Macrobb
Full Access Member
One thing to add here is that injector pop pressures and temperatures really make a difference.
A few years back, I had an unknown-wear IP that ran perfectly well. Cranked right up under all conditions, no problems.
I was messing with injectors, and after reading a post about someone having increased the pop pressures and found that it ran cleaner, I decided to do the same.
I made a set of injectors with a 2200 psi pop pressure, up from 1800 stock. Put them in and it ran just fine. Started fine to... Until the middle of summer. Middle of summer, I went to Costco about an hour away(so everything was fully warmed up), parked it, went in, and came out oh... 45 minutes later.
Wouldn't start - Obvious hot start issues. A bunch of cranking and cooling off later(didn't really know about the cold-water trick then), I finally got it started, got home, reduced the pop pressure back to 1800... and never had another hot-start problem after that.
My point being that even on a 'good' pump, it doesn't take much to go from 'start' to 'no start' and back - just a few degrees of temperature.
It's also one of those things that if you start it up right away, it won't have heat-soaked and you are fine. Or if you let it set for a few hours, still fine. It's only a short temp+time window that you run into issues.
Also, cranking speed seriously affects it - the faster you can get it cranking, the more you can overcome any leakage issues.
Another idea, for someone who has such a problem with a worn IP - Install a high pressure E-pump. The 5-7 psi is simply to match the stock calibration, which is obviously gone by the time you have a worn IP. Go for 40 PSI or something, enough to hopefully overcome some of the leakage.
Yes, the extra PSI will result in more advanced timing... which is probably a good thing at that point.
A few years back, I had an unknown-wear IP that ran perfectly well. Cranked right up under all conditions, no problems.
I was messing with injectors, and after reading a post about someone having increased the pop pressures and found that it ran cleaner, I decided to do the same.
I made a set of injectors with a 2200 psi pop pressure, up from 1800 stock. Put them in and it ran just fine. Started fine to... Until the middle of summer. Middle of summer, I went to Costco about an hour away(so everything was fully warmed up), parked it, went in, and came out oh... 45 minutes later.
Wouldn't start - Obvious hot start issues. A bunch of cranking and cooling off later(didn't really know about the cold-water trick then), I finally got it started, got home, reduced the pop pressure back to 1800... and never had another hot-start problem after that.
My point being that even on a 'good' pump, it doesn't take much to go from 'start' to 'no start' and back - just a few degrees of temperature.
It's also one of those things that if you start it up right away, it won't have heat-soaked and you are fine. Or if you let it set for a few hours, still fine. It's only a short temp+time window that you run into issues.
Also, cranking speed seriously affects it - the faster you can get it cranking, the more you can overcome any leakage issues.
Another idea, for someone who has such a problem with a worn IP - Install a high pressure E-pump. The 5-7 psi is simply to match the stock calibration, which is obviously gone by the time you have a worn IP. Go for 40 PSI or something, enough to hopefully overcome some of the leakage.
Yes, the extra PSI will result in more advanced timing... which is probably a good thing at that point.
