Peter engine 4hp diesel pump plunger install _ 1cylinder engine fuel pump repair

Here is a simple and practical guide to repair the China Peter-type 1-cylinder diesel engine fuel pump (common on Chinese 12HP–25HP engines like Sifeng, Changfa, Peter, etc.).


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✅ China 1-Cylinder Engine Fuel Pump Repair Guide

These engines usually use a plunger-type inline pump with a single element.


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🔧 1. Remove the Fuel Pump

1. Close the fuel tap.


2. Remove the fuel pipe from the pump.


3. Remove the two bolts holding the pump.


4. Pull the pump straight out.
⚠️ Do not rotate the tappet when removing.




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🔧 2. Disassemble the Pump

Place the pump on a clean cloth.

1. Unscrew the top delivery valve holder.


2. Remove:

Delivery valve

Delivery valve spring

Copper washer



3. Unscrew the pump barrel retaining nut.


4. Gently pull out the plunger (piston) and barrel (sleeve).




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🔍 3. Check the Internal Parts

✔ Plunger & Barrel

These must be tight.

If plunger is worn, fuel leaks down and pressure becomes weak.

If scratched → engine will not pick RPM, produces smoke.


Fix:

Light scratches: polish with 2000-grit paper and diesel.

Deep wear: replace plunger–barrel set.


✔ Delivery Valve

Carbon buildup can cause back-flow.

Clean with diesel and a soft brush.


✔ Spring

Weak spring → low pressure.

Replace if broken or soft.


✔ Pump Cam (inside engine)

Check with finger: should be smooth.

If worn → pump timing becomes late.



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🧼 4. Cleaning

Use diesel only.

Clean all parts in diesel.

Blow air or let it dry.

Never mix parts from another pump.



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🔧 5. Reassembly

1. Insert the plunger back into the barrel (match marks if present).


2. Fit the barrel into the pump body.


3. Install the delivery valve + spring + holder.


4. Tighten everything properly.




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🔩 6. Reinstall on Engine

1. Align the timing mark on pump side if present.


2. Push pump in.


3. Tighten mounting bolts.


4. Connect fuel pipe.




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💨 7. Bleeding Air

1. Open the bleeder screw on pump.


2. Pump the manual primer until diesel flows without bubbles.


3. Tighten screw.


4. Loosen injector pipe nut, crank engine until fuel comes out.


5. Tighten the nut and start.




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🔥 8. Common Problems & Fixes

Problem Cause Solution

Engine hard start Air lock Bleed pump
White smoke Late timing Advance pump slightly
Black smoke Worn plunger Replace
No diesel at injector Stuck plunger Clean and free plunger
Knocking sound Early timing Retard pump slightly



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If you want, I can guide you step-by-step with photos/diagram, or tell you how to set timing on your exact China Peter engine model.

Just tell me engine HP or model number.