ISM CM870- fuel pressure
06-28-2020, (Subject: ISM CM870- fuel pressure ) 
Post: #1
ISM CM870- fuel pressure
Hi there- 2004 International 8600 with an ISM CM870.

Has a no code low power issue- hooked up fuel pressure gauge and took down the road. When driving and it run good pressure is like 160-225. When it becomes a dog fuel pressure drops to as low as 90-100. Let truck sit pressure comes back, always have to drive for a while before it messes up. Had vac guage on suction side of pump system and vacuum stays 1-2" no matter what happens. Is the pump repairable or must I replace? Any suggestions?

Thanks
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06-28-2020, (Subject: ISM CM870- fuel pressure ) 
Post: #2
RE: ISM CM870- fuel pressure
When's the last time the fuel filter was changed? Although you should get a code for that.


User's Signature: Warranty??? Yeah right, I am the warranty!!!
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06-28-2020, (Subject: ISM CM870- fuel pressure ) 
Post: #3
RE: ISM CM870- fuel pressure
Filter was changed recently- had problem before and after change.
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06-29-2020, (Subject: ISM CM870- fuel pressure ) 
Post: #4
RE: ISM CM870- fuel pressure
truck being that old, it may be a lot of things... things like collapsing fuel lines, sucking air, leaky injectors, trash in tanks clogging pick-up tubes once in a while then settling again,.. faulty shut-off solenoid or other fuel related component like mentioned ... a lot of things.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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06-29-2020, (Subject: ISM CM870- fuel pressure ) 
Post: #5
RE: ISM CM870- fuel pressure
Have you checked the vents at the tank? Sounds simple, but I had a bee build a small nest on the vent of my driver tank, causing the passenger tank to suck down faster damn near running it dry. (I thought I was just getting phenomenal fuel mpg since my sending unit is in the driver side lol)

If you have a similar situation and the other tank vent is partially clogged, it may be creating a vacuum while driving, but slowly equalizing the pressure when the engine is shut off...

Sounds simple but I'd prolly look for simple 1st being that the truck is 16y/o
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 Thanks given by: tree98 , Rawze
06-29-2020, (Subject: ISM CM870- fuel pressure ) 
Post: #6
RE: ISM CM870- fuel pressure
Hi all,

I have a few things to go back over- had vac gauge on intake side of pump and 1-2" of vacuum was pretty much the MAX reading (while crapping out) so I do not suspect a clog or the like.

That being said I will carefully inspect... one thing I did not consider was a weak shutoff solenoid. Not really sure of any way to test that but I will watch the voltage to it to make sure I do not have a problem with that.

Northern truck- rusty plow truck- so anything is possible. I know I am on the right track just looking for enough evidence to condemn or not condemn the fuel pump.

Swen
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06-29-2020, (Subject: ISM CM870- fuel pressure ) 
Post: #7
RE: ISM CM870- fuel pressure
Could be air or pump when things get hot cool down and reseal if there's not a restriction


User's Signature: 2010 Lonestar - CM871 - 13sp - 3.70s, 2016 T680 - cm2350 - 13sp - 3.36s - skateboarder
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07-28-2020, (Subject: ISM CM870- fuel pressure ) 
Post: #8
RE: ISM CM870- fuel pressure
Hi all- update on this one.

Wanted to investigate fuel pump assembly along with shutdown solenoid. Unit was crusty/rusty (due to this being a truck with a salt/sand spreader). Once overall condition was clear (bolts frozen for solenoid and other parts looking ready to disintegrate) discussed options with customer and he decided to replace pump assembly with a REMAN unit. This unit included a new shutdown solenoid.

After multiple test drives with a gauge hooked up pressure pretty much stayed around 225-250 and low power issue is now gone.

I am not sure if was a weak solenoid or the pump itself but the pump and the solenoid were very corroded, in poor condition from a visual standpoint and obviously one of the two items was the cause of the problem.

This one appears to be FIXED.

Swen
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 Thanks given by: Rawze





  
  
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