My friend's 1990 SP is being quite difficult to start. As I'm cranking the starter, it will only start with FULL throttle applied and after a few minutes of cranking.

The fuel filters are nice and clean, both the in-tank pickups and the "water seperator" filter looks good. I'm pretty sure it's not a fuel delivery issue because the Doo is equipped with a primer pump delivering fuel to the carb and I get the same issue when using the primer pump while cranking.

wHile cranking, it often gets about a 1/2 second of obvious firing (almost starting), then dies.

I'm trying to limit the cranking time to 20 seconds per attempt, but it always seems like it's JUST ABOUT to start, so I continue to crank for about 40 seconds max, then I'll let it rest for two minutes. Once it starts, it runs pretty good and idles fine, but if this problem remains, I know the starter isn't going to last long!

Can anyone help direct me on what to troubleshoot?