my first issue..... Help!

[DuncanMoto]

Vacuum is needed to move those floating cylinder thingies you're looking at there.
Slides have needles under them. I don;t know much about those type of carbs, but, you won;t see them move by just moving the throttle.

This might help. http://www.bikerenews.com/Stories_Ar...rburetors.html

So I would now say slides ma be stuck closed or you are generating vacuum when trying to start?

[P_easy]

Alright I have 3/4 tank of gas, so I'm going to "tap the bowls", re-attach the airbox, then the fuel tank and vacuum lines, and pray.

[DuncanMoto]

Where are you?

[richw]

It is almost impossible for all 4 float bowls to be stuck closed

Is possible for gas petcock to be not functioning

There may also be a fuel pump (my last Yamaha had one)

Time to be prepared and pull fuel line from carb and see if gas flows.
Outside quick like a bunny if fuel comes rushing out.. no smoking

Also trace back vacumm line from petcock see if its happy and leak proof.

[P_easy]

If my gas tank is disconnected from the bike, and I turn the petcock to "on" or "reserve", should gas just start pouring all over me? or do I need vacuum to draw the fuel through?

P

[richw]

Only if it has a "PRIME" should gas pour out

on or reserve should require vacuum

I am sure a good mouth muscle suck on the vacuum hose
would be enough to activate the valve.

If its less than 1/2 full then roll the tank on its side on like grass and then you should be able to unscrew the petcock assembly. Drain the old shitty gas into a bucket.

The petcock may be corroded or full of rust etc. Try to make nice and see if it works

[P_easy]

My bike does in fact have fuel pump just to let whoever suggested that know, so now I have another thing to be pissed and worried about! yay!

rich, thanks for the quick responses. Unfortunately, I'm down to the last two things I can inspect with my Shop Manual and Clymer's Guide. These two things are, the vacuum line (which, after visual inspection seems ok), the Petcock, and the Fuel Pump. after that its time to call the Doc

P

[P_easy]

The petcock seems fine, I tested it and gas was goin thru it no problem.

[richw]

TIP OVER SENSOR

Most bikes with fuel pumps have a sensor that detects if the bike
is vertical or near vertical. If not it assumes you have crashed and the flow of electricity
to the fuel pump is cut off.

There is also probably a fuel pump relay controlled by the TOS and ignition. You should be able to hear or feel the fuel pump turn on . if not

If you are handy just try jumping 12v+ directly to the fuel pump see if it spins or buzzes at least

If yes then follow it back the manual should have schematic

REMEMBER

Once you let out the magic smoke it stops working

[P_easy]

alright, I followed the fuel pump inspection in the manual as closely as possible. The pump definitely runs, I have no idea if the sound I'm hearing is it working at 100% or not at all. Anyhow, the manual said to 1) start the bike 2) pinch the vacuum line 3)stop engine 4) turn ignition on blah blah.... My point is, I couldn't start the bike because thats why im doing all this sh!t in the first place. I did, however follow the manual exactly after that one point, which included jumping the relay, as you previously mentioned rich. So the result of this was just a few minor drops coming out of the fuel line that would normally go into the carb. This is very far away from the 700cc per minute thats supposed to come rushing out of there, but I'm still not 100% sure I'm doing it right, so I don't want to just condemn the fuel pump.

will look into TOS now

[DuncanMoto]

Where's your fuel filter? In the tank? inline before the pump?
Also their may be a leak or obstruction in the line inside the tank.
Your bike is old enough for rust in the tank. Especially if it was stored with little fuel for extended periods of time. Rust can clog things when you run the tank low fine particles of rust get sucked into places you don't want them.

[P_easy]

there is a filter in the petcock, but as far as I can tell, it's not clogged. Fuel appears to be running fine until it gets to the fuel pump, which is housed in a body cavity on the left hand side opposite the battery on the rhs (underneath the seat).

[richw]

:IWS:

Yes route around fuel filter.

Pump may be corroded as back in 1984 the idea that alchohol and possibly corrosion attracting alchohol/water would be in the fuel would have been laughed at.

See if you could at least like blow out everyuting with compressed air
(don't go nuts)

It would be interesting to see if the tank blanced on top for direct drain into the carbs would make it run.

Yess gas should run out of the pump 700cc is about 3 cups a minute

You can buy aftermarket fuel pumps for like 20 bucks but you would need to watch the pressure probably should only be a few PSI output.

[gregp]

IIRC - on my old '85 700 interceptor, one could actually remove the fuel pump entirely and run just a gravity flow to the carbs. You will only be able to run your fuel tank down to about 3/4 empty, though. This will eliminate the tip over circuit entirely, but, be warned that it will also render your reserve petcock position useless as well.
You can take your chances and try to get a used fuel pump off of e-bay or just get a generic 12v pump at an auto parts store. There will be at least two different pressure ranges available. Get the lowest one (2-4 psi?). They run $20-$40.
Also, make sure that your tank vent is working Ok. I had to take mine apart and remove the little white plastic diaphram entirely. The bike still did not puke fuel from the cap when topped off.
This was a common issue on all older VFR's.
Getting those carbs in/out is a PITA because, usually, the carb boots are hard as a rock.

[P_easy]

Alrighty, I just sat down with the fuel pump for a bit, and managed to determine, by disconnecting it from the fuel lines, that it is not sucking into the inlet. It is blowing out air fo sho, but the inlet has no suction at all. my questions are, where is the air coming from that its blowing out? is this pump busted, as it has no suction?

thanks in advance,

P

[richw]

Speculation

If diaphram type might have internal leak

try the run the bike just using gravity feed.... its Sept.

[gregp]

Alrighty, I just sat down with the fuel pump for a bit, and managed to determine, by disconnecting it from the fuel lines, that it is not sucking into the inlet. It is blowing out air fo sho, but the inlet has no suction at all. my questions are, where is the air coming from that its blowing out? is this pump busted, as it has no suction?

thanks in advance,

P

Do not concern yourself with asking where that air is coming from. You can blow into the hose that leads from the petcock to the fuel pump to clear the inlet filter in the tank. Fuel should then come running out of that hose (with the petcock in the "Prime" position). This will tell you that you have to remove the petcock assembly from the tank, and flush all of the crap in your tank out.
The fuel pump can also "run dry" if the tank vent is clogged, as mentioned earlier.
You may also have a clogged/broken/leaking vacuum line that runs from your carbs to the petcock. With the petcock in the "Prime" position, fuel should run out of the hose without the engine running or cranking. No if's, and's, or but's. If fuel does not run out of the line with the petcock in the "Prime" position, you either have a clogged inlet screen, or a clogged fuel cap vent.