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ISM CM870- fuel pressure - Printable Version

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ISM CM870- fuel pressure - swenlarson - 06-28-2020

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


RE: ISM CM870- fuel pressure - tree98 - 06-28-2020

When's the last time the fuel filter was changed? Although you should get a code for that.


RE: ISM CM870- fuel pressure - swenlarson - 06-28-2020

Filter was changed recently- had problem before and after change.


RE: ISM CM870- fuel pressure - Rawze - 06-29-2020

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.


RE: ISM CM870- fuel pressure - SquareOne - 06-29-2020

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


RE: ISM CM870- fuel pressure - swenlarson - 06-29-2020

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


RE: ISM CM870- fuel pressure - Lonestar10 - 06-29-2020

Could be air or pump when things get hot cool down and reseal if there's not a restriction


RE: ISM CM870- fuel pressure - swenlarson - 07-28-2020

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


RE: ISM CM870- fuel pressure - Zocaid - 11-01-2023

(06-28-2020 )swenlarson Wrote:  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

How often did it start acting up on you and what did it take to start running good again before you finally fixed the issue. I have an issue I cannot figure out.