Briggs and Stratton 18.5 Twin Cylinder Won't Start

So like a dumbass I was jump starting this new to me lawnmower I purchased for $250 with a dead battery, well in my rush I crossed wires and killed something. I've replaced the ignition switch, and the started solenoid with no luck. Funny thing is I found a button inside the engine bay that if I hold it down I can turn over the engine but even when doing this the engine will not stay running it will just briefly fire up.

Here's some engine specs

Model: 42a707
Type: 1237 01
Code: 95012558

Here are photos of the switch I found that if I hold I can turn the key and it will start the engine but won't stay running, I also want to add before I didn't have to hold the switch to start it, it started just fine before crossing cables.



I also want to add I replaced the starter solenoid with a 4 pole solenoid, here is a picture of how I have it wired in case it is incorrect.

First and very IMPORTANT !! provide the machine info. WE need to know EXACTLY what YOU want help with..see example ..



yes the eng. is briggs ... mower is a White..?? but we need the rest , from what I see in your pics ..
1. the "button you refer to is a safety switch , it's either from the blade engage lever or most likely the brake linkage

2. NOT entirely sure without the mower wiring diagram but your "White" mower was most likely MFG. by MTD products.
meaning it should use a 3 wire solenoid, some 4 wire solenoids use one of the small wire terminals as a ground ( like what I see in your pic. ) HOWEVER , some .. use that as a power terminal which is fed from the hot feed side of the solenoid when the key is in the start or the run position THAT could be your problem ... you need to know what type of solenoid your engine requires , found in the wiring diagram of the owners or shop service manual and WE don't know which manual that would be because YOU have'nt provided the mowers information !! WE can't help YOU until YOU help US .. Is THAT clear ..?? also lets handle 1 problem at a time jumping around creates chaos !

Unfortunately I cannot provide exact specs the serial number has been painted over and it was just a sticker under the seat. The model and brand is White LT-135 OHV Plus.

Also I tried swapping the starting solenoid back and same thing it will start and runs for 1-2 seconds and dies, I'm starting to think it's fuel related at this point.

According to the Engine # you supplied , (42A707-1237-010 ) thats a "flathead" engine, NOT an OHV engine ...
something is NOT right somewhere, .. when you say its a White OHV !! .... was the engine changed out ??

https://docs.google.com/file/d/0B6NaqjIxWV1ybHphbUNTQUNNR2s/edit

http://www.ereplacementparts.com/br...-engine-parts-c-16758_17347_17465_236786.html

you can post some pics of the mower , and of the engine, take plenty of pics MAYBE ...we can figure it out .
without the CORRECT info of the machine , ..IT'S just a guessing game , ESPECIALLY if the engine has been
swapped out !

trumbo71 said:

Unfortunately I cannot provide exact specs the serial number has been painted over and it was just a sticker under the seat. The model and brand is White LT-135 OHV Plus.

Also I tried swapping the starting solenoid back and same thing it will start and runs for 1-2 seconds and dies, I'm starting to think it's fuel related at this point.

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Engine info. should be located on the engine ........

That switch is one of the safety switches.
There are 3 of them
one on the brake
one on the blades ( pto )
one on the seat

That one will be either the PTO or Brake
So get a good light and look under the dash for a lever with a flat on it that would push that switch down when the brake is on or when the blades are off.
The mounting bracket is broken so the switch will need to be replaced.
Take it to a mower shop because there are quite a few similar looking but different operating safety switches.


The brake & pto switches must be pushed in to start the engine however it will not stay running if that switch is out and there is no bum in the seat.

Boobala said:

Engine info. should be located on the engine ........

Click to expand...

I listed the engine info on my first post I was referring to the chasis model and serial number.\

I think it has either had an engine swap or side skirt swap because thats where I got the LT 135 OHV info.

trumbo71 said:

I listed the engine info on my first post I was referring to the chasis model and serial number.\

I think it has either had an engine swap or side skirt swap because thats where I got the LT 135 OHV info.

Click to expand...

SORRY my goof... I got ahead of myself on the info. bit yes thats how i got your engine info..
OH , it does look like a swap.. yes pics are in order to try and straighten this out..