Hard starting Perkins when warm.

Working on a JCB 1550 backhoe with a turbo Perkins engine. I believe it's a Perkins 4.236.

I know this backhoe has seen lots of hours. The owner ran it out of diesel and could not get it started.

I replaced the lift pump and fuelshut off solenoid and blew out the fuel line coming from the tank. The line from the tank was severely plugged up. After bleeding the system, I still couldn't get it started. I found a can of ether in the cab, apparently the owner had been using it to try to start it.

I gave it a slight mist of ether and nothing. It took a direct, short shot into the intake before it would start. Once it started it ran great. However, it won't restart when hot. It will start no issues when it's cold, even without using the intake heater. But will not start hot.

I noticed when I shut it off hot and immediately try to restart, it hardly blows smoke. After about an hour, it will smoke while trying to start, but still will not start. Only after it's completely cold will it start.

Any ideas?

Or delivery valve not seating or broken spring.        MACK

MACK wrote: Or delivery valve not seating or broken spring.        MACK

Thanks Mack, this is where I'll start at. Hopefully it's something m minor like a broken spring.