2002 Blazer 4X4 four-door 137k.

Starting problem started a couple of months ago.

Initially, need to crank it for a few times each morning, especially harder on Monday when it sat for the weekend.

Then, about 3 weeks ago, it won't start at all. It was determined to the fuel filter problem. changed fuel filter, start better...

But it still two or three attempts, it seems like the engine is struggling at 300-400 rpm at the first attempt. If it can pass that threshold, it starts normally. But most of the time, it will not pass the 300-400 mark.

I tried to turn in on/off (before cranking the engine) a few time before starting. I heard this is a way to check the fuel pump. It seems this does not help.

Another problem is that when it's idle, the engine gives more noise and vibrating.

Could it be spark plug, distributor cap, fuel regulator, spider injector?

Any opinion would be very appreciated.

 

btw: I think there was fuel mileage drop but not very certain. I will start to watch it closer now. also, I've been driven for short trips for the last three years. will that be a concern?

 

see if the d-cap is cracked or if the regulator is clogged

 

Could be a problem with fuel pressure or excessive leakdown. Most auto parts stores rent/sell fuel pressure testers. Key ON, engine OFF, fuel pump running: Pressure must be 60psi to 66psi and it must remain above 55psi for at least 10 minutes after the fuel pump shuts off. Best to diagnose the problem before replacing parts Post your results.

 

I was trying to bury my head in the sand. But my blazer won't start again today. The engine was trying to run up to 300-400 rpm and fail.

I will run a pressure test tomorrow.

Any other ideas?

 

Post the results of the pressure test and we'll go from there

 

Ya, this sounds like leaking fuel regulator or injector. Get a fuel pressure reading and leakdown

 

Friday night: did not start.

Saturday Morning: starts "normal" (means started on the second attempt). did pressure test. key on (not cranking engine), pressure around 55psi. key off, pressure slightly drop to 52psi for around 10 minutes. cranking engine, the pressure initially run up to 62psi for 1 second and then drop to 55psi. and staying 55psi when engine on.

Sunday: start "normal" (means started on the second attempt), changed spark plug, distributor cap and rotor. Mechanic recommend changing pressure regulator. but he was not sure if the fuel pump was the real issue.

don't really want to try to change fuel pump or injector, almost broke.

 

Your initial psi is too low. You can try to look down the throttle body with a flashlight ( sometimes a small mirror helps) and look for any gold spots or signs of washing. If it looks really clean then you know the regulator or injectors are leaking. You can also modify a gauge to dead head at the fuel filter to test if the pump is the problem. I know the write up is on here somewhere for making a gauge and the specs for fuel pump numbers. I'm on the mobile or I would find them for you, or captainhook will chime back in lol.

 

For your 2002, here is another method: In the underhood fuse panel, connect a fused jumper wire from battery positive to the "fuel pump prime" terminal. This will bypass the fuel pump relay and activate the fuel pump continuously.



With the ignition in the OFF position, fuel pressure must be 60psi to 66psi. This is regulated fuel pressure.

Disconnect the jumper wire, and the fuel pressure will drop slightly, but it must remain above 55psi for at least 10 minutes. This tests the systems ability to hold fuel pressure. If it fails one or both parts of the test, it means a problem exists and that further diagnosis is necessary to determine what the problem is.

If you're showing 55psi, (key on, engine off) and dropping to 52psi, there's a problem. But without doing more testing, it's impossible to know what the problem is. Could be a weak fuel pump, poor electrical connection for the pump, faulty pressure regulator, leaky fuel injector etc etc.

Next step is to check the fuel pump maximum output pressure and the pumps ability to hold pressure. To do that you'll need to modify the pressure tester so it will connect directly to the fuel filter. All fuel flow & pressure must end at the tester. With the pump activated, pressure must be 73psi to 108psi. Deactivate the pump and pressure must remain above 55psi for at least 10 minutes. The results of these 2 tests will determine if the pump is good or bad.

Just an FYI: Fuel pressure readings taken while the engine is running, are meaningless.