[Professorfate]

I have a 12 hp Briggs & Stratton model 280707, Type 0128 01, code 89022431 that will not start after sitting for a few days or more. The engine has good compression. The carburetor is clean and rebuilt and the throttle shaft is not worn.
It has a new fuel filter, new air filter, new spark plug that is properly gapped. New fuel lines. Fuel tank is clean also. After attempting to start the engine multiple times, I checked the spark plug and it is dry with no traces of any gas on the spark plug.

I have tried starting fluid in the air cleaner without success.The only way I can start the engine is by putting about a teaspoon of gas directly into the cylinder spark plug hole. Then it will start. After it is started it runs fine. Any help appreciated. This has really got me stumped.

 

[flintknapper]

Does it have a pulse type fuel pump?

 

[Professorfate]

Does it have a pulse type fuel pump?

I am not familiar with the fuel pumps. I believe the fuel is delivered via vacuum from the engine. It is a 1989 model engine. Sorry for my lack of knowledge here.

 

[flintknapper]

I am not familiar with the fuel pumps. I believe the fuel is delivered via vacuum from the engine. It is a 1989 model engine. Sorry for my lack of knowledge here.

Follow the fuel line from the fuel tank. IF it connects directly to the carb then it is gravity fed and doesn't have a fuel pump. But I believe your engine does use a Pulse Type pump that works off of engine vacuum.

Look to see if there is a pump somewhere along the fuel line that looks something like this:

 

[Professorfate]

Thanks for getting back to me. I don't recall seeing anything like this but when I get home from work, I'll snap a picture and hopefully be able to post it. Thanks again, Joe

 

[flintknapper]

Thanks for getting back to me. I don't recall seeing anything like this but when I get home from work, I'll snap a picture and hopefully be able to post it. Thanks again, Joe

Photo would be helpful. It sounds as if your fuel pump (if so equipped) is not priming your carb for some reason. It could be the pump itself, the vent on the back of it or the hose going to your crankcase that provides the vacuum/pressure pulse to activate the diaphragm in the pump.

 

[Professorfate]

Photo would be helpful. It sounds as if your fuel pump (if so equipped) is not priming your carb for some reason. It could be the pump itself, the vent on the back of it or the hose going to your crankcase that provides the vacuum/pressure pulse to activate the diaphragm in the pump.

Here's some photos I just took this evening. I think you are right on target about the carb not priming as there is no fuel on the spark plug and not wet at all after cranking away at it. I tried to get a decent picture of the hose that attaches to the right side of the carb and goes back to the crankcase. There are two screws that secures a small panel where the other end of the hose attaches to on the crankcase. I have never had that small panel/door open or apart before. Thanks again for replying. I really appreciate it as this thing has me stumped. Joe

 

[J. Baker]

Carb shouldn’t need to “prime”. It has a fuel bowl and is gravity fed.

Hose from carb to engine is not a vacuum line, it is a crankcase vent. No need to check or remove it.

You should remove the fuel filter and replace it with a fuel screen. Paper in line filters will restrict fuel flow on a gravity system. A screen will not. I don’t care what anyone else tries to say, a screen is a sufficient filter for a carburetor, and I’ve seen paper filters restrict fuel on a gravity system 100 times over the years. Learned that lesson as a dealer tech 20 years ago.

As a note, don’t dump gasoline into the spark plug hole to attempt starting. Dump it into the carb throat instead. Much easier on the cylinder, and less likely to foul a spark plug.

I would say you likely need to adjust your choke. Make sure the butterfly is correctly installed since the rebuild. Check to make sure the fuel shut off is on also.

 

[sidemouse]

That red fuel shut off is turned OFF.

This is a shut off in a position that's allowing fuel through:

 

[flintknapper]

Here's some photos I just took this evening. I think you are right on target about the carb not priming as there is no fuel on the spark plug and not wet at all after cranking away at it. I tried to get a decent picture of the hose that attaches to the right side of the carb and goes back to the crankcase. There are two screws that secures a small panel where the other end of the hose attaches to on the crankcase. I have never had that small panel/door open or apart before. Thanks again for replying. I really appreciate it as this thing has me stumped. Joe

OK thanks for the pics. Your engine does not use a pulse operated fuel pump. It is directly gravity fed. The tube on the back side is just a breather tube.

Even though the weighted pressure from the fuel in the tank should push fuel to the carb, try this anyway.

Shorten the fuel line that comes directly off the bottom of the tank (to the filter) such that the fuel line is at least level (or better sloping down towards the filter). Make sure fuel filter is facing the correct direction.

Open your fuel shut off valve (which I am sure you are only using when you shut the engine down) and then remove the screw in the bottom of the carburetor bowl and tell us if fuel flows out of it.

 

[Professorfate]

Carb shouldn’t need to “prime”. It has a fuel bowl and is gravity fed.

Hose from carb to engine is not a vacuum line, it is a crankcase vent. No need to check or remove it.

You should remove the fuel filter and replace it with a fuel screen. Paper in line filters will restrict fuel flow on a gravity system. A screen will not. I don’t care what anyone else tries to say, a screen is a sufficient filter for a carburetor, and I’ve seen paper filters restrict fuel on a gravity system 100 times over the years. Learned that lesson as a dealer tech 20 years ago.

As a note, don’t dump gasoline into the spark plug hole to attempt starting. Dump it into the carb throat instead. Much easier on the cylinder, and less likely to foul a spark plug.

I would say you likely need to adjust your choke. Make sure the butterfly is correctly installed since the rebuild. Check to make sure the fuel shut off is on also.

Thanks, I'll go back to the screen type filter and give it a try.

 

[Professorfate]

OK thanks for the pics. Your engine does not use a pulse operated fuel pump. It is directly gravity fed. The tube on the back side is just a breather tube.

Even though the weighted pressure from the fuel in the tank should push fuel to the carb, try this anyway.

Shorten the fuel line that comes directly off the bottom of the tank (to the filter) such that the fuel line is at least level (or better sloping down towards the filter). Make sure fuel filter is facing the correct direction.

Open your fuel shut off valve (which I am sure you are only using when you shut the engine down) and then remove the screw in the bottom of the carburetor bowl and tell us if fuel flows out of it.

Thanks for getting back to me. I'll try that next along with going back to a screen type fuel filter and get back with you guys soon. Appreciate the help, Joe

 

[Professorfate]

That red fuel shut off is turned OFF.
View attachment 518681
This is a shut off in a position that's allowing fuel through:
View attachment 518682

Thanks, yes I only switch if off after I put it away.

 

[Professorfate]

Carb shouldn’t need to “prime”. It has a fuel bowl and is gravity fed.

Hose from carb to engine is not a vacuum line, it is a crankcase vent. No need to check or remove it.

You should remove the fuel filter and replace it with a fuel screen. Paper in line filters will restrict fuel flow on a gravity system. A screen will not. I don’t care what anyone else tries to say, a screen is a sufficient filter for a carburetor, and I’ve seen paper filters restrict fuel on a gravity system 100 times over the years. Learned that lesson as a dealer tech 20 years ago.

As a note, don’t dump gasoline into the spark plug hole to attempt starting. Dump it into the carb throat instead. Much easier on the cylinder, and less likely to foul a spark plug.

I would say you likely need to adjust your choke. Make sure the butterfly is correctly installed since the rebuild. Check to make sure the fuel shut off is on also.

On a Briggs fuel filter # 298090 I forgot if the small round end goes to the carb or the large round end does. Thanks Joe

 

[sidemouse]

Thanks, yes I only switch if off after I put it away.

Just making sure, I know I've made some boneheaded moves in the past, about tore a machine completely apart looking for what could be the trouble and it turned out to be something simple like that... 😅

 

[J. Baker]

On a Briggs fuel filter # 298090 I forgot if the small round end goes to the carb or the large round end does. Thanks Joe

Unless it has an arrow on it, it doesn’t matter.

 

[Professorfate]

OK thanks for the pics. Your engine does not use a pulse operated fuel pump. It is directly gravity fed. The tube on the back side is just a breather tube.

Even though the weighted pressure from the fuel in the tank should push fuel to the carb, try this anyway.

Shorten the fuel line that comes directly off the bottom of the tank (to the filter) such that the fuel line is at least level (or better sloping down towards the filter). Make sure fuel filter is facing the correct direction.

Open your fuel shut off valve (which I am sure you are only using when you shut the engine down) and then remove the screw in the bottom of the carburetor bowl and tell us if fuel flows out of it.

Hopeful news this morning. Shortened the fuel line and changed out the fuel filter to a B&S screen type. Checked fuel flow from the tank to the carb. float bowl and it is good. After that it stated fine this morning. I'll keep my fingers crossed but the real test will be after I leave it sit for about a week so don't abandon me yet guys. I do appreciate all the help. So stay tuned. Thought you guys also might like to see my 1989 "Old Red" you all are helping me with. I'll give an update withing about a week.
Thanks again to all,
Joe