On this page
Diesel injection pump repair at Route 66 Auto Repair in Upland is for trucks whose single pump meters and times fuel for every cylinder, common on older diesels and early electronic engines. A tired pump leaks, starts hard when hot, smokes or loses power. Our ASE-certified technicians confirm the pump is the cause, then quote repair or a replacement pump, and your written estimate shows every step.
How is an injection pump different from a common rail pump?
On a common rail engine, a high-pressure pump fills a shared rail and the computer fires each injector. On many older diesels, the injection pump does the metering and timing itself, then sends fuel through individual lines to mechanical injectors. That makes the pump the heart of the fuel system, and its seals, governor and timing mechanism all wear with age and heat.
Owners of these trucks tend to keep them a long time, and many have heard stories of pumps that failed suddenly. Most give warning signs first.
What are the signs of a failing injection pump?
- Fuel weeping from the pump body or throttle shaft
- Hard starting when the engine is hot
- White or gray smoke with a clatter that sounds off-time
- Surging idle or hunting at steady speed
- Loss of power that does not follow a clogged filter
Our injection pump repair process
Step 1: Rule out supply
Filters, lift pump and air intrusion are checked first, since they mimic pump failure.
Step 2: Test the pump
We check for leaks, timing and, on electronic pumps, the related codes and data.
Step 3: Choose a path
Your estimate compares seal repair with a replacement pump and shows every step.
Step 4: Install and time
The pump is installed and timed to the maker's specification.
Step 5: Bleed and test
Air is bled from the lines, and the engine is road tested for smoke and power.
What's included in injection pump repair
Included on the work order
- 01Supply-side tests to rule out look-alikes
- 02Pump leak and timing inspection
- 03Seal repair or replacement pump as approved
- 04Injection timing set to spec
- 05Fuel system bleeding and road test
Is injection pump work need-now or need-later?
Need now: call
- Fuel leaking onto a hot engine
- No-start when hot that leaves you stranded
Need later: book
- A slight dampness at a pump seal with no drip
- A mild idle surge that has not worsened
How pricing and timing work
A seal repair is lighter than a pump replacement, but it is not always possible. The pump type, access and parts availability for older engines set the price and the wait. Your written estimate shows every step, and we tell you how long parts will take. AAA members save 10% on parts and labor, up to $75.
Aftercare
Keep fuel filters fresh; see diesel fuel filter replacement. Timing questions on these engines are covered on diesel engine timing adjustment, and calibration on diesel injector pump calibration. For an older truck you are thinking of buying, our pre-purchase vehicle inspection checks it before you pay.
Frequently asked questions
Can an injection pump leak be fixed without replacing the pump?
Sometimes. Certain external seals can be replaced on the truck. If the leak is internal or the pump is worn, replacement is the practical choice.
Why does my older diesel start hard only when hot?
Heat thins the fuel and exposes internal pump wear. A pump that is fine cold may not build enough pressure hot.
Do you still work on older mechanical diesels?
Yes, as long as parts are available. Call with your year and engine, and we will tell you honestly what we can source.