Fuel Pump Hose Fittings - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Subman · 08-19-2019, 03:30 AM

2002 Boxster S, 114,000 miles. Great shape, runs great, everything on the car works as original and no issues - except that the fuel gauge was inaccurate. Replaced the sending unit last week with an OEM part, along with a new seal. Perfect result...newly installed unit read accurately right out of the box.

But - after the initial startup, drove the car for a test run. Two blocks from home, engine dies. Pull the sending unit on the roadside to find the fuel line (supply) from the fuel pump had popped off the bottom of the sending unit. Reconnected - tightly, again - and drove away. Good to go, drove the car a couple of days with no issues. Fuel gauge tracks accurately, life's good.

And then - yesterday it happened again. Drove away from home and the same fitting popped loose. Same roadside result - pull the sending unit, reconnect the hose. Except this time it popped off again after no more than 30 seconds. Sigh. Tried once more, same result. The hose simply will not hold.

Fuel pump (and of course hoses) are apparently original, 17 year old parts. The clip on the QD fitting simply appears to have lost its "spring" and, despite pushing it into place firmly and getting a solid "click" when installing on the underside of the sending unit every time, it simply will not hold under pressure. No issue with the corresponding QD on the top side of the sending unit - that one holds pressure just fine, but then again it hasn't been immersed in fuel for 17 years like it's counterpart beneath.

So - new fuel pump ordered and on the way. After 17 years, probably not a bad idea to replace as a preventive measure anyway, but the failed fuel hose QD has made it mandatory. Just wanted to document the issue in case anyone else finds themselves with a similar situation. Those plastic clips on the QD's are a weak point after so many years.

Subman · 08-24-2019, 12:20 PM

New fuel pump installed...and as expected, the fuel supply hose fitting had failed. You can see in the photo that the plastic clip that's supposed to grip the pipe on the bottom of the fuel sending unit has failed. The "buttons" on either side should be popped out, proud of the fitting...but they're not. The plastic had, over the years, simply lost its ability to spring back to shape once the buttons were released. Thus, when the fitting was pushed onto the pipe and over the flange, a weak "click" was heard...but the clip's grip was so weak that fuel pressure would force it off the pipe.

In summary, if you're like me and have a failed fuel sending unit on a 986, you may want to consider replacing the fuel pump while you're at it. In my case the pump still functioned properly, but the fitting had failed and left me on the side of the road. At least now not only do I have a functioning fuel gauge, but a new fuel pump as well. One less thing to worry about.

Zzorro · 08-24-2019, 08:40 PM

Just finished the fuel pump replacement myself. I'll keep an eye out for this. I didn't pay too close attention to how it "clicked". I hope they are alright. Thanks for the post.

Subman · 08-25-2019, 04:15 AM

If you've installed a new fuel pump you should be good to go since you've got nice new hose fittings. The risk comes when replacing only the fuel level sending unit and retaining the old/original fuel pump (as I'd tried to do).