For the past 1.5 months, my wifes blazer has been having a hard time starting on monday mornings. This is only the case if it was parked on friday night and not driven all weekend. The past 2 weeks it has required a jump start on monday mornings to get it to turn on. I took it to Autozone and hade the battery tested which checked out good. I removed the alternator and took it in and they said it tested good. The battery is 2 years old, the starter is 1/2 year old, and the alternator is 3 years old. As long as it is ran over the weekend it runs just fine, it's only if it sits for 2 days it has trouble. It will turn over but never start unless jumped at which point it starts right up. This morning it again wouldn't start. I tried tapping the starter to see if it waslocked upinside and that didn't help, I jumped it and it started right up. I let it idle for 2 minutes, turned it off, and it started right up again. 2.5 hours later my wife tried to start it up to go to work and it wont start again. What do you guys think it is? 2 suggestions I've read on the forums are fuel pump and ignition module, but I don't know how to differentiate which is my problem if either, and I don't want to get screwed by a mechanic who is just guessing either.

 

Have you tried putting a trickle charger on it over the weekend to keep the battery fresh? It is possible that you have something on drawing current over the weekend that pulls the battery charge down. That's what it sounds like to me.

 

Maybe it once belonged to a UAW Union offical.

Really sounds like a draw down, disconnect the battery if you don't have a charger or circuit tester, see if that helps go from there.

 

If it's still got the original fuel pump in it, my money would be on a weak fuel pump. If I were you, I'd get a fuel pressure test guage and check fuel pressure at the fuel rail, with the key on but not started. Initial start up pressure needs to be around 60 psi to start. Lower than that and your pump may be going down for the count.

I experienced the same set of circumstances. Changing the fuel pump resolved them all.

BTW: Look out for pinhole leaks in the tank above the seam where the tank is against the driver's side frame rail. JB Weld will patch those holes nicely (when and if you end up dropping the tank).

 

Have an 2002 that does the same thing sitting from frimon and especially when damp out. After troubleshooting and having my mech friends tell me it's the distribuor cap (channged twice) and verified not a fuel delivery issue, I have narrowed it down to the ignition coil or ignition module. It's just over $100 for both parts together. Seeing as they are next to one another and interconnectedhave changed them both just for the peace of mind insteadjust one of them.

 

You should be able to have both the coil and ICM tested. I believe that both Autozone and Advanced Auto have the capability of testing these components.

If you find that it does this more on damp days, it could be the screen/drain in the bottom of the distributor not venting properly.

 

Try turning the key into the on position for 20-30 seconds before cranking the motor. This gives the pump time to bring the fuel pressure up. If it starts easy after doing this it's the pump or the pressure regulator or an injector hanging partially open causing it to lose fuel pressure. I drove mine like that for about 2 yrs, Just had to remember to cycle the key for 30 seconds before cranking the motor and it would start right away. The bad cap and such would really usually only rear it's ugly head when it was wet/damp out. Just my .02.

 

20-30 seconds. Wow that's a long time. A good fuel pump takes 1 to 2 seconds max. If your pump takes 20 to 30 seconds to pump up enough pressure then you have a seriously flawed pump or a significant leak somewhere. I would not allow the vehicle to remain in this condition for too long. You'd be wasting a lot of gas too. Too expensive to do that nowadays anyway.

 

You wont waste any gas if your injectors are not hanging open. The point of the post was to find a bad fuel pump or pressure regulator. As for mine it was a bad pressure regulator and there was no waste of gas as my injectors were in fine shape.