I have a 1996 4x4 chevy blazer LS 4.3 Vortec 4L60E auto trans 185,000 miles.The Truck suddenly started getting hard to start. The only time I got any OBDII codes was when I sprayed throttle body cleaner in such as Sea Foam thinking maybe the engine was carboned up.Well the truck doesn't burn any oil, and I have put a slew of parts in it.So Far It had a new fuel pump put in a couple of years ago and I put Marvel Mystery Oil in the gas to help lubricate the fuel pump and Fuel system cleaner such as chevron tech and still on a good day it's only getting 12 to 15 mpg. I put platinum plugs in about 52,000 miles ago, a direct fit Accel ignition coil, I've put a new magniflow cat, full exhaust system, 4 new 02 sensors, new EGR valve, New IAC valve and it still hard to start with terrible gas mileage. Any suggestions of what else could be causing this hard to start poor mileage problem.Any and I mean any help would be
of the greatest appreciation.
Help!!!!!

 

Read the DIY's for fuel on the first page.

 

Exactly...These units will deliver 23-25 mpg if maintained properly

 

Yeah maybe down hill with a tail wind and the truck turned off... And even then. lol

 

What, if the truck was changed over to all synthetic Lubricants when it was brand new and had a tune up and it's oil changed every (2000) miles?.It's a 1996 and I'm not a mechanic but i think that big 4.3 vortec V6 is (NOT) capable of that kind of mileage brand new or not.it got 15 to 18 when it was new.I expected a little more help on the subject than this and I must say this was not a very congenial experience in terms of asking for technical thoughts or help.I'm sorry I asked for the help.I'm out.

 

Well, let's start by saying this place isnt FB and most wont want it to be. It's more like a neighborhood bar at happy hour. Lot's of BS flying around to keep it interesting. Like that '23-25' claim. It's actually possible that Step is seeing that. But it's rare as hell and you cant MAKE it that way.. it's like stars aligning. That said... I'd quit claiming that, if I were Step.. cause for most it IS BS. However we ARE allowed to BS.

Now.. all that said. You have a very common problem. One that results in sudden mileage drops and one that's usually easily diagnosed and I am surprised you didnt get pointed to the procedure. The problem is there's about 3 or 4 a week with the same complaint.

1. easily found by searching 'hard to start'
2. sometimes folks expect the other guy to handle it.

If you're still here, get borrow or buy a fuel pressure test gauge and check pressure at key on - engine off then note the pressure after one and ten minutes. We dont need to know running pressure.

If you AREN'T still here.. well, sorry... next!

 

You got the wrong idea, everyone here is helpful, it's just that your issue is very common. If every time this came up a complete wall of type had to be written things would be left out or not mentioned, plus the time involved. This is the reason the nice people here have expended the time and effort to write and go over and over the diys. Your problem is most likely in the fuel delivery system. Pump, filter, nut kit, spider or regulator and there very picky as far as the fuel pump. When you go through the recomended tests and come back with some results we will get you fixed up. Nobody here gets paid for this. If you want to get pissy go to someone you are paying. We can't fix your ride for you, but more then happy to help get it done............... Petty we must have been typing at the same time ditto "Next"

 

Wow...I was kinda surprised by pettyfog's response! I have always related that I reside in a VERY flat terrain,with very high quality highways,very rural, and virtually all trips involve at least 20-30 mile jaunts at 55-65 mph! I figure every 2 or 3 tanks: Tuesday March 13 I fueled and found 22.6! Of course this is NOT in 4X4 or in the mountains-there I attain 14-20 as can be expected! Best to all!

 

The point is that is under optimum conditions. Hardly anyone gets those, so you shouldn't raise expectations.

 

Sorry for the unhelpful sarcastic response.. but yeah this is a widely covered topi, i think there have been 3 posts about bad gas mileage this week alone.

I just filled up and i think i got about 13.5 and that is with 31's and 100% city driving all on hills hitting every light in the morning. Blazers arent exactly gas friendly.