# Diesel Fuel System Flush in Upland > Diesel fuel system flush in Upland after water, gasoline or debris contamination. Tank drained, lines flushed, filters replaced and damage checked. Source: https://route66autorepairshop.com/diesel-engine-services/diesel-fuel-system-flush Updated: 2026-09-17 Business: Route 66 Auto Repair, 1775 W Foothill Blvd, Upland, CA 91786, (909) 608-7699 Hours: Monday to Friday 8 AM–5 PM, Saturday 8 AM–2 PM, Sunday closed **TLDR:** A flush is for **contaminated fuel**, not routine service. If you put gasoline in your diesel, **do not start it** and call us. A diesel fuel system flush at Route 66 Auto Repair in Upland is a recovery job for trucks that took on water, gasoline or debris. It is not a routine upsell. Our ASE-certified technicians drain the tank, flush the lines, replace filters, and check whether the contamination reached the high-pressure pump or injectors, then explain the findings on a written estimate. ## When does a diesel need a fuel system flush? - Gasoline was pumped into the diesel tank - Water keeps showing up in the separator after draining - Dark sludge or particles appear in the fuel filter - The truck sat for a long time and the fuel has gone stale - A failed high-pressure pump shed metal into the system ## What should I do if I put gas in my diesel? Do not start the engine, and do not turn the key to run if you can avoid it, since some lift pumps prime at key-on. Gasoline strips the lubrication that diesel pumps and injectors rely on. Have the truck towed to us; we accept tow-ins during business hours. If you already drove it, shut it off as soon as it is safe and call [(909) 608-7699](tel:+19096087699). The earlier the flush happens, the better the chance that the high-pressure parts avoid damage. ## Our fuel system flush process 1. **Sample:** We take a fuel sample and note what the contamination looks like. 2. **Drain the tank:** The tank is drained into approved containers and inspected inside where possible. 3. **Flush lines:** Supply and return lines are flushed with clean diesel. 4. **Replace filters:** All fuel filters are replaced, and the separator is cleaned. 5. **Check for damage:** Rail pressure and injector balance are checked once the engine runs, and any damage goes on the written estimate. ## What's included in a diesel fuel system flush - Fuel sample and contamination check - Tank drain and inspection - Supply and return line flush - All fuel filters replaced - Refill with clean diesel and full prime - Pressure and injector balance check ## Is a fuel flush need-now or need-later? **Need now:** - Gasoline in the tank - Metal debris in the filter - Water that returns right after draining **Need later:** - Old fuel in a truck that runs fine, which can often be used up and replaced with fresh fuel ## How pricing and timing work Tank size, contamination type, filter count and disposal of the old fuel set the price. If the flush reveals damaged pumps or injectors, those are quoted separately and we stop and ask before any added work. AAA members save 10% on parts and labor, up to $75. ## Aftercare Watch for rough running or pressure codes for the first few days. A deeper tank clean is covered on [diesel fuel tank cleaning](https://route66autorepairshop.com/diesel-engine-services/diesel-fuel-tank-cleaning), and testing on [diesel fuel system contamination test](https://route66autorepairshop.com/diesel-engine-services/diesel-fuel-system-contamination-test). If the pump was damaged, see [diesel fuel pump repair](https://route66autorepairshop.com/diesel-engine-services/diesel-fuel-pump-repair). ## Frequently asked questions ### Is a diesel fuel system flush regular maintenance? No. Routine care is fuel filters and draining the separator. A flush is for contamination, and we will not recommend one without a reason. ### Can a little gasoline in a diesel tank cause damage? It can. Gasoline reduces lubrication for the pump and injectors. Call us before starting the engine. ### Does insurance cover a misfuel? Coverage depends on your policy. We can give you a written estimate and photos of the findings for your records. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.