Ive been having a beast of a time with this. Basically a PC75 has a tiny fuel filter before injection pump and thats it. Id like more filtering and ability to see water in a bowl. Ive already(in the past) added a filter on the pressure side;basically just ahead of the factory tiny filter. It works ok but has no bowl(its a retrofitted filter off a navistar/ford 6.9 idi)I soldered in a drain petcock so I can drain off any water.The zexel primary pump puts out 40 pounds and it seems most of the fuel filters Ive researched are not made for this kind of pressure.Not sure what happens if theres too much pressure but Id imagine that if filter became plugged it would burst the paper? Anyhow I had this Racor filter the kind that a bowl goes on the bottom of element.Says its for suction side only. Its an R26S or T element. Ive got a S on there(2 microns). I plumbed it into suction side but it wont work right. Often when I start engine I have to pump the primer pump to get pressure going. A PC 75 has a neat system where theres a low pressure electric pump that pumps along a separate path bypassing zexel primary pump if the zexel is not working,so engine never actually quits. (Ive got a fuel pressure gauge in cab so I know which system is pumping). Problem with running on the bypass low pressure system is that it has its own disposable hard to reach suction filter which eventually plugs.Also the electric pump may not like running all the time and it is lower pressure than the injection pump wants. I had the racor up high a bit above engine. It seemed to work not bad if fuel tank was full but its a flat tank under cab so there was not that much elevation difference full to empty,which was confusing.Half tank and Id have to prime every time I restarted engine.I moved filter lower(longer lines to suitable location near front of cab). I could not get it to work at all then. Seemed to be endless amounts of air.Got frustrated and abandoned the whole idea for now. Im no expert on these matters .Something tells me I had a vacuum leak. Id like to know if what Im doing is even possible. Can a suction filter be above everything?Is 2 microns too small maybe? I found some online talk about fine elements being harder to suck thru.The flow spec for this filter is multi gph, way more than I burn for sure so i wouldnt have thought thats a problem.Thinking as I m writing,I could rig up a vacuum gun to the racor filter on a test bench,see if it has an issue. I did have an outboard type primer bulb ahead of it which generated significant pressure when squeezed and there was no sign of leakage so thought it was all pretty tight.The primer bulb is of course another potential leak source tho I could not observe any leaks. Suggestions /answers welcome.
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