Power loss at 1.5k RPM general ignition issues

[blockade]

The top line is the return. That means the fuel should have been coming from the Male QD on the left, connected to the short hose, that's connected to the plastic fuel distributor line. Was that it?

Based on what you've measured in the TPS, it is fine. I will suggest some O2 sensor measurements next.

No! I took a closer look and saw that the lines were crossed! Not sure when that happened. But I checked again to see what the flow looked like at ignition on, and at idle. No flow! Not a drop!



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[rxcrider]

No! I took a closer look and saw that the lines were crossed! Not sure when that happened. But I checked again to see what the flow looked like at ignition on, and at idle. No flow! Not a drop!
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I'm very surprised that it ran at all with the lines crossed. When I did that the first time I put my bike together, I was unable to get the bike to start and I got a fuel leak at the pressure regulator. I think your life would be easier with some extra QDs on open hoses to watch flow as well as a tap (with QDs) to hook a fuel pressure meter up. Let us know where you are located and maybe you will be lucky enough to find someone with tools close by. If you didn't already, pick up some extra o-rings for the QDs (Beemer Boneyard sells them) because you are bound to tear them eventually, even if you are careful. The bike can act all sorts of funky with a split U hose in the tank causing a drop in fuel flow / pressure. That is where I'd be leaning, but being able to test it quickly is much more enjoyable than pulling the tank apart for no reason.

 

[blockade]

Wait, clarification: the lines were connected correctly, their positions were just swapped - the top line seems to be longer than it should be and was under what should have been the bottom line.

So I wasn't testing the return line.

What does no fuel flowing through the return line mean?

 

[roger 04 rt]

So if you pressed in the check valve on the Male QD and you have no fuel flow at key on, you have a plugged filter or a split in-tank hose.

 

[blockade]

So if you pressed in the check valve on the Male QD and you have no fuel flow at key on, you have a plugged filter or a split in-tank hose.

In that case, my next steps will be to tear into the fuel tank. This could explain the issue with the fuel light not functioning, maybe something in the tank is preventing the float from functioning/causing the fuel flow issues.

Would a plugged filter or split in-tank hose cause the TPS and O2 codes?

 

[rxcrider]

I could see low fuel pressure causing an O2 sensor issue, but I wouldn't think it would cause a TPS problem. I'd check fuel pressure and flow prior to diving into the tank.

Maybe you have an intermittent open or short I the harness that is triggered by resonance at 1500 RPM...

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[fawudd]

Very similar symptoms on my former R850R turned out to be a leaking hose between the in-tank pump and the filter. Similar RPM issues leading to suspect the TPS, similar diagnostics. In my case there is a fuel hose that makes a 180 degree bend to keep things compact in the tank. That hose had a leak so the bike started and ran up until it needed more fuel than the leaky system could provide. Drove me nuts, but that was the culprit. YMMV


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[roger 04 rt]

In that case, my next steps will be to tear into the fuel tank. This could explain the issue with the fuel light not functioning, maybe something in the tank is preventing the float from functioning/causing the fuel flow issues.

Would a plugged filter or split in-tank hose cause the TPS and O2 codes?

The lack of fuel flow causes O2 sensor errors because the O2 sensor always reads lean. As for the TPS error, I have seen one other log where TPS errors occurred when the O2 sensor appeared shorted.

I think you should investigate and fix any tank problems and then see where you are.

 

[blockade]

I could see low fuel pressure causing an O2 sensor issue, but I wouldn't think it would cause a TPS problem. I'd check fuel pressure and flow prior to diving into the tank.

Maybe you have an intermittent open or short I the harness that is triggered by resonance at 1500 RPM...

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How would I check this?

 

[blockade]

Very similar symptoms on my former R850R turned out to be a leaking hose between the in-tank pump and the filter. Similar RPM issues leading to suspect the TPS, similar diagnostics. In my case there is a fuel hose that makes a 180 degree bend to keep things compact in the tank. That hose had a leak so the bike started and ran up until it needed more fuel than the leaky system could provide. Drove me nuts, but that was the culprit. YMMV


www.classicvelocity.com

This is encouraging. I have dug into the tank before, about a year ago, so I know my way around. If it is a hose issue it should be fairly easy to resolve.

 

[rxcrider]

How would I check this?

Thoughts on using 12V LEDs (aka noid lights) in this thread:

http://forums.bmwmoa.org/showthread.php?81073-1997-R1100RT-Gremlin-what-to-do

I'd still start with testing fuel pressure and flow. If you just pull it apart without testing first, at the very least, replace the filters while you are in there looking at hoses.

 

[blockade]

I'd still start with testing fuel pressure and flow.

How would I do this? I'd love to not have to dig into the tank.

 

[roger 04 rt]

Thoughts on using 12V LEDs (aka noid lights) in this thread:

http://forums.bmwmoa.org/showthread.php?81073-1997-R1100RT-Gremlin-what-to-do

I'd still start with testing fuel pressure and flow. If you just pull it apart without testing first, at the very least, replace the filters while you are in there looking at hoses.

Really all that he needs to do is confirm that there is no return flow. Once that is certain, if he hears the pump running, he can be 99% certain that there's a problem in the tank. It's unlikely the fuel pressure regulator is jammed but quite likely that a hose, filter or the pump has failed.

If the bike idles, he could try collecting return fuel in a container. It should be 2 liters per minute at idle.

 

[blockade]

If the bike idles, he could try collecting return fuel in a container. It should be 2 liters per minute at idle.

It's dry at idle.

 

[rxcrider]

Roger - I agree - maybe better to say check return fuel flow, then pressure only if he has flow. Either way, much easier with an extra set of QDs and some hose. Do you have a link handy for the write up you did on pressure and return flow a while back. If not, I'll search for it later.


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[rxcrider]

It's dry at idle.

You were checking the upper hose coming back from the pressure regulator, right?

Were you checking with another Quick Disconnect plugged into it to allow flow or while pushing the check valve plunger in on the QD?


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[blockade]

Yes, checked the upper and pushed the check valve plunger in on the QD.

 

[rxcrider]

Into the tank you go then. If nothing is obvious, take a close look at the "U" hose. It can split inside the bend and not be easy to see without flexing the hose.


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[roger 04 rt]

Roger - I agree - maybe better to say check return fuel flow, then pressure only if he has flow. Either way, much easier with an extra set of QDs and some hose. Do you have a link handy for the write up you did on pressure and return flow a while back. If not, I'll search for it later.


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http://forums.bmwmoa.org/showthread.php?69157-R1150-Fuel-System-Diagnostic-Tool&highlight=

 

[blockade]

Appreciate all the info guys. I plan on taking the tank apart this weekend and will let you know what the outcome is. Fingers crossed, it's just a hose and it will resolve all my issues and I can get back on the road.