3HP Briggs Need Help

[McGrew 461]

Hi Guys,  I need some help!  I bought a used edger off CraigsList.  I got it fairly cheap since it would not start without pouring gas down the carb.  Once primed, it ran good.  The engine is a 3HP Briggs horizontal, Thr model on the engine is 80202 Type 1765-02.  I have been tinkering with this thing on and off for a couple months.  The fuel pump diaphragm looks good, but I decided to get a new carb kit and start over.  In the process of disassembly of the Pulsa Jet carb, I think I found the problem, but wanted to hear your thoughts.  In the first picture, notice the rectangular slot in the base of the carb. Th long pickup tube supplies fuel to the fuel pump.  The slot in the base of the carb is directly connected to that tube.  

 

In the second pic, this is the gasket that was on the carb.  Notice the part of the slot that is exposed.   My theory is with that slot exposed, the fuel pump will have a hard time lifting the fuel into the smaller well in the fuel tank that the main jet draws fuel from.  

 

I was looking at the carb kit I bought (Briggs 495606), and do not see a gasket that will cover that slot...  According to Briggs, this is the correct kit.  Is my thinking correct?  Any thoughts appreciated!  Danny

 

 

 

Edited April 25, 2019 by McGrew

[oldredrider 2,553]

To my way of thinking, the slot provides a channel for over flow. That would allow the excess pumped fuel to recycle back to the tank. 

Your original fuel pump gasket may have looked good, but time has a way of hardening them up so they don't function as well. 

Let us know how things work out.

[wallfish 17,912]

There's a check valve inside of that long pick up tube. My guess is that is stuck. Without the check valve operating properly it won't pull enough fuel. Separate the white tube from the other and have a look see at it. There could be another in the short tube as well but I don't think so.

It's been a long time since I've had one of those apart so can't remember if that check valve is just a ball or what it was. Unfortunately my memory is leaving as fast as my hair and I have more and more face to wash everyday.

[McGrew 461]

Gentlemen,  Thank you for th replies!  Oldredrider, according to Briggs, any excess fuel pumped into the well that supplies fuel to the main jet spills over the top of the well back into the tank.  This will is inside the main tank.  With the carb fully assembled, when I blow into the long pickup tube, it comes out of that slot.  If that slot is open to the atmosphere, how can the fuel pump develop enough vacuum to pull the fuel up the tube?  I would think this problem would be worse when the fuel is low?

 

Wallfish, I will take that tube off tomorrow,  I hope you are right about the check valve.  I am still having a hard time getting past that exposed slot...  I think my OCD is kicking in...  FWIW, I have the same exact problem with hair and memory!

Danny

[wallfish 17,912]

To rule out that slot. pick up a sheet of gasket material and make a gasket.

Isn't that slot how it fills the upper well?

[Tuneup 1,451]

I love those old engines (have one in my shed) but they have never pumped fuel - it's a diaphragm carb as you noted. That being the case, I wouldn't expect there to be a return to the tank - expect a full seal on the gasket. If the tubes flow, and with today's garbage gas in those tanks over years that's a big if, and the diaphragm area is clean and the gasket fresh, it should be fine. So, runs fine when you spray fuel into the intake to start it so something in the choke circuit? Dang, I wish I had a crappy one to take apart. Mine is like NOS - found at an estate sale. If you get in a bind, I can see if I can drop its tank to inspect the gasket. Copper model with a deep tank - early 70s.

[gwest_ca-(File Mod) 11,403]

71 pages on carburetion in Section 03

Garry

[Sarge 3,465]

I have rarely ever had any luck cleaning out those tubes and getting those things to pull fuel up into the carb - have always had to replace them with new ones. Hunt around for the paper book on L-head engines, use the online files such as Garry posted - you'll find that most times the book recommends replacements. Now, due to Briggs having fun with the superseded part number game - it can be a challenge to find those parts and many of the older stuff is going NLA these days. The easiest way is to talk to an older dealer - I had one around here that was a magician at finding things but he finally expired and his kids closed the shop.

 

Sarge

[McGrew 461]

Thank you to everyone for the responses!   Wallfish, yes, that slot is in the circuit between the long pickup tube and the fuel pump.  The output from the fuel pump fills the small inner well.  So you see why I am questioning the gaskets I have...  If that slot is open to the fuel tank, the little vacuum those fuel pumps produce will never reliably be able  to lift the fuel under starting conditions.   Or at least that is my thinking...   I am going to make my own gasket and try it with the rest of the carb kit before I do anything else.  Will let you know what happens.  If you hear a loud bang coming from SC,  you know something went wrong...     

 

Tuneup,  I appreciate the offer, but there have been so many variations of that carb, yours may not be the same.  I watched about 50 videos on  YouTube, and only a few of the Pulsa Jet carbs are like mine with the 2 plastic pick ups.   I believe the choke is working properly.   It is a manual choke, and the butterfly closes completely when the throttle is moved to its maximum travel.  

 

GWest (Gary?), I appreciate those files.  While the diagrams did not help me with my theory, I learned a few things about the linkages that will help.   Sarge, the pick up tubes do not appear to have any obstructions.   And they don't leak.  I say they "appear" clear because I decided not to remove them if possible.  Since the are not broken or cracked, and can squirt carb cleaner through them in both directions, I believe they are fine.  I doubt I would be able to remove them without breaking them.  They are 31 years old and make of plastic...  I will tinker on it this evening.  Keeping my fingers crossed!  Danny

Edited April 25, 2019 by McGrew

[Howie 899]

I think all of those I have taken apart have the gasket like that. Pretty sure it is supposed to m

be that way. All of them in my stash are like that.

[McGrew 461]

Howie,  I agree.  I made a gasket that completely covered that slot, but when I went to put it on I realized the fuel tank has identical sized holes as the factory gaskets.  It makes no sense to us the gasket I made if it is not sandwiched between two surfaces.   So much for my theory...  Oh well, its not the first time I have been wrong, and probably won’t be the last.  I don’t under stand the theory behind leaving that slot open to the fuel tank, but am still working on that.  I will put it back together with all the factory gaskets and pieces and see what happens.  I’ve got my fingers crossed, and will report back after I try to start it.  Danny

[McGrew 461]

OK guys,  I need to file a follow up...  Houston, we have lift off!    I replaced all the gaskets with the factory gaskets, along with a new needle and jet.  Wallfish said something in an earlier post that I overlooked.  He suggested the slot I wanted to cover fills the upper fuel well.  He was absolutely correct!  Now I feel good about how this carb operates.  Thank you Wallfish!  It took a bit of fiddling, but once it started with the rebuilt carb, it sounded healthy.  I adjusted the carb, and used it for a couple minutes.  I then put it away.  The real test was today.  This thing has ben a beast to start since I got it.  I went to my basement and pulled it outside.  I choked it and gave it one pull and it fired up and ran like a champ!   Thanks to all who responded!  I think the fresh coat of paint on the carb and fuel tank did not hurt either...   Danny

[wallfish 17,912]

Glad to see you got her going!

[Tuneup 1,451]

Now I'm inspired to take the old 3HP out of the shed for a warmup.  Thanks!