Hard strarting M38 A1

gspatton3 · Post by **gspatton3** » Wed Jul 24, 2013 5:52 pm

Just rebuilt my M38A1 engine. The engine runs beautiful idles nice runs great on the road. My problem is when I shut it off it dosen't want to start back up. Rebuilt the carb and has a new fuel pump. I know it is not getting fuel at this point because it will start on carb cleaner or starting fluid. I had questions about the float setting the book says 9/64 but that is a tiny gap.I set it level with the air horn. Any suggestions on this ?

Post by **wesk** » Wed Jul 24, 2013 7:03 pm

Your float level will not normally affect a hot start any differently then it would a cold start. Lack of fuel on a hot start is usually the result of vapor locking.

Is your M38A1 completely stock fuel and electrical systems?

gspatton3 · Post by **gspatton3** » Thu Jul 25, 2013 5:06 pm

Fuel pump is after market dual stage by Crown. Electrical system is stock. The pickup in the tank is not stock but just a pipe going into the tank. There is a in line fuel filter in the line. Can't think of anything else out of sorts

Post by **wesk** » Thu Jul 25, 2013 9:05 pm

Is the carb the stock military YS950S?

gspatton3 · Post by **gspatton3** » Fri Jul 26, 2013 6:40 pm

Carb is ys950 military. Was wondering if float level is to low would that affect startup?I have an old Motors Repair book and it has some willys info the yf carbs want 5/16 float level.Anyone know how to set this properly?

Post by **wesk** » Fri Jul 26, 2013 9:42 pm

Not sure which book you are referring to for the 9/64" float setting. The only place that number appears is on the Carter spec sheet that has been floating around for years. The Carter carb manual TM9-1828A says 1/4" for the YS637S but of course has no data on the 950S. The F134 civvy YF uses 17/64" (very close to 1/4"). I would not use that 9/64" setting.

In any case that is most likely not your hard starting cause.