Fuel Feeder Line and Cylinder Misfires

[Richard_Meyer]

So where do i begin?

2005 Envoy 4.2L came to me in limp mode with bad wiring (fixed). It also came with a cylinder 2 misfire. I replaced with a Delphi OEM coil. Did new spark plugs while i was at it.

Car wouldnt start. Tried everything. Found out if we swapped the fuel relays around, it would allow me to start the car, and after the car shuts off, id have to swap relay again with the old one and it would start again.

Got vehicle up and running on Tuesday . Ran for 45 miles and the little grey clip for my fuel feeder line off my fuel pump broke and caused it to pop off. IT left me stranded, and i needed a tow.

Ive spent all weekend with the gas tank down and buying new fuel tank straps, cutting out old FS hardware, etc.., and i go to start the car. It starts without needing to swap relays, although i feel a little longer than it should. Thats progress, the car actually starts all the time.

But now, Im getting a cylinder 5 misfire. I can feel it idling, right about 600 rpm...

Now, I live in Wisconsin... and the past few days has been high humidity and raining off and on. Could the p0305 be because of the weather, or is this a legitimate concern? Am i chasing ghosts?

If anyone would like to comment, Id love to greatly hear your suggestions..

Thanks.

 

[Mooseman]

Could be a bad #5 coil. Try swapping it with another one and see if the misfire follows it. If it stay at #5, check if it actually has spark. If it does, then look at fuel and compression.

 

[mrrsm]

Since you mention the recent bout of Heavy Weather... There is a TSB that explains an issue with the Hood Cowl Seal leaking Rain Water onto the Upper Engine and invading the Spark Plug Wells and shorting out the Spark Plugs along the Rear of the In-Line Bank of Cylinders:

Water Sitting In Sparkplug Holes

Working on my 06 Trailblazer EXT with the I6 engine I found water sitting in (starting at the front of the motor) cylinders1,2,and 3. I found dried up water deposits before in cylinders 1 and 2 but not water. Any ideas on how to stop this ? The coil pack was pushed down all the way and last...

gmtnation.com

Cowl Grommet-Seal Part# 25788476

06-06-04-048B Chevrolet Ignition System Technical Service Bulletin

06-06-04-048B Chevrolet Ignition System Technical Service Bulletin

www.tsbsearch.com

Need to know what the new hood seal looks like.

I suffered the Cyl 4 misfire problem, but it hasn't reoccurred. It happened several weeks after I changed the plugs, so I may have disturbed the coil pack seal, 'cause it hasn't been a problem for 4 years of heavy rains & such. I think it was a matter of tree debris (acorns, twigs & leaves)...

gmtnation.com

Also...if your particular 2005 Trailblazer sports a MAF... consider Replacing the Air Filter and Cleaning the MAF as per Paul "Scanner" Danner's video on a visit to his brother James' Shop where he shows How To Clean the Delicate Resistors with a Right Angle Brush while using CRC MAF Spray (NOT Brake-KLEEN) to remedy the "Fish-Bite" Misfire condition:

 

[Richard_Meyer]

I think I'm going to look into the weatherseal and see if that is in fact causing this, and then swap IC#5 coil and plug.

Before the fuel feeder line blew, I had no codes regarding misfires.

Will report back sometime this week.

 

[Mooseman]

Could be some dirt got in and plugged the #5 injector. Check other stuff first and then might need an injector balance test to confirm a defective injector. Check that it is getting power too.

 

[Richard_Meyer]

So I promised I would report back.

I went ahead and replaced ignition coil #5, and I don't have a misfire. It's been running and starting all the time, until today. Since I swapped the IC, it's been getting harder to get it to turn over right away.

It was 1 second to get it to start, and was getting worse. But the time I'm posting this, it won't start the first set of cranking. The second time, it does immediately.

Now, last week I dropped the tank to add a clip to the fuel feeder line. Is there a possibility that one of those lines that I had to disconnect could possibly be coming loose again? Or the little canister on the tank possibly causing issues?

I have been smelling a faint gas smell.

 

[Mooseman]

Yes. If it's losing pressure, it takes longer to start. Had that when I had a leaking fuel pressure line.

 

[m.mcmillen]

l would think if you’re losing enough fuel pressure to make it hard to start that you would be seeing gas dripping somewhere and have a strong smell of gas.

If you shut it down, does it restart easily after waiting a minute or two?

It might be good to get a fuel pressure gauge and see what it is reading. There’s a possibility that the check valve in the pump is beginning to fail and the pressure is bleeding off internally.

 

[Richard_Meyer]

l would think if you’re losing enough fuel pressure to make it hard to start that you would be seeing gas dripping somewhere and have a strong smell of gas.

If you shut it down, does it restart easily after waiting a minute or two?

It might be good to get a fuel pressure gauge and see what it is reading. There’s a possibility that the check valve in the pump is beginning to fail and the pressure is bleeding off internally.

I have not attempted to shut it down, then check. I can if need be. Could it be something that isn't properly plugged in? Fuel Pump has less than 300 miles on it

 

[m.mcmillen]

Most likely not the pump then but it doesn’t hurt to check.