Diesel Injection Pump Repair, Matched to the Pump on Your Truck
Diesel injection pump repair is never one job, because a P7100, a VP44, a CP3 and a CP4 fail for different reasons. We prove it is really the pump before we talk options.
Four pumps and one oddball
The injection pump pressurizes fuel for the injectors. How it does that depends on the truck.
| Pump | Trucks | How it works | What usually takes it out |
|---|---|---|---|
| Bosch P7100 | 1994 to 1998 12-valve 5.9 Cummins | Inline mechanical pump | Age: weeping seals, supply problems, miles |
| Bosch VP44 | 1998.5 to 2002 24-valve 5.9 Cummins | Electronic rotary pump cooled by the fuel it moves | A weak lift pump, heat and failed pump electronics |
| Bosch CP3 | LB7, LLY, LBZ and LMM Duramax; 2003 to 2018 Cummins | Common-rail pump | Water, dirt and air in the fuel; the pump itself is well regarded |
| Bosch CP4.2 and CP4 | 2011 to 2016 LML Duramax; 6.7 Powerstroke since 2011; 2019 and 2020 6.7 Cummins | Common-rail pump with tighter lubrication margins | Poor lubrication or contamination; failure can spread metal through the system |
| HEUI (no injection pump) | 7.3 and 6.0 Powerstroke | The HPOP pressurizes engine oil to fire the injectors | Oil pressure leaks, the IPR valve and, on the 6.0, the FICM |
The pump is one part of diesel fuel system repair. A starved pump looks bad, and a smoking, missing truck may need diesel injector replacement instead.
How each pump fails and what we check
Not sure which pump you have? Use the table above or call us.
Bosch P7100 on the 12-valve Cummins
The P7100 is an all-mechanical inline pump with no electronics to fail, and a healthy one is known for running a very long time. Trouble usually means age: weeping seals, weak supply or high miles.
We check supply, leaks and fueling before anyone talks about pulling it. More on our 5.9 Cummins repair page.
Bosch VP44 on the 24-valve Cummins
The VP44 is the Cummins pump with the most failures, and the reason is often a weak fuel supply. It uses diesel to cool and lubricate itself, so a weak lift pump or plugged filter cooks it. When the electronics on the pump fail, the truck can stall, lose power or refuse to start.
We measure supply pressure, check wiring and read codes first.
Bosch CP3 on Duramax and Cummins
Plenty of CP3 trucks that come in with low rail pressure have a healthy pump. Air in the supply, a restricted filter, a regulator problem or injectors returning too much fuel all pull pressure down.
We check rail pressure under load, supply and injector return before replacing a CP3. Generation detail is on our Duramax repair page.
Bosch CP4.2 and CP4
A failing CP4 can send metal into the rail, the lines and every injector, so it gets a contamination check before any quote. The 2017 and newer L5P uses a Denso pump, and pumps were revised over the years on other platforms, so we confirm the pump on your truck first.
LML owners should read our Duramax CP4 pump replacement page.
HEUI on the 7.3 and 6.0 Powerstroke
The 7.3 and 6.0 have no injection pump. The HPOP pressurizes engine oil, the IPR valve regulates it, and that oil fires the injectors.
We test injection control pressure, oil leaks and, on the 6.0, the FICM before anyone blames injectors. Every Ford generation is on our Powerstroke repair page.
What a failing injection pump feels like
None of these prove the pump is bad.
Hard start or no start
Long cranks or no fire. The pump may not build pressure at cranking speed.
Power falls off under load
Fine empty, gutless with a trailer. A worn pump falls short at full demand.
Stalling or dying at idle
A classic VP44 complaint, and a sign of air or poor supply on common-rail pumps.
Rail pressure codes
P0087 says rail pressure came in low, not why. The cause can be anywhere from tank to injector.
Fuel leaks at the pump
Wet fittings or a fuel smell, often the first sign of age on older pumps.
Metal in the fuel filter
On a CP4 truck, metal in the filter or fuel sample is a warning the pump may be coming apart, and a clean filter does not rule it out. Stop driving and call.
How we handle a pump job, start to finish
Every pump job runs through the same four checks, in this order, before any part is ordered.
Identify and scan
Confirm the pump, then pull codes and pressure data on OEM factory scan tools.
Prove the supply
Lift pump pressure and volume, filters, water contamination, and leaking fuel lines or a pickup tube letting air into the system. We also run a bypass or leak test on the injectors, because leaking injectors can look like a failing pump.
Test the pump
Pressure under load, metering control and leaks. On HEUI trucks, oil pressure and the IPR.
Check for spread
A cut-open filter and fuel sample show whether water or metal moved downstream.
Why two pump jobs rarely cost the same
A pump complaint can end in a lift pump and filter, or a pump, rail, lines and injectors. Testing decides which.
- Which pump your truck runs, and what new or remanufactured units are available for it
- Whether the failure stayed in the pump or spread metal downstream
- How much has to come apart to reach and time the pump
- Nearby repairs where doing them together saves labor
"I can’t say enough good things about Bodacious Diesel. They’re team is knowledgeable, honest, and incredibly thorough. They took the time to explain exactly what was going on with my truck, gave clear options, and never tried to upsell unnecessary work. The repairs were done right and at a fair price. You can tell they genuinely care about their customers and take pride in their work. If you’re looking for reliable diesel mechanics you can trust, Bodacious Diesel is the place to go."Scott Campbell, Google review
Cold mornings, long grades and how the visit goes
Where Colorado changes the job
Cold starts find weak parts first. A diesel needs compression heat to light the fuel, so on Ford and Chevy trucks a cold start depends on healthy glow plugs as much as fuel, and HEUI trucks rely on them even more. A tired VP44 or a CP3 pulling air can fire on the first crank all summer and crank for a long time on the first zero-degree morning. On HEUI trucks, cold, thick oil builds injection pressure slowly.
Towing up I-70 or any long Front Range grade holds the pump at high demand for miles. A marginal pump or half-plugged filter can show up there as low power or a rail pressure code.
What to expect at the shop
Most pump work is drop-off. Diagnosis typically takes 24 to 72 hours depending on workload. Then you hear what needs attention now and what can wait. No work is done without your approval. More on our what to expect page.
Trucks come to Golden from across the Front Range and down from the mountains with fuel and pump failures their local shop could not pin down.
Tell us what your truck is doing
Send the year, the engine and what you are seeing, and we'll get back to you as quickly as we can.
- Year, make and engine
- What it is doing, and when it started
- Any codes or recent repairs
Rather talk it through? Call (303) 808-1563
Injection pump questions owners ask us
Straight answers to what comes up on the phone before a pump job.
LB7 through LMM Duramax and 2003 to 2018 Cummins run a CP3. The LML Duramax and the 6.7 Powerstroke, since 2011, run a CP4.2, and the 2019 and 2020 6.7 Cummins a CP4. Call with your engine and year to confirm.
Those engines do not have one. Engine oil pressurized by the HPOP (high pressure oil pump) is used to pressurize the fuel inside each injector, and the IDM or FICM fires the injectors. We test injection control pressure, the IPR and, on a 6.0, the FICM before replacing anything.
We test it first, and a weak one gets dealt with on the same job. The VP44 depends on the lift pump for supply and cooling. Skip that check and the new pump is at risk from the first mile.
Diagnosis typically takes 24 to 72 hours depending on workload. After that, repair time depends on the pump, whether contamination spread and how fast parts arrive.
Plenty of Bodacious customers think so, mostly for the failures a local shop could not pin down. Pump work is where testing pays off: a starved VP44 or a CP3 pulling air looks like a dead pump until someone measures supply and rail pressure. The shop sits at the base of the foothills, an easy run from the mountains or anywhere in the metro.
Think the pump is going? Tell us what the truck is doing
Call with your engine, year and symptoms, or use Request Service to send the details. Or drop us a line right here from the website and we'll get back to you as quickly as we can.