[Ted Miller]

Today when I went out to use the 646 it crank right over but wouldn't start. No fuel getting to the carb. The engine ran fine yesterday.
The unit has an electric fuel pump that I had laying around for 30 plus years but had never used. It worked when I first put it on and you can hear it running now put doesn't pump. The pump is sealed. I was wordering if there is a diaphram inside that might be bad from just old age? :headscratcher:

Thanks,
Ted

 

[Kenc]

In most pumps there is a diaphragm, but a few used a piston moved by a magnetic field. Your guess is very likely. Especially since anything built 30 years ago would not be alcohol resistant.

 

[Snotrocket]

Napa sells low pressure electric fuel pumps for around $25. I've been using one on mine for over a year without a problem.

 

[Bart]

A bad fuel line could also be a problem if it is letting air into the line.

 

[Ted Miller]

A bad fuel line could also be a problem if it is letting air into the line.

New line and worm type clamps. :letitsnow:

Ted

 

[Bart]

Ted,

While I understand that a number of people have installed electric pumps the original fuel pumps can be rebuilt for about the same amount of money and are quite trouble free. There are many engines with 30 year old pumps still getting the job done.

 

[Ted Miller]

Ted,

While I understand that a number of people have installed electric pumps the original fuel pumps can be rebuilt for about the same amount of money and are quite trouble free. There are many engines with 30 year old pumps still getting the job done.

Bart,
I would have if it had a pump on it to rebuild. When I got it there was a marine tank installed with a electric pump next to the tank hook to a huge regulator and then to the carb. I repaired the stock tank, installed it taking up the room the electric pump was. I never checked out the cost of a new stock pump though, buy I believe the cost of the rebuild kit was pushing $50.00.

Ted

 

[Ted Miller]

Well I got a new fuel pump Mr Gasket, 3lbs pressure, 12 volt negative ground. Hook red wire to ingition terminal on switch, black wire to ground. Tractor runs fine, problem is it won't shut off with the key. If I disconnect the pump tractor quits, it will restart and run with the pump disconnected using the gas in the carburator bowel. If I connect the pump directly to the battery it starts and stop as it should. Problem is the pump would keep running. Any suggestions? :headscratcher: :headscratcher:

Ted

 

[Bill.H]

You've probably connected to the wrong terminal at the switch. You want it on a terminal that only supplies battery when the key is on. Check the terminal with a meter (or trouble light) with the key in both positions before you reconnect the pump.

 

[Hydriv]

If you have the original Onan engine in your tractor, then it has an ignition coil that gets fed 12 volts from the key-switch. Run the the power lead for the pump to the + terminal on the coil.

 

[Ted Miller]

You've probably connected to the wrong terminal at the switch. You want it on a terminal that only supplies battery when the key is on. Check the terminal with a meter (or trouble light) with the key in both positions before you reconnect the pump.

It is connected to the ignition terminal. Looking at the terminal side of the switch, top left start, top right power, 2nd down right side lights, lowest on ignition.

Ted

 

[Ted Miller]

If you have the original Onan engine in your tractor, then it has an ignition coil that gets fed 12 volts from the key-switch. Run the the power lead for the pump to the + terminal on the coil.

I tried that, it still won't shut off with the key.

 

[Hydriv]

Help me out here.


You still have the CCKA engine in this tractor?

Prior to installing this pump, the engine would start with the key-switch and shut off with the key-switch.. no problems.

All you have done is add this 12volt negative to ground fuel pump and you have run one pump lead to a good ground on the engine or tractor frame and the other pump lead to the ignition coil.

And as soon as you do that, the key-switch will no longer make the engine shut off.

Do I have it correct?


And if the engine is running and you disconnect the pump lead from the coil and then turn off the key-switch at that point, then the engine will stop. YES.

 

[Bart]

Ted,

I know you've tested a lot of things and have put in new parts but you need to doublecheck everything including those things you are "sure" are right. Start by disconnecting the pump from the switch then use a voltmeter to verify each pole of the switch to make sure it is operating as you believe it is (should be). With the key off see that you have power only at the hot connection then turn the key to the first position and you should have power at two more of the terminals--ignition and lights. Then turn the key to the second position and make sure that there is power to the ignition but not the lights. Finally turn to the start position and check for power to the ignition and start but not the lights. That should set to rest the issue of whether the switch has the correct configuration and is working properly. Even though you've probably looked at these connections a dozen times in the past few days you may have overlooked something quite simple--I know it's happened to me enough times. :sidelaugh:

Next I would check the voltage on the disconnected hot lead to the pump and see if somehow it has been crossed with a hot wire somewhere.

 

[Ted Miller]

Help me out here.

You still have the CCKA engine in this tractor?

Prior to installing this pump, the engine would start with the key-switch and shut off with the key-switch.. no problems.

All you have done is add this 12volt negative to ground fuel pump and you have run one pump lead to a good ground on the engine or tractor frame and the other pump lead to the ignition coil.

And as soon as you do that, the key-switch will no longer make the engine shut off.

Do I have it correct?

And if the engine is running and you disconnect the pump lead from the coil and then turn off the key-switch at that point, then the engine will stop. YES.

You ae correct

 

[Hydriv]

Help me out here.

You still have the CCKA engine in this tractor?

Prior to installing this pump, the engine would start with the key-switch and shut off with the key-switch.. no problems.

All you have done is add this 12volt negative to ground fuel pump and you have run one pump lead to a good ground on the engine or tractor frame and the other pump lead to the ignition coil.

And as soon as you do that, the key-switch will no longer make the engine shut off.

Do I have it correct?

And if the engine is running and you disconnect the pump lead from the coil and then turn off the key-switch at that point, then the engine will stop. YES.

You ae correct

If you have a DC voltmeter set to read low voltage, then connect the meter's negative probe lead to the battery's negative post and the meter's positive lead to the fuel pump supply lead while it is still connected to the ignition switch or ignition coil. Are you seeing 12 volts with the key switch in the ON position, as well as the OFF position?

If so, what happens when you turn the key to OFF and then remove the supply lead to the pump? Do you still see 12 volts at the coil or is it now gone?

If it is gone, then put the meter lead onto the supply lead to the pump that you just disconnected. Do you see 12 volts there?

If so, then where is the ground lead for the pump attached? Something is backfeeding 12 volts to the coil to keep the engine running after the key switch is turned to off.

 

[Ted Miller]

Ted,

I know you've tested a lot of things and have put in new parts but you need to doublecheck everything including those things you are "sure" are right. Start by disconnecting the pump from the switch then use a voltmeter to verify each pole of the switch to make sure it is operating as you believe it is (should be). With the key off see that you have power only at the hot connection then turn the key to the first position and you should have power at two more of the terminals--ignition and lights. Then turn the key to the second position and make sure that there is power to the ignition but not the lights. Finally turn to the start position and check for power to the ignition and start but not the lights. That should set to rest the issue of whether the switch has the correct configuration and is working properly. Even though you've probably looked at these connections a dozen times in the past few days you may have overlooked something quite simple--I know it's happened to me enough times. :sidelaugh:

Next I would check the voltage on the disconnected hot lead to the pump and see if somehow it has been crossed with a hot wire somewhere.

Bart,
I chack the switch as you advise. The switch checks out okay.

Ted

 

[Ted Miller]

Help me out here.

You still have the CCKA engine in this tractor?

Prior to installing this pump, the engine would start with the key-switch and shut off with the key-switch.. no problems.

All you have done is add this 12volt negative to ground fuel pump and you have run one pump lead to a good ground on the engine or tractor frame and the other pump lead to the ignition coil.

And as soon as you do that, the key-switch will no longer make the engine shut off.

Do I have it correct?

And if the engine is running and you disconnect the pump lead from the coil and then turn off the key-switch at that point, then the engine will stop. YES.

You ae correct

If you have a DC voltmeter set to read low voltage, then connect the meter's negative probe lead to the battery's negative post and the meter's positive lead to the fuel pump supply lead while it is still connected to the ignition switch or ignition coil. Are you seeing 12 volts with the key switch in the ON position, as well as the OFF position?

If so, what happens when you turn the key to OFF and then remove the supply lead to the pump? Do you still see 12 volts at the coil or is it now gone?

If it is gone, then put the meter lead onto the supply lead to the pump that you just disconnected. Do you see 12 volts there?

If so, then where is the ground lead for the pump attached? Something is backfeeding 12 volts to the coil to keep the engine running after the key switch is turned to off.

With the key on, the coil is getting battery voltage(12.19 volts) Key off 0 volts. Key off pump disconnected 0 volts, Key off engine still running 10.43 volts, disconnect the pump engine shuts down. Pump is grounded to the negitive post off the battery.

Ted

 

[Bart]

Did you measure for voltage at the pump lead when disconnected from the switch? I'm running out of ideas.

 

[Ted Miller]

Did you measure for voltage at the pump lead when disconnected from the switch? I'm running out of ideas.

Yes 0 volts, and the engine dies so fast If there was any its gone. :sidelaugh: :sidelaugh:

Ted