Ken K
I'm Awesome
When it comes to trucks, the CAFE & DOT place them into different categories. In the world of OBD-II, misfire is the worst offence to emissions. The application of fuel pumps experienced a serious change in 1992 when on board computer controlled engine controls began. Electric fuel pumps where on a stick, referencing the top of the tank. The problem is when the tank is low and fuel sloshes off to the side in turns or hard acceleration, air is introduced, volume drops and pressure is reduced, causing lean spray & misfire...and CEL.
Then came the "Bucket Type" or "Modular Reservoir Assembly" (MRA) uses a catch basin to keep a constant supply of fuel to cool and lubricate the pump and allow air out. This is bottom referencing, with two designs. First design is has with a simple inlet and sock, while the second design uses a small high pressure bleed, into a hose to a brass venturi on the bottom that creates a low pressure, drawing fuel into the bucket. These types have two filters or socks.
The problem of check engine lights due to lean misfire was so bad that manufactures ask for and got a the misfire parameters reduced in 1997. This was a software change between the number of detected misfires, crank sensor variation and CMP helping to find the offending cylinder(s).
So now what? As trucks are sold and many countries and fuel is not same, nor clean, leds to pump codes and descriptions like "Robust" that changes to type of pump and components.
Dirt is the villain. If you calculate the MPG, current miles on the vehicle, divide to estimate how many tanks of gas have been pumped over the years? Carb guys, for years have cut open paper filters to find dust / dirt inside the filter you can not blow thru. It comes a little at a time, when you pump gas, so it adds up and remains in the tank, require cleaning or face a new fuel pump that fails quickly. The procedure to clean the tank, is to properly drain & dispose of fuel. Fill tank with HOT water, shake vigorously, drain and dry.
What to look for? MRA's have two filters or socks. One is inside on the pump. A pocket screw drive and three tabs will allow most pumps to be removed to see inside the bucket. Attached are a few photos of field shots as to get warranty, the card in the box requires inspection and action. Warranty is declined if contaminated.
Then came the "Bucket Type" or "Modular Reservoir Assembly" (MRA) uses a catch basin to keep a constant supply of fuel to cool and lubricate the pump and allow air out. This is bottom referencing, with two designs. First design is has with a simple inlet and sock, while the second design uses a small high pressure bleed, into a hose to a brass venturi on the bottom that creates a low pressure, drawing fuel into the bucket. These types have two filters or socks.
The problem of check engine lights due to lean misfire was so bad that manufactures ask for and got a the misfire parameters reduced in 1997. This was a software change between the number of detected misfires, crank sensor variation and CMP helping to find the offending cylinder(s).
So now what? As trucks are sold and many countries and fuel is not same, nor clean, leds to pump codes and descriptions like "Robust" that changes to type of pump and components.
Dirt is the villain. If you calculate the MPG, current miles on the vehicle, divide to estimate how many tanks of gas have been pumped over the years? Carb guys, for years have cut open paper filters to find dust / dirt inside the filter you can not blow thru. It comes a little at a time, when you pump gas, so it adds up and remains in the tank, require cleaning or face a new fuel pump that fails quickly. The procedure to clean the tank, is to properly drain & dispose of fuel. Fill tank with HOT water, shake vigorously, drain and dry.
What to look for? MRA's have two filters or socks. One is inside on the pump. A pocket screw drive and three tabs will allow most pumps to be removed to see inside the bucket. Attached are a few photos of field shots as to get warranty, the card in the box requires inspection and action. Warranty is declined if contaminated.
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