I have a 98 blazer with the 4.3L. It has been getting very cold here at night (single digits) and after the blazer sits over night it its very hard to start, sometimes it may take a few minutes before it will fire. After I drive it to work a few miles it may sit for 4 hours or so it then will start fine. If the temp is in the upper 20's or warmer it seems to have no problem starting after sitting over night. The blazer has about 170,000 miles on it and I believe it still has the same plugs and wires, but after it finally starts it runs fine, i.e. smooth. Just wondering were to start looking for a potential problem or if its just getting old and that’s the way its going to be now when its really cold. Thank You in advance for your help.

 

With 170K miles, it's overdue for plugs, wires, distributor cap & rotor, and most likely a fuel filter. These engines are pretty fussy when it comes to plugs, cap & rotor, AC Delco should be used for best results.

The long cranking could be caused by low fuel pressure. Most auto parts stores rent/sell/loan fuel pressure testers. Key ON, engine OFF, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes after the pump shuts off. The results will tell where to look next.

 

I'd start with new spark plugs, cap and rotor. If that doesn't fix it start looking at your plug wires and do a pressure test on the gas pump. First items are pretty cheap..good wires are a bit more expensive but all those parts should have been replaced 70,000 miles ago. Other things could cause hard starting but your skill level and tools will determine whether you can do it yourself or not. Many tools can be borrowed from places like Autozone with a deposit.

 

thanks for the input. I will start with the plugs, wires, cap, rotor and fuel filter. I would hope that the pump is still good because I replaced it about two years ago.

 

If the pump is AC Delco or Delphi, chances are it's ok. If t's aftermarket, who knows. Better at least check pressure and leakdown.

 

Before you go tearing into the engine bay, try a bottle of HEET ISOheet gas line antifreeze and ice remover. Sounds like it could be ice in the gas or fuel lines.

Pour in, physically shake the truck a little, drive and see if that helps.

If that's not it, could be coil, fuel filter, or many other possibilities

Good luck

 

Sorry about the long delay in replying but I finally got a fuel pressure tester. Here are the results. After sitting for about a hour or two after running KOEO was 56 psi, after 10 minutes dropped to 42 psi. with the engine running it is at 53-54 psi. after its been running for a few minutes I can turn off the engine, relieve the pressure in the gauge, turn the key on and it will go to about 60 psi and then itt will slowly drop. If I cycle the key off and relieve pressure the cycle key back on and the pressure goes to 54 to 56 psi it will take about 5 to to seconds to start. If I cycle the key and it goes to about 60 psi it seems to start right up. I also replaced the fuel filter prior to preforming these tests. Any insight on where to go from here would be much appreciated. Thanks in advance guys.

 

Don't need to relieve pressure each time, in fact, it's best if you don't. Your pressure is in fact low. Next step is check fuel pump maximum output pressure at the fuel filter. All pressure and flow must end at the tester. You'll need to do some "creative plumbing" to adapt the tester to the filter. Pump running, pressure must be 73psi to 108psi and must remain above 55psi for at least 10 minutes after the pump shuts off.
If it passes both tests, there is a problem in the plenum. If it fails one or both tests, check voltage & ground at the pump module connector, if they are both ok, the pump needs replacement.


Checking fuel pressure at the service port indicates regulated pressure or maximum pump output pressure, whichever is LOWER. This is why the pressure needs to be checked at the filter... to make sure the pump can supply enough pressure to satisfy the regulator.

 

Thanks captain I will go out now and try to rig something up with the pressure testing kit from Autozone. There is a bunch of hoses and fittings in there so I can try to adapt something to the outgoing side of the fuel filter. I will let you know what I come up with.

 

Ok, I took off the quick connect side of the fuel filter and put a T fitting on the end of the filter with a plug on the end and the pressure gauge in the middle. KOEO the gauge read about 55 psi and then slowly dropped. Did the same test again with the same results. Not sure where to go now.