I've got a 97' ihi 28h excavator. It starts a little hard, seems a little worse when cold, I changed one fuel filter(all I could find), took glow pugs out, all look similar and glowed when hooked to power. Checked for power at wire to glow plug band. So, my question, how long does your glow plug light stay on? I was told it might be a bad timer/relay? Mine seems to stay on for about 5 seconds. It is a three cylinder isuzu engine and runs absolutely 100% after started, no hesitation or skip once it starts. Thanks.