Loss of Compression/Fuel Starvation?

N

npvos

Member
Apr 6, 2016
16
0
Birmingham, AL
Howdy,

I have a 97 Disco. I love it, but recently I've been having some issues with it losing compression while driving. It will slowly begin to die/drop power...and occasionally die. Historically this problem arose after driving a long time and then turning the disco off for a minute and trying to start back up...just would starve itself. That hasn't happened in a long time. However, now it just will randomly have moments of dropped compression where it feels like it has run out of fuel (while driving). Could this be a fuel pump issue, or possibly a clog in the line somewhere? Maybe a misfire/foul in another system? Any help/insight would be appreciated. Thanks!

-Nate
 
p m

p m

Administrator
Staff member
Apr 19, 2004
15,651
869
58
La Jolla, CA
www.3rj.org
How on the Earth can you make a conclusion that an engine is losing compression without a compression gauge? Besides, if an engine loses compression, it ain't coming back up.

If the engine feels like it dies for a second or two, then comes back - disconnect your Vehicle Speed Sensor (that blob of grease on the side of transfer case) and recheck. You'll lose the speedometer for the duration of the test.

If the engine loses power for extended period of time and is difficult to restart - it's a different story. A pressure gauge connected to the Schrader valve on the fuel rail (right side of the intake plenum, about 1/3 of its way back from the front) will tell you most of what you need to know.
 
WaltNYC

WaltNYC

Well-known member
Mar 3, 2010
714
142
NYC
+1. Check the VSS. When they get old they have been known to send bad data to the ECU making it seem as if the truck is traveling more then 120MPH. The ECU retards ignition until the speed falls back into range. If you have a smart phone check out the thread regarding getting live data from the OBD port and you'll see it.
 
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