The Stupid Engine Questions Thread

[SUBURBAN5]

Sorry been watching some vice grip garage lately lol. I poured gas down the air intake

In that case, anytime your trying to start your engine, you gotta yell " bring the thunder"

 

[Intimi88tr]

In that case, anytime your trying to start your engine, you gotta yell " bring the thunder"

Oh man I havent said that! maybe thats why it wont start LOL.

 

[SUBURBAN5]

Did you verify fuel pressure?

 

[Intimi88tr]

Did you verify fuel pressure?

I did...not even 20psi

 

[SUBURBAN5]

I did...not even 20psi

Found the problem

 

[Intimi88tr]

Found the problem

Thank you for your help!!

 

[1990 305]

recently bought a 1996 suburban k2500 7.4L Vortec. it was running a little rough so i swapped plugs and wires. verified the original to me wires were correctly wired from distributor to cylinders. plugs looked like they had been used way too long but no gas, oil, or fouling, just very worn. now that i have an issue when in gear (drive or reverse) at a stop i get a intermittent backfire. Fuel pressure is at 52psi at idle. went to advance auto and borrowed the OBDII scanner and the data stream is showing the ignition advance is bouncing between -23 and -27 degrees. that seems a bit much to be just one tooth off. im gonna try adjusting a tooth or 2 but its raining so not today. i figured i would look for answers before i get into it.

 

[AK49BWL]

Is that ignition advance or crank/cam correlation?? If the latter, then yes that's way off, should be as close to 0 as possible - spark is probably firing into the previous cylinder, which would cause your backfire... The distributor could be just one tooth off, OR it just needs to be adjusted in place - I don't recall if there's enough leeway in the bolt hole to go ~25 degrees off tho. Fuel pressure at 52psi is NOT enough for a properly running truck with the original poppet injector spider, you probably have a fuel pump going out or possibly plugged fuel filter as well. Fuel pumps are common on these trucks, but at least on the 96 you can replace the pump motor as a standalone piece, not have to replace the entire fuel pump and sender body.

 

[1990 305]

Is that ignition advance or crank/cam correlation?? If the latter, then yes that's way off, should be as close to 0 as possible - spark is probably firing into the previous cylinder, which would cause your backfire... The distributor could be just one tooth off, OR it just needs to be adjusted in place - I don't recall if there's enough leeway in the bolt hole to go ~25 degrees off tho. Fuel pressure at 52psi is NOT enough for a properly running truck with the original poppet injector spider, you probably have a fuel pump going out or possibly plugged fuel filter as well. Fuel pumps are common on these trucks, but at least on the 96 you can replace the pump motor as a standalone piece, not have to replace the entire fuel pump and sender body

Ignition Advance according to the code reader. Already has a brand new fuel filter (staryed here since it is cheaper and quicker than the pump), I have been meaning to replace the fuel pump because it does have a constant whine while the engine is running, just keeps getting pushed further down the list since i dont drive it much right now. Attaching pics of what the reader showed while i was there. I didnt have a good chance to look at everything because the kid at the store acted like i was gonna steal the thing and break it by having the engine running

 

[1990 305]

Also, according to the RPO code L29, I have the MFI not the SFI spider injector