Help fix my friend's bike

One of my friend has a 03 honda shadow spirit 750. She's been having some problem with her bike. Instead of me trying to explain her problem. I'm going to post her email. Any help would be awesome. THANKS

I have a 03 honda shadow spirit 750. It has been randomly shutting down. First 2 times, I was at 75 and 77 miles on the gas tank. My tank is a 3.4 gallon and I run out about 120 then I have a gallon for reserve. On Saturday, I was at 50 miles on the tank. It feels like I’m running out of gas. I pull in the clutch and rev the engine and then put it back in gear and roll the throttle. It took off for about 2 seconds and then shut the whole bike down. So far, it has started back up within a minute or so.

I have replaced the battery, spark plugs and air filter. Below is what Todd has done:

Drained the tank. – Not 1 speck of dirt
Pulled the fuel valve off the tank-Nothing
Pulled the fuel filter- New last year-Nothing
Checked the fuel shut-off check valve(under the battery)-Nothing
Tightened clamps on carbs.(4) 1 on right side on cylinder side was completely loose.
Carb intakes clean.
New air filter.

I’m hoping by cleaning the carb (our friend James is going to do this for her) , it will fix it. If not, we’ll go to plan B…whatever that is!


PS: it has 23,000 miles

Pinched vent line? Or....I had a problem with an older carb'd bike that the gas cap would not vent. This basically starved the carbs from gas. You can get the same effect by sticking a straw in a glass of water and putting your thumb over the top of the straw. Lift the straw out of the glass keeping your thumb on top and the liquid will that occupied the inside of the straw will stay in it. Take your thumb off and out will come the water.

I'm going to guess clogged vent, or if the bike has a vacuum opperated petcock, its got an air leak or the diaphram is ruptured. With a full tank, there is more gravity pressure to force the diaphram open, as the tank drains, it no longer has enough head to hold it open. Check the vaccum lines for cracks and perhaps rebuild the petcock.

your comments are well appreciated guys. Susan thank you and I just think you guys ROCK

Vacuum line on the petcock

How far has she run when it dies? If it is the whole distance it could be heat.

Does it start right back up? If not how/when?

Here's her reply:

Don’t know what petcock is so need to learn that

So far the 3 times have been within a couple miles then dies. One time I ran 200+ miles and it died.

So far, starts up or within a min or 2. Pulled choke to help it start

Electrical like a coil from heat would not be that quick. Therefore I think petcock. If it is similar to my old Ascot there is a vacuum line on the back that opens the petcock. If the hose is cracked or the valve damaged it would run out of gas. The fact she needs to choke it seems to point more to this.

Petcock is the valve she switches from off to on to reserve

I sent her a picture of the Petcok LOL She understands now... LOL Thanks Sheep

Oh and to test the theory of a vent clog on the cap. When it stalls open the tank and close it, the bike should start without waiting (though might still need choke as you did run it dry). If the cap is not venting enough this will let the needed air in fast.

Also, if she can have her pull her helmet off before popping the tank so she can hear. If it's a vent thing she'll be able to hear the tank suck air in when she pops the filler. From the symptoms that certainly sounds like the cause to me.

So will she join and let us know if its resolved?

We will need pics to property diagnose the issue. Of her, not the bike.

I just looked at the microfish, that thing has an electric fuel pump (somehwere, looks like an external one, probaly under the tank) that may be crapping out.

I will try to make her do it so she can at least thank you guys

I can come up with some pictures of her


Thanks guys for all your help.

subscribed for the upcoming pics

Just got this back from Susan

James said gas cap is fine and so is petcock. i forgot to ask him about the carb. next step, i'm going to order the repair manual on my bike and he'll start looking at the electrical system

There is an off chance dad has the manual for that bike, I will check tonight.

ok Thanks Your my hero Sheep

Dad's book is 04-07 so the details might be off.

1) The carb has a strainer. Looks to be where the fuel line plugs on. That could be clogged and would be a good guess. It is in a place that would be hard to notice and easy to overlook unlike the filter.
2) I assume no one has messed with the pilot, idle or other jets but if so that was mentioned as a potential fix (not something that you could tell how over the net though)
3) Intake air leaks. These are easy to test for the old two stroke way should work. Start the bike and with a can of carb cleaner spray around the carb and intake. If the idle suddenly changes you likely have a leak in that area.
4) they mentioned the Evaporative Purge Valve but again the way to test is not that easy to explain and requires 2 vacuum pumps

That is about all I saw skimming the book (again the year was 4-7 not 3). Hope this helps