Engine won't start when hot...

[Jackk]

1 hour ago, Fly Boomer said:

For a GPU start, he will need more amps than the typical GPU has available.  Most of these "GPUs" are for all-day in-the-hangar playing with radios and lights or battery charging.  For starting, I have thought about building a start cart -- a little red wagon with a half-dozen batteries that add up to 28 volts.

 Wasn’t talking a charger

 

 The average GPU I see on the ramp is north of 1000amps,  just make sure you’re not a 14VDC electric system as most are 28 only. 

[Fly Boomer]

1 hour ago, Jackk said:

The average GPU I see on the ramp is north of 1000amps

Sounds marginal, but it's worth a shot.

[Jackk]

1 hour ago, Fly Boomer said:

Sounds marginal, but it's worth a shot.

 It’ll spin up APU, start a electric starter jet or turbo prop, now the mighty 6 banger conti/lyc might be too much 

[Matthew P]

is your engine timing at 25 degrees or has it been set to 20 degrees, there is a SB out on it that is suppose to help with difficult starts....experiencing a similar issue with mine, seems the only way I can get it started is to intentionally flood it, wait 10 minutes and then it will fire right up, hot starts aren't an issue...only cold starts...never had issues until we went from 25 degrees to 20 degrees but that doesn't make sense.

 

Edited yesterday at 02:20 AM by Matthew P

[LANCECASPER]

On 6/29/2025 at 9:49 PM, rwabdu said:

For the last few months, my engine won't start after I recently shut down and the engine is still warm. The starter will crank and the prop will spin a few times. if I keep trying the starter it won't spin the prop at all and I need to turn the master switch off and wait a while.  I replaced the starter and the battery this year with no improvement. Also replaced the boost pump before this issue happened in the fall. It always took a little extra cranking when it was warm but I have almost been stranded twice now. If I give it an hour or two it will usually eventually start. I am kind of at a loss for ideas about what to do next.... Pretty annoying whenever making a fuel stop. 

Two videos:

https://drive.google.com/file/d/151idG2w5KEFizbbxkTloKfWZXjtDOx4w/view?usp=share_link

https://drive.google.com/file/d/102h7BNLJavxX8N1Hw0XMnbLMo8wWxuv0/view?usp=share_link

Plenty of reading available when you do a search on "hot start":

https://mooneyspace.com/search/?q="hot start"&quick=1&updated_after=any&sortby=relevancy

[PT20J]

20 hours ago, Matthew P said:

is your engine timing at 25 degrees or has it been set to 20 degrees, there is a SB out on it that is suppose to help with difficult starts....experiencing a similar issue with mine, seems the only way I can get it started is to intentionally flood it, wait 10 minutes and then it will fire right up, hot starts aren't an issue...only cold starts...never had issues until we went from 25 degrees to 20 degrees but that doesn't make sense.

 

When you changed the timing, did you change the left magneto to one with a reduced lag angle. If not, it will be firing late during start. Here is the Lycoming SI. It's no longer on Lycoming's website (Lycoming only posts the most commonly requested service literature) but is still available from Lycoming if you ask tech support.

SI 1325 Timing Change for IO-360 Series Engines.pdf

[Matthew P]

1 hour ago, PT20J said:

When you changed the timing, did you change the left magneto to one with a reduced lag angle. If not, it will be firing late during start. Here is the Lycoming SI. It's no longer on Lycoming's website (Lycoming only posts the most commonly requested service literature) but is still available from Lycoming if you ask tech support.

SI 1325 Timing Change for IO-360 Series Engines.pdf 470.94 kB · 7 downloads

Thanks, I will forward to A&P to verify as the left magneto is a Surefly to make sure it can/was adjusted properly.