Fuel Pump??

[Hamers88]

Hey Guys So took the vs800 out for a shake down ride and ended up stranded 44 miles from home.. It was running great then when I came off the highway it started sputtering and died. I could not get it started again it would crank and sputter but no start.

Back Story: I had just installed a new but after market fuel pump off amazon as the stock one failed. I got the little 20 dollar two wire one. All I did was find the constant hot wire and ground out of the four from the factory pump harness and hooked it to those. Ran fine, kinda noisy with the clicking from the pump but seemed to be fine.

Now I have noticed when I turn the bike on the pump no longer clicks like it did before. So I am thinking the pump failed again causing a no fuel condition. I haven't had time to do any electrical tests but am I missing something with the four wire to the two wire setup?? Is there a better alternative pump that's not 400 bucks like the OEM ones?? Are the after markets garbage??

As always thank you for the help!!

[sgtcall]

I recently bought this one for my VS1400 and no issues as of yet. In fact it runs and starts much better than before.

$27.00

[enforcer]

The four wire has a tip over relay that's shuts off the fuel if it's laid down. Don't necessarily need it.

A vac pump has no motor to fail and you can scavenge vacuum from the rear carb. They're used on snow mobiles and rarely ever fail. A knockoff Mikuni one can be had on eBay for ~$25.

[Hamers88]

Yup thats the pump I got too. Maybe I got a bad one... ? Might look into the vac thing though.

[enforcer]

Yup thats the pump I got too. Maybe I got a bad one... ? Might look into the vac thing though.

You bought this one?

http://pages.ebay.com/motors/link/?nav= ... 55&alt=web

Because that's the $25 one I was referring too.

[Hamers88]

No I mean I ordered the one sgtcall posted a link to. Sorry.

[sgtcall]

Here is a thought for someone that knows more about the pump. You said that it keeps clicking when it is running? Mine only clicks when I prime it. Or at least it is not loud enough to hear it when it is running. What would cause it to keep clicking that loudly?

[Hamers88]

Yes good call.
Under "normal" operation mine was always loud. It would start off fast then the clicks would slow.

[enforcer]

Here is a thought for someone that knows more about the pump. You said that it keeps clicking when it is running? Mine only clicks when I prime it. Or at least it is not loud enough to hear it when it is running. What would cause it to keep clicking that loudly?

The 800 has no priming ability. Most fuel pumps will click, then whir, then shut off ones l once the bowls are full or the fuel rail is up to pressure. The clicking is usually a built in relay that delays power to the pump and disengages the pump when appropriate pressure has been reached.

It's not uncommon for the pump to disengage then reengage and on a stock 800, it would be very audible with stock pipes. It wouldn't be constant, but rather internment.

My guess, the relay failed. Really want a rewire a $25 pump? I thought not.

I vac pump is powered by vacuum pulses, like a later Harley petcock, difference being, it's not gravity fed. No motor, no relay, no moving parts. Just a diaphragm. For piece of mind, use a vac pump.

[Lechy]

Turn on the ignition, tap the pump with a screwdriver handle, sometimes the tripping mechanism stalls out.
Then I would be looking for collapsed/pinched fuel lines.
[emoji41]

[XanRevent]

It's not uncommon for the pump to disengage then reengage and on a stock 800, it would be very audible with stock pipes. It wouldn't be constant, but rather internment.

THIS!!!! When it disengages and re-engages, does it make kind of a loud "click" and you lose power for like a split second! It's been bothering me for MONTHS, and my shop hasn't been able to figure it out.

[Hamers88]

Ok the vac pump is sounding good to me but this is the first time I have heard of it. Has anyone done this? What pump would give the proper fuel pressure? And what port would you hook it up to? Also how would you mount it so the fuel lines dont kink?? Thanks again for the help!!

[Hamers88]

Hmm that I did not see.. I was only seeing them on Suzuki parts sites and I sewer they were like 400 bucks. But I could be totally wrong. I am not used to doing parts buying on line. Definitely going to take another look at mine though. Maybe it is just stuck. And I need to verify power to the unit as well. All I know for sure right now is I dont here the pump working like before.

[enforcer]

Ok the vac pump is sounding good to me but this is the first time I have heard of it. Has anyone done this? What pump would give the proper fuel pressure? And what port would you hook it up to? Also how would you mount it so the fuel lines dont kink?? Thanks again for the help!!

A guy from the other site, Tilos (Ken) suggested it as and option. He installed one on his S50. In a carbureted system, a fuel pump only fills the bowls and doesn't provide pressure to the fuel system, like one in a fuel injected system. The vacuum from the engine is what draws fuel from the jets.Carbureted motors utilize only low pressure, up to 6 PSI, so pumps are not very vehicle specific. As long as the fittings are the same size as your current fuel pump, 6mm or 5/16 SAE, you'll be fine. You would scavenge vacuum from your carb vacuum port, via a vacuum fitting.

[Hamers88]

Hmm ok but what happens when the bowl is full and the vacuum continues to run the pump? ?? I know the float would close the passage to the bowl but would the vaccum pump continue to run and damage itself? ?

[enforcer]

Hmm ok but what happens when the bowl is full and the vacuum continues to run the pump? ?? I know the float would close the passage to the bowl but would the vaccum pump continue to run and damage itself? ?

I could go though a long winded explanation of why, explaining vacuum and positive and negative pressure, but the short answer is no. Just like an electric pump, it essentially shuts off when the bowl is full.

Everything you want to know about vacuum fuel pumps here.

http://wiki.bssd.org/index.php/Diaphragm_Fuel_Pumps

Harley also employs essentially the same thing with their vacuum operated petcocks, just without the pumping action.

[Hamers88]

Ok cool thank you ! If I dont find something simple and I do in fact have another bad pump I think ill give this a try. Sounds kinda cool to me. Ill update after I look at it closer. My last question for the vac set up is does anyone have a pic of the port on the carb to plug the vac into?

[enforcer]

Ok cool thank you ! If I dont find something simple and I do in fact have another bad pump I think ill give this a try. Sounds kinda cool to me. Ill update after I look at it closer. My last question for the vac set up is does anyone have a pic of the port on the carb to plug the vac into?

Don't have a pic, but it's hard to mistake. It's on the same side of the bike as the pump, on the rear carb anyhow. Blocked off by a flat head screw and washer. You'll need a 6mm vac port adapter, so you don't create a vacuum leak.

[Hamers88]

Adapter like a barb fitting the vac hose slides onto then? 6mm thread? Sorry for all the questions. I appreciate the help!

[enforcer]

Adapter like a barb fitting the vac hose slides onto then? 6mm thread? Sorry for all the questions. I appreciate the help!

Yep, but it can be flared end style as well. I found the one I used at a hobby store. Brass is best.