1985 VF500F ReBuild

I have been on a good role lately, finding good cheap project bikes and bringing them back to life, until recently. An '02 YZFR1 has me over a barrel, as does my VF500F. After a 1/2 year of procrastinating I swapped the engine. It ran - not great- before I did that. Now, well, not. The starter was sluggish, so I recycled my old one. It's been over 6 months since I heard it turn over, so I THINK it cranks ok. My old starter certainly spins better than the one I replaced.
I have spark (honestly, I only checked one...will check the others.)
I guess the fuel pump worked before, but I feel there is an issue. Now with just straight 12V to the pump gas pours out. If I short the white and black (I think) it pulses, not a stream of gas, just a plup....plup....plup....plup.....like it's not getting enough voltage.
I'm tempted to remove it and let Newton do his magic, but I like solving issues, too.
Thoughts? Thanks,
Shawn

 

Jump the bike with a car battery (car not running if still in car) and repeat previous steps.

Don't care how new or fresh you think the bike battery is.

How long have the carbs been sitting with fuel in them now?

Converting to gravity feed isn't going to miraculously make this bike fire and run properly I feel. These pumps usually either work or don't.

 

And don't ignore fuel pumps. You can rebuild them. Yamahas from this era seem to eat them. I've put a few in my track bikes and a R1 I had.

 

Thank you for the reply. I'll try that with a known good car battery. I did a quick check of all 4 sparks last night and do have decent spark.
I was riding it almost up until I did the engine swap. The swap has taken me about a month of slow off-and-on.
I just noticed last night there are 2 smaller nipples on the petcock - one goes down, the other goes sideways. I'm not seeing any reference in the factory manual. I had the horizontal one connected to the vacuum port on carb #1. With a fuel pump I don't understand why it appears to be vacuum assisted?

 

The vacuum line allows the petcock to open while the engine is running, and it automatically shuts off when the engine is no longer running.


Taken from here: https://daughertymotorsports.com/howto/tankvalve/tankvalve.html

 

Thanks. This R1 was a track bike until it took a spill last August (not me).
In general, can a fuel pump be bad even if it passes the straight 12V test? Do they develop a resistance as they age?
On another Yamaha I was measuring ~ 5V on the fuel pump plug. My new Carter FP would not work, but a Mr Gasket one did.

 

Wow! That really helps. That did happen last summer. I thought it was some kind of vapor lock. It disabled me for a good half hour, then started and off I went. Thank you!

 

You can rule out the battery by jumping from known good car battery as Captain 80s said.
You can remove from the equation the fuel pump and petcock at the same time by using an auxiliary fuel tank directly to the carburetor inlet. Something like the "Motion Pro 08-0032 Auxiliary Fuel Tank" or any other knockoffs/alternatives. This would also bypass your fuel filter which could be another source of obstruction.

If everything runs right off an auxiliary fuel tank, you're much closer to finding the culprit(s).

 

These pumps (if OE) typically either work or don't. They can leak and still "work".

That being said, anything is possible.

If you decide you are going to replace the pump. don't buy the cheap chinese ebay pumps. Match up a similar style from this chart and then look at what models take that pump. Then find the newest, lowest mile used OE pump off eBay. It will be a genuine Mitsubishi and is the only one worth getting. Probably any of them except 18-5528 with it's nipple vent. 18-5529 is the style I buy.

I routinely do this and it saves a BUNCH of money and grief. Most sellers have a return policy and I've only had one dud in the 6 or so I've replaced. They didn't even want it back, just refunded me. And I ended up with some nice formed fuel line and clamps in the process.

Example:

https://www.ebay.com/itm/116024063891?hash=item1b0392b793:g:kioAAOSw6W1ljviT&amdata=enc:AQAIAAAA4IdV2hbxpabCj+d6IqKNb2Cbw8eOJWu5Ot88CXjIeXn4L/QKozNy38hFXCRzTjkCzxsUHULD7e61qeGpUPm2j8FAQVKnKrM5XMY6OKweIcmQYJazqrDdY8eRcsSjIEJdp5c6r6JsnEyFDWZ5/in7ucXcVko+ml2TvlZcofCeIGRANYn0BduNJRNxIqJax8jpU7vXvSgNY2aMGW5xm4THhIQvgojmbP4GH7IK471ZakWwAV7iGGuShi8Qyiit6SCkdQJ7H6kWvXuMChj0H+Rlg3skgRDU/+bMyAdM118Uy9H1|tkp:Bk9SR7D2iNSsYw&LH_ItemCondition=4

 

Thanks Cap'n.
I took my pet ock off and am already bummed: One of the two selector face screws is missing and the second is phillips head is so stripped I don't know if I can get it out. Tiny little screw.

 

I can tell you that mine have all failed with strange and intermittent symptoms. That R1 would run fine much of the time, then it would fall on its face with only 2-3 cylinders firing. I can't tell you how many people looked at it. I decided to try a pump and it magically came to 100% life...and was a beast!

 

Yeah, the R1 has become one of my favorites, (I have two, a 2001 and the dead 2002)- love it!
I had a minute to spare before leaving to pick up the kids and hooked up my Carter fuel pump, I mentioned earlier, to the VF500. I touched the start button, the pump whirred for about 15, maybe 20 seconds (didn't count) then shut off. Is that what it's supposed to do? Seems right. The stock one does none of that.

 

With the relay in place, the pump will only operate if the bike is being cranked or running.

If the relay was bypassed, was the Carter hooked to to a fuel supply and feeding the carbs when it whirred, then stopped?

 

I basically replaced one for one, so yes, the relay was in place.

 

Then please clarify... relay was in place and not jumped. When key turned on, the pump started working without the start button being pressed to crank the engine?

 

Cap'n, I put the Carter in the place of the stock pump, pushed the start button for a second and the Carter whirred into action. I did not jump the wire, just the normal setup and connections.

 

It is still not clear to me...

You briefly pressed the start button, released it and the pump kept going?

Or the bike is fully operational and it started and then the pump built pressure while the bike was running?

 

The tank is off, no fuel, just testing the functionality of the pump. After depressing the Start button the pump activated, ran for some time then shut off by itself. It appears to me the relay is doing its job?

 

Please, please, please.... clarify. After briefly depressing the start button AND THEN RELEASING IT (?!) the pump continued to run?!

Or are you cranking the engine the whole time?!

 

I'm sorry if I wasn't clear - Yes, I pushed the start button for just a brief second, let it go and the pump activated.