Engine/Transmission (1998.5 - 2002) I have new info on 24V LP issues...

[NoSeeUm]

BECAUSE any pump outside the tank depends ONLY on atmosphereic pressure to get the fuel to the pump. So if the pump pushes the fuel faster than the suction line can flow it,it cavitates and frothes the fuel. If the pump is in the tank it does not have to draw it thru a long section of restrictive line,the only other way is to install a bigger line into the tank. Mopar has concluded that the old fuel module cannot flow enough fuel for 235hp.

I just got back to this thread and this is for sure interesting, and the second time that you mention it. Not sure if it has been tossed around much on TDR, but it is the first time I have read about this. Nor have I given it much thought.



How long does it take the frothing to show up at the filter or the VP suction banjo? On a stock fuel tubing system, lets say you have disconnected the the fuel line at the VP and just let the LP run. Would this be the worst case for a situation to create frothing? I suppose fuel temperature would have a significant effect?



I can see the lowest differential pressure existing across the LP at idle, I would guess roughly 16 psid. But at higher VP demands the LP discharge pressure drops as well as the suction pressure. Overall I would think that the differential pressure across the LP would rise by quite a bit, maybe go as high as 25 psid at WOT. This would be pulling fuel through the suction tubing at maximum capability. To me, this would seem unlikely for a more or less "designed" stock fuel system? If I read correctly, you say Dodge acknowledges this is in fact the case? Hence the in tank pump?



Combine cavitation from froth with an increasing D/P, especially suction pressure going to a pretty good vacuum. Well, that really can't be too good for it. Who knows how much froth is passed on to the VP, which can't really be all that healthy for it either.



Thanks;

Jim

 

[Bob4x4]

I just got back to this thread and this is for sure interesting, and the second time that you mention it. Not sure if it has been tossed around much on TDR, but it is the first time I have read about this. Nor have I given it much thought.



How long does it take the frothing to show up at the filter or the VP suction banjo? On a stock fuel tubing system, lets say you have disconnected the the fuel line at the VP and just let the LP run. Would this be the worst case for a situation to create frothing? I suppose fuel temperature would have a significant effect?



I can see the lowest differential pressure existing across the LP at idle, I would guess roughly 16 psid. But at higher VP demands the LP discharge pressure drops as well as the suction pressure. Overall I would think that the differential pressure across the LP would rise by quite a bit, maybe go as high as 25 psid at WOT. This would be pulling fuel through the suction tubing at maximum capability. To me, this would seem unlikely for a more or less "designed" stock fuel system? If I read correctly, you say Dodge acknowledges this is in fact the case? Hence the in tank pump?



Combine cavitation from froth with an increasing D/P, especially suction pressure going to a pretty good vacuum. Well, that really can't be too good for it. Who knows how much froth is passed on to the VP, which can't really be all that healthy for it either.



Thanks;



Jim

Put a clear plastic line in series and you will see that there is no frothing



unless you have leaks,it sounds like some of you think That cummins engineers are babbling idiots :-laf :-laf



Bob

 

[Huff N Puff]

Put a clear plastic line in series and you will see that there is no frothing



unless you have leaks,it sounds like some of you think That cummins engineers are babbling idiots :-laf :-laf



Bob

Bob do you have that line on the steering wheel with you so you can look at it under all driving conditions from idle to wide open throttle I have'nt put a clear line in series but I have put the supply line into a pan and saw alot of frothing of the fuel. :-laf

 

[NoSeeUm]

Put a clear plastic line in series and you will see that there is no frothing



unless you have leaks,it sounds like some of you think That cummins engineers are babbling idiots :-laf :-laf



Bob

No not really Bob, but this is not stacking up so well.



Jim

 

[NoSeeUm]

Bob do you have that line on the steering wheel with you so you can look at it under all driving conditions from idle to wide open throttle I have'nt put a clear line in series but I have put the supply line into a pan and saw alot of frothing of the fuel. :-laf

Hmm.....



This should be pretty common knowledge then, especially with the number of LP volume checks that are / were being done in diesel shops.



Funny to read about it just now. I think I'll just take the blue pill and maybe not care to know how deep the rabbit hole goes.



Jim