I have a 2006 Harley Davidson Ultra Classic with an oil pressure problem. When I start the engine sometimes it will not build oil pressure at all. If I do not see the oil pressure guage rise I will shut it off and start again. Sometimes it will build on the second or third try and once in a while it has taken up to 13 times before it builds pressure. A few times it has actually lost it's pressure slowly while riding and I will shut it off and restart and it will build it's pressure up again. There is no pattern to this, (temperature ambient or engine), oil type (I've tried synthetic, petroleum based, lighter and heavier weight). The oil pump has been changed to a high volume pump by Fueling with a matching Cam plate (contains the pressure release valve). Still have the problem. The pressure sending unit has been tested and replaced just to make sure. I have installed a mechanical guage to verify against the electronic, they are equal. I replaced the 2 hoses between the tank and engine casing. If the engine is let to run with no pressure readings the top end will get noisy so I'm positive it is a pressure problem not a reading problem. I removed the pump a second time to ensure the installation is correct and still have this problem. I have tried different oil filters. I need a new idea since I will be working on it again soon.
Make: Harley Davidson
Model: Ultra Classic
Engine: 80 ci
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you have covered all the usual suspects.
verify your breathers are not restricted.
at this point I would also recommend dropping the oil pan and checking for an obstruction at the feed port and also at the feed inlet to the engine, and the passage between the inlet and the oil pump/cam plate.
it sounds like the feed is obstructed or air bound.
in fact....the first thing I would do is pressurize the oil pan through the dipstick hole while cranking the engine and see if your problem doesn't go away. use no more than about 5 psi. wrap a rag around a compressor nozzle to get a "tight-ish" fit in the hole. most tech's have a dipstick cap with a hole drilled in it just for this purpose.
30+YRs,MMI,HD tech,HD early,engine rebuild/perf,bike builder,kit bike program manager, cci 2001-2004