Oil/Gas out of fuel pump / Gas in Oil: Briggs and Stratton; 13 HP OVH Intek

[roysglen]

Hi,
Some background and information for everyone that will hopefully lead to a solution

1. I have a Briggs and Stratton; 13 HP OVH Intek that is on a 33" walk behind mower. Model is 21A902-01490-E1
2. A few weeks ago I had the following symptoms:
   1. Smoking in general
   2. A bit of engine knocking (I could only hear the knocking when wearing noise cancelling headphones)
   3. Oil out of the fuel pump
   4. "Smoke" from the oil dip stick
3. A bit of reading and research (much of it here) led me to a blown head gasket
4. Parts were researched and ordered while I read up on replacing the head gasket (full discourage: although I am mechanically inclined, engines are not my forte)
5. Replaced head gasket without any big issues beyond snapping a bolt on the muffler
6. Engine started and ran OK for a couple of minutes
7. Again oil began to come out of the fuel pump and a bit out of the hose between the head and carburetor
8. Remembered that I did not change the oil (dumb oversight)
9. Changed oil (it smelt like gas which I expected), cleaned line between the head and carburetor and also cleaned the carburetor (not a full tear down....cleaned bowl, removed needle etc and gave it a good spray with cleaner)
10. Engine started and ran OK. Let run for 5 - 10 minutes without issue.
11. Tried cutting ~ 30' of grass: Once again I have oil (most likely a fuel/oil mix?) coming from the fuel pump. Oil smells of gas. The line between the head and carburetor is clean.

So....I am at a loss to be honest and would appreciate any guidance, education and thoughts.

Thank you very much for having a look.
Glen

 

[bertsmobile1]

Clean the carb.
The float needle is sticking & flooding the engine
If it has an impulse fuel pump, pump diaphragm might be torn ( rare )

 

[Scrubcadet10]

2 different carburetor were used, a Nikki and Walbro.
Nikki: https://www.partstree.com/models/21...-engine/carburetor-kit-carburetor-overhaul-3/

Walbro: https://www.partstree.com/models/21...-engine/carburetor-kit-carburetor-overhaul-4/
The Walbro appears to have a replaceable brass seat and rubber tip needle, while the nikki uses a rubber tip needle with no replaceable seat.

 

[roysglen]

Thanks Bert and Scrubcadet

1. I did clean the carb, but did not replace the needle...only removed and cleaned. Perhaps I should be looking at replacing the needle and brass set (I have a Walbro)?

2. I do believe I have a pulse type pump (and here is where my ignorance shows). This would be its replacement: https://www.amazon.ca/gp/product/B000A13FHO/ref=ox_sc_saved_title_4?smid=A3DWYIK6Y9EEQB&psc=1

Perhaps given its age (at least 12 years old) I should look at replacing?

Thanks again for your help,
Glen

 

[Scrubcadet10]

Yep, that's a pulse pump.
I would replace the needle and seat next... Not sure since the seat is brass if it SHOULD be replaced, or leave it alone and just install the new needle

 

[Mower King]

Yep, that's a pulse pump.
I would replace the needle and seat next... Not sure since the seat is brass if it SHOULD be replaced, or leave it alone and just install the new needle

If its not the carb flooding your crankcase with gas.....those pulse fuel pumps work off a vacuum / pulse from the crankcase via a rubber hose. Sometimes they go bad and start pumping fuel in the crankcase, via that hose, and the carb too.....thus gas in oil.

 

[roysglen]

Yep, that's a pulse pump.
I would replace the needle and seat next... Not sure since the seat is brass if it SHOULD be replaced, or leave it alone and just install the new needle

Thanks Scrub - I will replace the fuel pump this weekend and then go from there.

 

[roysglen]

If its not the carb flooding your crankcase with gas.....those pulse fuel pumps work off a vacuum / pulse from the crankcase via a rubber hose. Sometimes they go bad and start pumping fuel in the crankcase, via that hose, and the carb too.....thus gas in oil.

Thanks Mower King
I will replace the pump will also sourcing a new needle.
G

 

[roysglen]

UPDATE: August 23

So I have gone ahead and replaced the fuel pump, carburetor needle and carburetor bowl gasket (and of course, changed the oil).

Ran the engine for 5-10 minutes for 3 times over the course of an hour without an issues (leaks etc).

On the 4th run, I engaged the mower (ie: under load) and sure enough....I once again have oil from the fuel pump. Shut the mower down and opened the dipstick and there is a bit of "smoke" .

So....where to go from here? Should I be revisiting my head gasket replacement?

Any and all suggestions welcomed.

Thanks!
G

 

[Scrubcadet10]

smoke from the dipstick sounds like a headgasket to me..
Let others chime in