The fuel pump arrived today, a $20 unit off eBay. The fuel pressure regulator also arrived separately.

This evening, I pulled the old pump back out and discovered, as I suspected when I opened the package, that the new pump is slightly smaller. As you may recall, a neoprene sleeve joins the body of the pump with an adapter I built. This adapter allows the pump, originally designed to reside submerged in the tank to instead be fed from a fuel line.

Well, the new pump, which I neglected to photograph (you can’t get good help these days), is enough shorter that there is only a small fraction of an inch of actual pump showing beyond the adapter. Also, the body of the pump is smaller in diameter, but not so much that the neoprene and hose clamp couldn’t seal it. I soldered pins on the wires and put them in a connector, plugged it in and verified that it would run dry. It was quite noisy, which surprised and concerned me at the time.

The new regulator is bigger than I’d hoped, but not as big as I’d feared. I took the adequate but busy stock gauge off and substituted my spiffy oil filled one. As for mounting, the size of the regulator would not turn out to be the problem.

The regulator has a straight hose barb for input from the pump in what I’m going to arbitrarily call the ‘back’. In the front is the fuel pressure gauge. Sticking out from the lower right is another straight hose barb for the fuel return. Above that is a vacuum fitting (used to modulate the pressure according to vacuum; I will experiment with this, but for now, I have it capped) and finally on the top is the pressure adjuster screw. In short, the unit is roughly cubical in shape, but in operation, you need access to four of the cube’s six sides. I saw no point is orienting the device where the gauge could not be seen, so it pretty much had to mount with the gauge facing outward. After LOTS of trying and tweaking and test fitting, I finally decided to put it at an angle with the return fitting facing at about a 45 degree angle. The gauge is in almost the same position as before. The assembly is nestled between the air filters for 1 & 2, forcing the bottom edges of each to rotate out slightly. Filter #1 is almost vertical but #2 is angled more. Filter #2 isn’t normally visible, so I can tolerate it. Even with all this difficulty, the fuel system plumbing is simplified, largely because the pressure gauge fits on the regulator itself. Upon reflection, I can replumb the system with the regulator placed for better access to the adjuster and with the fuel pressure gauge remotely mounting where I can see it while riding. I have some ideas about that, too.

The engine is not running in this picture, but the system holds pressure well, indicating about 30 here. I have the regulator set to 38 psi, down from the fixed regulator’s 45ish. I had to reroute the return line, which involved accidentally pulling the line off the tank, which started it pouring. Argh. The clamp is on there much better now.

Then I had trouble getting fuel to start flowing. I think the filter element was wet (with fuel), so gravity couldn’t produce enough pressure to push the air in the line through the filter. I used the trust old siphon bulb and got it flowing. Once some fuel was flowing through the pump, the noise went away and now it sounds like it should, a tiny little whine. Likewise, the regulator has a quiet little honk while running with fuel, but when I used the air compressor to verify the the input and return, it sounded like an air impact wrench.

After all that, I finally was able to hit the starter button and Buzz leapt to life! While he was warming up, I unloaded all the tools from nooks and crannies and put the seat on. I took him down the street, around the block. I didn’t have to push him home, not even once.

I think he runs a little better on the lower fuel pressure. It’s hard to tell because the previous ride was so useless. In any case, Buzz runs at least as well has he did before the conversion, which is good, but not great. Good power on acceleration, but it could be quicker. It felt like I was rolling the throttle on, when in fact, I’d nailed it. In other words, rather than Vrooomm, it was more like Vrrrrrrroooooomm…

After circling the block and a little farther for several laps, I actually managed to get about 4 miles on the odometer. I then went to the gas station and filled the tank with 93 octane and endeavored to ride more. I spent more time on long straight streets with minimal stops. At the time, I was not brave enough to hit a freeway. I will try that in the warm daylight, just in case. In all, I clocked about 12 miles with no troubles.

At speed and very low throttle openings, it runs pretty rough. I’m pretty sure this is because at low consumption levels, the granularity between enough fuel and too much fuel is pretty narrow. At higher throttle openings, he seems to run really well.

All in all, a good day!

Tonight, I pulled the fuel pump out and verified that it would not turn under power and that I could not turn the impeller through the intake port with small sharp tool. I shook it firmly and got small chunks of hard black stuff out of it. With nothing left to lose, I disassembled the pump and found that about 1/3 of the vanes on the impeller were broken off. I pulled the impeller off the motor shaft and washed the bits and pieces out of the pump. I reassembled it (it still amazes me how often I use my anvil in motorcycle work. I used it to make some muffler brackets for Toni’s trike Tuesday night) and reinstalled it, with a filter this time. I also put the valves on the feed and return lines. I fired up the pump and even using a funnel to try to prime it, it would spin but not flow any fuel. I suspect that, while the impeller is badly damaged, it could probably still move fuel. Most likely, the check valve or the body of the pump is clogged with impeller vane bones or perhaps the original debris that destroyed the pump.

I have found several suitable pumps on eBay. Just waiting on the first auction to end

I looked into connecting the Honda tilt switch, but it will need a little bit of electronics to work. The tilt switch is open in the normal upright position and “closes” to 23K ohms when tilted. A single transistor and a resistor or two is all that will be needed to connect it.

In the mean time, I’ll be updating the wiring diagrams and impatiently awaiting the new pump.

I had a few minutes at lunch to troubleshoot the fuel pump issue. I unplugged the fuel pump and put the meter on the harness. Key on, no juice. I pulled the seat off and checked the fuse. The 10A I’d installed while I was in the parking lot down the street was still in place and not blown. I checked the hot side of it and found no juice there, either. I pulled the relay from it’s socket and the battery side of it had no juice. I traced that down and found an inline fuse holder I’d forgotten was there! The 10A fuse in it was blown.

I replaced that one, put a 5A back in the fuel pump fuse holder and verified that I had power to the connector. I turned the key off, plugged in the connector, turned the key on and SNAP! The 5A blew with considerable alacrity.

The coil on the motor reads a pretty normal 1.5 ohms, so my second theory that some debris has jammed the impeller seems likely. Stall current would be about 8A.

I have looked around… A fuel pump from a local bike salvage yard (which moved across town, much closer to me now!) is still a bit high. The one model he has several of and thus charges the least for is still $150. I can get them all day on eBay for half or less of that, but I can’t just walk into eBay and pick one up….

Before I purchase one, I will pull the pump out and see if I am lucky enough for the debris to be lodged in the back of the pump where it can be removed or flushed backward or something before replacing it..

In related news, it occurs to me that I may be able to use these throttle bodies for a while longer by lowering the fuel pressure a bit, delivering less fuel, thus perhaps get a leaner minimum mixture. As it stands, at idle the injectors are opening for what is just about as short a period as possible and it’s delivering too much fuel. The regulator I have is the hard set unit that came with my salvage fuel pump. It appears to be set to about 43 psi, which is pretty much normal. I ordered an adjustable regulator which will run 0 – 100 psi. I think I am going to try about 35 or so to start with.

While I’m doing all this fuel system work, I think I will wire in that tilt disconnect switch that I’d forgotten about… And since I forgot about the other inline fuse holder between the battery and the relay, I will update the wiring diagram, too.

Got a bit done on Buzz today, enough to get in a short ride. Very short.

I built a fuel feed and return thingy that bolts in place of the stock petcock. I neglected, however, to photograph it before I installed it. With luck, we’ll never see it again. It is quite simply a 5/16″ tap for feed and an elbow with a 1/4″ hose barb for return. It’s actually a single part found on the shelf at AutoZone that I cut. I cut a piece of 1/8″ plate into the proper shape, drilled two 1/4″ holes to mount it. The OD of the tubing is .370 and I had a drill bit that was .373, so I drilled two holes for the tubing. I put those two too close together, however and I had to angle them away from each other to allow for clearance to put hoses on the tubes. I brazed the tubing in, wire brushed the whole thing, cut a gasket and bolted it up. Voila!

This is an intentionally simple design with no valves. I will procure a suitable feed valve and locate my existing return valve and install them soon. Besides the safety issue, it’s tough to have to drain the tank each time it’s removed, so the valves will definitely go on sooner rather than later.

I had previously drilled a hole in the tank for fuel return. I got a flanged bolt, put a gasket on it and used a piece of wire to pull it through the inside of the tank. I put a washer and nut on the outside and applied LocTite. Hopefully, that’s the last of that, too.

After that, it was just a matter of putting the tank back on (and rerouting hoses), buttoning up the wiring and putting the seat on.

The front tire needed air and I felt obligated to lube the chain.

The ride down the road was a LOT more fun than the push home…

He ran pretty good, actually. I went down my street a couple of blocks, jumped over a block and was headed back toward the main street when Buzz suddenly bogged down and died. He restarted easily, so I figured I just didn’t have enough gas in the tank. I went back to the house and put in about a gallon. My plan was to take him to the car wash, knock some dust off and come back. I decided that if I had troubles, I didn’t want to be on the main road, so I went to a parallel side street and headed for the carwash. When I went over the hump crossing the next street, he died again. This time he didn’t restart.

I pushed him up in a nearby parking lot where there was some light and had a look. I noticed that the fuel pressure wasn’t coming up and I didn’t hear the pump running. I pulled the seat off and found that the fuel pump fuse was blown. I didn’t have a spare 5A, but I did have a spare 10A. I put that in and it didn’t blow, but the pump didn’t run, either. I pushed him home from there. It was only two blocks.

I suspect something pinched. It’s too dark to troubleshoot now. I’ll take a look tomorrow.