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**fastbysuzuki** · 09-01-2018, 04:35 PM

assuming your petrol tank vent is clear then It sounds like the diaphragm in the petcock may have a hole and it's unable to open to allow petrol through or the vacuume line is kinked, become disconnected and not opening the line.
By putting it on prime this bypassed the vacume part of the petcock and allows petrol to flow unrestricted, do not leave it on prime very long when the engine is not running as it may fill your sump with petrol as the float valves are not strong enough to hold that weight of fuel and will let petrol past

**Brendan W** · 09-01-2018, 04:48 PM

I agree. Which fuel line did you replace? If it was the vac line and it's leaking you will have fuel starvation.
Don't leave it on prime. The float valves are only looking for excuses to drain fuel into the sump or airbox.
They may be Ok but no point tempting fate.
Fate has zero willpower

**Big T** · 09-01-2018, 07:22 PM

You ran out of gas

**fbody_mike** · 09-01-2018, 07:49 PM

Originally posted by Big T View Post

You ran out of gas

I think so too. Should have moved the petcock to reserve.

**Steve** · 09-01-2018, 10:47 PM

If it only took 3.3 gallons to fill, it was still over a gallon away from REServe, unless the petcock has been replaced with one that provided a larger REServe capacity.

You can test that theory in the luxury of your own garage. Lift the back of the fuel tank enough to remove the two hoses from the petcock. Run a new hose from the fuel outlet to a 5-gallon can. Run another line from the vacuum port to a vacuum source. If you have a Mity-Vac, it works great.

With the petcock selector in the RUN position and the fuel hose into a catch tank, apply vacuum to let the fuel flow. When it stops, note your fuel gauge position, then turn the petcock to REServe to see if fuel continues. If it does, stop it. Find a way to catch another couple gallons of gas, then continue. You can drain your 5-gallon can into your car, then use it again. Start the fuel flow again in REServe, note how much fuel comes out. Also note the fuel gauge position when fuel finally stops. You now know: 1. where the needle will be when you need to switch to REServe, 2. where the needle will be when you are EMPTY and 3. how much fuel you have in REServe.

.

**Tom R** · 09-02-2018, 01:46 PM

You mentioned new fuel lines, are they routed correctly? I had a similar issue years ago that baffled me for a while... I was convince it was the petcock vacuum and went through that several times before I eventually replaced it; still the problem persisted. It turned out that I made the fuel line too long and it would kink when it got hot.

**mrhedges** · 09-02-2018, 07:52 PM

after filling up I put it back to ON and didn't have another problem. Fuel Lines can get kinked up? That's probably the issue unless I have way less reserve then I thought or this tank is smaller then the spec sheet.

**Uncamitzi** · 09-02-2018, 08:04 PM

Originally posted by Steve View Post

If it only took 3.3 gallons to fill, it was still over a gallon away from REServe, unless the petcock has been replaced with one that provided a larger REServe capacity.

You can test that theory in the luxury of your own garage. Lift the back of the fuel tank enough to remove the two hoses from the petcock. Run a new hose from the fuel outlet to a 5-gallon can. Run another line from the vacuum port to a vacuum source. If you have a Mity-Vac, it works great.

With the petcock selector in the RUN position and the fuel hose into a catch tank, apply vacuum to let the fuel flow. When it stops, note your fuel gauge position, then turn the petcock to REServe to see if fuel continues. If it does, stop it. Find a way to catch another couple gallons of gas, then continue. You can drain your 5-gallon can into your car, then use it again. Start the fuel flow again in REServe, note how much fuel comes out. Also note the fuel gauge position when fuel finally stops. You now know: 1. where the needle will be when you need to switch to REServe, 2. where the needle will be when you are EMPTY and 3. how much fuel you have in REServe.

.

Steve, excuse me for butting into someone else's thread..(again) but with your experience with 850Gs I was wondering if the tank from a 1979-1981 GS850G tank has the same mounting as the tank for a same year Gs850GL ... GL's only have 3.3 gallon tanks... I would kill for two extra gallons sometimes.

**Chuck78** · 09-03-2018, 01:56 AM

A similar thing JUST happened to me at 125 miles on a tank...(I usually get 135mi til Reserve, but was twisting the throttle verry heavily with the revs up high throughout 75 miles or so of great twisties). I had to push it 1.8 miles in full leathers on the freeway to a gas station, as reserve did not work!!!! 4.5 yr old petcock, new OEM Suzuki that I only replaced for reliability!!!!

I flipped it back to Prime, & back to Reserve, the bike still was getting no gas.
I turned down offers to get some gas assistance, as I needed to see how much it would take, measured at the pump. Guess what??? 3.3 gallons to top off my tank to the brim!!! Guess what??? Fired right up!!!

Every internet specs source and my factory service manual all say 4.8 gallon tank. That means with 3.3g to top it off, I had 1.5 gallons left for my now non-functional reserve. Suzuki literature states actually, that it has a 1.8 gallon reserve! I had no idea it was that much! I could realistically get 185 miles between fillups if it weren't for this serious problem I have with my right wrist!

Now to drain 4.7 gallons out in the AM!!! I think the problem is either dirt, or ethanol/h2o gel formation. Or ethanol just ate the rubber (neoprene/nitrile) parts.

**Boriqua** · 09-03-2018, 10:27 AM

I will say it again for anyone that hasn't heard me say it yet but ... Pingel.

Two weeks ago at 150 miles on the clock my bike started to balk on the highway, I very smoothly slide the pingel to the reserve and wala. I love that valve!!

**Chuck78** · 09-03-2018, 10:42 AM

The only problem is, Pingel doesn't make vacuum petcocks! And as stated before, they wear out so much faster because you have to turn them on and off every single time you get on and off your bike, leaves a lot of margin for error and filling your crankcase full of gasoline! Which will also ruin your clutches! And also can cause serious problem with hydrostatic pressure if it's at long enough with the fuel on to put a sizable amount of gasoline into the cylinders...
The OEM Suzuki units are far better than the Pingel solution...
The float needle and seat will not hold back 4.8 gallons of gasoline pressure at 10 inches of water column for any duration.

**Chuck78** · 09-03-2018, 10:46 AM

Another side note, I'm sure this type of problem could also happen with a pingel petcock, because there is no problem with the vacuum function to automatically turn these on and off, this topic was solely on the reserve not functioning, which the original poster and I had both experienced.

And also, another side note, I do remember my friend putting a pingel fuel cock on his gs850, and within about 3 years it started leaking externally... that reinforces the theory of how frequently they used and how that will affect their lifespan. I do remember having that thing apart a couple times for him.

Also, I don't believe Harley ever used any vacuum petcocks on their older models. My wife always comments about how great her bike is, because it looks like it leaks oil absolutely everywhere, even just 3000 miles after a top-end rebuild, the 19 FXR top end gaskets seals and O-rings ( love the Japanese bikes with only about 1/3 of that, so much better engineering than Harley!) all are prone to leaking! But she never seems to be low on oil! Out of protest, and because she travels for work more than she is ever around here, I don't really work on her bike much, if it was basically anything but a Harley I would... But I eventually realize that she was not turning her fuel off and she was just replacing the engine oil that leaks out with gasoline! Yesterday on a long ride, she commented about someone else's Harley at a gas station, and she herself it finally figured out what was going on with hers. The other Harley barely cranked over the first time or two and made a loud pop, but then the starter was able to spin the engine substantially faster and it fired up. What happened was so much fuel was leaking past the needle and seat through to the owner not understanding what a petcock is, and causing almost near hydrostatic lock up, reducing the combustion chamber air space compressible volume @ TDC to almost nothing (as with all liquids, liquid fuel is also not compressible, unlike are which is), to the point where the starter motor could barely crank it over... she had a flash of genius and said "Ha! My bike used to do that when I try to start it when I would leave my fuel on!"

**850 Combat** · 09-03-2018, 11:07 AM

According to Cycle World data from a contemporary road test of a 1000G, the fuel capacity is 5.8 gallons. Saturday, I rode my 1000G for a couple hours. The fuel gauge got close to the bottom of the red. It took almost exactly four gallons to fill it. It was not yet on reserve. That said, I don't think that it holds a usable 5.8 gallons.

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The petcocks are kind of expensive. On one 1000G, I put a petcock off of a 1982 and later 850/1000G. Not much needed to make it work. The routing of fuel and vacuum lines is more of a PITA. Putting the fuel tank on is also more of a PITA as far as getting the bolt started.

My first GS850G, which was six years old and had 1,600 miles. It suffered a hydraulic lock from a failed open petcock. I didn't understand why it wouldn't turn over until it finally did turn over and fuel came out the exhaust. It did not bend a rod or twist the crank, thank goodness. Leak by from Kawasaki petcocks is known to make rods look like pretzels. Its disturbingly common.

**Boriqua** · 09-03-2018, 11:10 AM

Originally posted by Chuck78 View Post

Another side note, I'm sure this type of problem could also happen with a pingel petcock, because there is no problem with the vacuum function to automatically turn these on and off, this topic was solely on the reserve not functioning, which the original poster and I had both experienced.

And also, another side note, I do remember my friend putting a pingel fuel cock on his gs850, and within about 3 years it started leaking externally... that reinforces the theory of how frequently they used and how that will affect their lifespan. I do remember having that thing apart a couple times for him.

Also, I don't believe Harley ever used any vacuum petcocks on their older models. My wife always comments about how great her bike is, because it looks like it leaks oil absolutely everywhere, even just 3000 miles after a top-end rebuild, the 19 FXR top end gaskets seals and O-rings ( love the Japanese bikes with only about 1/3 of that, so much better engineering than Harley!) all are prone to leaking! But she never seems to be low on oil! Out of protest, and because she travels for work more than she is ever around here, I don't really work on her bike much, if it was basically anything but a Harley I would... But I eventually realize that she was not turning her fuel off and she was just replacing the engine oil that leaks out with gasoline! Yesterday on a long ride, she commented about someone else's Harley at a gas station, and she herself it finally figured out what was going on with hers. The other Harley barely cranked over the first time or two and made a loud pop, but then the starter was able to spin the engine substantially faster and it fired up. What happened was so much fuel was leaking past the needle and seat through to the owner not understanding what a petcock is, and causing almost near hydrostatic lock up, reducing the combustion chamber air space compressible volume @ TDC to almost nothing (as with all liquids, liquid fuel is also not compressible, unlike are which is), to the point where the starter motor could barely crank it over... she had a flash of genius and said "Ha! My bike used to do that when I try to start it when I would leave my fuel on!"

I certainly cant refute your experiences because .. you had them!

Me .. I have had pingels on three different motorcycles without issue and I freagin hate those vacuum petcocks. They tend to be a bit needy for me.

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GS850G Died suddenly on freeway

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