i have a 1997 blazer 4wd 4 door all stock i had 3 gallons of bad gas and the truck quit running and started misfiring what a job to get it home thank god i was only 1 mile away i would turn the key all the way off then on to prime it drive 20-30 feet or so then the truck would die. I have changed the fuel pressure regulator it had some grit in it and dropped the tank to get the bad fuel out and changed the fuel filter and the spark plugs the truck runs better but its not fixed i can not hold a pedal 2000-3000 rpms it will start to run rough or die if i floor the pedal it pops and dies right away i can feather the pedal and keep it running for a while. any suggestions fuel pump injectors ??? stumped is there a fuel pressure test i can perform thx mike

 

it is possible that the fuel injectors are bad/clogged from the old gas.

to test the fuel psi go to autozone or where ever and ask to rent out a Fuel pressure gauge kit and follow the fuel lines on the rear of the motor and you should see a little nipple that the gauge will click on to. turn the key on and let the fuel pump prime the system then read the gauge. if its low then id say its a fuel pump.

on the other hand if it turns out the fuel PSI is okay, try running an injector cleaner like techron or Lucas fuel treatment with higher octane fuel. left it run through and try to clean some of it out. also pull some of the plugs you put in and look at them, based off of their condition you might be able to tell whats going on. also keep in mind there might be a vacuum leak some where.

EDIT: also a fouled O2 sensor could cause the engine to run lean and choke out

 

If your FPR had grit in it, that's pretty dang bad gas. Not ot mention raising questions about the filter.

And if you didnt have injector problems it would be a miracle, esp in a vortec. And depending on the nature of the grit, aint no cleaner gonna fix it, I'm thinking.

- Sidenote: Old farm boy wisdom - NEVER EVER dump all the gas in any can into a fuel tank. IOW never turn the can all the way up. Always leave at least half a pint to dump on gravel somewhere. Light it off if you're that 'Green'.

 

well personally id rather try a 10$ cleaner than taking off the intake to get to the damn spider assembly and replace the injectors

 

Just curious how do you know it was bad gas??

 

got autozone pressure tester 62 for 2 sec then 60 then after 5 min 58 and holds truck running at idle 800 rpm 51-52 steady for ten plus min then shut it off gauge went back up to 59 key off i hear a hissing towards extream rear of motor kind of under neath the distributor on the intake looks like there is a fitting with something attached to it and wires maybe cannot see it

 

some additional codes popped up po102,po300,po740,po785,po1860

 

did you look those up?

I did.. suppose I should'a listed them but hey..
sounds to me like you have a wiring harness problem.. maybe a bad ground.. or two
LOTS of things can cause random misfire including MAF circuit

Perhaps it wasnt bad gas after all. Why I always check that old filter before chucking it.
heh.. 'Check before Chuck!'

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BTW. You didnt say how long you've been driving it and if it had any problems at all prior to the incident.

 

i had changed the multi function switch about 2 years prior latley the key would not come out had to manulaly push the electric cam up to remove it also it had a vacuum leak aroung the spiders gasket was shot at the time i replaced the fuel pressure regulator also when i changed the plugs they were extremly carbon fouled

 

Make sure these grounds are clean and tight, click attached:

G102. 103, 104, 105
Make sure there's .2v or less measured between engine and chassis gnd near battery.

And look for that hiss. Disconnect IAC connector, start engine. UNLIT propane torch around area of hiss. If it's pulling air and shouldnt be, the engine rpm will change or run smoother.

The reason to disc IAC is so the PCM cant compensate and hide a change in rpm due to mixture.

If engine wont run without IAC, shim the throttle stop a little. Do not adjust throttle stop, EVER, unless you KNOW it's set wrong and it's the last resort.