OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines start issue

Hi All.
I have a starting issue which I hope you can help me with.
Mower in question is Rover colt 45.
Model 91202
Type 13711
Code 0203143A

I have never had an issue with starting this one. Has always started first pull every time.
Recently an issue developed when after starting and subsequently turning off the choke the engine then proceeds to rev flat out for about 3-5 seconds and then comes back to idle.
I have replaced the air filter element thinking it may be a factor but it made no difference.
Would love to sort this out as it makes my blood run cold having it rev like this before it warms up.
Thanks in advance,
Craig.

Hi Craig, welcome to Outdoorking.

There seem to be a couple of irregularities in your Model, Type and Code information. First, the Type should consist of 4 digits, a dash, and two more digits. Second, the Code cannot contain a letter, it is all digits. Third, you have posted in another forum that the mower is from 1986, but your Code would date the engine in 2002.

Until we can look up the engine in the Briggs records, we can't get very far with diagnostics. I also think we are going to need a picture or two of the mower, and a more complete description of the fault. In your other thread you refer to serious engine faults that might, on their own, cause the brief burst of overspeeding that you have reported. Please give us the whole engine story in this thread.

Hi grumpy.
Should have clarified that I have two mowers. One that I use regularly(rover) and one that I am fixing up(scott bonnar).
Rechecked the numbers, this time out in the sun. Type was wrong, should have read 1371E1.
I apologise for the confusion.
To try and clarify my problem.
1. Prior to starting I set choke to full and throttle lever to just above idle.
2. Pull start cord and engine starts.
3. Run for 5 seconds and return choke lever to the off position
4. Engine will then slowly pick up revs until it is running at what I believe to be full throttle. It will rev hard for about 3-5 seconds then return back to just above idle speed. This happens without the throttle lever being touched.

Now we are cooking. Here is the Illustrated Parts List for your engine:
http://bsintek.basco.com/BriggsDocumentDisplay/18jsBLXBnfBhU7y.pdf

Here is the Operator's Manual:
http://bsintek.basco.com/BriggsDocumentDisplay/flmvtLX-nfBhU7y.pdf

The engine's date of manufacture is 14 March, 2002. The last two digits of the Code should identify the plant where the engine was made, but I do not recognise 3E. By 2002 the engine may have been made in Chongqing, which is Plant 28, but I think Briggs had a certain reticence about putting 28 on some of the engines in the early days for understandable reasons. However I'm speculating, all I can say is it does not have a code I recognise. Now all of the side-valve engines, even the large ones for ride-ons, are made in Chongqing, and all of the small OHV engines are made in the US. Some of the large OHV engines are made in the US, and the remainder in Japan.

The carburetor is a Pulsa-Prime, which is a decent carburetor and does not usually give trouble except occasionally when the primer fails. Please read the Operator's Manual. The engine is supposed to be started with the speed control at maximum speed, then should be dropped back in speed as soon as it is running smoothly with the choke off. (In cold weather you may not be able to open the choke completely until it warms up - this is an emissions engine.)

Please try it as per the Operator's manual, and report back on how it behaves.

Thanks for that grumpy.

Will do as you advise and report back.

Regards,
Craig.

Hi grumpy,

Mowed this morning and started her up as per the manual. No problems and started easily.

Personally I have always had a concern with running engines at high revs when they are cold and this particular engine has always started well at low throttle settings.
In saying that I am but an amateur in this field and will always accept the manufacturers opinion but more importantly the advice from experts such as yourself.

Thanks for your help in clearing up my concern.

Regards,
Craig.

Craig, if you recall the days when cars had carburetors, whether they had a manual or automatic choke, they always ran at well above the normal idle speed when on choke. There was a mechanical link between choke and throttle so that as the choke was reduced, so was the engine speed - but the choke was wide open somewhat before the idle speed reduced to normal. The reason was that you tend to get cold-running lean-mixture malfunctions (sags, spits or stalls) if you don't elevate the idle speed at first. You could also rich-load the engine rather easily if you over-choked it without raising the idle speed. (You probably know that rich-loading engines is bad for their health, since the excess petrol tends to wash the oil off the cylinder wall.) As soon as the engine will run smoothly without either increased idle speed or choke, you can dispense with them both and reduce the idle speed to normal.

The objective is just to get a clean, smooth warm up, and the brief fast idle immediately after the choke is opened will help to achieve this, especially in cold weather. Remember, the maximum governed speed for that engine (a little over 3,000 rpm) is less than twice its idle speed (1,750 rpm) - it's not as if you were revving it hard, as you easily can with a car engine for instance.