DI fuel pump clatter
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Intermediate
Joined: Nov 2017
Posts: 32
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DI fuel pump clatter
Running Cam Motion cam with fuel lobe, had the same issue with Tx speed cam.
I have a clatter when there is back pressure on the valve train. When I gently accelerate to 2-3000 rpm and then barely back off the gas pedal. I also hear it on shifts.
Not at idle, or on hard acceleration.
Sounds like a rod knock, only in the valve train, like a rocker with too much lash.
With cam lobe at high lift, I can tighten the pump bolts all the way down without the gasket, so no fuel pump bind.
With cam lobe at low lift, I can see .035 of clearance between pump base and valley cover, so plenty of preload on fuel pump. there should be no excessive lash.
Is it possible the roller lifter/cam follower is not holding its lash adjustment, I assume this is a big hydraulic lifter with internal check valve and leak down clearance?
The pin holding the lash caps has .040 of movement in and out of lifter body. normal?
Weapon X sells a heavier spring, but have not been able to get any information on why they developed it.
WEAPON-X: High Pressure Fuel Pump Spring [Camaro Corvette CTS V, LT1 LT4 LT5]
Considering changing lifter/cam follower and fuel pump?
I have a clatter when there is back pressure on the valve train. When I gently accelerate to 2-3000 rpm and then barely back off the gas pedal. I also hear it on shifts.
Not at idle, or on hard acceleration.
Sounds like a rod knock, only in the valve train, like a rocker with too much lash.
With cam lobe at high lift, I can tighten the pump bolts all the way down without the gasket, so no fuel pump bind.
With cam lobe at low lift, I can see .035 of clearance between pump base and valley cover, so plenty of preload on fuel pump. there should be no excessive lash.
Is it possible the roller lifter/cam follower is not holding its lash adjustment, I assume this is a big hydraulic lifter with internal check valve and leak down clearance?
The pin holding the lash caps has .040 of movement in and out of lifter body. normal?
Weapon X sells a heavier spring, but have not been able to get any information on why they developed it.
WEAPON-X: High Pressure Fuel Pump Spring [Camaro Corvette CTS V, LT1 LT4 LT5]
Considering changing lifter/cam follower and fuel pump?
