# Kubota B1550 Starting Issues



## Johnny Mac (Jan 10, 2022)

Good Morning Everyone, Greetings from a very cold South Dakota.
I have a Kubota B1550 and I am having starting problems with it. I would like to ask if anyone else has experienced "timer relay" failure with their Kubota B1550? The lights on the dash work, however the fuel cut off solenoid is not working and it appears that the glow plugs are not working. I have checked the resistance at the gow plugs and all read around 1 ohm. If I hook up power to the fuel cut off solenoid, (which is a single wire system), it works. However when all connected to the ignition system it will crank but not fire up. At one point I got the engine to fire up however once I release the ignition key to the run position, it cuts out? Can the timer relay be at fault here? Thankyou for reading this post and I would appreciate your comments. Johnny Mac


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## SidecarFlip (Mar 25, 2021)

Sounds to me like a faulty ignition switch. 30 bucks at you local friendly Kubota dealer will get you a new one,. I'd be checking all the connections as well, that tractor is old enough to be on Social security.


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## Johnny Mac (Jan 10, 2022)

Hello Sidecar Flip, Thank you for your reply, it is appreciated. The overall condition of the wiring is brittle, including the connectors.They are hard and coated with dirt and diesel. I found several broken wires and connectors and have repaired those, however the timer relay is "dead" when I tested it. It is a very expensive part to replace and this relay cost me from my local Kubota dealer $180. Which is expensive for someone on Social Security. Is your tractor now running well?


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## FredM (Nov 18, 2015)

How many positions does your ignition switch have?, I have a B2400 around your era for the B1550 and I bet your system will be close the mine, preheat, turn key to left to activate the glow plugs, turn key to far right to start, release to run position and turn to left from run position to shut down, was I close?.

There is no timer for the glow plugs, holding the key to the left for about 6 seconds should be enough to preheat, maybe a little longer seeing you have colder winters.

What is this timer relay you mention?, I have a relay and this is in the start wiring to supply battery power to the starter solenoid, the fuel pump shut down solenoid is by direct voltage from the ignition switch, if the relay you speak of is a four or five pin, clean the pin base area and see if you can get a photo and attach here, this may show up the pin numbers, and I think you will find an Auto electrical store will be able to match the pins, I am in the same boat as you as far as having unlimited cash, so I would be thinking about that $180 also.

In the morning, I will try and find a wiring diagram for your tractor, this may be easy, most times it is hard to find a diagram for the popular tractors.


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## SidecarFlip (Mar 25, 2021)

My tractors always run well at least I hope they do anyway...lol I never buy relays from my dealer, the markup is insane. relays can all be crossed by their stamped in catalog numbers. and purchased at Digikey or Dell Electronics for a mere fraction of what the dealer prices are. Both have online websites too. I had to replace a faulty relay that controlled my AC blower on my cab tractor. Dealer cost was just under 100 bucks. Digikey had the same relay, same manufacturer(Denso), exact copy for 7 bucks. I bought an extra just in case. I'm on SS as well.

Just like bearings, I always buy bearings from a bearing retailer, not the dealer. Bearings, like relays, light bulbs and other components all have catalog numbers that can be cross referenced and obtained much cheaper elsewhere.

If it's a unique part, I get it from my dealer. If it's not I don't.


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## Johnny Mac (Jan 10, 2022)

FredM said:


> How many positions does your ignition switch have?, I have a B2400 around your era for the B1550 and I bet your system will be close the mine, preheat, turn key to left to activate the glow plugs, turn key to far right to start, release to run position and turn to left from run position to shut down, was I close?.
> 
> There is no timer for the glow plugs, holding the key to the left for about 6 seconds should be enough to preheat, maybe a little longer seeing you have colder winters.
> 
> ...


Hello Fred Thank you for your message and comments, they are appreciated. I share your sentiments about relays and pricing, however this timer relay is different to a regular relay as it controls the glow plugs and solenoid cut off. It has four pins and there are no regular relay related numbers, (eg 30, 85, 86 ,and 87 as you would expect). The battery supplies voltage to the ignition switch and the relay via the fusable link. The other side of the relay goes to ground and the fourth terminal to the fuel cut off solenoid and this wire has a line fuse. The ignition switch has three positions which rotate clockwise from the left; they are off, on and at that point three lights on the dash come on and this includes the glow plugs. You are then supposed to count to 10 on a cold day and 6 when warmer, before turning the key to the crank position which is then the final position. Once it starts you release the key to the run/on position and the engine should stay running. The initial problem was that there was a broken wire on the timer relay which I fixed, however the four pin connector is old brittle and broken and the wire I fixed won't stay attached via the connector. The relay woud operate and then stop and I could see this via the cut off solenoid. I repositioned the relay so to not to have stress on the wiring, as it did in its original position. The ignition switch seems the be working, however I will check it. I will also fit a standard everyday automotive relay in place of the timer relay and see if that works. I will keep you informed. Thank you for your comments. Johnny Mac


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## Johnny Mac (Jan 10, 2022)

SidecarFlip said:


> My tractors always run well at least I hope they do anyway...lol I never buy relays from my dealer, the markup is insane. relays can all be crossed by their stamped in catalog numbers. and purchased at Digikey or Dell Electronics for a mere fraction of what the dealer prices are. Both have online websites too. I had to replace a faulty relay that controlled my AC blower on my cab tractor. Dealer cost was just under 100 bucks. Digikey had the same relay, same manufacturer(Denso), exact copy for 7 bucks. I bought an extra just in case. I'm on SS as well.
> 
> Just like bearings, I always buy bearings from a bearing retailer, not the dealer. Bearings, like relays, light bulbs and other components all have catalog numbers that can be cross referenced and obtained much cheaper elsewhere.
> 
> If it's a unique part, I get it from my dealer. If it's not I don't.


Hello Sidecar Flip, I agree with your comments and I will put in a everyday standard automotive 20 amp relay and see what happens. I will keep you informed and will also remove and have a look at the ignition switch. Thank you once again Johnny Mac
PS Where abouts do you live and do you have a "real" name?


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## FredM (Nov 18, 2015)

Johnny Mac said:


> Hello Fred Thank you for your message and comments, they are appreciated. I share your sentiments about relays and pricing, however this timer relay is different to a regular relay as it controls the glow plugs and solenoid cut off. It has four pins and there are no regular relay related numbers, (eg 30, 85, 86 ,and 87 as you would expect). The battery supplies voltage to the ignition switch and the relay via the fusable link. The other side of the relay goes to ground and the fourth terminal to the fuel cut off solenoid and this wire has a line fuse. The ignition switch has three positions which rotate clockwise from the left; they are off, on and at that point three lights on the dash come on and this includes the glow plugs. You are then supposed to count to 10 on a cold day and 6 when warmer, before turning the key to the crank position which is then the final position. Once it starts you release the key to the run/on position and the engine should stay running. The initial problem was that there was a broken wire on the timer relay which I fixed, however the four pin connector is old brittle and broken and the wire I fixed won't stay attached via the connector. The relay woud operate and then stop and I could see this via the cut off solenoid. I repositioned the relay so to not to have stress on the wiring, as it did in its original position. The ignition switch seems the be working, however I will check it. I will also fit a standard everyday automotive relay in place of the timer relay and see if that works. I will keep you informed. Thank you for your comments. Johnny Mac


G'day Johnny Mac,please don't install a auto relay as this will not work as intended, doing so will keep power to the glow plugs "on"all of the time the ignition switch is in the run position, have you tried squeezing the female connectors in the plastic connector just a wee bit so they will hold a little better to the male pins, from what you describe, both relay and ign. switch are working, just bad connections.

To bypass the timer relay for the glow plugs, you could use an auto start push button switch to activate the glow plugs, you would have to use a full bridge starter switch, (power in and power out) and wire the glow plug hot wire through this, push in and count for heating and release when time done, the older tractors used this method and so simple.

Sorry, my bad, thinking your Ignition was setup like my B2400, there are ways around these small problems though.


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