Oil pump line check valve allows gas to leak out?

steveg_nh

steveg_nh

New member
Joined
Jan 13, 2013
Messages
152
Location
Southern NH
My 04 Viper ER started leaking gas the other day onto the trailer floor. Not a lot, a slow leak. Got in there tonight and took a good look around. Looks like the oil link check valve is leaking. I don't mean it's allowing leak back through the valve, I mean it seems like it's actually leaking externally. Is that possible? Or could it be the hoses? This is the check valve in the hose that comes from the oil pump (a T fitting) and goes into the fuel pump.

It was hard to find the source of the leak, but I'm pretty sure this is it. I could dry the whole area, and then slowly watch is wet down with gas. I put some paper towel under the valve and saw it slowly saturate. Is the Yamaha check valve, part 8CH-1316A-00-00, some type of pressed valve that could allow the body itself to develop a leak?

If this is it, or the hoses (which are smaller than I have on hand), if I pull any of that line apart, do I have to bleed the oil system when I'm done to get air out of the lines?

Here's a picture of the suspected failed part circled and the hose it's inline on. Any thoughts?

Thanks for the help. I'm supposed to go on a trip Saturday, so really hoping this IS the problem, and I can source it locally. Just can't believe the valve itself could be leaking externally.

Check.jpg
 
No problem pulling those lines for inspection. It is downstream of the oil pump so it will just pump any air out after reassembly. You can pull your oil cable to go full rich oil until the oil fills the line back to the fuel pump.

As far as the root cause, usually the lines fail before the check valve. However, I would check it closely for leaks. You may have an issue in your fuel pump with the valve diaphragm not working properly. There was a couple bulletins on the fuel pump - one for a freezing issue with the vent on the bottom, and the other for improperly machined outlets.

I would carefully go over the line again to see if it is actually just running down the line and building up on the check valve.

You can easily take the fuel pump off and take it apart to inspect, just be sure to keep track of how everything goes as it won't work right in the wrong order. Quick pics with your phone can be a big help upon reassembly.
 
Last edited:
Hmm. Interesting. I'll try to wrap the line near the filter to see if it's actually leaking at the valve or not. I suspected the fuel pump at first, but the valve seemed to be it. It would be a lot easier if the carb rack was out of the sled, but really trying to not go through the work to remove them.
 
Actually looking at your pic a little closer - that looks like fuel in that line not oil. That is a problem as it should have oil in it. I now suspect the fuel pump machining debris issue. I'll look to see if this bulletin is on this site somewhere.
 
The bulletin I found (S2002-001) was about the oil inlet not being bored out at all on some of the fuel pumps. However I have seen some that had machining debris in them causing the fuel pump to not work properly
 
Thanks. I looked at the bulletin and that's for 2002 models. I have a 2004. I would think it was fixed by then, no? I've never had a problem with a frozen fuel pump either, even in temps down to -15.

It is fuel in that line, not oil. Or a mix. I noticed last week I had some oil on the floor as well. Wasn't sure where it came from. Checked chaincase and two stroke oil and both were full (fine). Maybe the check valve leaked some oil?

If no oil in the line, I assume sled would be having an issue, but it runs fine (that I know at least), and smokes (as it's getting oil). Then again, maybe it won't run right now if this just started happening. Wondering if I should just replace the fuel pump and that check valve/hose.

Now to add one more thing, even past the check valve, the line looks like gas in it, not dark oil....does that change the thinking at all? Maybe after sitting gas has been able to flow back through the check valve?

edit: called around. No one local has fuel pump, and check valve is available 2.5 hrs away. I am willing to make the drive tomorrow and back, but that's a haul for a $15 part. I assume I must have it inline. Any other options? Non Yamaha part that would work equally as well?
 
Last edited:
I definitely would get the fuel pump out and taken apart (very carefully - don't tear gaskets or get parts out of order) on the bench. I think the main problem is in you fuel pump. The check valve is not as critical as the fuel pump at this point. Generally they simply need a good internal cleaning. Sitting with non-stabilized fuel they like to corrode up especially with ethanol in the gas.

You are sure of course that the check valve is installed in the right direction, right? (arrow towards the fuel pump)

You can easily test the check valve once you pull that line - clean it good and then see if you blow in the end the arrow points toward, does it seal off. And if you blow in the end the arrow points away from does it flow freely. They are very simple devices.

fwiw: the debris in the fuel pumps has been seen on 02 thru 04 models - not sure about 05.
 
Last edited:
Thanks for all the advice you are giving. I appreciate it. Hoping to not miss my trip Saturday. I do have the check valve and new hose for it coming overnight from a dealer in Maine. They hooked my up for reasonable overnight shipping. Was worth it to me in case that is the problem.

On to the fuel pump. So these are serviceable/repairable? What are the chances I could tear a gasket and then be up the creek? I was looking to buy a new one, but they are only available online and will take a week to get here. What is the deal with what you're talking about too, debris? Just junk inside that was never properly cleaned out before assembly at factory? And to clean it up, just open it up carefully and clean it all out as best you can? I'm a bit worried about ripping some gaskets.

If I do pull it, I assume I need to drain the fuel in the tank, otherwise once I pull the line from the tank, gas would just keep on flowing, yes?

And yes, the check valve is in properly, it has been that way likely since new. I've had the sled 4 years.
 
Checkvalve looks to be faulty, it will let gas go back to the oil tank. The line should be green or whatever color your injection oil is, if the valve leaks it lets gas go back thru the line and will fill the oiltank if not full.

I would make the drive for the check valve, you need it.
 
The valve will be here tomorrow. It's being overnighted to me by a Maine dealer. I'm really hoping that is it.

What about the leaking though - you ever see a check valve actually develop a crack/leak? Could be the hose too. I'll replace that as well. Or worst case, the fuel pump.
 
steveg_nh said:
Thanks for all the advice you are giving. I appreciate it. Hoping to not miss my trip Saturday. I do have the check valve and new hose for it coming overnight from a dealer in Maine. They hooked my up for reasonable overnight shipping. Was worth it to me in case that is the problem.

On to the fuel pump. So these are serviceable/repairable? What are the chances I could tear a gasket and then be up the creek? I was looking to buy a new one, but they are only available online and will take a week to get here. What is the deal with what you're talking about too, debris? Just junk inside that was never properly cleaned out before assembly at factory? And to clean it up, just open it up carefully and clean it all out as best you can? I'm a bit worried about ripping some gaskets.

If I do pull it, I assume I need to drain the fuel in the tank, otherwise once I pull the line from the tank, gas would just keep on flowing, yes?

And yes, the check valve is in properly, it has been that way likely since new. I've had the sled 4 years.
Click to expand...

Ah good (you have one coming) - once you have the check valve replaced - fire it up and pull your oil cable to go full rich oil. Then check the oil line by the fuel pump to see if it turns back to oil color. You can do this with the air box removed on the stand or even just sitting. If you don't see oil in the line after a little bit you may still have an issue in the fuel pump. If you do see oil I would replace the airbox and run it for a bit. Then check the oil line again after it sits a bit - should stay looking oil color.

Be sure to reseat your oil cable properly.
 
I have seen them cracked only a couple times - I have seen debris in the fuel pump much more often.
 
the valves will leak, sure, especially with gas going thru it, the ethanol in gas eats rubber parts over time. if your oiltank was not full it would likely be diluted with gas as it will travel back thru line thru pump and into oilfeed line from tank, up into tank. I have replaced these check valves before not super everyday common but more then a couple times for sure.
 
Thanks guys. I will report back after I check out some more stuff tonight...

If I'm not pulling the full pump off, I'll only get a little bit of gas when I pull the oil line off the pump right? Or should I expect it to keep flowing? What about the oil, will it flow when I pull the hose off that T fitting under the carbs? I assume not as easily as the gas, given it's viscosity.
 
gas will flow out of the pump when you remove that line, as that's going into the mixing chamber of the pump, put a rubber vac cap on it while you change out the valve. After you replace the valve I would myself bleed the oil pump via the screw located on the side of the center reed cage, just remove the 8mm headed screw and be carefull not to lose the sealing washer. You can place a rag under it to catch the oil, as I suspect youll get some fuel out of it. Let it bleed for a minute or so, replace screw. When you start up the sled, pull the oilpump cable at the adjuster sleeve, open up the gap holding the cable apart from sleeve making the pump go wide open to force any remaining gas back into the pump and fill line with injection oil.
 
mrviper700 said:
gas will flow out of the pump when you remove that line, as that's going into the mixing chamber of the pump, put a rubber vac cap on it while you change out the valve.
Click to expand...
Got it.

mrviper700 said:
After you replace the valve I would myself bleed the oil pump via the screw located on the side of the center reed cage, just remove the 8mm headed screw and be carefull not to lose the sealing washer. You can place a rag under it to catch the oil, as I suspect youll get some fuel out of it. Let it bleed for a minute or so, replace screw.
Click to expand...
Not following. You are talking about one of the screws on the fuel pump?

mrviper700 said:
When you start up the sled, pull the oil pump cable at the adjuster sleeve, open up the gap holding the cable apart from sleeve making the pump go wide open to force any remaining gas back into the pump and fill line with injection oil.
Click to expand...
Got it.
 
A little hose comes up the side of the oil pump (down under your carbs) and has a Phillips / Hex screw in the fitting on the end of it which is attached to the engine with a bracket. Just take the screw out carefully and let the gas (and then hopefully oil) run out.

Like Don says, don't lose the sealing washer.
 
Last edited:
Ah thanks. That helps. Is it possible to get at that screw while the carbs are still installed in the sled? I'm hoping to not have to remove them.
 
ya, but its down in there, just simply loosen up the screws on carb clamps on intake and pull the carb rack back, you don't need to disconnect the fuel lines or thorottle cable, just pull the rack back and then your hand will fit in there, you already have the airbox out by your pics.

youll see the screw sticking up will be attached to the center cylinder reed cage bolt.
 
You must log in or register to reply here.


Back
Top