1992 K75s - bogged down - fuel pump issues

[jbmccarthy]

Ive been experiencing some issues with a K75s i bought recently: the bike feels "boggy" and lurches when at low rpm, almost like its not getting a smooth supply of fuel, and the throttle response is noticably delayed. Not only this, but when I was idling at a stoplight, the bike hovered around 800 rpm for a second and just died in first with the clutch pulled. I was worried it might be something in the fuel tank so i opened it up and found this...



I'm far from an expert on these bikes, but this sure raised some red flags for me. The pump is obviously not sitting in the surround as it should, but whats not so evident from the pictures is the fraying of the wires that connect to the pump. I wanted to get some insight from you guys on wether or not you think I have to replace the pump completely, replace the wiring, or both? Ideally I want to find a work around, but this doesnt look like a quick fix. Either way, as a newbie I thought itd be best to seek out some knowledge before going and replacing an expensive part like the fuel pump.

Thanks,
Jack

[ackgs]

If it makes you feel better my fuel pump and damper looked a lot worse and the pump was non functional when I got it. As my pump was toast I replaced. Guys much more knowledgeable than I can advise you on if you should buy a new pump or not. If you are enjoying the bike I would bite the bullet and get a complete pump kit. That eliminates having to fool around matching new and old parts. I went with all new tank internals as the handy Andy that last worked on mine hacked it badly. After I got mine started it ran poorly so I sent the injectors out for cleaning. That did the trick. Good luck with your project, now that mine is running well I really enjoy my S.

[Zampano]

I had a similar situation and replaced the rubber damper, filter screen, fuel filter. I also had the injectors reconditioned (mr. injector) because I had been planning on doing that.

This is the thread i posted when I pulled the pump.
http://www.motobrick.com/index.php?topic=5576.msg35083#msg35083

I followed Johnny's idea; removed the fuel pump and let it soak overnight in a glass container full of chevron techron. I wired the pump straight to the battery (I just held the wires against the ground bolt battery positive, nothing fancy); ran it backwards for less than 5 seconds then forward for a minute or two. It did not seem to pump violently as I expected. I had a hose loosely over the nipple and circled towards the bottom. No big blast of fluid. I thought maybe the pump had lost its power but put it back in and the bike has been fine since. It may not have been clogged with any black rubber bits to begin with. I saw nothing in the techron.

The bike did run better after all that. Before it ran similar to what you are describing. I say follow the gas and clean or replace what it flows through. If there is a good amount of black specks of rubber in the tank then some of it must have made its way through the pump, filter, fuel rail, injectors and fuel pressure regulator.

It all boils down to fuel, air, and electricity.

Replacing the ignition wires helped mine. Easy to check. On a dark night take the spark plug cover off and look for flashes while it is idling. Plugs ok? Valves in spec?

Vacuum leaks were another problem I had. The small rubber caps which go on the throttle body ports were cracked, the hose to the fuel pressure regulator (located in the 5th circle of hell), and the crankcase breather hose.

If wires / plugs are good, no vacuum leaks, and fuel pump/filter/injectors/regulator are solid, then the coup de grace is the throttle body sync. If that doesn't fix the issues then there is another level of fuel/air/electrics, but in my case those things helped significantly. Not perfect but much improved.

There are a few places to buy the damper/etc. This is where I purchased my things. No complaints.
http://www.euromotoelectrics.com/category-s/787.htm

Also, the small hose which connects to the filter screen was missing on mine. I needed to go to the dealer for it. Important b/c without it the screen is useless.

This was the soak. Then in a slightly bigger jar I wired it to the battery. I also poured the techron through a coffee filter and added it to a few tanks of gas.

[rbm]

Your pump definitely looks out of place, like it has slipped down in the plastic surround.  The correct positioning is like the photo below:

Also, the clip on the surround appears broken, like someone forced it.  Hopefully, it's not broken.

The rubber isolator is looking really bad and will have to be replaced.  Others have posted how to possibly recondition the pump and that means only a new isolator. Euro Motoelectrics sells a foam pump surround.

There's also a detailed thread in the Lieberry that talks about aftermarket fuel pumps, in case you can't resurrect your OEM pump.

As for the wires, if the insulation is cracked, that probably is ok.  broken and frayed wires will need to be replaced with wires that can withstand fuel immersion.  Normal PVC insulation is not useable so you may have to go to an aftermarket auto parts supplier to get the right stuff.  Also remember that the ring terminals on the ends of the wires are different sizes, as a method to polarize the connections.  Be careful with soldering any new wiring you may install to the fuel level sender unit; you don't want to damage that piece.

[Scott_]

It almost looks to me like it is already an aftermarket pump...... and what ever was used as a filler material didn't hold up well to gasoline submersion.
Also agreed that it is setting way too low in the mount, unless...... if it is not OEM, and happens to be shorter, it may have to be that low for the pickup screen to be at the original level.

[Inge K.]

It almost looks to me like it is already an aftermarket pump......

+1.