I'm really worried about fuel injector issues in my 1996 F53 460 motorhome after installing a Banks Power system with Accel 24 lb. injectors. It's been running rough, especially at idle, and I'm getting intermittent check engine lights. I don't want to make things worse by guessing or doing the wrong repairs.
I'm honestly a bit intimidated by fuel system work - I've heard horror stories about people causing expensive damage. The injectors I installed were Accel 24 lb., and I want to confirm if these are correct for this engine. I'm planning to pull a plug soon to check my fuel mixture, but I need some expert advice on the safest way to diagnose whether my injectors are actually the problem. I want to be absolutely sure before I start throwing parts at it or risk damaging something else in the fuel system.
Injector issues cause misfire and rough running. Diagnose by scan codes and swap test. Clean or replace as needed.
When diagnosing fuel injector problems, oversized injectors are a common issue. For example, 24 lb. Accel injectors would likely be too large for a 1996 F53 460 engine, which typically runs 19 lb. injectors from the factory. The Banks Power system may have called for slightly larger injectors (possibly 21-22 lb.), but 24 lb. injectors are probably causing your CEL by running the engine rich. The intermittent nature of your code suggests the ECM is struggling to compensate for the oversized injectors, especially under varying load conditions. You'll need to either step down to the correct size injectors for your Banks system or have the ECM tuned to accommodate the 24 lb. injectors.
Since you mentioned the engine runs and idles great now but throws CEL codes when underway, this confirms the injectors are oversized. At idle and light loads, the ECM can compensate by reducing injector pulse width, but under acceleration and highway loads, it can't pull enough fuel out of the equation. The good news is your installation technique appears solid since the engine performance improved dramatically from your poorly running original injectors.
Before you pull those spark plugs, you should definitely flash that trouble code first. Even though it's intermittent, most OBD-II systems in your 1996 F53 will store the code in memory. The code will tell you exactly what parameter is out of range - likely oxygen sensor readings indicating rich conditions, or possibly fuel trim codes showing the ECM is maxed out trying to lean the mixture.
Your 1996 F53 chassis with the 460 engine came with 19 lb/hr injectors from Ford. When Banks developed their power system for this engine, they typically specified larger injectors to support the increased airflow from their intake and exhaust modifications. However, Banks usually went to 21 or 22 lb. injectors, not 24 lb. The jump to 24 lb. injectors represents about a 26% increase in fuel flow over stock, which is significant.
The Banks Power system for your 460 includes several components that affect fueling requirements:
The intermittent CEL you're experiencing is classic behavior when injectors are oversized for the application. Here's what's happening: At idle and light throttle positions, your ECM can reduce the injector pulse width enough to maintain proper air-fuel ratios. The oxygen sensors read normal, and everything seems fine. However, when you're driving down the highway or climbing hills, the engine needs more fuel naturally, and the already-oversized injectors push the mixture too rich for the ECM to compensate.
The fact that your code clears on its own is actually diagnostic information. This suggests the problem is load-dependent rather than a hard failure. When you return to cruise or light load conditions, the ECM regains control of the air-fuel mixture, the oxygen sensor readings return to normal, and the code clears. This cycle repeats every time you encounter the conditions that trigger the rich mixture.
Banks Power systems from the mid-1990s were designed when fuel injection tuning was much more limited than today. They had to work within the constraints of the factory ECM programming, which means they couldn't just throw massive injectors at the engine. They had to size everything carefully to stay within the ECM's ability to compensate. Your 24 lb. injectors have likely exceeded that threshold.
To properly diagnose and fix your injector sizing issue, you'll need several tools and some reference materials:
Safety Warning: Always work on fuel systems in a well-ventilated area away from ignition sources. Fuel vapors are extremely flammable. Relieve fuel system pressure before disconnecting any fuel lines or components.
You'll also want to gather your Banks Power system documentation. If you don't have the original paperwork, Banks customer service can provide specifications for your specific kit based on your engine and chassis details (verify with manufacturer documentation). They'll be able to confirm the correct injector size for your system.
For measuring fuel pressure, you'll need to access the Schrader valve on your fuel rail. **CRITICAL: Relieve fuel rail pressure before connecting the gauge to prevent fuel spray and fire hazard. Remove the fuel pump fuse, start the engine, and let it run until it stalls to depressurize the system.** On the 460, this is typically located on the driver's side fuel rail. Normal fuel pressure should be within manufacturer specifications (typically 35-45 PSI for most Ford fuel injection systems, but verify with service manual for your specific engine). If your Banks kit included a modified fuel pressure regulator, the pressure specification might be different.
When you do get around to pulling spark plugs for inspection, focus on plugs from different cylinders to get a representative sample. Look for:
Start your diagnostic process by retrieving that trouble code, even though it's intermittent. On your 1996 F53, you can access codes by:
Common codes you might see with oversized injectors include code 44 (right oxygen sensor lean), code 45 (right oxygen sensor rich), code 41 (lean exhaust indication), or codes in the 170s related to fuel trim problems. Write down any codes you find, as they'll guide your next steps.
Safety Warning: Before testing fuel pressure, ensure engine is cool and work area is well-ventilated. Wear safety glasses and have a fire extinguisher nearby.
Next, verify your current fuel pressure. With the engine warmed up and idling, connect your fuel pressure gauge and record the reading. Compare this to your Banks system specifications. If pressure is too high, it compounds the oversized injector problem. If it's too low, you might have other issues affecting fuel delivery.
Test your injector electrical connections and resistance values. Each injector should have approximately the resistance specified by the manufacturer. Significantly lower resistance could indicate internal injector damage, while much higher resistance suggests connection problems or injector coil issues. Use your noid lights to verify each injector is receiving proper pulse signals from the ECM.
Document your current injector specifications completely. Remove one injector and verify it's actually a 24 lb. unit - sometimes online information about parts is incorrect, and you might have installed different injectors than you think. Check the part number against the correct specifications for your application.
Once you've confirmed the oversized injectors are your problem, you have three potential solutions:
The first option is most straightforward and maintains the engineered balance of your Banks system. Contact Banks Power directly with your system information to confirm correct injector specifications. They may have updated recommendations since your system was originally manufactured.
While diagnosing oversized injectors is within most DIY capabilities, certain aspects of this repair may require professional assistance. ECM reprogramming or custom tuning definitely falls into the professional category, especially for older OBD-I systems like yours. Most tuning shops that work on performance applications can handle this, but finding someone familiar with Banks Power systems and older Ford truck platforms might take some research.
If you choose the ECM reprogramming route, expect to pay $400-800 for custom tuning work. The tuner will need to adjust fuel maps, ignition timing, and possibly other parameters to optimize performance with your 24 lb. injectors. This can actually result in better performance than simply installing smaller injectors, but it's significantly more expensive and complex.
Professional fuel system diagnosis might be worthwhile if you discover additional issues during your testing. If your fuel pressure readings are erratic, if multiple injectors show resistance problems, or if you find evidence of fuel contamination, a qualified shop can perform more comprehensive fuel system testing including flow bench testing of your injectors and pressure testing of your fuel pump and lines.
Safety Warning: Fuel injectors operate under significant pressure. Always relieve fuel system pressure before removal and ensure proper installation to prevent dangerous fuel leaks.
Consider professional help if you're not comfortable with fuel system work. If you're recovering from surgery and not up to the physical demands of this repair, having a shop handle the injector replacement might be worth the cost for your safety and peace of mind.
For finding the right professional help, look for shops that specialize in older Ford truck performance or RV service centers familiar with F53 chassis work. Banks Power may be able to recommend certified installers in your area who are familiar with their systems and common issues that can arise with improper modifications.
Finally, document everything you discover during this diagnosis process. Whether you complete the repair yourself or hand it off to a professional, having detailed information about what you've tested and what you've found will save time and money. Take photos of your current injectors, write down all your test measurements, and keep copies of any trouble codes you retrieve. This documentation will be invaluable for anyone who works on your fuel system in the future.
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