TECH
Air and fuel system blues – Part Two Bringing the Flying Brick back to life
By Ken Tuvman #133210
Part One of this story appeared in the Tech Section of the February 2016 issue of BMW Owners News. This is the continuation and conclusion of that story.
WHILE WAITING FOR MY PARTS, the next step was removing the throt- tle body assembly. In order to do that, I first needed to remove the throttle and choke cables, sensor switch that runs to the dash light that shows when the choke is engaged, fuel pres- sure regulator, throttle position sen- sor, and the six Allen head bolts that secure the three manifolds
to the
engine. I inserted paper towels into the holes beneath the manifolds to prevent road debris from falling inside. Once all was removed, the throttle body assembly slipped right out and I could vacuum 28 years worth of accumulated sand and debris from the top of the engine. Next, I slipped on rubber disposable gloves and used a brake cleaner- soaked paper towel to remove the black oily soot covering the throttle bodies. Always work in a well-venti- lated area when spraying brake cleaner - it’s very toxic! I wasn’t familiar with the one-
time-use Oetiker clamps. I used a pair of tin snips to cut each of the six clamps. Once cut, the clamps sprung apart, making easy work of removing them from the throttle body and air plenum box. I took this opportunity to clean up the throttle bodies and butterfly valves. I planned to replace the fuel line that goes from the fuel pressure regulator to the rear fuel injector rail. The fuel rail had some rust spots, so I roughed it up with sandpaper and sprayed it with several coats of heat-resistant black paint. About an hour before closing time,
58 BMW OWNERS NEWS March 2016
Melissa called from The Hitching Post say- ing my parts had arrived. I dropped every- thing and got them. I requested about two feet of fuel hose and was presented with an attractive gray hose that would compliment the gray color of my bike. That evening I used my new Oetiker
clamp tool to secure the new clamps to the new throttle bodies. I took it slow and suc- cessfully secured the new clamps to the new throttle tubes. I compared the new mani- folds with the existing set that came off my bike and concluded the originals were still in good shape. Prior to ordering the parts, I’d asked Melissa about their return policy and she said I could return any of the parts purchased if they weren’t used. The following afternoon, I reinstalled the
three original manifolds to the engine base and the throttle body assembly. After instal- lation, I discovered I routed the wires that connect
to the fuel injectors behind the
throttle bodies instead of in front of them. Dreading removing the
throttle bodies
again, I discovered the harness plugs into an accessible area on top of the engine. I also discovered the harness is secured with a thin wire that holds the plug in place. I tried using a very small flat-bladed jewelers screwdriver without success. After posting my latest challenge to removing the con- nector, Lee suggested I buy a set of pick tools from Harbor Freight. I found a set with long handles that allowed me to access and remove the safety clip. Once the plug came off, it took no time to re-route the electrical wires. Now it was time to install my renewed
fuel injectors. I followed the correct proce- dure of inserting all three injectors in the fuel rail and then gently but firmly pressing
them in their respective holes on the engine. It’s important to coat the seals with engine oil to avoid damaging the O-rings. After installation, I reattached the electrical con- nectors to each injector securing with the thin safety wire clips and then reattached the three clips that secure the injectors to the fuel rail. The next day, I cut my new gray fuel hose
and installed it between the fuel pressure regulator and the two connection points on the fuel rail. About two years ago, I replaced the return fuel hose that runs from the fuel pressure regulator to the fuel tank, so I left that alone. After carefully installing the hoses and securely clamping them in place, I reinstalled my now mouse-free air box assembly and put the tank on the bike. I was now ready to start the bike, hoping not to see any fuel spraying from the reinstalled fuel injectors. I said a little prayer, asking for blessings from the BMW mechanical gods before pressing the starter button. When I turned on the ignition and
pressed the starter button, she cranked and cranked and sounded like she was going to start, but I quickly stopped when I noticed fuel spraying from the front left underside of the fuel tank. Fortunately there were no explosions or fires! Always keep a fire extin- guisher handy when working with gas and electrical systems. Disappointed, I forced myself to walk away and regroup. “Okay, what could be the problem,” I
thought. A bolt of lightning floored me when I asked myself if that cool-looking gray fuel hose was rated for fuel injection systems. Our bikes require fuel injection hose with a minimum rating of 100 psi. I Googled the name on the fuel hose and dis- covered it was basic fuel hose used for
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