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apeterson17

Sunstar Won’t Restart After Dry

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apeterson17

Ran out of gas, won’t restart. Sunstar 20H. Have starter fluid run it, Gas in the carb run it, but no matter how often, long that goes, it’s still not pulling the 3 gallons I just filled it with. HELLLPPP!!!

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apeterson17

Update: no gas getting to the carb. Took the line off that connects the filter to the carb and it is not pushing gas during startup. Does that help any one? While I’m waiting for a response, I’m gonna start working backward

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fishnwiz

If you have an air compressor, open your gas cap and blow back through the fuel line. You can also use your mouth but be cautioned that gas may come back at you. Clogged gas tank screen or filter ?? Fuel line may look good but could be collapsed on the inside of the line.

Edited by fishnwiz

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MikeES

The Sunstar (and it AC brothers) are prone to air lock in the gas line (ran out of gas).  With the long line from the back to the engine, it is more than the fuel pump can overcome when there is air in the line. 

Also if you are having issues change the fuel line completely.  I had problems starting a DA1920, it was all solved when I completely changed the fuel line from the tank to the fuel pump.   The hose was checked and cracked, it did NOT leak gas, but I determined that it would draw air into the line,  I installed a short section of clear hose between the filter and the fuel pump and it had constant bubbles in it...New fuel line...no bubbles.

Edited by MikeES

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apeterson17

Seems to be getting stopped at the filter. I backfilled it from the carb end and pushed gas back into the filter, all good. Started for a sec and died again- acted like it was starved. Pulled the fuel on the engine side of the filter and gravity only gives me a trickle. Normal? Filter looks clear-ish.

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apeterson17

Ok, final update for the day: on the engine side of the filter I injected 30 ml of gas and it fired and I could control it for another 30 ml, killed the power and hooked back up to the filter. Turned over again and only ran for 5 ish seconds. Is this a filter thing or a pump thing. I swear I see the filter pulsating a little before it dies but then not after it won’t re-fire. Everyone aligned this is a fuel filter thing? Or you thinking otherwise?

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fishnwiz

It's possible when you ran it dry that you plugged the outlet of the tank. Not sure if there is a tank filter in the Sunstar or not. Sounds like fuel delivery issue or air in the line as stated above.

Believe it or not...I have cupped one hand over the fuel filler hole and blew air into the tank with my air  filled lungs,  to move the fuel through the filter and into the fuel pump thus eliminating the air in the line. This has worked for me several times with vapor lock conditions.  I know it sounds strange. sm00

Edited by fishnwiz

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Richard Wright

I agree with Mark that blowing in the tank is often enough to clear an air/vapor lock, though maybe not a real clog. I don't suggest using compressed air in the tank for several reasons, not the least of which is the possibility of blowing something out. I have made this mistake.

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apeterson17

Just put three fresh gallons in it. Any acceptable techniques to salvage? The thing that keeps me pushing away from the tank clog is that I get a full stream on the tank side of the filter using gravity only. I will replace the hose in the event it is collapsing under vacuum.

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PhanDad

Since you just stated "I get a full stream on the tank side of the filter using gravity only", a plugged tank outlet or fuel line probably isn't the problem.

I don't know the plumbing of a SunStar, but if the fuel pump isn't mechanical, temporarily remove it and have it lower than the lowest point of the fuel inlet line, do this with with out adding additional fuel line.  If you can't do that, then make a temporary fuel feed that is higher than the fuel pump.  Have the fuel pump outlet "unplumbed" and see if it passes fuel.  If not, run it until it passes fuel.  If it won't pass fuel, it needs to be cleaned or replaced.  I'm thinking the fuel pump check valves are either air bound or not sealing well.  Flooding the fuel pump with liquid should alleviate the problem. 

  

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SimpleOrange

Inside the fuel pump are a pair of check valves, when you ran the tractor out of fuel its possible that some crude has lodged itself between the valve and its seat rendering the pump inoperable. 

The valves are spring loaded, as others have suggested blowing air into the fuel tank will push fuel forward possibly clearing the crude from the valve.

A cheap fuel test gauge connected to the fuel system is the only sure fire way to test the integrity of the fuel pump.

One winter I had an engine equipped with a pulse fuel pump quit while blowing snow, turned out that the vacuum line for the pulse had formed an ice ball inside. Regular oil changes will keep you engine free of moisture. 

The image below is only used to show the basic parts that make up the fuel pump.

The mechanical pump is vented on the backside of the diaphragm fuel pump casting and must be kept free of dirt, the pulse pump is not vented but instead uses the backside of the diaphragm to pick up pulsations from the crankcase. 

 

check.jpg

Edited by SimpleOrange

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puttputt

If he has the Kohler Magnum in his Sun Star then it is a mechanical pump unless someone has changed it to a vacuum pulse pump at some point. Take your fuel line off of your fuel filter. Take a piece of copper tubing, or something similar, and join the line where the filter was removed. This swill eliminate any filter problem if you said you have good gravity flow from the filter to the tank. If it will not run after the filter is removed then you have a pump problem.

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SimpleOrange
21 minutes ago, puttputt said:

If he has the Kohler Magnum in his Sun Star then it is a mechanical pump unless someone has changed it to a vacuum pulse pump at some point. Take your fuel line off of your fuel filter. Take a piece of copper tubing, or something similar, and join the line where the filter was removed. This swill eliminate any filter problem if you said you have good gravity flow from the filter to the tank. If it will not run after the filter is removed then you have a pump problem.

Mechanical or vacuum pulse fuel pump both have check valves,  if one of these has faulted then it's time to call in the heart surgeon with his fuel pressure test gauge to diagnose the problem.

Dirt lodged in the valve seat is a common problem and this often happens when the fuel level is low or completely used up. As the fuel level become lower the particulate ( rust ) becomes more concentrated.

A fuel pump is not a trash pump.

Removing the fuel filter is not a good idea.

Edited by SimpleOrange

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puttputt

I'm not saying remove the filter permanently. Removing it for 2 minutes to see if the fuel pump is the cause is not going to hurt anything, especially if he says he has good gravity flow.  If he has good flow to the filter then dirt from the tank now is not the problem as to why it won't run so removing the filter for 2 minutes or less isn't going to hurt anything. Fuel flow should not be a hard problem to diagnose. If you have good flow to the filter as you say, then we know it's not blocked up to that point. Remove the line from the pump to the carb then crank it over. If no flow out the line then you know it's likely either the pump or the filter. Then if you want to locate someone with gauges, or load the tractor up to take it to someone with gauges, then go for it. Or you can do what I suggested. If you have fuel flowing out the line at the carb, then you most likely have a carb problem which could indeed be dirt lodged in the valve seat.

Edited by puttputt

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apeterson17

Ok y’all, today’s progress: replaced fuel line from filter back to tank, drained tank, replaced fuel filter. Primed the fuel to the carb using a syringe. Ran (even turned on and off) for about 10 minutes- but only at full choke applied. Then turned it over after about 5 minutes of reassembly  and it died and wouldn’t start. Very similar to what i saw yesterday. I am getting frustrated at this point, so I appreciate your patience with me. I took apart the fuel pump out of desperation. Attached are the photos of what I see, after a wipe with dry towel. I’m not sure the correct way to seat the pump ‘out’ side ‘upper diaphragm’ as it fell out when i lifted it. The bottom spring supported shaft popped out as I was cleaning one of the two gaskets. I compressed and turned it back and the ‘key’ seemed to seat back down- bottom photo shows it popped up. For what it’s worth, one of the diaphragms (car speaker looking thing) is really tight and the other fell out when opening- didn’t unseat the second one. Sorry to keep bugging you guys. Getting quite disheartened about this purchase- 3 days ago

90C71EB2-3560-4CDA-A7FA-DF00F4A55791.jpeg

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98963B5B-7BA5-451F-BF94-902790D494AF.jpeg

9C7C428B-F35A-4618-84C7-681ABD14FE9C.jpeg

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SimpleOrange

If the valve on the left hand side is the inlet side it's installed correctly the other valve should be installed crown down.

There's a spring under the crown, while the pump is apart examine the fibre disks.

In the old days you could flip the disk over for a fresh surface.

 

98963B5B-7BA5-451F-BF94-902790D494AF.jpeg

Edited by SimpleOrange

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