high temperature insulation

This is on a waste vegie oil diesel conversion car.

I'm in need of fibreglass tube insulation or other advise on how to insulate injector line heating elements on  diesel fuel lines. I'm using a PWM motor control with home made .045" stainless steel elements. This works fine but the lag between the temp sender & adjusting the PWM has melted the 250*F insulation. While I could be a bit more lite fingered on the rheostat adjustment, I'd rather make this fool proof & use proper insulation. The only material I've found in 1/16" ID is 500' spool & I need 20"! I have scrounged some from old coffee pots.

Injector fuel lines are electricaly (tape) insulated to 600 Volts.

I realize there is an issue with boiling the fuel & I believe I can avoid that but with cold startups (Wisconsin winters) I would like to have any 'safety' resistors in the circuit on a switch so I can have full amps (roughly 10 amps) to the heaters of needed. Return fuel pre-heats the fuel lines so even 8 amps will work (on paper). This is not for daily driving but trips & only when engine is at opperating temps or emergency purges.

 Any advice or susgestions are welcome.

Run the injector lines in Flexible aluminum conduit you buy, btf from Home Depot off a spool.

You can buy Flexible Steel conduit from your local electrical supplier.

It's possible to get high temp flexible PVC and if you can find a mfr or major distributor, tell them you need a sample for "proof of concept" and tell them the total # of feet you need.

A lot of placed will donate this for free.