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Fuel issue on an 18hp vanguard b&s


Robert Hole's Avatar
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01-20-17, 07:58 AM   #1  
Fuel issue on an 18hp vanguard b&s

This is a puzzle, I have a Jacobsen Greens King IV plus with a 18hp vanguard b&s. What happens is it won't keep a steady flow of gas. Everything on the fuel system has been replaced, tank has been drained and fresh gas, solenoid is working properly. Even bypassed vacuum pump with an electric pump and it just doesn't seem to keep up with engine demand under full load. I am at a loss anything you all might think of I could have missed. Thanks in advance for any thoughts.

 
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01-20-17, 09:21 AM   #2  
Did you replace the fuel lines? Maybe there is a partial clog or restriction. Maybe the old fuel line is collapsing under the suction from the fuel pump?

 
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01-20-17, 09:32 AM   #3  
Yep new lines. And as I said I bypassed the vacuum pump with an electric pump and it still won't keep up under full load

 
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01-20-17, 11:20 AM   #4  
How are you monitoring fuel flow?
If the symptom is a surging engine rpm, try using partial choke and see if it will smooth out.


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01-20-17, 01:35 PM   #5  
Has a clear fuel so you can see the gas flow, fact you can watch the gas level go down and disappear in the line to the carb, all the while none is coming from the pump. It does that with both pumps, with the exception of the electric pump it will refill the filter to between a third to half then stop but the pump never stops.

 
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01-20-17, 02:09 PM   #6  
How is your system plumbed? Where is the filter in relation to the pump?

 
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01-20-17, 03:09 PM   #7  
That is not a good sign and certainly not an accurate way to measure fuel flow. Those filters can appear bone dry and have no affect on engine performance.

What, if anything, is the engine doing that has you concerned about the fuel flow???


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01-20-17, 03:53 PM   #8  
No filter inside the tank?
Disconnected the fuel line from the carb. and made sure there was flow?
All that work on the fuel system, and not one word about having rebuilt the carb. which with ethanol fuel is the first thing that would be giving you trouble.

 
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01-20-17, 04:30 PM   #9  
What is it doing that it should or should not be doing?

If the engine is performing without issue and you are simply concerned about fuel flow due to an observation, then I don't believe you have any problem.

If the engine is not performing, please enlighten us with some symptoms to help us diagnose the problem with you.


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01-21-17, 06:06 AM   #10  
While unload will bog down almost to the point of stalling. I have also pressure tested the lines with a tool and get around 4psi both before the electric pump and after still want to test between the filter and carb.

 
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01-21-17, 06:21 AM   #11  
Brand new carb, but just to make sure I opened it up to make sure that no trash snuck in and it is clean.

 
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01-21-17, 08:35 AM   #12  
Try running it with the fuel cap loose or off, maybe it is not venting properly. Have a good one. Geo

 
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01-21-17, 10:07 AM   #13  
Here is the issue, engine running full throttle and under full load will sputter with an out of gas condition, does the same with cap on or off. Have observed fuel filter completely empty of fuel and paper inside appear to be dry.
Corrective actions taken, replaced carb, replaced fuel lines, replaced fuel pump (by passed vacuum pump with electric also), pulled fuel shut off valve cleaned and verified no blockage, while that was out of tank drained tank into clean bucket verified no debris in tank, gas is no older than what was delivered to our fuel point. Have put a pressure gauge on fuel line and have pressure in, out of pump. Have opened new carb to make sure no debris got in, while open ran electric pump, if not for the gas tank gas likely would have hit shop ceiling, everything reassembled, ran and the condition is still present. As simple as the fuel system is you can see why I am puzzled at this continued problem.

 
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01-21-17, 01:31 PM   #14  
I am more inclined to think that something else is causing the bogging down and not the engine itself. Belt, pulley, bearing...etc.
Any chance you could post a video?

This is a part and maintenance manual might help you out.


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01-21-17, 01:33 PM   #15  
When you say under full load, do you mean into the turf of just engaging all?


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01-21-17, 02:07 PM   #16  
There shouldn't be pressure before the pump, but that's not really something indicative of a problem It might indicate a problem with the gauge though.

Take the bowl off the carb and put a bucket or bowl under it and turn the fuel pump on and see how freely fuel flows through the needle inlet. Let it run a while and see if the flow slows or what. If not, I would suspect other problems than fuel delivery.


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01-21-17, 02:41 PM   #17  
There shouldn't be pressure before the pump, but that's not really something indicative of a problem It might indicate a problem with the gauge though.

Take the bowl off the carb and put a bucket or bowl under it and turn the fuel pump on and see how freely fuel flows through the needle inlet. Let it run a while and see if the flow slows or what. If not, I would suspect other problems than fuel delivery.
cheese


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01-21-17, 06:06 PM   #18  

Been slow lately with the winter season (althout it has been in the 70s daily for quite a while around my neck of the woods, very strange for January).


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01-22-17, 03:51 PM   #19  
After reading what everyone has posted and suggestions, I am now leaning towards a more serious engine problem.

 
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01-22-17, 06:43 PM   #20  
Try popping off one of the plug wires to see if engine behavior changes when this happens. If it bogs down but still runs, then it's probably firing on both cylinders. If nothing changes, then that cylinder is not producing power for either lack of spark, compression, or fuel. If it dies completely, then the other side is the one not producing power.

The vanguard twin is a very durable engine and the problem is likely not serious. Could be as simple as a bad diode in the kill wire.


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