[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: fuel system-The nightmare continues

Although you're having problems with the fuel lines, I had problems with the vent tubing.

When my '94 R1100RS was about 4 years old (with about 45k on the odometer), the fuel overflow tube developed a slight, but constant leak. I took the tank off, the filter and sending unit out, and found the rubber tubing was stiff and had developed cracks around the ends around the clamps.

At that time I decided to "externalize" the fuel filter following Lentini's instructions. I also swapped out the RS fuel filler neck for an RT to make topping off the tank easier. FYI...here's the original RS filler and the shorter-necked RT model...

I checked with my BMW dealership for replacement vent tubing and clamps. The replacement tubing was much thicker walled than the original tubes. Here's the pic showing the replacement tubing on the left and two of the original tubes on the right...

The new vent tubing wasn't cut to exact length, there was plenty to work with.

For clamps I found some small ones with three prongs which, at first seemed like they'd work and would be easier to use than the BMW clamps. However, I found I could pull the tubing off of the nipple with the alternate clamps where as the BMW clamps wouldn't allow the tubing to slip off at all. Here's the BMW clamp and the alternate on the right...

Although these weren't pressurized lines, I decided to use the BMW clamps although I wasn't sure what I'd use to close them. After a little trial and error at the auto parts store, I found this tool, a CV Boot Joint Plier #25326 for $5. It worked reasonably well...

For the conversion of the fuel lines I used 5/16" fuel injection hose. No problems with or hint of any leaks from the connections to a Deutsch FF401 filter.

Anyway, the fuel filer is certainly much simpler to replace and ten years later, no leaks from the vent tubes or fuel hoses.


On Sep 22, 2008, at 10:17 PM, Clive Liddell wrote:

Hi Will,

No. there is no regulating device in the filter for the Oilheads.

I placed the filter outside the tank on my RT a couple of years back and have never looked at the connections since... Really, 3 Bars is fairly
high but its not an "uncontrollable" pressure!

A couple of thoughts:

You may have chosen the fuel hose a size too big, and if so it will leak. Did you have to push on the hose with a little bit of "force" which would
have been correct? (5/16" or US-7.9mm is good)

The fuel pump incorporates an over pressure relief and I am not sure of the
"relief" pressure but it can't be more than say ~4 Bar (just a WAG).

Have you made sure that you have not "switched" the hoses where they go onto the FP regulator or, worse, that a hose has become "kinked" where it takes a
sharp turn?

I avoided sharp turns in the hose by just lengthening the hose from the pump back and up over the air filter area and that it where my filter is. From the filter output I loop the hose down and towards the front on the LH side of the bike, through the space behind the alternator and then straight onto
the FPR.

Good luck

Clive Liddell
South Africa