# Briggs and Stratten 4.75



## rickyjoseph70 (Jan 29, 2011)

I picked up a poulan with a b&s 4.75 engine model 9t702 code 3858. it will not prime the engine.I took it apart, cleaned everything put it back together and it primed for a couple of times and then it was no priming again.Can anyone offer some advice what to try next?Yhe model number suggests that it is a flo-jet carb, but it is a vertical shaft pulsa prime.


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## 30yearTech (Sep 14, 2006)

This engine has the pulsa prime carburetor. Most often when they will no longer prime, the diaphragm needs to be replaced.


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## rickyjoseph70 (Jan 29, 2011)

That's kind of what i thought but wanted some "expert" advice on it.


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## geogrubb (Jul 28, 2006)

You need to install a new diaphram kit, it is Briggs part # 795083 or old # 495770 also Lowe's has a kit #5083 which has the same parts.
Here we go;

Remove air cleaner, there are 2 bolts that hold things together, one on the front of the tank 3/8" and one into the block 1/2", remove these bolts, now "slowly" slide the carb/tank off the intake tube and breather tube, now tilt the tank in to release the throttle linkage and waalaa the carb/tank is removed. Check the intake tube to see if the “O” ring seal and plastic retainer are still on the intake tube, if so remove them and re-install them into the carb. Remove the 5 screws from the carb/tank remove carb(don't loose the spring) now spray all holes, cracks and crevases in both the carb and tank surface with brake parts cleaner, remove the main screen(looks like a thimble), now with a small screwdriver pry out the main jet(carefully) and clean it, check the “O” ring on the main jet for damage, if it is damaged it must be replaced, reinstall the jet, it can be difficult some times to get it to snap back in place(I use the rounded end of a screwdriver handle). Remove and clean the fuel pickup stem(not necessary if the fuel tank was clean). Clean any junk/rust from the tank. Install the diaphram on the tank then the gasket(no goo or sealer) now carefully replace the carb(the spring will try to misalign the diaphram), tighten all screws a little at a time so as not to crimp the diaphram until they are all tight. Install the carb/tank in reverse order and you are done. If I missed something one of the real mechanics will correct me. Have a good one. Geo


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## geogrubb (Jul 28, 2006)

rickyjoseph;
In response to the Private Message:

Success is a wonderful sound. Have a good one. Geo


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## rickyjoseph70 (Jan 29, 2011)

*4.75 b&s*

Thought I had this thing fixed, but just tried to prime it and it would not prime.The bulb feels as though there is no pressure on it,however if i close the little pin hole by the primer,it will build pressure and squirt a few times.Any suggestions???


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## rickyjoseph70 (Jan 29, 2011)

Thought I had this thing fixed, but when I tried to prime it, it did not priime.It feels as though there is no pressure on the bulb, but if I close off the little pin hole by the primer it will build pressure and squirt a few times.Any suggestions out there???


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## dehrhardt (Apr 1, 2009)

If you haven't already seen it, this link shows how to disassemble the Pulsa prime carb.
Good luck!

http://outdoorpowerinfo.com/repairs/briggs_pulsa-prime_carb.asp


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## rickyjoseph70 (Jan 29, 2011)

Thanks I have not seen this site before.I will try to disassemble the primer bulb tomorrow.


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## rickyjoseph70 (Jan 29, 2011)

hey there, i put in a new diaphram kit, it primed once and then nothing again.I am going to try to replace the ball check and spring tomorrow.Don't know what else to try. Any ideas?


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## 30yearTech (Sep 14, 2006)

rickyjoseph70 said:


> hey there, i put in a new diaphram kit, it primed once and then nothing again.I am going to try to replace the ball check and spring tomorrow.Don't know what else to try. Any ideas?


If anything maybe just cleaning, I work on a bunch of these type of carburetors every year, and I can't remember the last time I had to replace the check ball or seat. Sometimes the pick up needs cleaning or there is some debris preventing the check ball from sealing, but nothing I have ever had to replace.


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## rickyjoseph70 (Jan 29, 2011)

Cleaned the carb again real good, took the primer off and the ball and spring came out to.Put everything back together and it primes!,now to replace the brake bail cable.


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## 30yearTech (Sep 14, 2006)

Glad to hear you got it figured out. The cable are usually pretty easy to replace.

Best of Luck....


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