Bizarre problem with '96 Blazer 4x4

I have a 1996 Blazer LT 4-door 4x4 (4.3 liter) with approx. 157000 miles on it. While it has been a great truck for all the years I have owned it (purchased new), in the last 12 months, it has gone berserk.
Basically, it starts and runs great about 60% of the time, and the other 40%, it won't even crank, much less start. I have had this vehicle into a multitude of different garages, and no one seems to be able to decipher what is wrong here. I have had 3 fuel pumps put in in 11 months. I have also had the wiring completely replaced. I cannot locate the problem, and neither can a good half dozen ASE certified mechanics.
I was curious if anyone here has had similar problems, or has any idea what might cause such freakish behavior from an otherwise wonderful automobile. ANy help is greatly appreciated. Thanks in advance.
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freakish things like this can be caused by bad battery connections.
detach the battery cables and inspect them very well...look for thread damage, worn cables, frayed cables, inpect the threads inside the battery sometimes if the cable is a little loose the arc's can melt the threads right out. check the ground at both ends and the bottom of the positive cable.
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Thanks for the reply. I'll give it a shot. Frankly, at this point, I'd try about anything to get this thing running again.
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Demonseed wrote:

I had a similar situation with a car - 1987 Olds Toronado. Bad connection in the dash caused the car to just completely die while driving down the road! Hit the dash in a certain spot & it would work again. Never really fixed the problem & got rid of the car. Did you replace the wiring in the dash? Intermittent wiring issues are a bitch to track down...
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Wiring was replaced from the distributor to the fuel pump, with no result. I have been doing some research into this problem, and am considering replacing the fuel pump relays along the firewall, and seeing if this has eany effect.
Strangely, the problem only manifests itself at startup. Once the truck starts, it runs perfectly, with no stutter or miss. The trick is getting it to start.
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Run a test on the fuel pump at the firewall first, run a hot wire to the fuel pump test lead and listen for the fuel pump. Intermitant starting problem can also be the fuel injector drivers in the ECM but it will get worse to the point that it won't staart at all. Not very common with the Blazer but it does happen.

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I had a 91 Grand am that would do about the same thing, only it would die at anytime and cook the ignition fuse and die, replace the fuse and let the car cool off the car would run fine,. after DAYS of troubleshooting I found that the wire leading to the ignition module had come out of the wireing harness and rubbed itself bare on the engine block. When the car was cool the wire would lift off the block, as the car heated up the wire would soften and fall on the block and cause my grief. Check to make sure that you have no wires going to ground that are not supposed to Steve

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I went to GM school back in 1993. Boy did they ever stress how important the ground wires are! They said make sure all the seperate ground connections are made. Do not cut all the eyelets off and crimp them together. They all need to be seperate even though they are on the same bolt.
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Flat spot on the starter? Intermittent ignition switch?
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jesus, mary and joseph
'a half dozen ASE certified mechanics'
doesn't speak well of the 'certification' process, does it ?
look, when it don't crank: main path is battery + to starter to engine block to battery negative; an auxiliary path is battery + to ign sw to starter to battery negative
how goddam hard is it to check out a pair of 4-component circuits, fer chrissakes ?
if it cranks but won't start, you have 4 (and only four) possibilities: no spark, no fuel, no compression, or wrong timing
since it DOES start sometimes, we can rule out no compression and wrong timing
which leaves lakkafuel and lakkaspark
'ASE certified'................big f-ing deal
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LOL. To their credit, I have not been charged a dime (except by the guy who put the fuel pump in the truck). The mechanics that have looked at it have even eaten the towing cost rather than charge me.
I apprecaite all the replies here. Looks like I'm going under the hood for some serious wiring checks. I'll let you guys know if I can find the problem.
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See Training is not a substitute for experience.
It does sound like an electrical issue.
Try looking at the Bulk Head connector that runs thru the firewall. The MetriPak connectors are notorious for poor contact. You can try grabbing the harness behind the Relay center and wiggle it and see if the problem disappears.
Otherwise, open up the Bulkhead connector and look for Blacken pins.
Happy Holidays.
Martin

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I know what you're saying. However, I had the same problem about a month ago. My problem turned out to be *too much* fuel. My problem turned out to be the *Fuel Pressure Regulator*. It has a vacuum hose on top of it that goes into the air intake plenum.....and gas was leaking into it from the vacuum hose. This is what caused the long cranking to start when the engine was warmed-up. I actually stumbled on the problem when I was checking the 8 new fuel injectors that I just installed. I was checking them, for leaks. I had just installed them, and with the air intake plenum still removed, I turned the key on (ignition only) to pressurized the fuel rail and fuel injectors to see if I had any leaks. There it was. Fuel was pouring into the air intake plenum from the vacuum hose on the Fuel Pressure Regulator. I installed a new Fuel Pressure Regulator, completed the assembly.......and BINGO! The problem was gone.

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Re: " >the other 40%, it won't even crank,

---------------------------------------------------- If it won't even begin to crank sometimes but starts up others,I would check the neutral safety switch,then the starter/solenoid,then the ign.switch,etc. Best...BrianO.
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