Can you reference the material that specifies a 20-40 micron pre-filter? Everything I've seen for that mentions a 100-120 micron size.
Thanks,
Todd Z.
It's complicated but I'll do my best. I've spent the last 3 days trying to design this system (2 tanks) and have talked with a lot of people. I'm using the set-up Holley sells for their Sniper, but I sourced it independently. Thus I'm using a Walbro GSL392. The independent retailer I used for Walbro states on their website 20-40 Microns pre pump because Walbro has you send your pump AND filter back for warranty claims and if it turns out you used the wrong filter, they'll deny. I called Jeff (the product manager) at Peterson Co (US Walbro wholesaler distributor) and he says it's not so clear cut. They officially VERBALLY recommend 40-100 microns, but prefer 20-40. It's not published anywhere. My retailer says 20-40 because he's never had a problem with a warranty claim if you're using that size. So I went with what my retailer said to use. No difference in cost.
For the Bosch 044 or 69100 it's a similar story with slightly different numbers. No published rule except using a pre-filter. Retailers suggest 40-100 microns, but if you have a warranty claim, you must send your filter with the pump. What they told me is they've had claims rejected by Bosch because it wasn't a maximum of 40 microns and some accepted that were 100 microns.
It seems like the manufacturers like to keep it a grey area to give them more leeway to deny claims.
While it sounds like simply being bully corporations, Walbro told me 98% of pumps sent back weren't defective. It's a clogged fuel filter that's the problem. So they make you now PAY $40 to test it. If it's a faulty pump, you get a new pump and your $40 back. This has cut the number of pumps sent in, but even the ones now sent in STILL mostly have no problem with the pump.
Your 69100 is a standard pump used on millions of cars from the factory. They come with 100 micron from the factory.
Are you dizzy now? So I'm running an entirely new fuel system. I didn't want to restrict fuel flow with something too small, but I didn't want to have a problem with warranty. So 20 microns was what they said. They said with my set-up even 40 would be OK since the chance of dirt in a new system is limited. With an older system, 70-100 is acceptable since you'll have more of a chance of rust and dirt (bigger sized particles), but then it's a grey area on warranty. If your filter gets clogged and starves the pump, no warranty.
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