Vacuum assisted pet****

[snow_htr]

1986 FZ600.
Can anybody give me the lowdown on this vacuum assisted pet****? The manual details how to take it off and clean it, but damn if I can find the place where it tells you how the thing works?
I have anemic fuel flow - both with and without the vacuum hose attached.

Possible crap in tank. Possibly something else?

 

[snow_htr]

HAHAHA! It censored the word pet****! HAHAHA! I love it.

 

[iSteve]

The vacuum does not assist the fuel flow. It turns the fuel on and off. When there is vacuum it pulls a diaphragm opening the pet**** allowing the fuel to flow. There should be a prime or reserve that will bypass the diaphragm circuit.

If the fuel is coming out slow check the filter screen in the tank that should be connected to the pet****. Also make sure air can get into the tank maybe through a breather.

 

[fb40dash5]

I always pull them out of the tank when I'm working on a new-to-me bike. Check the filter sock/screen thing. My XJ didn't have when I got it, which was good to know, since it turns out that's how the reserve functions... would have made for a bad day the first time it puttered and I turned it to reserve to get gas!

The back side is the diaphragm, comes off with 4 screws. The front is just held on by those 2 tiny screws, the face comes off and the knob pops out. Then you can check the passages, and check the o-rings and diaphragm. If it dribbles fuel in the 'On' position with no vacuum, the o-ring on the diaphragm is probably messed up. No fuel could mean a hole in the diaphragm. Beware the generic (K&L) rebuild kits, I went through 2 of them before giving up, the first one had the little metal plate folded in half, the second had the little metal snout machined wrong, it was too short and wouldn't seal, so it dumped fuel... yay.

My personal recommendation besides that is to get an inline fuel filter, and remove the mesh "hats" from the needle seats in the carbs. Then your filter is easy to maintain, and affects all 4 cylinders, instead of the possibility of crud blocking up one cylinder and leaning it out. I'd hate to learn I needed to change my fuel filter by burning a hole in a piston.

 

[fb40dash5]

Oh, question #1... do you have vacuum on the vacuum line? :homer:

I think it's supposed to be hooked to the #3 boot nipple, though I don't think it would matter which cylinder.

 

[snow_htr]

THanks for the info folks!
I'm used to the gravity feed. Now I'm expecting the o-ring to be f'ed up, because it would fill the float bowls and run for a while with the pet**** set to open and no vacuum.
Yes, I tried the vacuum line both ways. Same result each time. I wonder if the whole thing is full of KREEM or whatever this tank was lined with? Probably. I'll clean it and see how things go. I'll also have to get the crud out of the tank. Figured that if the guy lined it he also cleaned it but I suppose not. Silly me!

Thanks again! What eats KREEM by the way?

 

[fb40dash5]

THanks for the info folks!
I'm used to the gravity feed. Now I'm expecting the o-ring to be f'ed up, because it would fill the float bowls and run for a while with the pet**** set to open and no vacuum.
Yes, I tried the vacuum line both ways. Same result each time. I wonder if the whole thing is full of KREEM or whatever this tank was lined with? Probably. I'll clean it and see how things go. I'll also have to get the crud out of the tank. Figured that if the guy lined it he also cleaned it but I suppose not. Silly me!

Thanks again! What eats KREEM by the way?

Oh god no!

Um, I don't think anything eats Kreem, unfortunately. The bike wrecker I used to use had a bunch of old Gold Wing tanks cut in half hanging on the wall. Instead of removable 'sock' filters, they have a heavy-gauge metal screen over the outlet, like a thick sink aerator. Guess what happens when you put Kreem in that tank?

Hopefully that's not the case, since it's flowing some fuel. Of course, if the dude screwed up Kreeming the tank, it may be FUBAR anyway. From what old timers have told me, half-***ing that stuff is worse than letting your tank rust from the inside out, it ends up flaking off and clogging everything. Bummer, since those old tanks seem to go for a small fortune.