jd 300 wont stay running

[irocz28l9841u]

hey i have a 74 300 with a kohler engine and a walbro carb, i got the sled in non running condition the motor wouldn't even turn over, now that ive got it put back together it wont stay running, it will start and rev up, when it would run it ran pritty good, could you please help me out please

[JDT]

What did you do to get the engine freed up?

[irocz28l9841u]

i used pb blaster but once it got broke free i took the engine apart because i only had 75 psi in each cylinder so its got new pistons, seals, coils, and plugs. i also had to put a used crank in it. the compression is now at about 120psi in each cylinder. this thing was in bad shape when i got it.

[JDT]

How long will it run before it poops out?

Did you go through the carb?

[irocz28l9841u]

it depends, when i first got it running it ran for five minutes but now it seems to only run for little over a minute and i have to keep the throttle in it,

i did go through the carb several times, i put a genuine walbro rebuild kit in it, and that's when it finally started to run

[JDT]

Well it sounds like you have the spark, fuel and compression parts under control.

Could your exhaust be pugged up?

Is it flooding out when it dies?

[irocz28l9841u]

when i pull the plugs out they are dry, and that could be a possibility this sled had mouse homes in the intake tube so it could very well be plugged, i did run water through it for about 45 min though.

if it were plugged how could i get it unplugged

[400brian]

If the plugs are dry, I tend to wonder if it's getting fuel.

[irocz28l9841u]

yep its deffenatly getting fuel i can see it returning through the return line when it runs plus when im trying to start it i can smell fuel after several attempts to get it running and the plugs are wet so i swap them out with a different set once it stops running and the plugs get pulled they are dry but when trying to start it and it wont the plugs are wet
could it be that ive got the wrong plugs in it they are a ngk br8es

[JDT]

Sounds like we are back at spark again than.

Immeadiatly after it dies have you rechecked for spark ?

It may be that when it does start the coils are getting hot fast and than lossing spark.

Spend some time looking around with an ohm meter.

[irocz28l9841u]

the external coils are new and by the time i could get to the internal coils they would be cooled down enough and i am getting spark right after it shuts off

[400brian]

You could try putting an in-line spark tester on while it runs, to see if you can detect the spark getting weak or erratic.

[irocz28l9841u]

ya i will give that a try tomorrow along with checking the exhaust for being plugged