Author Topic: fuel system setup  (Read 2308 times)

McAnic

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fuel system setup
« on: December 28, 2013, 08:19:22 PM »
Is there some one that can help me, I posted lasted year with an issue I had with my FL350R.
I purchased a Oddy which had a engine issue were it would die after 1/2 throttle. If the throttle was pulled the Air fuel gauge would lean out immediately, exhaust temp would rise to 1400'"c instantly but die, release the throttle and the engine would run great below 1/2 throttle. It would start perfect idle perfect lots of power up to 1/2 throttle then die?:(
I have full rebuilt the motor. Resealed no air leaks, new carby 41mm PWK 200 main jet 55 idle jet. New Vforce3 reed cage.
But the same symptoms are present. The oddy is running a spun alloy small remote tank above the motor where a electric fuel pump, pumps to the alloy tank and gravity to fill the carby the over flow back to tank.

 ""Should the original fuel tank be vented as it is not at the moment" And should the carby require some pressure to the carby bowl to allow the carby to keep up too the demand.

Any help would be appreciated
Thanks Loc

nevadanotch

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Re: fuel system setup
« Reply #1 on: December 28, 2013, 08:37:26 PM »
Your motor is being starved for fuel past 1/2 throttle.  Unless you run a large enough fuel shut off valve, you can not gravity feed your carb.

Is there a specific reason you are running from the main fuel tank to an auxiliary tank?

Your tanks need to be vented.
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LiveWire

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Re: fuel system setup
« Reply #2 on: February 25, 2014, 06:01:12 PM »
I won't go into the full reasons why I hate those spun tanks, just the couple likely specific to your current problem: the hole in the tank, inside the bung, is likely only 1/8" in diameter. They do not clean out the tanks after making them. It probably has aluminum shavings in it clogging the already small hole.

McAnic

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Re: fuel system setup
« Reply #3 on: June 08, 2014, 10:59:26 PM »
Hi folks I have made some progress with my fl350 fuel issue, what I have done may not make to much sense but it has worked.
I have had continual issues with a lean running Oddy with a 35 mm, 38mm and a 41 mm pwk carby. It did not matter how big the jets were the engine would run lean and a high exhaust temp. I tried all three cabys with different jets and needles. The motor ran well started easily up,to 3/4 to wot the engine would lean out and cut out. It is a water cooled race port vforce reeds engine from aftershock.

I added a electric fuel pump which feeds the alloy tank above the motor on the return to the main tank from the alloy tank above the motor I placed a jet with a 2 mm hole to allow a positive pressure to the carby for added supply, enough to not flood the carby. This helped the motor but didn't solve the issue. What I have is a 41mm pwk ddl needle on the fourth clip, main jet 170 pilot jet 45. Motor runs well but at 3/4 throttle the engine leans out and gets high exhaust temp 1600'c

What I did next made all the difference... I placed a 37mm restrictor after the carby (bearing in mind it is a 41mm carby) this richened the fuel mixture and cooled the exhaust runs a treat. My theory is what the motor was not drawing the fuel up from the carby from to slow air speed over the jet Venturi, with the restrictor it created a low pressure at wot only which assisted in draw the fuel up out of the carby?

As I said I tried 3 different carby a with 50 needle jet changes.

Any opinions would be greatly appreciated, McAnic form Down under.

mcgyver331

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Re: fuel system setup
« Reply #4 on: June 16, 2014, 08:47:17 AM »
May sound stupid but have you checked the spark plug boot. I had a yz490 once that ran superb but at 3/4 throttle would just die/sputter/cut out. it went through the motor twice.

A friend was over and we were running it on the stand and he said hey look over at your plug boot. Sure enough it was vibrating so much the crimp on the plug kept opening up. and bouncing the boot up so high it had no contact.

ZeroClient

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Re: fuel system setup
« Reply #5 on: June 19, 2014, 06:58:06 AM »
McAnic - I couldn't really understand your setup, so I've posted my setup which works great and instructions:

Here is my fuel delivery setup

Parts required:
1. Gravity fed tank (Really its just the tank mounted high, but does not have to be gravity fed actually)
2. Aftermarket mechanical fuel pump from eBay $20, or a stock one is fine too.  ANy brand will do as long as it works and doesn't leak.
3. Honda 3-way fuel valve part #16710-VM0-770 available from EBay $25
4. Fuel on/off valve of your choice (or not, but this is good for safety) ~$20
5. Fuel filter of choice

Fuel line setup:
1. Tank fuel outlet gravity feed connected to Part #4 and #5 above
2. Part #4 above connected to Part #2's fuel inlet (Fuel pump)
3. Part #2's Fuel Pump Fuel outlet connected to Part #3's inlet above (The 'horizontal' side without the 'block')
4. Downspout of part #3 connects directly to the carburetor
5. Restrictor 'block' side of part #3 connects back to the TOP of the fuel tank
6. VERY important - Fuel pump's signal line connects directly to the signal feel nipple on the side of the engine (Behind the Drive Clutch)

I suggest also using Tygon Yellow/Clear PVC fuel line available from McMaster-Carr
http://www.mcmaster.com/#5552K24
This is 3/16 fuel line which installs TIGHT and very tough to remove (That is what you want).  You can heat it slightly or use WD40 to get it on, then its very hard and secure and will not come off without cutting with a razor blade.

The clear fuel-line is transparent and is sooo nice actually seeing what is happening with your fuel supply.  I can easily see how the gravity feed portion works while the fuel pump up's the throughput substantially.  You cant see this with black rubber fuel hose.

I feel it is very important that you use Honda 3-way valve especially if you don't know what you are doing.  This above setup is exponentially important for fuel pump operating systems in which the fuel will circulate from and back to the fuel tank.  The fuel literally circles round and round while the carb is connected to the pressurized side of the circular motion by cause of the Honda 3-way fuel valve.
« Last Edit: June 19, 2014, 07:08:53 AM by ZeroClient »