OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines B&S starting problem

Hi. Just wondering if anyone can help me with a starting problem with my Briggs & Stratton on a Scott Bonnar 45. Engine numbers are.
Model-80202
Type-0607-02
code-76060803
My problem is after sitting for a few days or weeks the engine won't start but if you remove the spark plug and put some fuel in the hole, replace the plug it will go with one pull and continue running nicely. You can than stop and start it all day without any problems. However if left over night it will take up to 15 pulls to start it and if left for a few days its back to square one. The engine seems to have good spark, I've used fresh fuel and have replaced the diaphragm on the side of the carby to no avail. I also have a 1997 Briggs & Stratton on a Rover cylinder mower with a simular issue. I would appreciate any tips to solve this issue.
Thanks. Bergy.

Here is the Illustrated Parts List:
http://bsintek.basco.com/BriggsDocumentDisplay/Z6jmyBVJ1DajI.pdf

Here is the Operator's Manual:
http://bsintek.basco.com/BriggsDocumentDisplay/flivAJX-nfBhU7y.pdf

Your description of the symptoms sounds as if you have not been using the choke, which is circled in yellow in this picture:


Pull the choke all the way out (i.e. to the left in the picture - it will come out about 10 mm). When you pull the starter it will start, probably on the second pull after months in the shed, then after about 5 seconds it will stop if you haven't been able to push the choke in by then (I never can.) If it has stopped, push in the choke and it will then start first pull.

Hi grumpy. Thankyou for your reply. I have been using the choke when trying to start my engine, so unfortunately my problem my not be so simple but if you have anymore ideas I'm all ears. And thankyou for the links to the manuals, I'm sure they will come in handy in the future.
Bergy.

Bergy, because it will start immediately if you prime it, your problem is most likely in the carburetor. Being an 80202, your engine has a PulsaJet carburetor, which has a built-in fuel pump. The pump uses a rubber-like diaphragm, mounted behind a plate on the side of the carburetor in your horizontal crankshaft version of the PulsaJet. It is not unusual for the diaphragm to deteriorate eventually, and yours has been in service since 1976, which is a long time for a rubber-like substance exposed continuously to petrol.

Part of the diaphragm is a pair of flap valves which act as the fuel pump intake and output valves. Sometimes they curl up a bit after the first thirty or forty years, and when they do, the pump can become reluctant to prime. The pump is located above the fuel, so it has to suck fuel to prime itself.

I suggest that you consider cleaning the interior of the carburetor, inspecting it, and replacing the diaphragm. You could also clean the fuel intake screen, which tends to become clogged with grass over time.

Hi grumpy. I finally got around to removing the carburetor and gave it a good clean. The intake screens are also clean and as I said previously I have already replaced the diaphragm. I did however notice the base plate of the carburetor where it mounts to the fuel tank was quite warped so I fitted two gaskets on reassembly in the attempt to reduce any suction of air. There doesn't seem to be any fuel seepage in the area so hopefully this isn't causing any problems. So after this little exercise I'm still no further in front, the engine still takes around 15 pulls to fire from cold start . I feel I'm running out of options I may just have to find a replacement carburetor.

The base of the carburetor, and the top of the fuel tank, must be flat across the full width of the contact surface. Multiple gaskets provide an unreliable solution at best. You could draw-file the surfaces flat, or replace the carburetor and/or fuel tank, after finding out with a reliable straight-edge whether both of them are flat.