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Discussion Starter · #1 ·
I have a 1986 Honda Fourtrax 4x4 350 and the fuel pump keeps spraying fuel out of the small hole in the front of it, what is causing the fuel to leak? It sprays out in little bursts while the bike is running, but doesn't leak if the fuel pump is unhooked (Unhooking the fuel pump cut-off relay) or when the float isn't full of fuel (Directly after engine start). Anyone know how to fix this issue? I don't want to pollute the trails with fuel from this leak, or the fields where I use the bike to tow a utility trailer for maintaining a the yard on the cottage properties I maintence
 

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You're kidding right...? Another 86 TRX350 in nearly pristine condition can't possibly exist on this planet...?

But there it is in your pic, so it must be true...! :)

WELCOME to the forums!

Nice looking ole gal ya befriended there! Thanks for sharing the pic of her.

Ok, gotta ask you a question... is the fuel pump on your 350 an OEM Honda pump? China knockoffs are junk is why I gotta ask. Which end of the fuel pump is it leaking from, the rear (where hoses connect) or the front?
 

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I'll have to look at mine as I don't recall a port on the front. There's an innie and outie on the back and a vent on the side, right?

And daaang that rig looks good OEM ohtsu 401s decals look good. Did you install the racks Ray?
 

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I'm not sure if this little dimple looking thing in the center of the front cover on the fuel pump is where yours is leaking?



My eyes are too shot to see whether there is a hole there or not. I can't imagine why, if there is... this is the motor end of the pump and the motor is vented already, with a hose that runs up along the frame to the steering head.

If your pump is leaking out of the front anywhere it needs to be replaced immediately, because that is a very serious fire hazard. Replace with OEM Honda only... china knockoffs are all junk.

Hope this helps... You have a great looking old bike!
 

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Discussion Starter · #6 ·
Its the OEM pump from 1986 I believe, it has a small Mitsubishi logo on the front of it, the bike is practically untouched parts wise, the only things having been replaced being the filters, battery, and a spark plug back in 2008. It's leaking from the hole on the front side of it where no plugs come in to it, if I cover the hole it starts leaking out of one of the overflow lines in the fuel system
 

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Discussion Starter · #7 ·
I'll have to look at mine as I don't recall a port on the front. There's an innie and outie on the back and a vent on the side, right?

And daaang that rig looks good OEM ohtsu 401s decals look good. Did you install the racks Ray?
The racks came on the bike when i bought it, I've only done maintence to the bike so far.
 

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Discussion Starter · #8 ·
I'm not sure if this little dimple looking thing in the center of the front cover on the fuel pump is where yours is leaking?



My eyes are too shot to see whether there is a hole there or not. I can't imagine why, if there is... this is the motor end of the pump and the motor is vented already, with a hose that runs up along the frame to the steering head.

If your pump is leaking out of the front anywhere it needs to be replaced immediately, because that is a very serious fire hazard. Replace with OEM Honda only... china knockoffs are all junk.

Hope this helps... You have a great looking old bike!
Is that screw on the front stock? Because thats where it is leaking out of, and if I block off that hole then it leaks out of one of the fuel overflow lines.
 

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Discussion Starter · #9 ·
It is leaking out of the big hole on the front of the fuel pump, not a constant stream, just little squirts starting a short time after cold start. If I block the hole off with my thumb it starts leaking out of one of the rear overflow lines that dumps off onto the ground
 

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I'd take a look at that control circuit to see how the cutoff relay might be involved. Clean those connections with contact cleaner and an acid brush (really a cheap horsehair cleaning brush). You may want to test or replace the relay

Not the primary problem but you are also missing a screw for the fuel pump.
 

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I have rebuilt many of these old girls, and never had one leak at that cover end ?, that screw hole holds the top contact cover on the pump. that end of the pump should not have any fuel reaching it at all !. there are electrical contacts under that cover, the pump side is at the other end. the pump has a diaphragm inside it, it raises and lowers a solenoid inside the pump, which creates a vacuum to pull and push fuel. best advice I can give you ?, is buy a new oem pump, around 160 bucks, give or take from Honda. DON'T BUY A PUMP FROM EBAY FOR 20 BUCKS !!..THEY ARE CHINA KNOCK OFFS !!.
 
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Oh yeah if you remove that cover you'll see an exposed relay, arcing contacts and all
Probably only reason you haven't had a fire is that fuel vapor concentrations were above the explosive limit.
Definitely replace that pump or risk burning your rig down
 

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Discussion Starter · #13 ·
Alright, it's leaking out of wear that screw goes, and I cleaned the relay's terminals before making the form post
 

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Discussion Starter · #14 ·
I have rebuilt many of these old girls, and never had one leak at that cover end ?, that screw hole holds the top contact cover on the pump. that end of the pump should not have any fuel reaching it at all !. there are electrical contacts under that cover, the pump side is at the other end. the pump has a diaphragm inside it, it raises and lowers a solenoid inside the pump, which creates a vacuum to pull and push fuel. best advice I can give you ?, is buy a new oem pump, around 160 bucks, give or take from Honda. DON'T BUY A PUMP FROM EBAY FOR 20 BUCKS !!..THEY ARE CHINA KNOCK OFFS !!.
I didn't plan on buying a cheap part for such a nice bike, definitely will be getting a new fuel pump though! Thanks!
 

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You don't need a relay. The pump runs... so the relay is working fine. Its only task is to supply power to the fuel pump. The fuel pump then turns itself on and off to regulate fuel pressure. A new pump will be all that you'll need to buy, Though, it may be time for a new fuel filter if you've haven't changed that in quite a while. And hoses if it has had ethanol laced gas in it half of its life...
 

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Discussion Starter · #17 ·
You don't need a relay. The pump runs... so the relay is working fine. Its only task is to supply power to the fuel pump. The fuel pump then turns itself on and off to regulate fuel pressure. A new pump will be all that you'll need to buy, Though, it may be time for a new fuel filter if you've haven't changed that in quite a while. And hoses if it has had ethanol laced gas in it half of its life...
Lucky me, up here we don't have Ethanol in our gasoline
 

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The screw in mine has what looks like a stray blue Loctite stain on it. Either they used blue Loctite at the factory or someone else did it... I am the 2nd owner of the bike. My neighbor down the road bought it new and I doubt he ever touched that pump. If he had, it would have been missing! Hoses, filter, bracket and all! LOL
 
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