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View Full Version : 7 horse briggs backfires and pops at an idle


Robert Doubrava
08-31-2001, 11:27 PM
i was just wondering if this problem could be fixed somehow. i have the model, type, and code if it's useful to someone.

model-170702
type-151701
code-80032709


any help is appreciated.

Robert Doubrava
08-31-2001, 11:32 PM
i forgot to say, it is a vertical shaft engine. i believe it is an out of production engine, too.

khouse
08-31-2001, 11:34 PM
tell us more. does it pull fine otherwise? does it have good compression? does it backfire just above idle? ect.. this will help us help you.

Robert Doubrava
08-31-2001, 11:42 PM
it has good compression. its pretty hard to start, but it runs good if you have it at top speed. it is about 20 years old, but my dad and i overhauled it in about 1995-96.

khouse
08-31-2001, 11:45 PM
My guess is that your intake valve is not seating. Do you have a compression guage? What did you do to the valves and seats on the rebuild?

Robert Doubrava
08-31-2001, 11:46 PM
we bought new piston rings, a new rod, a gasket kit, i am not sure what else.

Robert Doubrava
08-31-2001, 11:49 PM
my dad has a compression gauge.when we over hauled it, we replaced the valve seats, and we made sure that they were still good.

khouse
08-31-2001, 11:54 PM
I would like to know the compression on your engine. First dry psi. Then give me the wet compression by adding a capfull of oil in the plug hole then retaking the test.

Robert Doubrava
08-31-2001, 11:57 PM
ok. when my dad is not working we'll try it.

khouse
09-01-2001, 12:01 AM
robert, just post back with your readings. good luck

Robert Doubrava
09-01-2001, 12:05 AM
ok, thanks

Fish
09-01-2001, 12:15 AM
Valves are a possibility, but a good bet is that the points need
replaced. It is easier to retrofit an electronic module, Briggs makes one, and you just need to cut the wire to the points,
and not have to bother removing the flywheel.
Fish

Robert Doubrava
09-01-2001, 12:18 AM
i forgot to mention the engine has an electronic ignition already.

Fish
09-01-2001, 12:27 AM
Well. What does it do when you adjust your idle mixture screw
on the top of the carb, does it change? How much up and down
play do you have in your carb throttle shaft?
Fish

Robert Doubrava
09-01-2001, 12:30 AM
i'm not sure. i haven't tried that yet.

Robert Doubrava
09-01-2001, 01:33 AM
what is the screw on the bottom of the fuel bowl for?
any answer is appreciated.

Robert Doubrava
09-01-2001, 02:23 AM
once, the engine even popped out a small flame!:blob2:

vipermanz
09-01-2001, 04:08 AM
most likely or not it is a drain screw rather then a needle since it's on the bottom,needles are usually on the top othe carb,

yea they will shoot out a flame every so often but i would think that would mean some sort of bad exhaust valve timing

Robert Doubrava
09-01-2001, 11:00 AM
ok. thanks vipermanz.:blob3: :blob4: :blob1: ::)

Robert Doubrava
09-23-2001, 08:17 PM
we used the mower recently, and for some reason it started screwing up again! i was mowing a yard and the dang thing started backfiring and shortly after that, it died. before we cranked it up we cleaned out the fuel filter, and it ran fine when we cranked it up.it runs very loudly. it gave us trouble four times in a row! can anyone tell me how to prevent this before it does it again? Thanks,

Robert

Robert Doubrava
09-23-2001, 11:42 PM
also, that fuel filter was dirty as heck. my dad sprayed lubricant in it and tapped it on a shop rag and all this rust came out. i think there is two things to blame. the fuel tank is made of metal, and my dad took the screen off of the fuel shut off valve because it is always getting clogged up. will any one please help me with my last post? :(

vipermanz
09-24-2001, 02:10 AM
did the rpm's increase?

Eric ELM
09-24-2001, 09:51 AM
Originally posted by Robert Doubrava
my dad took the screen off of the fuel shut off valve because it is always getting clogged up. :(

Taking that screen off of the shut off is just letting rust get through to the fuel filter and clogging it up. You have to eliminate the source of the problem, that tank.

It sounds like your main problem is the metal gas tank that is full of rust. See if you can get a plastic tank to replace it or take off the metal one and clean it up some how.

khouse
09-24-2001, 10:17 AM
Remove the tank and fill it 1/4 full of gravel and a cup of sand if you have it. Shake the tank for at least 10 minutes. Pour out the gravel mix and rinse with Kerosene or Diesel -(not gas) until clear. Reinstall the tank and fill with gas. Change the filter and your good to mow.

Guido
09-24-2001, 10:18 AM
Maybe with a parts cleaner if you have one.

Next, you put a handfull or two of gravel in there and shake it up for a while, rinse, and repeat untill all the rust and buildup is out.

It works I've done it before on an old toro walk behind edger that had fuel sitting in it for 6 years.

Good Luck!

vipermanz
09-24-2001, 05:36 PM
i'd dump that tank, get a plastic one, new fuel filter, new fuel lines, clean the carb, and try that out

Robert Doubrava
09-24-2001, 06:02 PM
i can't because the gas tank is riveted to the engine cover. i would have to spend a lot of money to replace it, too! thanks for your help. i appreciate it.

Robert

Kevin M.
09-24-2001, 06:21 PM
I have had a Briggs just like yours and I started to replace all that stuff and then went to Grainger and got a new Kohler 7 hp engine for $ 200 bucks and that was two years ago and always had problems with backfiring with the Briggs and the Kohler just keeps huming along every day on a spray rig for a chemical truck.

Robert Doubrava
09-24-2001, 08:28 PM
i just finished mowing a lawn with 2 foot tall grass with only a push mower! i did it by myself, too. no help from dad! :D i had fun, though. by the way i found a 5 horse briggs at www.smallenginewarehouse.com it is for riding mowers, i think. it is an old model, but it is brand new and it has a warranty on it as well. i think its only 175.00. it is a vertical shaft engine, i might add.lthe rider used to have a 6 horse on it but my grandfather burned it up!:eek: thanks for all the advice, guys!
Robert

vipermanz
09-25-2001, 02:57 AM
aww, rivets aren't anything much for a wizard or dremel to handle with a cutoff disc on it, zoooooooommmmmm!

Robert Doubrava
09-25-2001, 05:57 PM
the thing is, my dad said that all we have to do is keep on cleaning the fuel filter. over, and over! i dont like that idea very much.

vipermanz
09-25-2001, 06:22 PM
could you just rip a plastic tank off a non working machine?

Robert Doubrava
09-25-2001, 07:08 PM
a plastic tank would not fit that old engine that i have. it would have to fit a certain model of engine. besides, i dont have any equipment to get a tank off of! :D

vipermanz
09-25-2001, 08:38 PM
oh, ok , hold on then
if all else fails... (http://www.northerntool.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=319&prmenbr=6970) if all else fails# 2 (http://www.northerntool.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=317&prmenbr=6970)

vipermanz
09-25-2001, 08:53 PM
this might help you alot (http://partsandservice.com/bin/ipl.cgi)

Robert Doubrava
09-25-2001, 10:41 PM
there is one problem with both engines you showed. 1 we dont use tecumseh engines. [i dont know why] 2 the briggs engine has to have a fuel tank built on it because my mower is a very old model. its like a '72 model mower. junk, right. at least it gets the job done. when it breaks, im gonna buy a snapper rear engine rider with an electric start. to check it out, go to: www.snapper.com/residential/rear.html scroll down and click more residential mowers. i am looking at the 10 horse recoil and electric start M series mower.

vipermanz
09-26-2001, 02:27 AM
i'd go for a used 36" commercial walkbehind , you can get those cheaper than $1k, check around your local dealers for used equipment, you might be surprised with what you find!

Robert Doubrava
09-26-2001, 09:29 AM
i think ill stick to riders because my neighbors all have dogs, and i dont want to step in dog poop! :D

Guido
09-26-2001, 06:45 PM
The "Meeting of the minds" here is getting hilarious!!!

Martino
09-26-2001, 09:38 PM
You know, since I have absolutely no wrenching ability, I usually just skip over these types of posts, but I keep coming back to this one. I can't help myself!:dizzy:

Robert Doubrava
09-26-2001, 10:01 PM
we mowed two yards today. while i was at school, my dad checked my rider's engine and adjusted the main jet on the carb and we had no trouble with it today. it runs great at an idle now! no backfiring yet. one bad thing about it, that engine uses oil like crazy! its because the cylinder is worn out and oil gets in it. if i rub my fingers on the muffler, they will turn solid black from the carbon on the muffler. i know we need to clean the exhaust port very soon.

Guido
09-27-2001, 02:03 AM
Originally posted by Robert Doubrava
we mowed two yards today.

I thought guys from Texas were supposed to be tough. All you had to do was sit on a rider after school for a few hours (if that??)

This thread is turning into your diary.:alien:

vipermanz
09-27-2001, 02:14 AM
Originally posted by Robert Doubrava
i think ill stick to riders because my neighbors all have dogs, and i dont want to step in dog poop! :D

get a sulky, no walking or dog crap:D

Robert Doubrava
09-27-2001, 07:44 PM
what kind of mower is that?

75
09-27-2001, 08:58 PM
"Sulky" is an attachment for the back of your WB mower that you can either stand or sit on, as opposed to "walking behind". There are wheeled versions, as well as ones that slide along.

They resemble the sulkies used in horse racing, hence the name. (Or so I think - I'm a welder, not an LCO so correct me if I'm wrong guys!)

Robert Doubrava
09-27-2001, 10:11 PM
my dad said that i just need a regular mower. i prefer commercial though, but my dad said no. thanks for the suggestions, guys!
Robert

thelandscaper27
09-27-2001, 11:10 PM
IN Ag Mechanics class, we took a center punch to the metal material around the vales to help stop the popping because it wouldn't sit tightly like it should.

You have a circle. go the opposite , 1 at top then 1 at bottom,
next, 1 at left side and the other at right. keep going around in a
circle.

Don't ever start let's say the top, then just go clokwise or counter clockwise. it won't work. Helped us in class. :D





the landscaper27@hotmail.com

Robert Doubrava
09-27-2001, 11:15 PM
i dont think we will be tearing it apart anymore, unless it needs it. my dad really doesnt have the time to do it. the reason why i cant do it is because i dont know much about the internal parts, yet! :D
Robert

plow kid
09-28-2001, 09:38 AM
just rip it apart, then when you cant find all the pieces you can ask dad for a riderhttp://members.aol.com/ncls484/smilies/neener.gif

Robert Doubrava
09-30-2001, 09:46 PM
as ong as i can remember where everything goes, i wont have any problem tearing it apart. :D

Robert Doubrava
10-22-2001, 05:54 PM
the next time i get the chance.im gonna need it!

Guido
10-22-2001, 06:42 PM
I'm puzzled!:alien:

Robert Doubrava
10-22-2001, 07:08 PM
sorry. i was trying to say that i needed a repair manual for small engines and that as soon as i got the chance that i would buy one. i just noticed that i screwed up! :D