* Fuel pressure doesn't guarantee deliverability: You have pressure at the rail, but that doesn't mean fuel is getting to the injectors properly. The problem could be:
* Clogged fuel injectors: The injectors might be clogged, preventing adequate fuel flow even with sufficient pressure. This is a very common cause.
* Weak fuel injectors: The injectors might be weak and not atomizing the fuel effectively, even if they are spraying some fuel. They need sufficient pressure *and* flow to operate correctly.
* Fuel pump issues (despite pressure): While you say you have pressure, the fuel pump may be struggling to maintain sufficient pressure under load (when cranking). It might be weak, nearing the end of its life, or have a problem with its internal components.
* Fuel filter: A severely clogged fuel filter can restrict flow despite sufficient pressure at the rail. This is a cheap and easy thing to check first.
Carb cleaner works because it's highly volatile and easily ignites, bypassing the fuel delivery system entirely. This confirms the problem lies in the fuel getting to the cylinders properly, not in the ignition system.
Troubleshooting Steps:
1. Check the fuel filter: This is the easiest and cheapest thing to do first. Replace it if it's dirty or old.
2. Test the fuel injectors: This requires specialized tools, but you can have them tested at an auto parts store. Many will perform a flow test for free or a small fee. Look for a consistent flow pattern across all injectors and the correct flow volume.
3. Check fuel pressure *during cranking*: The pressure you measured might drop significantly when the engine is cranking. Use a fuel pressure gauge that can monitor pressure dynamically, not just a static reading. A pressure drop indicates a weak fuel pump or other delivery problem.
4. Inspect the fuel pump relay: Make sure it’s clicking when the ignition is turned on. A bad relay can prevent the fuel pump from powering up.
5. Inspect fuel lines for leaks or blockages: Check all fuel lines visually for cracks, kinks, or other damage that could restrict fuel flow.
6. Consider the intake manifold gasket: A leak here could cause a vacuum leak that disrupts fuel/air mixture even if the injectors are working.
Don't attempt extensive fuel system repairs without proper safety precautions. Fuel is flammable, and working on the fuel system requires careful attention to avoid fire or injury. If you are uncomfortable working on your fuel system, it is recommended to take your vehicle to a qualified mechanic.
