Leak from behind CM870 fuel pump
08-31-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #1
Leak from behind CM870 fuel pump
Hello.I have a leak on the back end of my fuel pump just behind the fuel filter.There is two triangle shaped ports and it has a constant leak from one of them.Just discovered this morning in my pre-trip when I noticed two drips of fuel on the block and a weird idle at startup


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08-31-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #2
RE: Leak from behind CM870 fuel pump
So I found a picture of the two triangle pieces that are leaking.What are those and is the leak common?


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08-31-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #3
RE: Leak from behind CM870 fuel pump
Yeah it’s pretty common, cheap fix just a few gasket, but the whole ISFM does need to be removed. Take your time, clean everything nicely before putting it back together, torque the bolts and use anti seize


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 Thanks given by: Redland1
08-31-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #4
RE: Leak from behind CM870 fuel pump
Those triangle pieces are dampers for the fuel solenoids to help them with a more consistent plunger operation.


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 Thanks given by: Redland1
08-31-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #5
RE: Leak from behind CM870 fuel pump
(08-31-2023 )Andre_The_Giant Wrote:  Yeah it’s pretty common, cheap fix just a few gasket, but the whole ISFM does need to be removed. Take your time, clean everything nicely before putting it back together, torque the bolts and use anti seize

Hopefully I didn’t mess them up I tried tightening them to see if the leak stopped
.
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09-01-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #6
RE: Leak from behind CM870 fuel pump
Once the damper’s are reassembled is there supposed to be a little gap between both covers?
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09-01-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #7
RE: Leak from behind CM870 fuel pump
Can u take a pic? I’m sure it’s fine it would be pretty hard to f them up


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 Thanks given by: Redland1
09-01-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #8
RE: Leak from behind CM870 fuel pump
(09-01-2023 )Andre_The_Giant Wrote:  Can u take a pic? I’m sure it’s fine it would be pretty hard to f them up

I looked and they weren’t cracked.Got the O-ring’s and diaphragm replaced.Tested the truck for about 15-30 minutes today and it didn’t leak.Goong to take it down the road tomorrow and see what it does.
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 Thanks given by: Rawze , Andre_The_Giant
09-11-2023, (Subject: Leak from behind CM870 fuel pump ) 
Post: #9
RE: Leak from behind CM870 fuel pump
Was just thinking about this today and remembered that 2 weeks prior to the leaks I started to use Fuel OX Asphaltene additive to try and keep Asphaltene at bay.Could this have caused the O rings to go bad or was it just age?
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