Discussion
I just thought I'd let you all know of a little problem I encountered last season with the 4.8 litre lump in my Ultima.
It gradually (as I realised later) lost power over time, and at one race, developed a misfire (rather annoying to get a DNF like that).
After a lot of investigation, it looked like I had 2 injectors that weren't running properly. That would nicely explain the misfire
I duly took all the injectors to John Eales (who had built the engine for me), and he tested them all for me. It turned out that it wasn't a problem with 2 injectors. It was a problem with 7
He told me that the current crop of super unleaded fuels (which I had obviously been running on) have very little lubrication in them, so they have a tendancy to dry out injectors. This is exactly what happened to mine.
If you think about it, if you spill a bit of fuel on your hand, it doesn't leave that oily residue that you remember from days of old.
The solution (which seems to work very nicely for me now) is to put about an egg cup full of 2 stroke oil in for every 20 litres of fuel.
I know that my engine is in a higher state of tune that the average road going engine, and it has a harder life. It also has higher capacity injectors than a standard engine, so the problems may manifest themselves slightly less in a standard engine, but the same principles apply.
James
It gradually (as I realised later) lost power over time, and at one race, developed a misfire (rather annoying to get a DNF like that).
After a lot of investigation, it looked like I had 2 injectors that weren't running properly. That would nicely explain the misfire
I duly took all the injectors to John Eales (who had built the engine for me), and he tested them all for me. It turned out that it wasn't a problem with 2 injectors. It was a problem with 7
He told me that the current crop of super unleaded fuels (which I had obviously been running on) have very little lubrication in them, so they have a tendancy to dry out injectors. This is exactly what happened to mine.
If you think about it, if you spill a bit of fuel on your hand, it doesn't leave that oily residue that you remember from days of old.
The solution (which seems to work very nicely for me now) is to put about an egg cup full of 2 stroke oil in for every 20 litres of fuel.
I know that my engine is in a higher state of tune that the average road going engine, and it has a harder life. It also has higher capacity injectors than a standard engine, so the problems may manifest themselves slightly less in a standard engine, but the same principles apply.
James
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff