Identify the Symptom

Goal: pick the right path No guesswork

Be honest about what it is actually doing:

1. Cranks, no start – go to Step 2
2. Starts then dies / falls on its face – go to Step 4
3. Pump noisy / repeat pump failures – skim Step 5, then Step 6 and Step 7

This hub behaves like a flow chart. Follow your condition.

Quick “Do I Have Fuel?” Check

Goal: prove fuel is reaching the engine Fast driveway checks

1. Listen for pump prime on key-on
2. EFI: check the rail Schrader. Carb: check for accel pump squirt
3. Touch the relay. Feel for a click on key-on
4. Check fuse and any add-on kill switches or alarm devices
5. Briefly power the pump directly (fused) to see if it wakes up

Full walk-through: Cranks, No Start: Fuel System Quick Check

Run the full QT page: Universal Fuel System Quick Tests (QT)

Decision: Pump dead -> Step 3. Pump runs but weak -> Step 4. Runs on direct power only -> Step 5.

Pump Won’t Run (No Prime / No Command)

Goal: prove command vs dead pump Relay / wiring / safety

Start here (QT links):

1. QT 1 – Power & Prime Check
2. QT 3 – Voltage Drop
3. QT 6 – Pump Amperage

If it keeps pointing to undersized/abused hardware: When To Upgrade the Whole System

Pump Runs, But Performance Still Sucks

Goal: read pressure behavior Find restriction vs regulator vs voltage

Run these (QT links):

1. QT 4 – Fuel Pressure Behavior
2. QT 7 – Return-Style System Check

Decision: proven pressure but still bad -> Step 5. voltage issues -> Step 6. undersized combo -> Step 7.

Deep Dive Explainers:
Base Fuel Pressure | Fuel Pressure Regulator Function | Fuel Pressure vs Injector Flow | Differential Pressure Across the Injector | Fuel Pump Flow vs Pressure | Fuel Pump Voltage Sensitivity | Residual Fuel Pressure (Leakdown)

Hidden Gremlins Builders Overlook

Goal: find the thing killing pumps Tank, pickup, filters, venting

1. Dirty tank and rust scale
2. Pickup sock plugged or collapsed
3. Fine filter installed before the pump
4. Suction hose collapsing under load
5. Return line kinked or undersized
6. Tank vent / vacuum lock

QT to catch mystery devices: QT 5 – Safety / Interruption Switch Check

Dirty tank path: Dirty Tank Checklist + Bottle Test

Fix the Power Delivery (Where Most Fuel Problems Live)

Goal: kill voltage drop Grounds, wire size, connectors

1. Voltage drop on power feed while pump is running
2. Voltage drop on ground side while pump is running
3. Ground points on bare metal, not paint or rust
4. Correct wire gauge (no 16-ga feeding a big EFI pump)

Start here: QT 3 – Voltage Drop Test

Wiring guide: Wiring 101 – Fuel Pump Power & Grounds

Decide If It’s Time to Upgrade Everything

Goal: stop patching Build a system that fits the combo

1. What horsepower are you actually aiming for?
2. Carb, TBI, or port EFI?
3. Return or returnless?
4. Street, strip, or mixed use?
5. Factory tank, fuel cell, or sump?

Explainer: When To Upgrade the Whole System

Tools: Fuel Pump Sizing Calculator | Injector Size Calculator

Checklist PDF: Fuel System Upgrade Checklist

Safety While You’re Under the Car

Goal: do not burn the project down Fuel work is not casual

1. Relieve fuel pressure before cracking lines
2. No sparks, grinders, or drop lights near open fuel
3. Ventilate the garage
4. Catch pan and rags ready
5. Class B extinguisher within reach
6. Jack stands on solid ground

Safety guide: Fuel System Safety Guide

Next Moves

Goal: keep you moving No looping

1. If you have not run QT yet, do that first: Universal Fuel System Quick Tests (QT)
2. Need tools and downloads: SpeedNeeds Resources
3. Still stuck: Message SpeedNeeds with what you already tested