99 Tahoe misfire

[Ry_price]

Hey guys, I just want to start off and say that this site is great. I've had problems with my truck before and I've always turned to this forum for the answer every time.

I'm hoping that someone can help me with this problem.

Alright currently, I have an error code coming up telling me that I'm getting random misfires (PO300). I know the 300 is the misfire.

I'm trying to correct this issue with the misfiring and nothing seems to work. I tried putting in a fuel system cleaner, which didn't seem to do anything. And I am currently dealing with what I believe is a bad fuel pump. I couldn't start it this afternoon and its stuck at work. Could the fuel pump cause the misfiring? Any feed back would be great! Especially before tomorrow when I go to work on it.

Thank you!

 

[Tahoe_96]

When mine was throwing a P0300 it ended up being a stuck EGR valve. Cleaned it real good and problem was fixed.

 

[lxsolocam]

My 99 2dr did the same thing right before the fuel pump crapped out. My check engine light came on showing thousands of misfires on #3 cylinder (I never even felt them). Filled it with gas on the way to work one day and 9 hours later go to start it to head home and notta. just cranked and cranked. Changed the fuel pump that night (which is big fun with a 30 gal tank full to the top!) And she started right up. Never had another problem.

 

[Ry_price]

My 99 2dr did the same thing right before the fuel pump crapped out. My check engine light came on showing thousands of misfires on #3 cylinder (I never even felt them). Filled it with gas on the way to work one day and 9 hours later go to start it to head home and notta. just cranked and cranked. Changed the fuel pump that night (which is big fun with a 30 gal tank full to the top!) And she started right up. Never had another problem.

Of course it has to go bad when its full. I'm not looking forward to dropping this sucker but I'll try and suck some fuel out before that thing crushes me lol. Did replacing the pump solve the misfire problem right away for you? It's becoming such a headache to keep seeing the damn check engine light pop on because of it. I can't even do highway speeds anymore because of how bad it is.

---------- Post added at 08:58 PM ---------- Previous post was at 08:56 PM ----------

When mine was throwing a P0300 it ended up being a stuck EGR valve. Cleaned it real good and problem was fixed.

Fingers crossed that maybe it's the same with mine. I'm trying from the cheapest fix and up haha. I still have a lot of OEM parts on the truck, which is surprising since I've got about 145,000 miles on it, but I'm sure a lot of parts on my truck need a cleaning or just be flat out replaced.

 

[keruzam93]

every time ive had missfires in my 96 it was the distributor cap and rotor, might wanna check that out. usually if mine was missing i could pull the cap off and see all kinds of green corrosion from moisture getting in there.

 

[SunlitComet]

cleaning yes, just flat out replace no. keep in mind your first tune up is at 100,000 so it is a good idea to get techron cleaner on a regular basis or a pressurized bottle solvent injector cleaner around the same time to give injectors a good cleaning. check the inside of cap and rotor for cleaniness and look for burn marks near the terminal inside. check you fuel pressure reading. a simple screw on fuel pressure gauge will suffice and if possible read your misfire history to determine exactly what cylinder are acting up. it goes a long way in diagnosing misfire concerns.