Having Starter problem, among other things
- Thread starter ljms
- Start date
Hammermechanicman
Lawn Addict
The concept of measuring voltage drop can seem counter intuitive. Here is an example. Lets say you have a starting relay with burned contacts and has some resistance across the contacts. When you connect the meter to the +battery post and the terminal on the starter and there is resistance at the starting relay you will see battery voltage at the + batt terminal but a slightly lower voltage at the starter. This difference will show up on the meter. This test needs to be done at high current draw. Measuring voltage with little to no current flow can be deceiving. A bad ground can measure good with a meter but be a problem with high current flow. A voltage drop test does not check a component like the starter. It checks the current carrying capability of the wiring to the component.
Hammermechanic,
So then the test I did at home just removing the starter and hooking a charger up to it didn't really show the condition of the starter, just the ability to turn while under no load. The starter repair man did that first thing, then he tore it apart and examined the internals finding nothing at all out of sorts, (" this looks like it is brand new inside"). He then put a meter on it and checked something and said there is nothing wrong with this starter that he could see. He did say he had another one on the shelf and would be glad to sell it to me but he felt it would not solve my problem. That is when he told me how to check it. He said if the voltage at the starter when the key was turned and under load should be very close to the voltage measured across the battery terminals. I guess that is why I thought the 12.7 to 2.6 voltage drop indicated a problem in the wiring or electrical components. So with all that being said, I guess come the weekend I will one more time, check the valve adjustments and go from there. Thanks for your input and time.
LaVern
So then the test I did at home just removing the starter and hooking a charger up to it didn't really show the condition of the starter, just the ability to turn while under no load. The starter repair man did that first thing, then he tore it apart and examined the internals finding nothing at all out of sorts, (" this looks like it is brand new inside"). He then put a meter on it and checked something and said there is nothing wrong with this starter that he could see. He did say he had another one on the shelf and would be glad to sell it to me but he felt it would not solve my problem. That is when he told me how to check it. He said if the voltage at the starter when the key was turned and under load should be very close to the voltage measured across the battery terminals. I guess that is why I thought the 12.7 to 2.6 voltage drop indicated a problem in the wiring or electrical components. So with all that being said, I guess come the weekend I will one more time, check the valve adjustments and go from there. Thanks for your input and time.
LaVern
Hammermechanicman
Lawn Addict
If you took the starter off and bench tested it with a charger you are correct it tests the the no load ability of the starter which is generally a good indicator the starter is good. Doing that and the voltage drop test will test the starter and wiring. Connecting the meter across the battery while cranking the engine will test battery voltage sag. Usually a sag to around 10 volts is normal depending on battery capacity and condition. If it sags to below about 8.5 volts there is a problem.
I guess what I need to figure out then is where or what is the problem. Is it electrical as in solenoids, regulators, safety switches, etc.? Or is it bad wiring? Or is it mechanical such as the incorrect valve adjustment, or bad camshaft? A few days back I did a search looking for a schematic or wiring diagram and what I found confused me. The one terminology I kept coming across was, after fire solenoid. That is a completely unfamiliar item to me. Where can one find a good, detailed service manual for that particular engine? Thanks again.
LaVern
Hammermechanicman
Lawn Addict
The after fire solenoid is located on the carburetor. It is supposed to block fuel going into the main jet and stop engine from backfiring when the engine is shut off.
bertsmobile1
Lawn Royalty
Here is a standard reply for these problems.
Basically you bypass things one a a time using a pair of jump start leads and a spare battery.
Please run through these and post the results.
Battery cables are not sealed and on more han one occasion I have come across a cable hat has corroded through inside the insulation so they look good & ohm out fine but will not carry the 100 amps that the starter can draw
I like to start from the starter motor and go backwards .
Do the following 5 tests, regardless of the results from an or all of them as there can be more than one problem and you want to isolate where the problem lies.
Elimination of individual parts is important so you know by the end, the battery, solenoid & heavy power circuits are all in good order.
1) try to jump the starter motor directly from your car or truck.
+ on the starter first then - to a good ground near the starter ( drain plug of lift hook are good )
Starter turns = starter good
2) do the same directly from the mowers battery
Starter turns = mower battery good
No turn = duff battery, recharge it & try again.
3) check for voltage ( + 12V ) at the solenoid trigger wire with the key in start position
3a) same with ground trigger wire ( 4 wire solenoid ) or body of solenoid ( 3 wire solenoid)
( I like to test V from the battery hot terminal to ground terminal rather than ohms as they give funny readings )
4) leave ground jumper in place ( from step 2 ) & try key start.
Starter turns = power connection good but ground connection suspect ( most common )
Confirm it by trying again, extra ground removed
5) Remove the trigger ( thin ) wire / wires from the solenoid.
Ground one on a 4 wire solenoid & bridge from the hot terminal to the other.
Starter cranks = solenoid good.
Solenoid is not polarity sensitive, BUT THE WIRING IS so make sure you remove the thin control wires.
Note a thinner wire on the hot terminal is not a control wire. It is the main power feed to the mower.
From here on things become very mower dependant as starting circuits are getting changed all the time.
Basically the power goes in a loop from the hot side of the solenoid ( saves wire, no other reason ) through the fuse to the B terminal on the key switch then to the PTO switch then to the parking brake switch then to the solenoid trigger switch , easy peasy after you grow the 3rd arm. Use a test lamp and follow the power.
However a lot of mowers with a 4 pole solenoid, run a secondary ground control circuit to the ground solenoid wire through the lap bars.
Then to stop this interfearing with the normal safety function of the ground kill, it goes to a relay with the ground as the switched connection.
These are a PIA as the + control wire to the relay comes from the power loop above and the ground side of the control comes via the normal cut out functions of the lap bars.
Be very careful because if you have a system like this and accidentally send 12V down the ground loop you can fry the magnetos on some circuits.nd from the grounding bolt to one of the starter mounting bolts & paint over both with liquid electrical tape.
Basically you bypass things one a a time using a pair of jump start leads and a spare battery.
Please run through these and post the results.
Battery cables are not sealed and on more han one occasion I have come across a cable hat has corroded through inside the insulation so they look good & ohm out fine but will not carry the 100 amps that the starter can draw
I like to start from the starter motor and go backwards .
Do the following 5 tests, regardless of the results from an or all of them as there can be more than one problem and you want to isolate where the problem lies.
Elimination of individual parts is important so you know by the end, the battery, solenoid & heavy power circuits are all in good order.
1) try to jump the starter motor directly from your car or truck.
+ on the starter first then - to a good ground near the starter ( drain plug of lift hook are good )
Starter turns = starter good
2) do the same directly from the mowers battery
Starter turns = mower battery good
No turn = duff battery, recharge it & try again.
3) check for voltage ( + 12V ) at the solenoid trigger wire with the key in start position
3a) same with ground trigger wire ( 4 wire solenoid ) or body of solenoid ( 3 wire solenoid)
( I like to test V from the battery hot terminal to ground terminal rather than ohms as they give funny readings )
4) leave ground jumper in place ( from step 2 ) & try key start.
Starter turns = power connection good but ground connection suspect ( most common )
Confirm it by trying again, extra ground removed
5) Remove the trigger ( thin ) wire / wires from the solenoid.
Ground one on a 4 wire solenoid & bridge from the hot terminal to the other.
Starter cranks = solenoid good.
Solenoid is not polarity sensitive, BUT THE WIRING IS so make sure you remove the thin control wires.
Note a thinner wire on the hot terminal is not a control wire. It is the main power feed to the mower.
From here on things become very mower dependant as starting circuits are getting changed all the time.
Basically the power goes in a loop from the hot side of the solenoid ( saves wire, no other reason ) through the fuse to the B terminal on the key switch then to the PTO switch then to the parking brake switch then to the solenoid trigger switch , easy peasy after you grow the 3rd arm. Use a test lamp and follow the power.
However a lot of mowers with a 4 pole solenoid, run a secondary ground control circuit to the ground solenoid wire through the lap bars.
Then to stop this interfearing with the normal safety function of the ground kill, it goes to a relay with the ground as the switched connection.
These are a PIA as the + control wire to the relay comes from the power loop above and the ground side of the control comes via the normal cut out functions of the lap bars.
Be very careful because if you have a system like this and accidentally send 12V down the ground loop you can fry the magnetos on some circuits.nd from the grounding bolt to one of the starter mounting bolts & paint over both with liquid electrical tape.
gainestruk
Well-Known Member
Same here, I normally tell people the by the book way, but I do it exactly like you ?