Bringing an 80s Legend Back to Life: First-Gen CRX Si Fuel System Restoration
There’s a specific kind of satisfaction that comes from hearing a long-silent D16A6 fire up for the first time in years—and getting there means methodically working through every component of the fuel system, from the tank to the injectors.
You know that feeling when you roll a forgotten CRX out of a dusty garage, pop the hood, and start mentally cataloging what’s been sitting there for a decade? The fuel system is almost always the biggest hurdle. Old gas turns to varnish, rubber hoses dry out, injectors clog, and the fuel pump gives up the ghost. But here’s the thing—these cars are simple, the parts are available, and the process is incredibly rewarding. Let’s walk through bringing an 80s legend back to life.
The Two Fuel Delivery Systems: Know What You’re Working With
The first-gen CRX Si (1985-1987) and second-gen (1988-1991) have different fuel systems, and you need to know which one you’re dealing with.
1984-1987 CRX (Carbureted and Early Si): The early Si uses a mechanical fuel pump, mounted to the engine block. These are simple, reliable units that operate at low pressure (around 3 psi) and are driven by the camshaft . If your car has one, replacement is straightforward—just unbolt the old unit, clean the mounting surface, and install the new one with fresh gaskets .
1988-1991 CRX Si (Fuel Injected): The second-gen Si uses an electric fuel pump mounted inside the fuel tank. This system operates at much higher pressure and is controlled by the ECU through the main relay . The main relay is a common failure point on these cars—it’s a small black box under the dash that controls both the fuel pump and the ECU power .
Step 1: Assess the Situation
Before you start throwing parts at the car, figure out what you’re dealing with.
Drain the Tank: If there’s old gas in the tank, it needs to go. On CRXs with a drain plug (many have a 17mm bolt), place a suitable container underneath and let it drain . If there’s no drain plug, you’ll need to remove the tank or siphon the fuel out through the filler neck.
One owner’s experience: “The car had about a 1/4 tank of varnishy seven-year-old gas in it when I got it. I drained it and put in some fresh UL with some injector cleaner additive. Unfortunately, it’s not running well enough to wash the injectors out” . This is a common story—draining the old gas is just the first step.
Check the Fuel Pump: For the 1988-1991 Si, listen for the fuel pump when you turn the key to “ON.” You should hear a brief whirring sound. If you don’t, it could be a dead pump, a bad main relay, or a wiring issue .
Step 2: Tackle the Fuel Tank
If the tank has rust or sludge inside, you have a few options:
Chemical Cleaning: Some owners drop the tank and have it professionally cleaned and recoated. This is the most thorough approach, especially for tanks with significant internal rust .
Replacement: Finding a clean, used fuel tank is becoming harder. Many original parts, including specific fuel pipes and hoses for the CR-X, are listed as “discontinued” by Honda . If you find a clean donor tank, grab it.
The Filter: The fuel strainer (a filter inside the tank on the pickup tube) is a part you should replace if you’re doing a full restoration .
Step 3: Replace Rubber Hoses and the Fuel Filter
Old rubber fuel lines degrade, crack, and leak. Replace them all—it’s cheap insurance.
The Fuel Filter: Located under the car near the fuel tank on some models, or in the engine bay on others. A clogged filter is a common cause of poor running after a car has sat . Replace it as a matter of course.
Lines and Hoses: Many of the original fuel hoses are no longer available from Honda . The good news is that generic fuel hose of the correct diameter works perfectly. Just make sure you use hose rated for high-pressure fuel injection systems on the pressure side of the pump.
Step 4: Clean or Replace the Fuel Injectors
The D16A6 in the 1988-1991 Si has multi-port fuel injection with four injectors on the fuel rail . Injectors that have been sitting with old gas are almost certainly clogged.
What the community recommends:
“Those ‘off the shelf’ fuel injector treatments don’t work. Period. The only true way to have your injectors cleaned is professionally, by a company that can perform a flow test on them before and after” .
DIY Cleaning Method:
- Remove the injectors from the fuel rail
- Use a clean jar with Sea Foam or an injector-safe cleaner
- Let them soak for 24 hours
Even Better:
- Rig up a cleaning system using a syringe or tubing
- Use a 9-volt battery and a momentary switch to pulse the injector
- Push cleaner through the injector using a bicycle pump and a Schrader valve
Seals: When reinstalling injectors, replace the o-rings. Part numbers include Seal Ring (16472-P10-A01) and Injector Cushion Ring (16473-PD6-000) . These seals get brittle with age and can cause vacuum leaks or fuel leaks .
Step 5: The Main Relay (1988-1991 Si)
This little box is the most common cause of “cranks but won’t start” on EF Civics and CRXs . It’s a small silver or black box under the driver’s side dash that controls the fuel pump and ECU.
Testing: The main relay can be tested by turning the key to “ON” and listening for a click from the relay, followed by the fuel pump priming. No click? The relay may be faulty.
Replacement: This is a common fix. Solder joints can crack over time, causing intermittent failure.
Step 6: Replacing the Fuel Pump (1988-1991 Si)
If the pump is dead, you’ll need to drop the tank to access it. When replacing:
- Upgrade: A Walbro 255 lph fuel pump is a popular upgrade for high-performance builds
- OEM Replacement: Carter and other brands offer direct-fit electric fuel pumps for the CRX Si
The Final Result: A Restored Legend
Fuel system restoration is the heart of bringing any long-sat CRX back to life. The process takes patience, but the payoff is huge—the sound of a D16A6 firing up after years of silence is one of the most rewarding experiences in classic Honda ownership.
As one owner put it after restoring their 1988 CRX Si: “This 36-year-old CRX definitely needed a lot of love when it rolled off the transporter, but I just could not pass on this rust-free, 1st-year/2nd-gen that I sniped from eBay Motors” .
Frequently Asked Questions
What’s the easiest way to get old gas out of my CRX Si tank?
If your CRX has a drain plug (many have a 17mm bolt), place a suitable container underneath and drain it . If there’s no drain plug, you’ll need to siphon the fuel out through the filler neck or remove the tank entirely.
How do I test the fuel pump on a 1988-1991 CRX Si?
Turn the key to “ON” and listen for a brief whirring sound from the rear of the car. If you don’t hear anything, test the main relay (under the dash) first—it’s a common failure point .
Do I need to replace the fuel injectors or can I clean them?
Most owners successfully clean their OEM injectors using professional cleaning services (they flow-test before and after) or DIY methods using a battery, switch, and cleaner . New injectors from aftermarket brands are also available.
Where can I find replacement rubber hoses for the fuel system?
Many OEM hoses are listed as “discontinued” . The practical solution is to use high-quality generic fuel hose of the correct diameter, rated for high-pressure fuel injection systems.
Should I replace the fuel pump as preventative maintenance?
Yes. A fuel pump that has sat for years with old gas is a time bomb. Replace it while you’re in there. A Walbro 255 lph upgrade is a popular choice for reliability and future power upgrades .
Why does my CRX run rough after starting for the first time?
This is almost always due to clogged fuel injectors or a failing main relay. Old gas turns to varnish in the injectors, and the main relay’s solder joints can crack over time .
References
For further reading and to verify technical information:
- Charm.li – Main Relay (Computer/Fuel System) for 1989 CRX Si
- CRX Community Forum – Cleaning Si Injectors
- Amayama – Genuine Honda CR-X Fuel System Parts Catalog
- CRX Community Forum – Restored 1988 CRX Si Turbo Build
Have you ever brought a long-sat CRX back to life? What was the biggest challenge in your fuel system restoration? Drop your stories in the comments below.
