nice, smooth action and you can twist the knob to lock it on or off. NAPA also sell the little keeper gizmo that you can screw into the stock pump linkage arm. When you tighten the screw it clamps down on the cable, locking it into place. When I do one of these conversions I drill a 1/2 inch hole in that panel next to your left thigh and run the cable out back to the injection pump.

 

[Tazza]

Put a can of Seafoam in the fuel tank. that will help in cleaning out your fuel system. If you find that the fuel shutoff is bad MY suggestion is to put a manual one on it. They NEVER fail and will last a lifetime. Go to NAPA and tell the man you need a Morse-type cable with the big red knob on it - like they use for a PTO cable on a dump truck. Those things are Teflon-lined and have a really nice, smooth action and you can twist the knob to lock it on or off. NAPA also sell the little keeper gizmo that you can screw into the stock pump linkage arm. When you tighten the screw it clamps down on the cable, locking it into place. When I do one of these conversions I drill a 1/2 inch hole in that panel next to your left thigh and run the cable out back to the injection pump.

The glow plugs will not always come on, if the engine is warm, it's not needed so they will not come on.

 

[Vintagecarlover]

Put a can of Seafoam in the fuel tank. that will help in cleaning out your fuel system. If you find that the fuel shutoff is bad MY suggestion is to put a manual one on it. They NEVER fail and will last a lifetime. Go to NAPA and tell the man you need a Morse-type cable with the big red knob on it - like they use for a PTO cable on a dump truck. Those things are Teflon-lined and have a really nice, smooth action and you can twist the knob to lock it on or off. NAPA also sell the little keeper gizmo that you can screw into the stock pump linkage arm. When you tighten the screw it clamps down on the cable, locking it into place. When I do one of these conversions I drill a 1/2 inch hole in that panel next to your left thigh and run the cable out back to the injection pump.

Now ya tell me! I ordered a replacement that'll be here today. I'll go manual next time. Thx

 

[farmshop]

Now ya tell me! I ordered a replacement that'll be here today. I'll go manual next time. Thx

I would keep the original design. They will last for many years. As others said New fuel filter and if the primer is hard replace that also.

 

[Vintagecarlover]

I would keep the original design. They will last for many years. As others said New fuel filter and if the primer is hard replace that also.

Installed fuel solenoid shut off but still no start. Turns over well. Glow plug countdown working. Fuses all tested good. Swapped working relays in places I had questions about those are working. Primer bulb hard but squeezed fuel up to injector pump. Opened water separator and let the mud out. Going to find a fuel filter tomorrow. Is there a fuel pump before injector pump? If yes, where and how does it get power? I got a lil smoke through exhaust when cranking over but didn't start and run. Getting close. Anything else I can check? How do I check hose at or in fuel tank that goes bad??

 

[bobbie-g]

Installed fuel solenoid shut off but still no start. Turns over well. Glow plug countdown working. Fuses all tested good. Swapped working relays in places I had questions about those are working. Primer bulb hard but squeezed fuel up to injector pump. Opened water separator and let the mud out. Going to find a fuel filter tomorrow. Is there a fuel pump before injector pump? If yes, where and how does it get power? I got a lil smoke through exhaust when cranking over but didn't start and run. Getting close. Anything else I can check? How do I check hose at or in fuel tank that goes bad??

First, congrats on your new Bobcat! Sorry it's giving you fits. I have experience with a 751 (Peugeot engine, different fuel setup), 763, and 863, so lemme give you some guesses as to how yours works. Fuel comes from plastic tank under the engine. The tank drains via a rubber grommet/steel plug in the bottom, located under a steel plate about 2" x 10", bottom of belly, held on with three bolts. Two plugs inside there, one fuel and one chain case oil. So if you feel the need, you can drain the fuel tank and start afresh. Two rubber grommets on top of the tank, one for fuel pickup and one for excess fuel return. Can be hard to reach, or can be nearly impossible. There will be a metal elbow in the grommet for the fuel pickup (I think the return is a smaller elbow, go figure). Inside the tank, a frequent failure mode is the plastic pickup tube breaks off right at the elbow. So the engine will get fuel only when the tank is filled completely up, and will stop running soon as it uses a half inch of fuel. To diagnose this failure mode, you could take the fuel line loose at the primer bulb and run a length of hose into a can of diesel, giving the engine an alternate source of fuel. Or, the primer bulb should always be spongy with air in it. Next, fuel probably goes to a mechanical lift pump mounted against the side of the engine, then out from there to the fuel filter. Fuel filter has a plastic wing nut on the bottom which can be loosened to drain water. You said you had let the mud out. If there is any contamination at all coming out of the filter, I would stop right there and replace the fuel filter before trying anything else. You don't wanna run anything bad thru the injectors and clog them. So with a new filter, primed, and a good pickup tube (pickup tube also has a filter on it, complete with check valve, so don't try to blow the filter out with air while it's in the tank), you should be able to disconnect the hose coming out of the fuel filter, turn the engine over, and get good clean diesel pumping out of the filter. That should get you a little further down the road. --- Bobbie-G

 

[Vintagecarlover]

First, congrats on your new Bobcat! Sorry it's giving you fits. I have experience with a 751 (Peugeot engine, different fuel setup), 763, and 863, so lemme give you some guesses as to how yours works. Fuel comes from plastic tank under the engine. The tank drains via a rubber grommet/steel plug in the bottom, located under a steel plate about 2" x 10", bottom of belly, held on with three bolts. Two plugs inside there, one fuel and one chain case oil. So if you feel the need, you can drain the fuel tank and start afresh. Two rubber grommets on top of the tank, one for fuel pickup and one for excess fuel return. Can be hard to reach, or can be nearly impossible. There will be a metal elbow in the grommet for the fuel pickup (I think the return is a smaller elbow, go figure). Inside the tank, a frequent failure mode is the plastic pickup tube breaks off right at the elbow. So the engine will get fuel only when the tank is filled completely up, and will stop running soon as it uses a half inch of fuel. To diagnose this failure mode, you could take the fuel line loose at the primer bulb and run a length of hose into a can of diesel, giving the engine an alternate source of fuel. Or, the primer bulb should always be spongy with air in it. Next, fuel probably goes to a mechanical lift pump mounted against the side of the engine, then out from there to the fuel filter. Fuel filter has a plastic wing nut on the bottom which can be loosened to drain water. You said you had let the mud out. If there is any contamination at all coming out of the filter, I would stop right there and replace the fuel filter before trying anything else. You don't wanna run anything bad thru the injectors and clog them. So with a new filter, primed, and a good pickup tube (pickup tube also has a filter on it, complete with check valve, so don't try to blow the filter out with air while it's in the tank), you should be able to disconnect the hose coming out of the fuel filter, turn the engine over, and get good clean diesel pumping out of the filter. That should get you a little further down the road. --- Bobbie-G

Hey Bobby and everyone assisting. Thx all. Headed out to bobcat in a few and looking now for a fuel filter first while in town. Tractor is out at my cabin. Yes, air is likely my enemy right now. Can be bad fuel line too but although 753 only has 240 hours (thx to govt waste) it's an old 01 model so with 16 yrs of sitting unused deterioration doesn't stop. When I cranked it and it ran, runs so sweet makes me smile. Can't wait till it runs again. I'll be checking everything mentioned. Thx.

 

[Vintagecarlover]

Hey Bobby and everyone assisting. Thx all. Headed out to bobcat in a few and looking now for a fuel filter first while in town. Tractor is out at my cabin. Yes, air is likely my enemy right now. Can be bad fuel line too but although 753 only has 240 hours (thx to govt waste) it's an old 01 model so with 16 yrs of sitting unused deterioration doesn't stop. When I cranked it and it ran, runs so sweet makes me smile. Can't wait till it runs again. I'll be checking everything mentioned. Thx.

Ok. Figured out my problem and it's the fuel line problem that I've heard about. Filled bobcat to full and after bleeding well it cranked right up. It ran for a half hour and then shut off starving for fuel again. Do u guys buy a premade hose or piece something together? Best place to get that hose? Anything else I need to know about removal or installing the check valve/hose Assly? Looks as much a pia as anything thus far. Lol. Thx for helping a fella out. Matk

 

[bobbie-g]

Ok. Figured out my problem and it's the fuel line problem that I've heard about. Filled bobcat to full and after bleeding well it cranked right up. It ran for a half hour and then shut off starving for fuel again. Do u guys buy a premade hose or piece something together? Best place to get that hose? Anything else I need to know about removal or installing the check valve/hose Assly? Looks as much a pia as anything thus far. Lol. Thx for helping a fella out. Matk

When I redo the hose in the tank, I just buy all the stuff new from Bobcat. That's probably overkill, but I would rather pay the bucks and not have to do that job again for many years. The pickup hose (or tube) is a Bobcat-specific item (stiff plastic). I suppose a piece of rubber fuel line would do OK, but why not go first class. There are some special teensy clamps that hold the check valve/screen and right angle fitting to the hose. The upper clamp needs to slide thru the rubber grommet in the top of the tank, so a normal hose clamp won't work. Get a new rubber grommet whilst yer in there too. And replace the fuel line that runs from the tank elbow over to the primer bulb. My philosophy: restore everything back to new so I don't end up troubleshooting yet another aged item. As I recall, I had to think the assembly/install process through several times to get the sequence correct. Something like: put the tube partway thru the grommet, then assemble the check valve and elbow onto the tube; then work the grommet into the tank lid, then clamp the external hose to the elbow, then slide the elbow into position in the grommet as the last step. ---Bobbie-G

 

[farmshop]

When I redo the hose in the tank, I just buy all the stuff new from Bobcat. That's probably overkill, but I would rather pay the bucks and not have to do that job again for many years. The pickup hose (or tube) is a Bobcat-specific item (stiff plastic). I suppose a piece of rubber fuel line would do OK, but why not go first class. There are some special teensy clamps that hold the check valve/screen and right angle fitting to the hose. The upper clamp needs to slide thru the rubber grommet in the top of the tank, so a normal hose clamp won't work. Get a new rubber grommet whilst yer in there too. And replace the fuel line that runs from the tank elbow over to the primer bulb. My philosophy: restore everything back to new so I don't end up troubleshooting yet another aged item. As I recall, I had to think the assembly/install process through several times to get the sequence correct. Something like: put the tube partway thru the grommet, then assemble the check valve and elbow onto the tube; then work the grommet into the tank lid, then clamp the external hose to the elbow, then slide the elbow into position in the grommet as the last step. ---Bobbie-G

If you can get it started raise the arms and lock them up. It is easier to work on. Tip the cab up. The fittings are way down in there under the hydro a variety of screw drivers and other prying tools you can pop them out. If your screen is still attached it can be reused if it broke off replace it it is also a check valve. The hoses screen and clamps are about 20$ at bobcat. When reinstalling put some grease or Vaseline on the grommet to help it go together. Getting it started and pry against it to seat it

 

[bobbie-g]

If you can get it started raise the arms and lock them up. It is easier to work on. Tip the cab up. The fittings are way down in there under the hydro a variety of screw drivers and other prying tools you can pop them out. If your screen is still attached it can be reused if it broke off replace it it is also a check valve. The hoses screen and clamps are about 20$ at bobcat. When reinstalling put some grease or Vaseline on the grommet to help it go together. Getting it started and pry against it to seat it

Good suggestions from farmshop. Raising the arms will help immensely in giving you better access. When you do that and lift the cab, the machine tends to get tippy and will have most of its weight aft. Opening the rear door makes it even more prone to tipping. Support the rear of the machine with blocks to keep it from going over backward. And make sure you put the factory lift arm safety brace in place. It's that 3 ft long orange thingy most likely on the right lift hydraulic cylinder. If it isn't there, then at least use a long 4x4 to brace the arms up while you're working under them. An untimely lift arm descent could ruin your day. ---Bobbie-G

 

[Vintagecarlover]

Good suggestions from farmshop. Raising the arms will help immensely in giving you better access. When you do that and lift the cab, the machine tends to get tippy and will have most of its weight aft. Opening the rear door makes it even more prone to tipping. Support the rear of the machine with blocks to keep it from going over backward. And make sure you put the factory lift arm safety brace in place. It's that 3 ft long orange thingy most likely on the right lift hydraulic cylinder. If it isn't there, then at least use a long 4x4 to brace the arms up while you're working under them. An untimely lift arm descent could ruin your day. ---Bobbie-G

I'm gonna post pics of what I used in fixing the fuel pickup tube. It's better than new. I bought a fuel strainer off the net cause of old hose in tank may deteriorate further and used new clear line from motorcycle race shop. Not cheap but won't rot. My new issue is the hyd low pressure warning in the new thread. Any help there appreciated. Mark.