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Discussion Starter · #1 ·
1991 caprice with 305 throttle body, bit of a unique help request because i'm disabled, lack the money for a mechanic, and have to get to medical treatment so need hopefully something simple within my abilities to get running again. :( My mechanical knowledge is splotchy/self taught only and my confidence low - I successfully swapped a clutch on a saturn SL, but failed rebuilding a carburetor for a lawnmower which never ran again, so apologies if i'm slow or unexperienced at knowing what to do or how properly.

Had to have this parked (due to low mpg) for the last year or plus, I put Pri-G in the tank so wasn't too concerned, had a half or 3/4 tank (not sure how accurate gauge is) or so when I did.

Had my saturn car break down so suddenly needed to use this/the backup. Didn't start instantly due to sticky residue in TBI, I sprayed carb cleaner (yes carb cleaner, only thing I had handy and couldn't get proper TBI cleaner without a running car) onto it which both cleaned up the spray near instantly and worked as starting ether - idled perfectly smooth with no misses or problems. Drove to the gas station and put on 3 gallons gas to mix out some of whats already in there.

Drove 60 miles around town with absolutely no trouble the last two days, have been expecting no trouble.

Suddenly went to crap out of the blue when pulling into a parking lot - died on me, on restart it ran HORRIBLE, missing so bad I could barely keep it running no matter what I did with the throttle, accelerating any near impossible, but would maintain jerky speed once I was there. Stopping at a stop sign or light would have it die every time.

I immediately filled the tank at the nearest gas station to dillute out what was left, putting in about 7 gallons, then struggled to start the car and limp it home which was 5 miles away.

I put 2/3 of a container of fuel injector cleaner into the tank (all I had left) and probably a triple dose of Pri-G (which unlike Stabil can be used to revitalize old gas, and yes it works, quite amazingly even) into the tank, but could only stick about a liter of additional gas into the tank to try mix any of it. If i'd had the Pri-G with when filling at the gas station it would work better i'm sure.

Tried to start it again today, it will start but immediately dies without abusing the throttle. Tried to run a few minutes to get what I thought was bad gas through it but it still runs bad. Worked the throttle body with some carb cleaner on a toothbrush assuming maybe the spray was just cloggy like when it first started - this noticibly improved the spray pattern but it runs just as bad so maybe it's the gas..?

I'm aware I need to give the Pri-G 24 hours or so usually and don't know how well it will be mixed under the circumstances, but other than sitting and waiting (as i'm needing to get to medical treatment 250 miles from here as soon as possible) and hoping it starts better later I need to look at other strategies...

Not sure how hard it is to replace a TBI but that assumes that's even the problem and dunno if a junkyard part run any better from sitting, A-graded or not. I'm hoping the mix of Pri-G and 11 gallons fresh gas by now (which should have mixed with what was maybe 15 gallons older gas) will take effect, and i'd assume anything nasty would have been caught by the fuel filter... and if that were clogged i'd assume it might idle okay but have problems maintaining a higher rpm, when it's more the opposite. Obviously pretty sure my ignition is fine when it ran the first 60 miles fine.

Open to suggestions. :(

· Registered
23 Posts
Discussion Starter · #4 · (Edited)
NOTE for some reason it's refusing to let me post for a reason I cant discern, telling me "must be at least 5 characters" when i'm trying to post the below block of text. Just in case it takes awhile to follow up again. (EDIT: a block of text it has deleted for the FOURTH TIME now)

I'm going to have to rewrite entirely a few lines at a time using Edit or it seems to eat my post not letting me put up anything. Hope it doesn't annoy mods with endless message change messages. (edit: ok I think this is my last addition for now)

I replaced the fuel filter. Nothing is running any better. I didn't cut open the old one, not sure i'd know what i'm looking for anyway or if it will tell me anything when the new one works no better...

I cannot idle the vehicle for even 1 minute - it instantly dies if it starts at all. Only violent throttle manipulation will sometimes (like 1 in 20 "starts") keep it running for a few seconds. Which if I slammed it roughly into gear (this is how I got home) would jerk the vehicle forward, long enough for momentum to keep the engine turning, so it catches again until it finally gets up to 25mph in 1st where it's still obviously missing about 3 cylinders but at least stays running if I never stop for a moment. Getting home involved running red lights.

Multiple cylinders are missing, probably the entire right bank.

The one drive I took in it after it ran bad (a few days ago when it was half running) it got fully up to warm temperature - once stopped it would NOT restart when hot. No change of behavior vs cold - after sitting it wouldn't start any better while cold.

Could a fuel pump make it idle terribly yet run at 40mph much better? I'm confused how this would work. :-/ I would think it would be the exact opposite?

What would be the best way to test the fuel pump to rule it in or rule it out, put a tee behind the fuel filter or something and try to read a pressure with... i dont know what you'd even use? I assume a fuel pump would show no code. I also assume a fuel pump might randomly die maybe... FWIW when I put in the new fuel filter it seemed to take longer than i'd expect to get fuel to the TBI, like 45 seconds of cranking it seemed. Unless the introduction of air from swapping it creates a problem.

Remember RAN PERFECT on same tank of (old) gas no changes one week ago. Only thing I touched was removing the air cleaner assembly to spray the throttle body to get rid of some varnish on first start.

I'm very confused because it was a sudden out of the blue change, not some slow or constant degradation. Was running perfectly until someone 'threw a switch' and now I can't even start and idle. It's also showing no codes (although it showed a lean engine code when I limped it out a few days ago, nothing after reset, yet ran even worse after resetting). So it has to be something which could crap out, without the computer knowing there is a problem.

Battery out resetting of the auto-learning whatever makes no change - batt has been out hours at a time to see if that had anything to do with it.

I may not have the skills or tools for advanced work either, i'm going to try a few more things and if it doesn't work it's probably staying parked possibly permanently despite being a nice car that I like because I don't have money to fix. :(
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