P1351 Fault Code Diagnosis: 1998 Chevrolet Pickup Engine Won't Start Despite Spark

P1351 points to an ignition control module (ICM) fault — either high voltage output or malfunction in circuits 1 and 4. First step: check fuel pressure using a gauge. A low or inconsistent fuel pressure could contribute to starting issues, even with spark. Also confirm if the vehicle is stock — no modifications or aftermarket parts? This helps narrow down potential causes. Fuel pressure testing should be done before moving on to other diagnostics.

The P1351 code suggests a high voltage condition in the ICM circuit, even though spark is present. Given that this truck has over 150,000 miles and the fuel pump has been replaced twice due to low fuel or contamination, it's possible the fuel system is clogged with debris — leading to poor fuel delivery. The starter fluid test showed a weak start attempt, indicating intermittent ignition. I added four gallons of gas but still no start. A failing ICM or wiring issue could also be at play. Also note: P0463 indicates a float sensor failure in the fuel level system, which may point to a faulty fuel tank sending unit.

Low fuel levels do shorten fuel pump life — but more importantly, an OEM-quality fuel pump is essential for reliable performance. Please post all diagnostic codes (not just P1351) so we can get a full picture of the system. For now, let’s focus on confirming spark and fuel pressure. Step one: measure fuel pressure with a proper gauge. This will help determine whether the issue lies in fuel delivery or ignition control.

I have a similar 1996 Chevrolet pickup with a 5.7L V8 that won’t start and shows P1351. About three weeks ago, the issue worsened — it would crank slowly and start only intermittently. After replacing the cam position sensor, it stopped starting entirely and cranked poorly. However, when I disconnected the coil wire, it cranked fine. Replacing the crankshaft position sensor resolved the initial issue. Since then, it has started and run normally for a few days but now exhibits intermittent stalling — either cranks slowly and dies or cranks normally and stalls immediately after releasing the key. Exhaust smoke from the air filter is also present. The distributor cap is dry (due to recent rain), and fuel pressure readings are normal. This suggests a possible timing or sensor-related issue, possibly linked to moisture ingress in the ignition system.

This thread seems inactive — I’d love to know what the resolution is, as my aunt’s 1998 Chevrolet Pickup has the same symptoms. I want to fix it without replacing unnecessary parts or components.

Could you please specify the exact model and engine size of your truck? Also, does it start at all under any conditions? Do you have access to a digital multimeter (DMM) or test light for voltage and continuity checks?

The issue is likely either a failing ICM, VCM/PCM module, wiring, or connector. There should be a clean 5-volt square wave signal on the white EST timing wire from the ECU to the ICM — above 4.9 volts. If this signal is missing or distorted, it will cause ignition misfires and prevent starting. A scope reading would confirm whether the signal is present and stable.

Moisture appears to be a key factor — every time I wash the truck with a power washer or during heavy rain, the issue returns. I’ve replaced both the camshaft sensor and distributor cap/rotor, even applied RTV sealant to prevent moisture ingress. Despite these efforts, a quick spray from a power washer causes immediate failure. The problem seems to stem from internal moisture affecting ignition components — but I can’t identify exactly which part is vulnerable. Any insight or testing suggestions would be greatly appreciated.