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R1150 Fuel System Diagnostic Tool

roger 04 rt

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roger 04 rt

It seems every week someone on one Board or another has a suspected fuel system problem. After my system failed last summer I realized that there was a very simple diagnostic point that can check the pump, strainer, filter and in-tank hoses. To test the integrity of the system takes only a couple minutes, after you have the right side plastic off.


The in-tank pump has a capacity at standard pressure of about 120 liters per hour, which is 2 liters per minute. At idle the bike uses very little fuel. Therefore in a good fuel system there is about 2 liters per minute returning from the fuel distributor to the fuel tank.


To make the test you need two feet of hose with a female QD installed on one end and a collection tank. Open the return line QD (upper QD pair on an 1150 RT), plug in the hose and measure the fuel at idle for one minute. If you get a couple liters your system is most likely in good health. The only thing you don't know is the accuracy of your FPR but they don't fail often.


If your bike won't start the test is to connect the hose and make sure you have at least some flow for two seconds at key on. That says the pump has pressurized the system enough to open the FPR.


I keep a hose with a QD for just that purpose. The kit below has a collection tank and fuel pressure gauge with QDs but the best part is the two foot hose with one QD that couples to the line going from the distributor back to the tank. If I'm pushing fuel out that line, the rest of the system is good.


The return hose is light enough that you can add it to your tool kit for longer trips.






PS: What often goes wrong are fine cracks in the in-tank hoses that can leak for years before they suddenly rupture. The return test may give some warning to avoid this event: Fuel System Failure and Highway Breakdown.



Edited by roger 04 rt
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  • 1 year later...

With winter coming, and beginning to plan maintenance projects, I thought I'd bump this thread and suggest testing of R1150 fuel systems (and R1100s that have QDs) as an alternative to fuel filter replacement or externalization.


You can tell the health of your fuel system by measuring the volume of fuel returning to the tank from the fuel distributor, which should be about 2 liters per minute. That tells you that the pump is delivering enough fuel volume at pressure; that the in-tank hoses/clamps aren't leaking; and that the fuel filter isn't restricting fuel flow.


The photo at the start of the thread shows a pressure gauge but that tool isn't usually needed since fuel pressure regulators are very reliable.


Some information on the system

--Fuel Pump: 110 liters per hour, which is just under 2 liters per minute.


--Injectors: 310 cc per minute, which means that both injectors, fully on deliver 0.62 liters per minute, only 1/3 of the pump's capacity.


--The R1150 produces 94 HP. Most engines consume less than 0.5 lbs. of fuel per HP per hour at WOT. Fuel weighs 6 lbs. per gallon. 94HP times 0.5 lbs./HP divided by 6 lbs./gal = 7.8 gallons per hour, which translates to 0.5 liters per minute. In other words, the engine needs about 1/4 of the fuel pump's capacity to produce full power.


The reason I went through that engine math was to show that the in-tank hoses can leak quite a bit of fuel or the filter can be quite restricted and you won't detect it by the engine's performance.


Even pulling the tank to inspect the hoses won't necessarily allow you to find cracks and leaks visually. It is easily possible to replace the filter (or externalize it) and miss the leaking hoses or a weak pump.


Bottom Line

Consider making up a hose with QD and measuring the fuel returning to the tank as an alternative to filter replacement or externalization. And if you do replace the filter or externalize it, make the return-flow test to know for sure that your system is up to snuff.

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Where can I purchase the correct connectors?


As the last post commented, I got mine when I removed the plastic and replaced them with metal QDs. You really only need one female QD for the return volume test. Maybe Beemerboneyard would sell one.

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The Rocketman

My R1200C's probably use the same ones as yours, if all boxers are the same?


Got them from http://www.quickcouplings.net/ in Dedham, MA.

I bought two of each of the following (can't say if pricing is the same, as I got them a while ago):

LCD170-05V for $ 17.29 each, and

LCD220-05V for $ 11.91 each


They come with one Viton O-Ring.

They were less than Beemer Boneyard, although Mike is a stand up guy, and I try to send as much business his way as possible. I would check current pricing on both sites first. These are the same metal CPC brand. Originally had plastic ones from McMaster-Carr, but they broke after 3 years.

Edited by The Rocketman
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  • 6 years later...

Great idea! It would also be good for draining the tank to make tank removal easier.😀

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