Poulan Pro 300 EX Riding Mower Puzzle

Blade Runner

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According to the mower model and product numbers under seat and according to the engine model and type numbers on engine, as well as the replacement parts sticker replacement fuel filter numbers, my Poulan Pro 300 EX B&S 18.5 hp 42" cut riding mower should have a fuel pump on it. But it doesn't. The Poulan Pro tech said that based on the codes it should have one but based on the physical description it should not????? Although, tech said replacement part sticker is generic and may not be accurate. Local Poulan Pro dealer said late model Poulan Pro riding mowers sometimes come stock without the fuel pump. He said if the fuel tank was under the hood, Poulan may leave off the fuel pump.

I bought the mower used. It was purchased new within several years ago. When I got it over several weeks ago, it still had tire hairs in the middle of the tires and it looked brand new. I asked the original owner if he removed the fuel pump for any reason and he said no. The fuel tank is mounted under the hood in front of the steering shaft above the carberator and looks stock. There is no gas tank mounting area in the rear. There is a plastic fuel pump mounting area next to and apart of the oil dip stick tube, that does not have a fuel pump and it looks unused.
It had a large fuel filter. I thought the large fuel filters were for gravity fed and therefore the mower did not have a fuel pump. Poulan Pro tech said those were for fuel pumps. It runs great unless there is an inch or less of fuel in tank. If so, you can not drive fast over bumpy ground without the engine sputtering. You have to slow down for it to run normal in that situation. Tech and Local dealer said that may be normal.

Can someone tell me if it came with a fuel pump and was removed and if I should install a fuel pump or leave it gravity fed? Thanks for any help.

SEE SPECS. BELOW:

Poulan Pro 300 EX Riding Mower Brigss and Stratton 18.5hp I/C, 42" cut, 6 speed. Model No. PB18542LT Product No. 960420088 Maintenance Level: 00; Briggs & Stratton Engine 18.5hp 500cc I/C Model No. 31N707 Type: 0301 B1 Build Date: 03/09; Replacement Fuel Filter: 394358; Carberator: Nikki 795366 G02708 9312 3A; Replacement Fuel Filter (According to Sticker Under Hood) 394358
 

WISCOPROUD

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i would say no fuel pump w/ tank under the hood. the mount on the dipstick is for a regulator for the charging system if so equipped which it isn't. if you want, try a gravity feed fuel filter for easier flow Briggs & Stratton part # 298090
 

Blade Runner

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Thanks for your comments. The black plastic bracket that is apart of the oil dipstick tube had me stumped. But it is rectangle in shape with 3 holes and the two fuel pumps that can fit this engine are round. Therefore, the engine has no mounting place for a fuel pump.

I just bought a B&S fuel filter because it was a B&S and color matched (red) the B&S shut off valve I just added. I just checked the numbers and they match what you recommended. I will try it and report back....the slightly bigger end of the red disk goes toward engine?

On another note, can the Nikki Carberator 795366 G02708 9312 3A be used as a gravity fed only or both gravity fed and fuel pump or fuel pump only? I thought the carberator would lead to the truth.

....on yet another note, if the engine does not have a charging system, how does battery recharge? Does the engine have an internal altenator or generator????
 
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Blade Runner

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Based upon diagrams from parts tree, the engine came with either a Walbro or a Nikki carberator like mine. It appears that both carbs could come equiped for gravity or pump feed. The Walbro has a Seat Inlet that can be either a gravity or pump feed. My Nikki carb has a Tube Fuel Transfer that can be either a gravity or pump feed. The diagrams also show that the fuel filter can be either a gravity (disk shaped) or pump (cylinder shaped) feed type. Therefore, it appears that my riding mower could have came from the factory with a gravity feed set up.

Diagrams also show an altenator, regulator, etc. Based upon the type of airfilter it takes, it appears the engine is an "AVS" I/C type.

Installed the B&S 298090 disk shaped fuel filter between the fuel tank and the B&S shut off valve that I added.. Filled fuel tank full. Starts and runs great. I will see how engine runs as fuel level decreases.
 

WISCOPROUD

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also make sure the air vent hole on top of fuel cap is clear of obstruction
 

Blade Runner

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Glad you mentioned the fuel cap. I just remembered that the mower came with a fuel cap that had a small hole in the middle of it. It looked like something may have been in the hole. It had no screw threads or screen, just an open hole. I temporarily replaced the cap with my Snapper rear engine rider fuel tank cap. It has a screw in the middle that can be unscrewed some to vent it. I guess I need to go buy the correct fuel cap for the 300 EX.

It is odd that the gravity fuel feed mower came with a pump fuel feed filter and a gas cap with an open hole in the middle??????
 

wildbill

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If the mower needed a fuel pump and did not have one, it would not run.... no different than a car.
 

Blade Runner

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Thanks for comments.

This evening I was mowing a trail through some very thick and tall weeds to reduce fuel level to see how the correct gravity feed red disk fuel filter compared to the pump feed clear cylinder filter that was on it when I bought it, since the engine was sputtering when driving at highest speed with an inch of gas in the tank with pump feed filter (mower is set up for fuel gravity feed).

I increased throttle and it began to sputter just like it did before. Yet, this time even after I reduced throttle, it still sputtered. I think I found my main problem. The throttle is not in correct postition with the speed level icons on the dash. So when I go toward the "rabbit", I was actually choking it. But I found that the metal choke arm, and carb. butterfly flap were not returning to non choke position after backing off from choke. I thought it was the spring. But the spring can not be winded tighter because it becomes too short to hold position and tention. Therefore, I removed the butterfly flap and stem that held it, I cleaned the hole that the stem sets in and the flap and arm began to spring back as it should. Runs even better than before. Will see how it runs when gas level is low.

On another note, about a week ago, I got an early father's day present....for myself. It was a brush guard for the Poulan. It was only $39 + $2 tax (did not pay shipping since I had it shipped to store). When I pulled it out of the box, I was shocked that it was so cheap. It is made of big heavy tubbing that covers the front like a guard should, with a very neat latch system. Its the coolest mower brush guard I have ever seen. It is very functional and makes the mower look beefier, tough and more expensive than it is. I got it from the Craftsman website as the stores in my area do not have this version in stores. Mine is black. It also comes in chrome ($179) and silver ($29). It was very easy to install. I will post pics soon.
 
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Blade Runner

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Update:

Ran it down to 1/4 of an inch of fuel in tank. It ran great at fastest speed with max throttle. Guess it was the pump feed fuel filter or the sticking choke and or the throttle not in alignment with speed level icons on the dash. Thanks for the help.
 

Blade Runner

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See pics below of brush guard I promised + my gravity feed fuel system :biggrin:
 

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