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Hard Starts

Hey everyone, I have a question about my 2000 pontiac v6 (3800ii). Recently, my car has been acting a little funny when I start it up. When the engine is cold, I start the ignition and engine cranks, but it doesn’t fire right away? I’d say it takes about 5 seconds. When the engine does fire, the car shakes a bit at idle. There are also times where the car will start right up with no hesitation. I thought it could be a bad fuel filter and had it replaced (which was definitely needed), but the car is still acting up. I’m wondering if it could be the EGR or an electrical problem? Any thoughts would be appreciated.



Thanks!

I’d start with the plug and wires. Then the dist cap and rotor (if if has one). Next the air filter, then clean the MAF. Only after you replace those, should you suspect something like the egr system or electrical problem.

Usually the best way to fix a problem is to find the problem. Throwing parts at it can get expensive. Testing your egr valve takes about 10 seconds, maybe you actually should start there.

If this only happens after the vehicle has sat for an extended period of time, the problem might be with the fuel pump check valve. This prevents the fuel from draining out of the fuel system back into the gas tank.

To confirm if this is the problem, the next time you go to start the engine and you know this is going to happen, turn the ignition switch to the run position so that the dash lights come on for two seconds and then turn the ignition switch off. Repeat this a half dozen times. This cycles the fuel pump enough times to reprime the fuel system. If the engine starts right away after doing this, the problem is with the fuel pump check valve.

Tester

I tried priming with the ignition, but the engine still cranked for a while. I also should mention that right after I start the car up, I can smell exhaust. I think that could be the exhaust manifold, though. A mechanic told me that it should be replaced soon, but for the time being, they just heated it up and tightend it down.

and now that I think about it, I didn’t have all of these problems before I had the exhaust system worked on. Makes me wonder what happened while I was sitting in the waiting room…

Okay. Try this. The next time you go to start it, hold the accelerator to the floor. This tells the computer that the engine is in a flooded condition, and the computer cuts the injector pulse widths in half to clear the flooded condition. If the engine starts, there’s fuel leaking into the engine as it sits.

Tester

Ok Tester,

I went out while my engine was cold and started it the way you wanted me to. It worked! Does this mean that I have leaking fuel injectors, and if so, what do I do?

No. It’s not one or two leaking fuel injectors. If it were, only those cylinders would be flooded. So the engine would start immediately with the good cylinders but run like crap until the flooded cylinders clear out the excess fuel.

What you describe might be caused from a leaking fuel pressure regulator. This is controlled by engine vacuum, And if the diaphram inside the fuel pressure developes a leak, it can allow gas into the engine via the vacuum hose. This then collects inside intake manifold. Then when go to start the engine, not only is there gas being introduced into the cylinders by the fuel injectors, but also the gas that’s in the intake manifold which effects all the cylinders. Causing a flooded condition.

Tester