1998 Chevy Blazer 4.3 p0306

[jfitz0121]

I have read some on this here and other places but I wanted to post my particular problem I am having. This is primarily my wives car and she said when it started she almost ran out of gas then got some cheapo gas from some county gas station and literally like 3 to 4 min after it started chugging and wanting to cut out. She put around 20bucks at 2.74 a gallon so I told her to fill it on up with premium and stop at advance and get seafoam and run it through. Well we did all that and after running all that gas out its still has error code but runs great other than a rough idle has same power justshakes a little at idle little hard to start. Has had a total tune up(Cap rotor pin plugs wires) with ac delco etc . Should I change the fuel filter to start or check the fuel supply lines(Poppets) to the cyclinder under intake?? Thanks

[Schrade]

Originally Posted by jfitz0121

I have read some on this here and other places but I wanted to post my particular problem I am having. This is primarily my wives car and she said when it started she almost ran out of gas then got some cheapo gas from some county gas station and literally like 3 to 4 min after it started chugging and wanting to cut out. She put around 20bucks at 2.74 a gallon so I told her to fill it on up with premium and stop at advance and get seafoam and run it through. Well we did all that and after running all that gas out its still has error code but runs great other than a rough idle has same power justshakes a little at idle little hard to start. Has had a total tune up(Cap rotor pin plugs wires) with ac delco etc . Should I change the fuel filter to start or check the fuel supply lines(Poppets) to the cyclinder under intake?? Thanks

Go to a local mechanic, get them to print out the PROPER diagnostic procedure for your code. Plug n Pray swap-a-part repair technique is a gargantuan waste of cash.

Post back if you get the printout, OR, in a day or 2, I will be able to post the procedure for your code (just got factory books, and they take a WHILE to sort through - 3 books, 8 inches).

[jfitz0121]

Originally Posted by Schrade

Go to a local mechanic, get them to print out the PROPER diagnostic procedure for your code. Plug n Pray swap-a-part repair technique is a gargantuan waste of cash.

Post back if you get the printout, OR, in a day or 2, I will be able to post the procedure for your code (just got factory books, and they take a WHILE to sort through - 3 books, 8 inches).

Ok thanks for the info. Just to add a note . Yesterday after she got fresh gas it slowly has gotten better.Its not as rough of an idle.. but still noticeable and a little hard to start. I will take and get a read out at a local mechanic and post what they say..

[Ralph123]

A P0306 code is a misfire on your #6 cylinder. First thing I would check is your spark plug wire on the #6 cylinder and make sure it's clean and tight on your coil and plug. If you fix the problem the check engine light will go away after a few trips.

[jfitz0121]

Thanks for the replies. I knew that a p0306 was a misfire on 6 and have pulled the plug and checked the wires etc already before I started this thread. I probably should have stated that. I talked to a local auto tech today and he told me to change fuel filter and if that didnt fix it to bring it in and he'd look at it and put a fuel pressure test on it and go from there. He said number six cylinder is the last to get gas so if the gas is being blocked that at idle it could be that there is not enough getting to all the poppets fuel lines under intake, that the fuel line could be blocked by something etc.. I am going to go ahead and change fuel filter today or tomorrow and see how it does. I will post after I change the filter and go from there. Drove it today and runs great plenty of power but when you stop or at idle it gets a little rough still....Hopefully its just a 10 dollar fuel filter fix..lol


Thanks

[Ralph123]

One thing you might want to check before turning it over to a mechanic is your fuel pressure regulator. It's on the return side of the fuel rail. Disconnect the vacuum hose from the fuel pressure regulator, if the vacuum hose has fuel in it the fuel pressure regulator is bad. Do you smell fuel at all?

[jfitz0121]

Thanks for the info Ralph123 I will definitely check it when I change the fuel filter! Its pouring the rain here today so hopefully tomorow will be a better day to work on it..

Thanks a bunch

[Schrade]

Originally Posted by jfitz0121

I talked to a local auto tech today and he told me to change fuel filter and if that didnt fix it to bring it in and he'd look at it and put a fuel pressure test on it and go from there.

NO. NONONO.

He DID say first to swap the #6 plug with another plug, right? And then he said to swap the #6 wire with another wire, right?

If he didn't, don't go back. Let's see if the computer is actually right (it is), when it says #6 misFIRE, INSTEAD OF P0174 Fuel System Too Lean (Bank 2) (NOT ENOUGH FUEL).

First swap 2 wires, disconnect the battery, and drive til FULL WARM, to an Advance / Zone, and get a scan. If you get the same code, then swap 2 plugs, don't forget to disconnect the battery, and return to Advance / Zone. Re-scan, and post back results.

[jfitz0121]

Ok update.. I changed the oil this morning and went ahead and changed the fuel filter because I already had one and it was due to be changed anyways. I already had swapped the sparkplug out of number 6 into number 4 and gave the same code. Today I have already swapped number 6 wire for number 4 going to see if misfire moves to 4 cylinder etc. After changing fuel filter it didnt change anything but its good to know that its a new one under there anyways.

I will post what the read out is later today after lunch.

Thanks

[old_master]

Originally Posted by jfitz0121

... I talked to a local auto tech today and he told me to change fuel filter and if that didnt fix it to bring it in and he'd look at it and put a fuel pressure test on it and go from there. A restricted fuel filter will affect ALL cylinders, not just one. He said number six cylinder is the last to get gas so if the gas is being blocked that at idle it could be that there is not enough getting to all the poppets fuel lines under intake, that the fuel line could be blocked by something etc. Totally inacurate information. All injectors receive the same amount of fuel, they are all mounted in the same housing and they are fired sequentially. ...

Thanks

Check fuel pressure and leakdown first, that will tell if there is a problem with fuel delivery to the injectors. If a poppet valve or injector is stuck open, restricted, or not functioning properly, further testing will be nesessary.

[Schrade]

Originally Posted by old_master

Check fuel pressure and leakdown first, that will tell if there is a problem with fuel delivery to the injectors. If a poppet valve or injector is stuck open, restricted, or not functioning properly, further testing will be nesessary.

OP: this is information that you NEED to know FIRST AND FOREMOST, if there's ANY tune problem. Watch the FP gauge when you turn the key, and if it goes right to max, the filter has no restrictions. Then you know the pump, filter, injectors, FPR, lines are all good - killing 5 birds with one test, 2 turtle doves, and a partridge in a pear tree uh huh.

Probably ought to swap out the air freshener too, just to know it's a good one.








(j/k about the freshener)


...

[old_master]

Originally Posted by Schrade

...Watch the FP gauge when you turn the key, and if it goes right to max, the filter has no restrictions.

Not necessarilly... a restricted fuel filter can allow fuel pressure through it but have severly reduced fuel flow.

[jfitz0121]

Ok update after swapping wires still says misfire on 6 po306 same code after unplugging battery for approx 25 min. Same code. So I know its not plugs or wires or fuel filter. I now have a new problem also. After plugging my battery back up my AC/Heater now only blows hot? I unplugged the battery and reset it again and still the same thing only heat. It has been raining and I thought well maybe something got wet? On my way to advance it seemed like it was going back and forth hot cold over and over. I have the automatic computer controlled climate thermostate.who knows just another problem. I ran the blazer pretty good and it has excellent pick up and power so wierd that it has this little hesitation /miss?????? What should I do next??

[old_master]

Is #6 plug wet with fuel or coolant, or dry after driving?

[jfitz0121]

Its dry looks like number 4 plug