Failed Fuel Pump Flyback Diode

[Aequitas4]

When I bought my Intruder 1400 I was having intermittent issues with the fuel pump and replaced it with one from Amazon. I have used the bike sparingly (<1000 miles) for over a year and now the new Amazon fuel pump has stopped working. Upon disassembly I found what appeared to be a broken/burned wire.



After some searching online I believe the two disconnected wires in the picture are what's left of a flyback diode. If I understand it correctly the diode is in place to prevent spikes in negative voltage going back and arcing across the switch when the switch opens and +12V is disconnected.



I have since replaced the Amazon fuel pump with a new one but I don't have the root cause as to why the old one failed or any confidence that the same thing wont happen to the new one.

1. What would cause the pump flyback diode to fail like this?
2. Where can I find what kind of diode this is to solder onto the old pump to see if it can be repaired?

[hillsy]

The simple answer is that you bought the pump from Amazon.

Cheap pumps .....are cheap pumps. I've probably been luckier than most using them with minimal failures but they are.....cheap pumps.

[Herb]

I would pull the new one apart and get the specifications off of the part on it.

There are a number of suppliers of electrical parts on line and if you have the specs it shouldn't be hard to find one.

As for why it failed, electrical components do fail and if there was a flaw in the manufacturing it would probably fail in a very short amount of use. There is also the possibility that the wrong diode was installed but with it gone there is no way to tell.

There is also the possibility of something else wrong that caused the failure.

If you repair it, I would carry another until I was sure that it wasn't a failure of something else.

[Aequitas4]

Absolutely agree. The fact that the previous pump (that appeared to be a stock part) also had the same failure made me worried I've got something else besides a cheap pump causing the issue.

At the end of the day if I have to buy a new $30 pump only once a year, I'm okay with it.

[hillsy]

The fact that the previous pump (that appeared to be a stock part) also had the same failure made me worried

You didn't mention this in your first post.

What is the charging voltage on your bike and in particular what is going to the fuel pump? They can be sensitive to prolonged excess voltage.

[Herb]

Absolutely agree. The fact that the previous pump (that appeared to be a stock part) also had the same failure made me worried I've got something else besides a cheap pump causing the issue.

At the end of the day if I have to buy a new $30 pump only once a year, I'm okay with it.

The problem isn't the cost, it is the probability of it failing, at the worst possible time. Murphy's law says that when something fails it will fail at the worst possible time. Say heavy traffic, in the left lane of 4, 60 mph. A loss of power will leave you up shit creek without a paddle.

You have a point about the reason for the failure.

There isn't any chance that the leads are swapped is there? Any chance that there is a power problem? Low or high voltage can cause failure of semi conductors. Even a bad ground connection in the circuit can cause circuits to overheat..

Keep in mind that I have a 99 with over 250,000 miles and it still has the original pump.

[Designer]

Absolutely agree. The fact that the previous pump (that appeared to be a stock part) also had the same failure made me worried I've got something else besides a cheap pump causing the issue.

At the end of the day if I have to buy a new $30 pump only once a year, I'm okay with it.

So,....both the Stock Pump and the "Cheap Pump" had the same failure. Interesting.

Obviously, it is not a Cheap Pump issue, but more along the lines of what Herb has said. I'd listen to him and his Diagnosis.
He has Experience that others don't have and his Expertise can help you track the issue(s) down that caused the failure.

I wouldn't want the pump to fail you when you are out Riding and far from Home!

[hillsy]

The fact that the previous pump (that appeared to be a stock part) also had the same failure made me worried

You didn't mention this in your first post.

What is the charging voltage on your bike and in particular what is going to the fuel pump? They can be sensitive to prolonged excess voltage.

Also - how is the pump mounted on the bike? Is it solid mount to the frame? I replaced my LC pump with aftermarket but rubber mounted it instead of being solid mount. Vibrations can hurt the pumps pretty quick as well. All you need is a crack to start appearing in one of the solder joints and the current can start to arc.

[hillsy]

Oh and one other thing - a fuel pump....is a fuel pump....is a fuel pump. As long as it is for a carb application they all run between 2-5 psi and pretty much all have 8mm hose ports. The differences between different model specific ones will the mounting, the wiring connector and whether the ports are straight or angled.

You can buy rebuild kits for some OEM fuel pumps (CBR900rr, etc) but not sure if you can for the Intruder ones....or if a rebuild kit will fit a cheap pump.

[Aequitas4]

The fuel pump was mounted to the frame using the stock bracket and rubber grommets. I'll check the voltage to the pump compared to the voltage on the battery tonight. I'm relatively sure the polarity to the pump is correct. The connector will only fit one way and upon disassembly the positive wire coming from the bike goes directly into the pump coil and the flyback diode which I believe is correct.

[Designer]

The fuel pump was mounted to the frame using the stock bracket and rubber grommets. I'll check the voltage to the pump compared to the voltage on the battery tonight. I'm relatively sure the polarity to the pump is correct. The connector will only fit one way and upon disassembly the positive wire coming from the bike goes directly into the pump coil and the flyback diode which I believe is correct.

Yes,...as anyone who really knows about a 1400 of your vintages,...the Stock Pump is rubber-mounted.

And the one you show pictures of is one of those pumps that fit the Stock Mounting Bracket.

Can you run a Voltage Output while the bike is running? Check to see what you get from Idle all the way up to about 4500-5000 RPM and get back to us please.

[hillsy]

Yes,...as anyone who really knows about a 1400 of your vintages,...the Stock Pump is rubber-mounted.

He's got an aftermarket pump - you cant assume it's mounted the same as stock.

[Aequitas4]

Havent been able to get the voltage yet. Had a slight hiccup and may have burned up my igniter module (update here: viewtopic.php?f=10&t=13554) once the igniter issue is resolved i'll get back to this one.

[Herb]

I have a hunch that the failure of the fuel pumps and the igniter might be related to a power issue. If it isn't resolved you will keep having problems.