753 bobcat starts and runs maybee 5 min then dies

Auwstin · Jul 4, 2022

hi my 753 bobcat is having an issue recently iv changed fuel filter air filter oil change and still having the issue where it will run for about as long as it would take to run the fuel thru the line (5 min) then die. I will have to go open the back door and reprime the ball and it will fire up just long enough to get in and move maybe 3 feet. with that being said let me say this my throttle will throttle up but as soon as u let off the throttle it will want to go back like the spring is holding good but it doesn't stay where u put it if that makes since please any help will do iv replaced the alternator and a few hydrolic lines and the arm within last 20 hrs since it's been ran. any advice will be much apreciated.

thepumpguysc · Jul 4, 2022

Sounds like the supply pump bit the dirt..

MarshallPowerGen · Jul 4, 2022

Also check where the fuel fitting at the tank is for an inline fuel filter buried in dirt/debris in the pan.

Auwstin · Jul 4, 2022

i will check this went out to start it a few min ago all of my keys for the bobcat will not turn my ignition so have to go get another one tomorrow when everything opens I will check the inline fuel filter. it ran, don't smoke, and how do I get the throttle to stiffen up when I push on the throttle to raise the idle all of a sudden one day it just stopped staying where you set the throttle and just goes back to however far the spriñg goes until it stay in place.? I appreciate the suggestions I'm a shade tree mechanic and really can't afford a diesel mechanic so iv got to figure out on my own. not much I know about diesel.

willie59 · Jul 4, 2022

Fill the tank full of fuel and see what it does. And that's completely full. The throttle lever has friction disks at the lever to hold position, if the lever is moving freely with little resistance then you have a problem with the lever assembly

Welder Dave · Jul 6, 2022

Does the throttle lever also shut the engine off, maybe using an electric solenoid instead of manually? There could be something wrong with that. My skid steer with a Kubota shuts off manually with the throttle lever. I think Bobcats shut off with the key but if the shut off works off the throttle might also explain why the throttle won't stay in position.

Auwstin · Jul 6, 2022

welder Dave no it doesn't shutoff when throttle backs off it just goes to a low idle

thepumpguysc · Jul 6, 2022

How about a supply pump.??

willie59 · Jul 6, 2022

thepumpguysc said:
How about a supply pump.??

That's part of the process. I suggested filling the tank fully because Bobcat machine are notorious for the fuel pickup tube breaking where it connects to the elbow fitting in the top of the tank. With tank fully full it's able to draw fuel and run. Once fuel burns down a bit that when you'll have stalling problem. Clogged pickup tube will cause primer bulb to suck flat, he doesn't have that problem as he uses the primer bulb to get it going again. With tank fully full, if it runs without stalling, likely a failed pickup tube. If it still stalls, likely a hole in the fuel supply hose or faulty lift pump. But at least when you figure out the problem you have a full tank of fuel to work with, no loss with that.

HarleyHappy · Jul 7, 2022

Unfortunately if he doesn’t have the coin to hire a mechanic how can he have the coin to fill up the tank. Lol that was sarcasm

Auwstin · Jul 9, 2022

well I got it to start, replaced the pickup tube, in the tank fuel filter, fuel lines, primer bulb, rubber graumet and replaced the metal o rings and gasket for the throttle also replaced the ignition switch, but now it starts and as soon as I let go of the key to stay running in the on position it automatically dies what would cause this? iv checked to make sure I hooked up the wires on the back of ignition switch correctly there is 5 wires, 2 wires however are ran to the center nut while I have one other wire ran to the battery nut, another ran to the ignition nut, and another ran to the accy nut on back of switch. so it would be a 4 nut switch any suggestions I cant understand the manual wiring diagrams and that book is larger then a Webster dictionary let me tell you.

CM1995 · Jul 9, 2022

Welcome to the Forums Auwstin!

You've got some good wrenches in this thread giving advice.

Welder Dave · Jul 9, 2022

Sounds like ignition switch might be the problem.

Tinkerer · Jul 9, 2022

Electric injection pump shutoff ?
What you describe is that the starter post on the ignition switch is supplying current to the IP shut-off. As soon as you release the switch from the start position the pump shuts off. IMHO !

willie59 · Jul 9, 2022

Did you use an OEM Bobcat ignition switch or an aftermarket switch? Is that a C, F, or G series machine?

Welder Dave · Jul 10, 2022

Tinkerer said:
Electric injection pump shutoff ?
What you describe is that the starter post on the ignition switch is supplying current to the IP shut-off. As soon as you release the switch from the start position the pump shuts off. IMHO !

On this line of thinking, take the ignition switch out so you can get at the wires. Have the wire for the injection pump shut off loose so you take it off after the engine starts and see if it keeps running. Read somewhere that Kubota ignition switches can get dirty and malfunction and spraying electrical contact cleaner or penetrating oil in the key slot sometimes helps clean them up.

willie59 · Jul 10, 2022

The 753 used a three wire solenoid, ground, pull coil, and hold coil wires. The C and F series used a timer module to control pull coil wire, ignition switch controlled hold coil wire, on the G series the main controller (computer) controlled pull and hold coil wires. On the C and F series, if you fit an aftermarket ignition switch it won't work, have to use an OEM Bobcat switch. I'm not certain about the ignition part of the switch, but an aftermarket switch will cause your auxiliary circuits to not work. The ignition may or may not work with aftermarket, I can't verify that, but it will for sure muck up auxiliary operation.

thepumpguysc · Jul 11, 2022

If it ran before u changed the ign switch.. put the old one back in..
IF u really need the machine, unhook the solenoid plug and remove the solenoid..
THAT should get u running and you’ll hafta shut it down manually.

753 bobcat starts and runs maybee 5 min then dies

Auwstin

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thepumpguysc

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MarshallPowerGen

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Auwstin

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willie59

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Welder Dave

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Auwstin

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Auwstin

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