Only a few cylinders firing?
 

My 99 Silverado has been sitting up for 8 years and doesn't want to fire on all cylinders. I've changed the fuel pump & dropped the fuel tank, and replaced with fresh fuel. Any suggestions on how to get Betsy back hitting on all 8 again?

Re: Only a few cylinders firing?
 

Well I added some fuel system cleaner to another 5 gallons of fuel and cranked her back up. After about 10 to 12 minutes she started picking up a little. Probably mostly running better from finally getting some heat built up. Anyway, before I go any further, I'm going to find a way to get under her and get the oil and filter changed.

Re: Only a few cylinders firing?
 

Do you have a Timing light?

If so, you can use that to quickly check if you're getting spark to each plug.

Sounds like maybe that new gas and some Seafoam will get you going.

Probably good idea to check the plugs also.

Re: Only a few cylinders firing?
 

Yeah definitely got the seafoam in and the plugs will be changed tomorrow after work. Didn't think about checking the timing.

Re: Only a few cylinders firing?
 

Yeah, It would be good to check the timing also.

What I was referring to is to check each plug wire for spark with a timing light as a tool. Since you had thoughts that it was only firing on a few cylinders.

Maybe this Video will explain it better.

http://youtu.be/0nZzp6ia1_w?t=70

Re: Only a few cylinders firing?
 

Think I located the problem. Actually me being older was my problem. My brain is still back in the carb days not fuel injection current times. Being there's 8 injectors, some are/were clogged up with ancient gas and sludge. So this weekend when I'm allowed to work on her, I'll be getting all the injectors back cleaned up and ready to rock again.

Re: Only a few cylinders firing?
 

New and better plan. Found a set of 8 brand new injectors for a very reasonable price so just kicking back waiting on them to arrive. I'll update once their exchanged and she's started back up.:smoke:

Re: Only a few cylinders firing?
 

Hang onto the GM originals. You can get them cleaned.

Re: Only a few cylinders firing?
 

You can't check the timing. If you have the proper scanner you can make sure the cam and crank sensors are in sync which is the closest thing to setting timing on it, but if they're not in sync the engine light will be on and a code will be stored for it.

Re: Only a few cylinders firing?
 

Hopefully hopefully the new injectors will arrive by Saturday. Been a long wait! Saving the old ones is a good suggestion, I didn't even think of it and yeah, your absolutely right without a distributor no way to advance or retard the timing. This has been an incredible truck, unfortunately she's sat way too long while life has been hammering on me.

Re: Only a few cylinders firing?
 

Just assisted a friend with his Sliverado with a miss-fire code.
Tracked it down to this. Actually four of them looked just like this.
He had pulled and inspected one and called them all good.
Bosch Platinum...

Re: Only a few cylinders firing?
 

If you stick with the OEM plugs and wires you won't have many issues. Don't just willy nilly change the coils either. The OE coils will literally run a half million miles.
The LQ4 6.0L in my truck used AC Delco 41-962 Platinum plugs Probably the GMT800 5.3 & 4.8 V8 engines as well. Changing to Iridium AC Delco plugs can cause issues too.

Bosch are typically for central Europe brands like Volvo, Saab, Benz, BMW, VW, Porsche, Audi, Skoda, and Seat among others.

Asian cars typically use NGK. My Stihl power equipment uses them too.

I stick with Mopar plugs in my Chrysler & newer Jeep stuff and Motorcraft in the Ford engines.

AMC is all kinds of fun. :lol::lol: They used from Ford, Chrysler, & GM parts bins. I've seen Motorcraft, Delco, and Mopar plugs in AMC engines.

Re: Only a few cylinders firing?
 

Injectors arrived today finally! AC Delco units going in on Thursday after work. Got my fingers crossed...going to be great getting Betsy back on the road after all these years. I'll try and get some photos of her soon.

Thankfully all 8 plugs looked great except for 2, smutty.


1999 ext cab Silverado 1500 4.8 v8 with a five speed. All stock.

Re: Only a few cylinders firing?
 

Got all 8 injectors in along with new plug wires. She cranked right up like a champ! Good to hear that dual exhaust burbling along even with an exhaust leak in one of the mufflers. Even at idle she had over 40 lbs of oil pressure.

Drove her through the neighborhood, yeah the neighbors stared. Tires are both low on air and badly flat spotted as well as dry rotted. Got an appointment today at 330 for fresh tires all around. So thrilled. She needs running bad, still have some cobwebs but hopefully I'll be around long enough to put some serious miles on her.

1999 ext cab 1500 Silverado 4.8 V8 5 speed
200585 miles

Re: Only a few cylinders firing?
 

What a difference! The new tires not only look great, she drives and rides like almost a modern truck now. Lots of different smells coming up but none that have stayed long. Guess we are burning up all the weird stuff I was trying to use to clear out the clogs previously.

1999 ext cab 1500 Silverado 4.8 V8 5 speed
200605 miles

Re: Only a few cylinders firing?
 

Been driving her for several days now, she just keeps running better and smoother each trip out. Tomorrow the muffler man ought to show back up to work so I'm hoping to get her up on the rack to have a look around. I know for sure there's at least one muffler leak that needs attention. Any comments on the possibility of chopping off the old cats?

Oh, and I have several photos to share but things have changed or my memory has failed me. So far i havent been successful loading photos.


1999 Silverado 4.8 v8 5 speed 200680 miles ext cab:sumo:

Re: Only a few cylinders firing?
 

Also while I'm thinking of it. Is it necessary for me to look into increasing the fuel she's getting with an inprovement in getting rid of the exhaust?

Re: Only a few cylinders firing?
 

You can't just cut off the cats on anything 96 and up unless you like looking at the check engine light all the time.

Re: Only a few cylinders firing?
 

Well I've had them for 24 years I guess a few more wont hurt anything.

Re: Only a few cylinders firing?
 

It's going to affect the way the engine runs because the computer is detecting a fault.