Compression loss
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Stage IV
Joined: Oct 2017
Posts: 4
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From: SAN BERNARDINO CA
Compression loss
2014 DYNA FXDWG 103, 62,000 MILES: Riding down the freeway at 70 mph feels like somebody turned off the fuel, I would roll the throttle back and forth a few times and it would come back to life. It did it several more times, thought it was the fuel pump, but you can hear the pump pressurize when you turn on the ignition. Leaving work, got a few miles down the road and it started to do it again, this time I couldn't get it to come back to life. Sitting on the side of the road I cranked it over and it was like one cylinder had no compression. I tried it several more times and then it turned over with no compression, finally started up real rough and then started to knock real loud. The engine never made any noise, it was always surprisingly quiet. I pulled the rocker boxes and lifters, the valve springs look intact, lifters pump up good, cam lobes look very good (hardly any wear patterns), push rods straight. I was thinking that it could be the ACR's, but that wouldn't explain the loud knock. I haven't tried turning it over since I heard the knock.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,830
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From: poway
6 minutes is would be pretty quick response time.. Have you looked at the plugs?
Compression and fuel pressure need checking.. Simply because the pump runs is not a good indicator of fuel pressure.
Compression and fuel pressure need checking.. Simply because the pump runs is not a good indicator of fuel pressure.
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Stage IV
Joined: Oct 2017
Posts: 4
Likes: 0
From: SAN BERNARDINO CA
Follow-Up
Compression check, should have thought of that first. I will pickup a compression tester tomorrow, already have the fuel pressure gauge. Guess I will be busy Saturday. Thanks for your input, I will post my results soon. Thanks again.
Road Master
Joined: Dec 2008
Posts: 872
Likes: 20
From: Niagara Falls Canada
will need to unplug acr wire
remember when u do the test u will have to test with the acr working and then unplug it for the second test to see if its stuck open. not sure how the 2014 are wired I added acrs to my 2009 had to move wires around fuse box, not sure if taking fuse out of panel for fuel pump would kill power to them or not, in my case the rewire ties them to fuel pump, then purple wire to ecm modual activates them when starter hit. would be easier than pulling tank off, Ive always had mine off doing work so it was already off in my case . maybe pro drag or scott would know easier way to disable them without tank coming off to get at acr connection. oh shoot that reminds I need to call scott right now .
Last edited by 2009blackpearle; Oct 13, 2017 at 10:26 AM.
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Road Master
Joined: Nov 2015
Posts: 1,230
Likes: 380
From: georgia
A failed ACR will not result in zero compression. Your problem lies deeper if there's zero compression.
Last edited by jbarr1; Oct 13, 2017 at 11:15 AM.
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