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Bobcatech
Bobcatech, Technician
Category: Heavy Equipment
Satisfied Customers: 54
Experience:  Repairing Bobcats and other Compact Equipment since 1990, now Independent Mobile Service Technician.
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shuts down..you turn key off..Happened several times.

Customer Question

Got CAT 416B. After I start it, it runs for ~ 10min and then shuts down like you turn key off. Happened several times. Drained and changed fuel, warmed it up, changed fuel filter, fuel pump looks not too old. Any directions and ideas?
Submitted: 5 years ago.
Category: Heavy Equipment
Expert:  Bobcatech replied 5 years ago.

Hey thereCustomer

 

I'm not sure if you've stated that you HAVE changed the fuel pump, or if it's just new-looking?

 

After it shuts off, what do you do to get it going again? Does it fire right back up or do you have to prime it again? Or does it just fire right back up?

Customer: replied 5 years ago.
several guys who looked at the fuel pump said that it looks like recently been replaced (I just bought this machine). After machine shuts off, it doesn't restart instantly. I had to give it ~30 min, sometimes put charger on batteries to start it again. Last time we also used that spray (Ethel?) to help starting it.
Expert:  Bobcatech replied 5 years ago.

Okay good and thanks.

 

The fuel pump: I'm asking about the lift pump, and not the injection pump. I'm not trying to insult you here, but I don't really know what you do and don't know, so bear with me.

 

The injection pump is the one with steel lines that go to the injectors on the engine. Is this the pump that looks new? If the machine will run for ten minutes, this pump is probably okay.

 

The pump I'm concerned with is the lift pump. It may be electric or mechanical and bolted to the engine block, but it is in between the fuel lines from the tank to the injection pump.

 

If you pull the line from this pump, leading to the injection pump, if it's working, you should get a stream of fuel flowing out: if it's mechanical, you have to crank the engine, if it's electric, you turn the key on. It should be a good steady stream.

 

So, we need to know if the lift pump is mechanical or electric, and whether fuel is flowing when you do this test.

 

If it's a mechanical pump, and not flowing well, you probably need a new lift pump, but you could have a leak or restriction in the line going to your fuel tank.

 

If it's an electric pump, and you don't have a good flow, it may be a bad pump. If there is NO flow, it may be a bad pump OR an electrical problem with no power to the pump.

 

I'm still not sure you don't have an electrical problem, seeing as you stated that the machine shuts down like you keyed it off. Fuel problems tend to make the engine die after dropping rpm.

 

You also need to check the fuel line from your tank to your lift pump to the enjection pump, and the return line from the engine back to tank for any leaks or kinks.

 

 

 

Customer: replied 5 years ago.
Pump is mechanical and looks like new. Will check lines today, will get back to you.
Expert:  Bobcatech replied 5 years ago.
Okay great!
Customer: replied 5 years ago.
Lines look good. Changed all filters, oil, etc. Machine works fine while idle. Had it running 3 times for ~ 30min just sitting. It shuts down looks like after ~ 10 min of driving.
Expert:  Bobcatech replied 5 years ago.

 

Okay-

 

If the machine will idle, but shuts off after about ten minutes of driving, you have one of two scenarios:

 

1. Fuel-lift pump-it is pumping good enough to give you enough fuel to idle, but not enough to deliver enough fuel when you need more to drive.

 

You have stated that the pump "looks new", but that dosen't mean that it is working. You must eliminate the pump, by disconnecting the line, cranking the engine and checking the flow of fuel. I can tell by looking at the stream whether the fuel pump is working correctly. Someone less familiar might put a gauge and measure the pressure, and although I don't know the exact numbers, I'm thinking 4-6 psi. Pumps can get weak, but they usually just don't pump at all. If the pump is not working, I have seen injection pumps back-pull fuel through the bleed lines, good enough for an idle, but rev it up and it starves.

 

You must do this test if you haven't already, and eliminate the lift pump.

 

2. Electrical or a Safety shutoff-If your engine runs at idle, but dies when driving, you are loosing power, for some reason, to your fuel shutoff solenoid.

 

Put a test light or meter on the connector or in the power wire for your fuel shutoff solenoid, and start the machine and get the test light or meter to show voltage while the engine is running, then run it at high rpm, or otherwise monitor the voltage to the fuel shutoff until the engine dies. If the voltage cuts off, the solenoid cuts fuel, and that kills the engine.

 

This means nothing wrong with your fuel system, but an electrical problem, and is a whole different can of worms.

 

I really need to know what your lift pump is doing before I can help you further.

Customer: replied 5 years ago.
Everything you said was working fine. Pump constantly had 12V of power. I'll try to make a video with sound and email it to you. Which email should I use?
Expert:  Bobcatech replied 5 years ago.

Okay dr vit that's good news-we don't have an electrical problem!

 

I am not sure you can post a video, but at this point it's not necessary.

 

We have missed something in checking out the fuel system.

 

There is either have a blockage in the line from the tank to the pump, or there is a bad or improperly mounted fuel lift pump.

 

You can check the line by removing it from the pump or filter, and blow short puffs of air back into the tank. This may blow out any obstructions. If it leaks along the line, replace the line-it's sucking air.

 

If you have an in-line filter, make sure it is going in the right direction. There should be an arrow and "flow" stamped on it. IF you have one......I can't see the machine so I don't know.....

 

I know you've already checked these things, but somewhere we've missed something. I'm sure the problem is in the fuel lines or lift pump.

 

After you double-check the fuel line, and it's all okay, prime it, start it and drive it. If it dies again, the problem is in the lift pump.

 

I know you said it "looks new." It may have been installed wrong. It still could be bad.

 

Hang in there! We're getting close!

 

 

 

If all that checks out, it has to be your mechanical fuel lift pump.

 

If it dies again when driving,

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Bobcatech
Bobcatech
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Repairing Bobcats and other Compact Equipment since 1990, now Independent Mobile Service Technician.