'93 K1100rs - ran after FI line replacement but now won't start.

[lhead]

First off, I'm refurbishing the FI system on my K and replacing 20 year old fuel lines with FI rated hose and clamps. I'm 45 days out from a stem cell transplant for lymphoma and I figured this would give me something to do while I wait for clearance to go back to work.

Last weekend, the bike was back together and it started and ran fairly well but a little rich judging from the smell. Each day after, it's ran a little worse and now it won't start at all. The fuel pump comes on as it should.

What I've done so far:

Replaced the fuel filter with a NAPA 3032.

Cleaned and reseated the Motronic connector.

Checked spark. Fairly weak - not snappy blue.

Checked for air leaks. Nothing obvious. The rubber manifold bushings were all good when it was apart. They look to have been replaced at some point before I bought the bike. New O rings as well in the plastic spigots at the bottom.

At this point, I'm stumped. It would be one thing if it never started after doing the work. But this, I just don't know.

Can someone help? I'd love to ride in the fall but at this point I don't know if that will happen. And it's discouraging to have a broken bike when it's so nice outside.

Thanks Friends.

Charlie

[Scott_]

Well, I can't say for certain how to test it, but you could be having issues with the Ignition Amplifier. This part is a hold-over from the K100's, and only on the '93 1100's.
More often then not the issue with the Amp unit is the degredation of heat-sink compound between it and the battery box that it's mounted to.
The issues with it are also more pronounced after the bike has run for a bit and started to heat up, then causing issues from over-heating.

[lhead]

Thanks Scott. I had the ignition amp out and cleaned and reapplied heat sink compound when I had the back end apart last fall to replace a driveshaft and do a spline lube.

I'm thinking fuel pump. I just pulled off the pump input line at the fuel rail and held my thumb over the end. I've read here that you're dealing with approx. 65 psi at that line and that you shouldn't be able to keep fuel from spraying out. When the key was turned, I was easily able to hold back the fuel. Also, I sprayed a 2 second shot of carb cleaner into the airbox and hit the starter and she fired right up for about 2-3 seconds. So that rules out ignition. Not that I don't need new plugs and plug wires - it's just not the cause of this problem.

Tomorrow I'm going to pull the pump and check for junk in the sock filter.

Charlie

[Grim]

What line did you check?  The rear line on the tank goes to the connection at the TPS end of the fuel rail. I'm not sure how the pressure regulator would act if you blocked the return line after it. It may well cause the regulator to close off the fuel.

I then the fuel filter has a check valve in it. Make sure that's not in backwards. 

[lhead]

It's running once more. The pump was good, the rubber sleeve was clean - not gooey. The prefilter was disintegrating so I removed it. Put everything back together, fired right up. BTW - the pump was marked VDO, not Bosch.

Thanks for the help fellas.

Charlie