How to test whether fuel filter is clogged
I've had some trouble with the fuel quality while travelling in central/southern Asia over the past couple months. In another thread I mentioned that the original fuel pump was failing (overheating, it appears) and how I found what seemed to be a suitable Bosch replacement at a dealer in Bishkek. Well, that replacement failed in India. It went about 2,500 miles before dying outright.
I'd like to get some idea whether it died because it was working too hard to push fuel through a partially clogged fuel filter, whether the pump wasn't properly speced for the application (e.g. in terms of liters per minute), or something else. I want to do this to help me decide whether to spend $500+ getting a new pump/filter assembly to India or whether to keep experimenting with $40 pumps from Bosch.
I'd like to test whether the filter is shot, first. When I had the pump failures I pulled the hose off the pumps and blew through the hose into the filter and, after pushing the remaining fuel out the other end, air does pass through. I've tried the same blow test on a new, generic fuel filter that was about the same dimension and it had about the same resistance.
Is this a fair test? Is there some other test I could try?