2013 maxforce 13.
3055 fmi 15
3055 fmi 0.
On the high way commanded fuel pressure is at 34,000 psi which the truck can do.
The actual fuel pressure will stay right with commanded for a good bit but without warning actual drops to 14,000 psi and never comes back up without key cycle.
Today I connected NED. I was watching commanded and actual and fuel delivery pressure what I noticed was floor the pedal and the fuel delivery pressure starts at 106 psi but slowly drops until it hits about 45psi.
My question is where is this fuel delivery pressure created? Is there another pump other then the high pressure?
Where is the sensor at for fuel delivery?
And why would it drop and stay there at 45psi give or take a few psi?
Maxforce 13 fuel issues
Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Transportauto, Nov 10, 2023.
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Swapped pump from a second truck, second truck had a locked engine so have no clue the fuel pumps condition.
Installed the new used pump now the truck gets up to about 5th gear once actual fuel pressure reaches 17,000 psi or so it drops on its face right down to 3,000 or so psi and 5% duty cycle of the fpcv. Let of and give it 50% throttle it immediately goes right back to commanded pressures 14,000 or so. Hammer it again right back to 3,000 psi.
Like clock work. Any advice? -
Low pressure fuel pump is part of the high pressure pump. Simple things first, new fuel filters? Low pressure system fuel delivery pressure sensor is located at the bottom of fuel filter module. Next step is fuel suction restriction and aeration testing. If you can look into the tanks, check for any foreign items in there swimming around that might be blocking a pick up tube. We have found some tricking items that very hard to see such as clear plastic wrap, water bottles that were cut in half and rags in fuel tanks to cause issues like this.
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Fuel rail pressure sensor replaced, no change
Low pressure or restriction Fuel senor replaced on filter housing, no change,
Doing the Fuel pressure test in NED it keeps up just fine and passes that test, driving this thing is a different story,
I plan to replace all the fuel lines tomorrow with new as it's a cheap repair when this truck probably is due for them anywayHeavyd Thanks this. -
Any update on your problem?
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Any updates? What about a fuel pressure regulator? I don't know, just guessing. I have been troubleshooting a low power problem for a long time.
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Can the fuel suction pull to hard on the first stage filter housing? I get aeration coming out of the Davco housing with the filter in it, if I remove the filter; no air. I have tried different filters, bypassing the fuel line coming from the tanks with a clear line, (no air). I have tried 3 different housings and they all do it. So with the filter in it is creating a vacuum strong enough to pull air in somewhere on the housing.
Can the pump be pulling to hard?Last edited: Feb 28, 2024
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You are likely seeing cavitation, not aeration. This can happen when there is high suction side restriction. Do you know what your suction side restriction is? It should not exceed 12" of Hg at idle, or 19" at full load.
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Many Thanks! -
The restriction is basically something blocking the flow of fuel. Anything inside a line, blockage, kink or simply a line or fitting that was replaced with one that is too small. Check your fuel pick up tubes in the tanks, make sure there is nothing inside the tanks getting sucked up to the bottom of the pick up tubes to cause fuel starvation.
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