Intermittent Fuel Pump Issue

[Paulnib68]

Perhaps I am missing something, so I'm hoping to get some suggestions. I'll start off by saying I'm no novice to engines so if I say I did something, I'm certain its good as I dont settle for good enough or "that'll work". This'll be a little long as I want to avoid wasting anyones time with the obvious stuff.

I have a 2001 Vs800 I inherited. Excellent condition, had 2600 miles, now just over 5k miles. Sat for 4 years inside a warehouse. It was well prepped for storage. Tank was empty, carbs empty, all fluids had been changed and looked like they had just been poured in.

Cleaned and rebuilt carbs. Looked like new inside, just some corrosion inside the pilot jets. There are no blockages in the carbs, the diaphragms are fine.

Carbs are synched.

Fuel pump was dead. Replaced with new.

Tank looks spotless inside, no rust or debris. I have not removed the petcock yet to inspect the screen.

Fuels lines good.

Repaired some bad wiring at the battery. New wires, all connections soldered not crimped, star washers on terminals, new battery.

Now for the problem. The bike ran fine for about 2500 miles after I did a full cleaning, freshening, new tires, new fuel pump, new fluids etc.

Riding last week it started randomly losing power, chugging and idling poorly. Noticed the front cylinder was not firing smoothly and getting some lean condition popping from it.

Stopped and looked over what I could and found excellent spark. After sitting a few minutes it began running normally again. On way home, it did sputter now and again.

Couldnt find any issues, suspected maybe bad gas or debris in gas. Installed clear inline fuel filter, flushed out the carbs.

Ran great again for about 30 miles. Then really started running bad. Limped home on one cylinder, front cylinder not firing at all.


Tore down front carb again, nothing out of sorts.

No debris in fuel filter.

Good spark.

Then noticed I was not hearing the usual fuel pump clicking when first turning on the key.

Checked fuel pump connections, nothing wrong, 12 volts showing at the connector.

After repeated turning the ignition off and on, then flicking the run switch repeatedly, suddenly the pump came on.

Fired it up and ran great for a couple minutes, held hand on fuel pump and could feel it running, then suddenly no more fuel pump running and no more running good.

Ordered a new fuel pump.

Problem remained.

Have a universal pump I KNOW is good, hooked it up, same problem. Sometimes pump runs, sometimes wont.


My questions.

Is there a fuel pump relay that could cause this?

Is there anything else in the power circuit with the fuel pump I am not aware of?

Any suggestions?

If there is one thing I absolutely hate, its electrical issues and this looks like a good one so far.

[FallenAngel]

Im not real familiar with the 800s and the book I have offers little information on the fuel relay
Navigator is the member I hope helps you out
The fuel pump relay is located under the seat and should be in plane view
I would pull the seat and Fire up the bike and when It dies or starts running rough wiggle the relay connects if that dosnt work Jump the Power wire to the pump.
Also double check the fuel pump connections



Electrical problems can be a pain

This might Help
http://www.mediafire.com/file/5ha60s9sk ... E.pdf/file

[Lechy]

Take a feed from the orange/white wire before it enters the CDI direct to the hot side of the pump. This will by-pass that fecking relay allowing the pump to prime with the ignition. it can be shut down with the kill switch in an emergency.
If that doesn't work, check for the routing of the fuel line from the rear to the front carb, sometimes the tank can nip it closed.

[Paulnib68]

Sounds like a good way to isolate the relay and determine if its good or not. If it works, I'll replace the relay. If I can keep things OEM I'd like to. Thanks.

[Paulnib68]

PLayed with it a bit and the pump started working again. Disconnected the small relay attached under the seat and pump still ran.

Put my multimeter on the pump connector and showed good voltage. Left it connected and started tracing wires. While doing so noticed the meter fluctuate, so something going on in the wiring. Narrowed it down to a large green connector running from the front of the bike down to the fuse block. That one when pulled apart cuts all power. Cleaned up those connectors, then checked every connector I could get to without more tear down. None of the connections LOOKED bad at all. But cleaned em anyways.

Seems to run fine now. Of course dont trust it yet. Going to take it for a ride and take a jumper wire with me in case so I can run the pump straight to power if it tries to leave be stranded.

Thanks.

[FallenAngel]

If there is one thing I absolutely hate, its electrical issues and this looks like a good one so far.

And Yet you found the problem
Open shorts can be a pain in the ass and many would say these are harder to find then a live short

You did a good job

[navigator]

The relay under the seat on the 800's has nothing to do with the fuel pump.
The 800 fuel pump relay is integral to the pump.
The 800 is not wired like the 1400. the pump doesn't "prime" like the 1400.
The pump runs during starter cranking, and while the engine is running. If the engine stops running, power is cut to the pump.
The floats will cut fuel flow when the float bowls are full.

[Paulnib68]

When the key is turned on and the kill switch flipped to run, the pump powers up and runs until the bowls fill then it stops. Least it does on this bike. There is constant power to the pump when the motor is not running. I dont see any indications of anyone altering the wiring.

Went for about a 40 mile ride yesterday and not a single sputter so I'm guessing cleaning the connections did the trick. Thanks again.

[tazmaniac_37752]

For the record the vs800 if carbureted will run fine without a fuel pump it just requires a rerouting of the fuel line!

[hillsy]

For the record the vs800 if carbureted will run fine without a fuel pump it just requires a rerouting of the fuel line!

Gravity is neat, huh?

Actually it might get a bit iffy when the tank is low - depends on the level in the tank v the carb bowls.