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Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Sun Jul 23, 2017 7:57 pm
by Kustomkarma
Finally got my 1984 Spree running today. I noticed that it continues to drain fuel through the line after I shut the engine off and drain the fuel line out. I have a clear fuel filter inline so I can see it pull the gas through when I kick it over. When I shut it off, fuel seems to drip drip drip down through the line. I've drained the tank for now just to make sure it doesnt run out all over the place. If fuel continues to flow, does it mean the valve thingee is bad?

Thanks!

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Sun Jul 23, 2017 8:28 pm
by Meatball
Kustomkarma wrote: If fuel continues to flow, does it mean the valve thingee is bad?
If you disconnect the fuel line from the carb, it WILL drip for a few seconds while it empties the fuel that sits in the line. Then it should completely stop. If it still drips after the line is clear, then its a Bad Petcock. Be sure to get a replacement for an 84-85 for your 84' Spree....The 86-87's have different threads! Be careful of "replacement" (non-OEM) petcocks on Ebay or elsewhere. They MOSTLY dont fit the 84-85.

Petcock Valve part# 16950-KJ9-000 is used on the following models:

1984 NQ50 A FUEL TANK
1984 NQ50 AA FUEL TANK
1985 CH150 A FUEL TANK 85-86
1985 CH150 AC FUEL TANK 85-86
1985 CH150D A FUEL TANK 85-86
1985 CH150D AC FUEL TANK 85-86
1985 CH250 A FUEL TANK
1985 CH250 AC FUEL TANK
1985 NH80 A FUEL TANK
1985 NQ50 A FUEL TANK
1985 NQ50 AA FUEL TANK

The Petcock Valve for 86-87' NQ50 is part# 16950-KJ9-752 and DOES NOT fit your 84's fuel tank threads. If you buy the wrong one and cross-thread your fuel tank bung trying to wrench it on....you'll have a bad day.

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Sun Jul 23, 2017 8:41 pm
by Meatball
As a temporary band-aid fix just to get you on the road until you can find a replacement, you can pinch off your fuel line when not in use to stop flow. Line clamps are cheap or needle-nose vise grips (not too tight to damage the line).

If left alone, your fuel tank will eventually drain out completely while it drips from your carbs' overflow leaving a nice puddle under your scoot. It will even fill up your crankcase and muffler with fuel. Good luck getting it started with the entire thing swamped! A few kicks and you'll foul a plug and pop your crank seals. Possibly damage rods, crank, etc since the motor will be locked or stiff when full of juice...another bad day.

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Sun Jul 23, 2017 11:13 pm
by Kustomkarma
Thanks for the info! ^^^ I think the one on there right now is some kind of aftermarket unit. I was trying to use what I had, but I'm definitely not down with a pool of gas under my scoot.

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Sun Jul 23, 2017 11:49 pm
by otto-man
If you have gas dripping out of the carb, you also have a bad float needle.

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Mon Jul 24, 2017 3:40 am
by kevinv710
-remove gas and vacuum's lines blow vacuum line to see if gas stop, suck it to see if gas comes out...otherwise bad petcock.
-remove the carb, drain out all the gas in there, shake it up a bit, you might have got float valve stuck, hook up an extra hose to gas supplies hole, blow by mouth to that hose then turn the carb up side down and now you cant blow it thru that mean float/valve are good to go......these simple tests must be done before install the carb,....its ok you can do it now. Good luck Kus!

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Mon Jul 24, 2017 10:11 am
by Kustomkarma
Thanks for the info!

I checked around. Man those little buggers aren't cheap. Has anyone found and aftermarket one that works?

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Wed Aug 09, 2017 10:59 am
by Kustomkarma
Well ... I have been looking but I haven't been finding one of these things. I was looking for a new one, but no luck. Has anyone substituted anything else for this part? Is there a regular petcock that will work or does it need to have the regulated vacuum drawing the fuel in?

Thanks.

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Wed Aug 09, 2017 12:16 pm
by motormike
Kustomkarma wrote:Well ... I have been looking but I haven't been finding one of these things. I was looking for a new one, but no luck. Has anyone substituted anything else for this part? Is there a regular petcock that will work or does it need to have the regulated vacuum drawing the fuel in?

Thanks.
While I would encourage that you continue to search for a replacement petcock, there is a very simple solution. With everything still in place as it sits now, install an "inline" on-off valve in the fuel supply line from petcock to carb. Many different styles and sizes of fittings are available. Consider the access needed to twiddle this valve each time you start and stop. Are you with me ?

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Wed Aug 09, 2017 3:13 pm
by Kustomkarma
That's pretty much where I'm at. I was thinking of installing an on/off valve/petcock inline with the vacuum one. It's an '84 so I guess I can just leave the cover off.

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Fri Aug 11, 2017 9:38 am
by Kustomkarma
Been hunting around for an inline petcock valve. The Honda fuel line is like 4.5 mm ID. What size hose barb / petcock fitting will fit inside there? When I measure the carb fitting with a caliper its 5mm. Will a 3/16 barb fit tightly enough to prevent leaks?

Re: Gas tank fitting pump / diaphragm thingee gone bad?

Posted: Fri Aug 11, 2017 1:14 pm
by motormike
Kustomkarma wrote:Been hunting around for an inline petcock valve. The Honda fuel line is like 4.5 mm ID. What size hose barb / petcock fitting will fit inside there? When I measure the carb fitting with a caliper its 5mm. Will a 3/16 barb fit tightly enough to prevent leaks?

yes, I think you will find 3/16 good...zip-tie to the barbs... :urban: