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5 Posts
Hey, newbie here. Had my Shadow for a few years now and haven’t really had too many issues until I was getting busy and riding less. I left the bike for 2 months and couldn’t start it on return. I didn’t use any fuel stabilizer, plus the gas cap has a little leak when the tank is completely full… so probably lets more air in to ruin the fuel.
The battery is good, the engine cranks, and it even started for a little bit, but then couldn’t start again afterwards.
I figured that the carbs are bad, but before pulling them out and learning how to rebuild them, I wanted to try a few things. My goal was to get seafoam into the carbs and let it sit to clean them out. (I was going to try the following: https://www.youtube.com/watch?v=FonLaCVFMcU)
I first cleared out the old fuel from the fuel lines and tank and changed out the old fuel-filter. I noticed that the fuel pump did not seem to work, at least I couldn’t hear it working when the ignition was pressed. I followed this post (http://www.hondashadow.net/forum/72-technical-discussion/65947-bridging-fuel-pump-relay.html) to troubleshoot the fuel pump system. Either the fuel pump went bad, or the fuel pump relay did.
After cutting out the relay, it seemed like the pump was working. I disconnected the fuel lines before and after and had fuel pumping through with enough pressure to shoot out of the downstream line.
? One question I have here is, does the fuel pump shut-off if the carbs and fuel lines downstream are full and there is no space to pump gas into? When I had all the lines connected and full of gas, the fuel pump did not crank. Even when the float boat drain screws were open.
So to get the seafoam in, I wanted to drain the float bowls in the carbs along with the bad fuel left over in the connecting fuel lines.
I unscrewed both of the float bowl drain screws.
From the left side, only a few droplets of fuel came out. From the right ride, maybe one ounce of fuel came out. I thought there would be much more.
Using a funnel I poured in a bit of fuel directly into the fuel line connected to the float bowls (by passing the fuel filter and pump). With the float bowl drain screws open, I would have expected fuel to flow through. I even added some pressure to by blowing into the fuel line, but still no flow.
? How much pressure is needed to fill up the float bowls? I expect it isn’t much. I have seen that people run without fuel pumps and use gravity feeds to get the fuel in.
? So what could be the problem?
- Is there something I missed in trying to get gas / seafoam into the carbs? There is no other little fuel pump or valve somewhere just for the carbs is there?
- Could the fuel line be clogged somehow so that even a bit of fuel can't go through?
- Could the carb be so gunked up that I can’t even pour seafoam through?
- Is there something else I can try before taking out the carb?
Thanks in advance for any help!
The battery is good, the engine cranks, and it even started for a little bit, but then couldn’t start again afterwards.
I figured that the carbs are bad, but before pulling them out and learning how to rebuild them, I wanted to try a few things. My goal was to get seafoam into the carbs and let it sit to clean them out. (I was going to try the following: https://www.youtube.com/watch?v=FonLaCVFMcU)
I first cleared out the old fuel from the fuel lines and tank and changed out the old fuel-filter. I noticed that the fuel pump did not seem to work, at least I couldn’t hear it working when the ignition was pressed. I followed this post (http://www.hondashadow.net/forum/72-technical-discussion/65947-bridging-fuel-pump-relay.html) to troubleshoot the fuel pump system. Either the fuel pump went bad, or the fuel pump relay did.

After cutting out the relay, it seemed like the pump was working. I disconnected the fuel lines before and after and had fuel pumping through with enough pressure to shoot out of the downstream line.
? One question I have here is, does the fuel pump shut-off if the carbs and fuel lines downstream are full and there is no space to pump gas into? When I had all the lines connected and full of gas, the fuel pump did not crank. Even when the float boat drain screws were open.
So to get the seafoam in, I wanted to drain the float bowls in the carbs along with the bad fuel left over in the connecting fuel lines.
I unscrewed both of the float bowl drain screws.


From the left side, only a few droplets of fuel came out. From the right ride, maybe one ounce of fuel came out. I thought there would be much more.
Using a funnel I poured in a bit of fuel directly into the fuel line connected to the float bowls (by passing the fuel filter and pump). With the float bowl drain screws open, I would have expected fuel to flow through. I even added some pressure to by blowing into the fuel line, but still no flow.
? How much pressure is needed to fill up the float bowls? I expect it isn’t much. I have seen that people run without fuel pumps and use gravity feeds to get the fuel in.
? So what could be the problem?
- Is there something I missed in trying to get gas / seafoam into the carbs? There is no other little fuel pump or valve somewhere just for the carbs is there?
- Could the fuel line be clogged somehow so that even a bit of fuel can't go through?
- Could the carb be so gunked up that I can’t even pour seafoam through?
- Is there something else I can try before taking out the carb?
Thanks in advance for any help!