Hard starting Briggs & Stratton 3.0 hp lawnmower engine

Page 2 of 3  


I have found that a lot of times the muffler is plugged. I have got some good byes because of a plugged muffler.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sorry you had to say good bye to a mower, just cause the muffler is clogged. Many of them have half inch pipe thread, and replace rather easily.
--
Christopher A. Young
Learn more about Jesus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I never heard that one, I have had a 2 stroke spark arrestor clog up.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

As Stormin suggested I agree you should check the "air gap" on the ignition coil even though it sounds like a fuel problem. I remove the ignition coil every few years and clean the edges and magnet on the flywheel with sandpaper and coat it with a little oil or vaseline or whatever. This helps keep down the rust. I generally use three thicknesses of printer paper to adjust the air gap. Check the spark plug connector and clean out any corrosion and squeeze it a bit with pliers to ensure good contact. Sometimes the spring for the governor will get a bit stretched and can be shortened to where it just barely has tension with the engine off. Try holding the throttle all the way closed while it's running and adjust the idle speed to where it seems about right. If it's too low it may be hard to start. Also, if the throttle/choke cable has slipped it can cause the choke to be on or off when you want it the other way. Removing the head might be in order to--scrape off the carbon deposits and clean the valve seats being careful not do damage the seats. I have had success many times simply by putting some high-temp silicone on the old head gasket and reusing it.
My old B&S lawnmower sounds very similar to yours but it's only 23 years old. My experience with these engines is that as long as the piston is still attached to the crankshaft they can be made to mow lawns. I was having a lot of trouble with mine in the past with hard starting and I even turned the engine sideways so I could pull the rope from the side. This arrangement also eliminated some problems with the cable moving out of adjustment as it eliminated the 90 degree turn in the cable. Also, check to be sure the blade is tight. These things need it to maintain momentum.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
muzician21 wrote:

I've worked on a lot of standby generators with small engines and one of the problems with older engines that have accumulated a lot of hours is valve seat wear. The valve recedes into the head decreasing clearance at the end of the valve stem. You can actually heat up such an engine with a propane torch and the expansion of the metal parts will allow it to start easily. If you can adjust the valve clearance, I do believe your engine will start easily again.
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On the early Briggs, that means pulling the head, and then using special equipment to get the spring ends back on.
--
Christopher A. Young
Learn more about Jesus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Stormin Mormon wrote:

I like the Vanguard engines because they have overhead valves that are easy to adjust. It makes it easy to get one of them running good again.
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

What about low compression, then its toasted.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
ransley wrote:

With butter and jam?
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
That will give you a heart attack..... butter. You should use margarine, but that has trans fats. Ah, well. Give up. Go be a monk in Tibet.
Did we hear back, why the engine isn't starting properly?
--
Christopher A. Young
Learn more about Jesus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Even worse. In Tibet, they like butter so much that they put it in their tea. But it's not just any butter, it's yak butter. And it's not just any yak butter, it's _rancid_ yak butter. No thanks.

If you have a yak, you don't need any lawnmower. --scott
--
"C\'est un Nagra. C\'est suisse, et tres, tres precis."

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I have my doubts whether we will - gg, spam war going on, and crossposted to four entirely different groups.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Try this: it won't cost you anything and it worked it my case. In fact I have to do it every year due to poor quality gas.
First drain the gas tank completely along with the hose to the carborator. Next either *temporarily* plug or otherwise stop any ability for liquid to come out of the hose. Vice grips on the end works fine if placed right. Leave the hose attached to the tank however and remove the tank from the mower. Put about 1 cup of Varsol into the gas tank. Screw on the lid for the gas tank so it won't leak. Shake the tank vigoursly for about a minute or so. Drain the fluid from both ends - the tank and the hose.
After a years mowing the filter at the bottom of my gas tank gets so clogged with gunk that it changes colour from silver to black. You can check by draining the tank and looking at it carefully if it's visible.
I went for two years having to start it with ether the first time every year. Even took it in for service with no improvement before I figured this out. Now it will start on choke first pull when it's 45 degrees F. Every time.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
muzician21 wrote:

If its a 70s mower with a 10-year-newer B&S engine, that would mean its an 80s-vintage B&S. That would be about the lowest point in the armpit of quality of B&S carburetors, and it agrees with your symptoms. The "pulsa-jet" carbs of that era used the vacuum pulses of the intake runner to operate a diaphragm that pumped fuel up from the tank to the carb. They also had a vacuum-operated choke that had a tendency to not choke enough when cold and choke too much when hot. They tended to work fine once you got them running, but they were HARD to get going the first time because there just isn't enough vacuum pulse to pump the fuel while you're yanking the rope. Especially when they aged a little and the pump diaphragm got a little stiff You could try a carb rebuild kit, but frankly the only way I ever made an 80s Briggs run truly great was to scavenge the carb (and fuel tank) off an older (70s or even late 60s) engine.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I got a new diaphragm, but looking at the old diaphragm, it looks to be intact and in good shape. The material still seems pliable, I held it up to a light and can't find any breaks in it, including where the choke plate rod is attached.
The longer of the two pickup tubes had a fair amount of crud on the screen, which I've cleaned off. Gonna put it back together with the old diaphragm and see if it starts any easier with that pickup cleaned off. If it does, I'll store the new diaphragm in the refrigerator for future use.
And why are there two pickup tubes and why are they different lengths?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

##### Look... When this sort of thing happens, most of us want to fix it, not to analyze it. I have had it happen lots of times over the years, and it is usually because of crud buildup in the fuel and/or the diaphragm. I have found that you save time by cleaning out the tank, cleaning the carb, and replacing the diaphragm. You can do this in a half hour in most cases. The diaphragm, IIRC, is not a ballbuster in price.

##### And this is also not unusual, especially when one has starting problems.

#### You must like to work on these engines. I normally keep one or two of the diaphragms around. But I wouldnt put an old one back in for anything. It is a waste of time to fiddlefart with this unless you have a lot more expensive diaphragm that I am accustomed to buying. Or have a lot of time on your hands
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I wouldn't think the two would be mutually exclusive.

To me there's a recreational aspect to it, absolutely.


I don't like tossing out perfectly good parts and if I can get more lifespan out of a part I'm all for it. Learning something and troubleshooting are also part of the goal. If I just slap a bunch of pieces on, even if it works I don't really learn what was causing the problem.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
muzician21 wrote:

There ARE no "perfectly good parts" on an 80s vintage Pulsa-Jet carburetor :-/
The old Vacu-Jet worked a lot better, but didn't have the "automatic" (automatically applies exactly the wrong amount of choke every time) choke feature I guess.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

A diaphragm that has been in service for some considerable time, then is taken out and allowed to dry, might work a while longer, but.... if you want to mow the yard or till the garden, it is foolish to go in and clean the carburetor and not install new elastomer parts, IMHO>
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I don't know what the part cost, but it should not have been more than a few dollars. Chances are if the new part was put in it would be good for life. If I had gone that far I would not worry about an inexpensive part. Even if it had been an expensive part I would use the new one and maybe save the old one.
Reminds me of what hapened at work. We had a large varitable speed moror drive to go out. Called in a factory man to work on it. He found two bad diodes. There was a third diode (three phase circuit) and I asked him to replace it also. He said it was $ 200. I told him to go ahead. If it went out that $ 200 was nothing to what it would cost to get him back in and the ammount of downtime on the equipment.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.