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View Full Version : Restarts with ULP blends



tbird650
17th July 2013, 06:48 PM
Just in case there were some that are struggling with hot/warm restarts when using ULP blended fuel mixes, I post up a workaround for the issue when you don't have time to evaporate the petrols' volatile content out.

Many of you know that I tested the ULP of NZs' pump petrol boiling point at 40'c. It's this factor that I believe causes the restart problem.
When I let my motor sit after shutdown for more than a couple of minutes, some extended cranking time is required with full throttle. The restart behavior persists if left sitting for up to 1-2 hours. Cold starts are always perfect. What I think happens is the petrol content creates bubbles from the engine heat soaking into it. The frothy fuel then doesn't want to pump or inject nicely after that. A clue to the goings on.... is to spray cold water all over the IP, lines and injectors, then the engine will fire right up!!

My workaround was to install a small hose to the inlet manifold from the drivers' cabin. I keep a can of Supercheap water dispersant (http://www.supercheapauto.com.au/online-store/products/Export-Multi-Purpose-Spray-400g.aspx?pid=1135#Cross) and squirt a small amount into the hose. The trick is to know how much to spray without hearing "diesel rattle". It's a small "sniff" only. WD40 or CRC should work the same.

I also point out that there will be a multitude of variables to consider. For example the boiling point of US gasoline is 80'c, vehicles vary in design and ambient temps play a role (to name a few).

Anyway, there's a few ideas to cherry pick. Hope it helps someone.