As some of you may know ive been having sputtering issues at very high rpms and super low rpms cruising around town. I have checked fuel pressure and its perfect, maf is fine, cats are fine, spark plugs and spark plug wires are fine, the computer has no codes stored in it, no exhaust leaks and vacume on the intake is good. But the weird thing is...my gas tank sending unit was gone when i got the truck and a local dealer told me to try this delco additive to put into my gas...i guess its some sort of cleaner ive been through 3 bottles and my gas guage is actually almost working again. What i found out though is when i add this stuff to my gas my truck actually runs almost as it should...like almost perfect but after i run that tank out about 4 days later she goes back to the crapper again and sputters, idles badly, and sputters/ crackles under high rpms. This tells me its obviously something in the fuel system causing this... any ideas?

 

Sounds like a placebo effect.When you say the plugs and wires are fine what do you mean exactly? They were tested or replaced ? With OEM? Codes?

 

Possibly the fuel pump. I know you say there good but check the plug wires again. Are the plugs gapped right? Have you tried seafoam? Has the truck ever run hot? This sounds crazy but make sure your battery is tight. Take the battery cables loose for about 15 minutes and see if that helps.

 

I pulled the plugs and they are gapped right...i know what plugs are supposed to look like and these were nice nothing wrong what so ever. I never replaced the wires but they seem all perfect and have never been pulled hard or stretched there is also no sparking in the pitch black at night. There are ZERO codes in the vehicles computer we checked. If it was the fuel pump would my fuel pressure go wacky? the fuel pressure was fine. I also tried the batt disconect and it did nothing either. Truck has never been over heated not even close. I have not tried seafoam..where do find this?

 

bad plug(s) can still look good externally, i would replace all 8 with NGK TR55's

 

I agree with DLH,you can crack one easily and not even know it.It will have a hair line crack you cant see

 

Alright well ill pick up 8 tommorow and replace them....but do bad plugs account for the fact that my truck runs perfect with that additive in the gas?

 

might want to test you fuel injectors, and clean your maf too, it can't hurt and it's free...
just my .02

 

I went through 2 sets of bosch wires in a month. They looked perfectly fine and I could never see a spark. Just and idea: Take some carb cleaner or something like that and spray around the intake gasket on both sides. If it revs up then you got a leak. You can get nkg plugs and taylor wires from summit for around $60. Like said above check your injectors. But i think if it was injector it would throw a code. Could be coilpacks but I doubt it, those throw codes also.

 

might wanna check your fuel injectors how many miles on the truck? doesnt the fuel additive have octaine in it, if this is the case when the injectors spray it would run better, may have corrision in the fuel injectors pull them and see if they need cleaning they might not all be spraying


you might only be getting enough fuel just keep the motor barely idleing..