Odd Fuel issue (m900 '95)

[erkishhorde]

So I was at the end of a 55mi freeway jaunt and I'm cruising along the surface streets at about 35mph when the bike starts acting like it's out of gas. This is in 3rd gear. I pull in the clutch and coast for a bit, worried that if I gas it it'll die but then decide I have to gas it anyway since I'm almost to a stop light. Give it some gas gently and hear the bike start to die so I stop. I try opening wide and the bike nearly dies instantly so I stop and coast a bit more. I stop and try to give it some gas to start moving again and the bike dies.

So, I'm 2 blocks from home and the bike won't run. I push the bike for a block and while I'm taking a  break I try the bike again. The engine turns over but it won't start. If I give it a bit of gas I can hear a second thing working which I assumed was the fuel pump but the bike still doesn't start. So I push it the second block home. Once I'm home I lift the tank and poke around. I find nothing but a battery bungee that isn't strapped down. No biggie. So, with the tank up, I try to start the bike and it starts up no problem.  Turn off the bike, put the tank down and it still starts w/ no problem and revs up just fine.

Any ideas what I'm looking at? I recently replaced the fuel filter so I don't think that's it. I was hoping to make a 250mi (ea way) run to see friends this weekend to ride w/ them. Think I'm OK to go?

[hooligan machinist]

  Kinda sounds like you may have some trash in the tank. Maybe a large piece was getting sucked against the pickup opening.
Or a pinched fuel line or vent tube.
Not much to go on, i know, but it's a place to start.

[greenmonster]

Kinked gashose or maybe the hose it`s about to go bad/soft so it has a to sharp angle on it
and wont let enough fuel through.
Raise tank - fuel flows - it starts.

[erkishhorde]

Not so sure it's a kinked hose since I haven't raised the tank since I replaced the fuel filter and haven't had any problems for the last month or so. I wouldn't be surprised if there's something floating around in the tank. Any ideas on how to find out if there is actually something in there or how to go about getting it out?

[Porsche Monkey]

Bet you a dollar its the fuel pump. Mine was doing the same thing till I ditched the oem vacuum pump and replaced it with a small low pressure electric one.  The diaphram in the oem pump quits diaphraming over time. There are a few rebuild kits out there. I do have a rebuild kit that I didn't use but I'm in Texas. Ill have to find it so I can get a part number and supplier for you.

This is my setup.

This is a Facet brand low pressure fuel pump from Pep Boys.  I believe you can run this without a pressure regulator but I decided to run one anyway.  The pump fits snuggly so I just used some wire ties and some old coolant hoses to isolate vibrations.  The reason I went this route was because the closest oem fuel pump rebuild was 3 weeks away and I didn't feel like waiting.  I removed the oem fuel pump and plugged off the vacuum port with a vacuum cap.  Wiring the pump in was a simple affair.  I just ran the ground to a hidden point on the frame (pod mount) and ran the red wire back to the fuse box and wired it in to its own fuse.  If you loosen the fuse box and turn it over, you will see that there are 3 or 4 empty fuse slots that are not used.  All the fuses are key on power only so I just used one of those and it has been flawless for the last 8000 miles.  This shouldn't cost more than $50 bucks for a do it yourselfer. 

[erkishhorde]

Bet you a dollar its the fuel pump. Mine was doing the same thing till I ditched the oem vacuum pump and replaced it with a small low pressure electric one.  The diaphram in the oem pump quits diaphraming over time. There are a few rebuild kits out there. I do have a rebuild kit that I didn't use but I'm in Texas. Ill have to find it so I can get a part number and supplier for you.

This is my setup.

This is a Facet brand low pressure fuel pump from Pep Boys.  I believe you can run this without a pressure regulator but I decided to run one anyway.  The pump fits snuggly so I just used some wire ties and some old coolant hoses to isolate vibrations.  The reason I went this route was because the closest oem fuel pump rebuild was 3 weeks away and I didn't feel like waiting.  I removed the oem fuel pump and plugged off the vacuum port with a vacuum cap.  Wiring the pump in was a simple affair.  I just ran the ground to a hidden point on the frame (pod mount) and ran the red wire back to the fuse box and wired it in to its own fuse.  If you loosen the fuse box and turn it over, you will see that there are 3 or 4 empty fuse slots that are not used.  All the fuses are key on power only so I just used one of those and it has been flawless for the last 8000 miles.  This shouldn't cost more than $50 bucks for a do it yourselfer. 

Aw... That makes it sound like something I shouldn't try a long trip on. 

[Porsche Monkey]

It can do bad things if you run a bike that lean for a long time.  I wouldn't do it.

[erkishhorde]

So how can I test that it's a bad fuel pump? I was thinking of riding around tomorrow morning to see if I get any more fuel issues since they seem to have disappear just as suddenly as they appeared.

[Porsche Monkey]

I don't really know that there is a surefire way to test this. This was just the only thing left on my bike to do.  It only failed when the bike was hot and when I was in traffic with little air flow.  It would start and idle fine when cold and run fine on cold mornings. On the ride home when it was warmer outside it would act up.  How mechanically inclined are you?

[erkishhorde]

How mechanically inclined are you?

Iono.  I can kinda solder. I can think analytically pretty well to solve problems and trouble shoot and sometimes am able to solve problems w/ things that I don't fully understand just by process of elimination. Then again I've also gotten myself into trouble taking things apart and not being able to put them back together. I've since learned to take better care in remember how I took things apart.

Speaking of the trouble shooting...
You said yours would die out when it got hot. Prior to the fuel issues I made a 55mi run at 85-90mph with no problems. The bike then sat for about an hour and half and I made a 55mi run at 70-75mph and then the bike died out on me on surface streets. If it were dying on me due to temperature I would think the first run should have caused problems too. Hmm... I guess that doesn't mean it's not the fuel pump though. I also have no idea if I'm still running the original or what.

[Porsche Monkey]

It really sounds like a fuel delivery problem to me.  If the filter is new and there are no pinched lines then I would be looking towards the pump. Replacing the pump is very simple. Let's wait till someone else chimes in.

[ducpainter]

Don't discount HMs suggestion about junk in the tank. If the tank is original there is bound to be rust and a piece of scale could be blocking the tank outlet.

Since it only seems to happen when the bike is warm...

...an electric replacement is not a ton of money and is a better alternative to the stock pump IMO.

[BastrdHK]

I would closely check your fuel hoses again.....I had a buddy with an '01 m900 that would have a fuel delivery problem intermittently.....once he stopped for awhile it would run normally.  If it was pushed hard it would have the same problem till it cooled down.    Turns out after the last time he raised the tank one of the fuel lines began resting on top of the vertical cylinder and it would get so hot it would cause vapor lock.  He experienced this during a 300+mi trip through the north Georgia mountains with a group of Yamaha YZF guys.  They gave him endless shit for how unreliable his Ducati was.  He still managed to lead the pack through the twisties with coughing bike

Pay close attention as you close your tank to make sure nothing gets pinched or is resting against the cylinder.

Good luck!

[erkishhorde]

Bet you a dollar its the fuel pump. Mine was doing the same thing till I ditched the oem vacuum pump and replaced it with a small low pressure electric one.  The diaphram in the oem pump quits diaphraming over time. There are a few rebuild kits out there. I do have a rebuild kit that I didn't use but I'm in Texas. Ill have to find it so I can get a part number and supplier for you.

This is my setup.

This is a Facet brand low pressure fuel pump from Pep Boys.  I believe you can run this without a pressure regulator but I decided to run one anyway.  The pump fits snuggly so I just used some wire ties and some old coolant hoses to isolate vibrations.  The reason I went this route was because the closest oem fuel pump rebuild was 3 weeks away and I didn't feel like waiting.  I removed the oem fuel pump and plugged off the vacuum port with a vacuum cap.  Wiring the pump in was a simple affair.  I just ran the ground to a hidden point on the frame (pod mount) and ran the red wire back to the fuse box and wired it in to its own fuse.  If you loosen the fuse box and turn it over, you will see that there are 3 or 4 empty fuse slots that are not used.  All the fuses are key on power only so I just used one of those and it has been flawless for the last 8000 miles.  This shouldn't cost more than $50 bucks for a do it yourselfer. 

Alright, after a night's sleep I'm ready to try this. I'm not quite sure what a vacuum port is but there aren't a whole lot of hoses going into the tank so I'm pretty sure I can figure out which hole is the vacuum. Also, for the power for the fuel pump, could I use the wires that go to the existing fuel pump instead of wiring into the fuse box? I assume I could get some hose from home depot too, maybe tygon tubing?. Also, how does the pressure regulator work?

[Porsche Monkey]

The original fuel pump for this bike is a vacuum actuated type. It is not electric. Look for the pump on the right side of the bike. It is mounted with two screws on the vertical frame tube just behind where my fuel pump is mounted in the picture.  It is shaped like a pentagon if I remember correctly.  There should be three hoses coming off of it. One supply hose from the tank, one hose that goes up between the carbs, and a smaller hose that goes to one of the intake manifolds. The smaller hose is the vacuum line and that's what needs to be plugged. When you buy your fuel pump pick up an assortment of vacuum caps and you will find one that fits. Your gonna want to remove the vacuum hose completely and put one of the plugs over the port on the intake manifold so you don't have any vacuum leaks. You should also buy some small hose clamps, some electrical wire the same diameter as the wire on the new pump and maybe an assortment of electrical connectors.  I didn't have to add any length to the fuel line so you should be okay there.  The fuel pressure regulator I used is just a Mr Gasket brand dial type that should also be available at the auto parts store. You want to get the smallest low pressure pump possible and I believe that is the Facet brand.  Look for the plastic body one instead of the metal one.  The metal ones are loud and the plastic ones are very quiet.  Post back when you get that far. 
Jon