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+--- Thread: Possible lift pump problem??? (/showthread.php?tid=1828)
RE: Possible lift pump problem??? - Rawze - 06-11-2017
Just a note... It is quite often that when the electric fuel pump starts failing, it puts metal shavings into the fuel lines feeding the gear pump. -- This leads to a failure of the gear pump a short time after the electric fuel pump is replaced.
I state this so that someone can be prepared for that day their engine will not start and they can't figure out why after replacing the electric pump. When the gear pump goes bad, you usually only get less than 50 psi or so at the fuel pressure sensor while cranking. This can be seen in insite. My CM871 is about 170 psi during cranking if someone is looking for as reference value to compare to.
RE: Possible lift pump problem??? - Nilao - 06-11-2017
Some blow from old age. The metal degrades till it no longer meets its rated amperage and blows. If the new one blows fast it's probably a bad pump.
RE: Possible lift pump problem??? - DKenworth - 06-12-2017
There is a fuse and relay for lift pump. They are all located between ECM and pump itself, im pretty sure it one of them. If not fuse, grab a screew driver and easy knock on relay. If u cant find relay let me know ill send you a picture.
RE: Possible lift pump problem??? - tree98 - 06-12-2017
Checked the fuse, wasn't blown. Tapped on the relay, nothing happened. What now?
RE: Possible lift pump problem??? - hhow55 - 06-12-2017
(06-12-2017 )tree98 Wrote: Checked the fuse, wasn't blown. Tapped on the relay, nothing happened. What now?
Replace the relay, they do fail. i recall my situation with several relay's going bad. When i replace all the relay's on mine, problem's went away.
RE: Possible lift pump problem??? - tree98 - 06-12-2017
(06-12-2017 )hhow55 Wrote:You said you replaced "all The relays" is there more than one for the lift pump?(06-12-2017 )tree98 Wrote: Checked the fuse, wasn't blown. Tapped on the relay, nothing happened. What now?
Replace the relay, they do fail. i recall my situation with several relay's going bad. When i replace all the relay's on mine, problem's went away.
RE: Possible lift pump problem??? - hhow55 - 06-12-2017
(06-12-2017 )tree98 Wrote:(06-12-2017 )hhow55 Wrote:You said you replaced "all The relays" is there more than one for the lift pump?(06-12-2017 )tree98 Wrote: Checked the fuse, wasn't blown. Tapped on the relay, nothing happened. What now?
Replace the relay, they do fail. i recall my situation with several relay's going bad. When i replace all the relay's on mine, problem's went away.
Not that i know of.
RE: Possible lift pump problem??? - tree98 - 06-13-2017
I checked the wiring today, I'm getting 12V to pin 85 of the relay for about a minute after I turn the key on then it goes out. No power to any other pins. Shouldn't there be a constant 12V to one of the relay pins?
RE: Possible lift pump problem??? - Hammerhead - 06-13-2017
No it should not be continuous.
It has a "timer" for the lift pump. Its purpose is to remove any potential air from the system, as air is very bad in injectors. After one minute or so, the system should be cleared of any air and no longer require the assistance from the lift pump, which is why the ECM then stops power supply.