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Cummins 3966154 is the mechanical diaphragm fuel lift pump: the aluminium body with the domed diaphragm cover, the rocker arm that rides on the camshaft, the hand priming lever and the mounting gasket. It is used on Cummins B Series engines. This aftermarket version is made to the same mounting and connections as the original, so it fits where the old one came off.
The same part is also sold as Cummins 3970880 and Cummins 4983584.
Sold as one unit. Check the number on your old part, or in the parts manual for your machine, before ordering.
| Part Type | Fuel Lift Pump |
| Replaces | Cummins 3970880 |
| Type | Fuel lift (transfer) pump, mechanical |
| Engine | Cummins 4B, 4BT, 4BTA, 6B, 6BT, 6BTA |
| Includes | Mounting gasket |
| Cross references | Cummins 3966154, Cummins 4983584 |
| Fits | Cummins 4B, 4BT, 4BTA, 6B, 6BT and 6BTA engines |
| Condition | New, aftermarket |
| Stat. HS-Code | 841330 |
| Country of Manufacture | China |
Cummins machines
Check the part number on your old unit before ordering.
| Cummins Part No.(SPM Part No.) | Fits |
|---|---|
| 3970880(SPM-HEP-5264) | Cummins 4B, 4BT, 4BTA, 6B, 6BT and 6BTA engines |
| 3966154(SPM-HEP-5264) | Cummins 4B, 4BT, 4BTA, 6B, 6BT and 6BTA engines |
| 4983584(SPM-HEP-5264) | Cummins 4B, 4BT, 4BTA, 6B, 6BT and 6BTA engines |
Hard starting
A weak lift pump starves the injection pump. Long cranking after standing is a common sign.
Loss of power under load
If the engine pulls well when light but dies off under load, check fuel delivery and the lift pump.
Leaks
Fuel weeping from the pump body or seals means it is time to replace it.
Bleeding the system
Prime and bleed the fuel system after fitting the new pump.
We check what other aftermarket sellers charge for this same part. Their prices on the date we checked:
| Seller | Price | Checked |
|---|---|---|
| eBay, aftermarket seller | USD 28.97 | 3 Nov 2026 |
| FridayParts | USD 30.38 | 3 Nov 2026 |
| All Aftermarket Parts | USD 45.00 | 3 Nov 2026 |
| WDPART | USD 52.80 | 3 Nov 2026 |
| YEMPARTS | USD 85.80 | 3 Nov 2026 |
| Spare Part Mart | USD 18.39 | Today |
Our price of USD 18.39 is 37% to 79% less than these sellers.
Found this part cheaper somewhere else? Send us the listing and we will beat it by 5% under our Price Beat Guarantee. Every order is also covered by our 30 day money back guarantee.
Yes, it was made for the Cummins 4B, and 4 more listed under compatible equipment. Check the old fuel pump is marked 3966154 or one of the cross references, because makers change parts between serial ranges.
On the Cummins 4B, often 5,000 to 10,000 hours with clean fluid, much less with dirt or air in the system. It is usually changed on condition, not by hours.
Leaks from the seal or weep hole, noise or whining, overheating, or falling pressure or flow under load.
Most failures come from contamination, cavitation from a restricted inlet, or running low on fluid. Check the inlet and the fluid before fitting the new fuel pump.
Clean them right back to metal and fit the new gasket or O-ring dry, unless the engine manual calls for sealant.
No. It is an aftermarket fuel pump made to replace the Cummins 3966154. It is not made by the original manufacturer; the number only shows what it replaces.
Live rates for the quantity selected, delivered to your door. Confirmed at checkout.
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