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1986 Unimog U1700L (435 series)
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305 Posts
Discussion Starter #1 (Edited)
Hello everyone,
Has anyone tried adding a fuel pressure sensor just after the lift pump ? I'm thinking it might be a useful parameter to monitor in case of blockage or the overflow return valve plays up.

Does anyone know the easiest point to connect a sensor, maybe one of the filter housing air bleed points?
I'm unsure if the bleed points are after the filter element or before it. After the filters would be best. Or perhaps the injection pump input bleed point should be used?

I am led to believe (Wikipedia) that the pressure to expect is 20psi at idle and up to 27psi at revs.
I could fit a Tee. One leg for the bleed the other leg for the pressure sensor.

Does anyone see any draw backs to doing this?
 

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Registered
1986 Unimog U1700L (435 series)
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305 Posts
Discussion Starter #2
The air bleeds in the top of the fuel filters holder measure as M8 x 1.25. Cannot find any pressure sender of this thread nor any adapter. May have to give this idea a miss.
 

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Premium Member
U1000Ag
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2,257 Posts
I suspect your lift pump is much the same as mine -from what I can recall, 4psi at idle and that is what mine was last time I checked it. Not worth worrying about. If you are concerned, just buy a new lift pump and be done with it.
Just checked my older post when I changed injectors, 15psi.
 

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Registered
1986 Unimog U1700L (435 series)
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305 Posts
Discussion Starter #4
Hi Krietpiel,
I was thinking more about monitoring for pressure drop, i.e. to detect if the filters start to block up from a dirty load (too much work to fit differential monitoring). I'm not sure where the filter canister holder bleed points are connected anyway, and I'm not prepared to pull it down to figure it out. I do have an independent water filter with alarm sensor pre-the standard filters, so this might have to do me.
 
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