bloard

Sorry if this gets long, but I want to give a full background...

My 1984 sat for about 7 years. Last month I had it towed to get it running again (It ran before, but rough). Basic tuneup stuff was done... changed plugs, wires, air filter, injectors, a belt or two etc. Got it painted, then new exhaust (stock), and new tires. It had been sitting with about 1/3 tank of gas during those 7 years. We mistakenly didn't drain it, but it ran pretty well from the shop until I got it to the gas station a day or two after leaving the shop. Filled up with BP Ultimate and stuck some Lucas Fuel System Cleaner in the full tank.

Drove it about a week before getting the new tires (all were flat spotted, so like riding a bull) and it more or less ran fine. The tank of new gas really helped it run a little smoother than before. After new exhaust, and half way to getting the tires (about 20 miles at highway speed... it's first real "drive" since sitting) It would start to cut out on acceleration and once it started it would not quit until I turned the ignition off and re-4fired. Then it would run great again for a few mins.

This continued for about a week and progressively got worse (more frequent) as I was burning down fuel from the initial fill-up. So, I replaced the fuel filter (didn't help) and then took it in an beat the core out of the catalytic converter (it's now hollow... didn't help).

At this point I couln't drive it 2 blocks without having to shut it off and refire. I stopped to refuel, adding about 2/3 of a tank of BP Ultimate to full and left the gas station with it running perfect. Since then the problem occurs far less frequently. After the new gas helped, I added some Heet thinking maybe it was a water issue, but that didn't eliminate the problem. Now as I'm getting down to about 3/4 tank of gas it seems like it's getting more frequent, but not as bad as before.

As for the actual problem... it's best described as "flooding" on acceleration. The car will be running fine, then when I try to accelerate from either a stop or while driving at any speed I push the gas and get nothing. To me it sounds like it floods, but perhaps its the opposite and it isn't getting gas. The car will continue to sputter along and try to accelerate and will not get out of this mode no matter what I do short of turning it off. Putting the car in neutral, shutting off the ignition and then re-firing solves the issue 100% of the time. I can then drive and accelerate perfectly for awhile until it happens again at which point a re-fire is the only way to solve it. The biggest problem is turning into traffic because you never know if you are going to actually "go" when you push the gas.

So... where do I begin to look? I'll have a good mechanic do the work, but honestly the guy I trust the most doesn't have as much knowledge of this particular car as most of you. I want to give him some options on where to look. It almost seems like a fuel pressure type of thing but I just can't solve why the ignition fixes it completely. I assume the ignition turn-off is taking the pressure off somewhere that causes fuel to somehow flow correctly until something gets "clogged" again? Or is it electronic?

I haven't completely proven the link between a full tank of gas and better performance yet, but so far there has been a correlation between the two but it might be coincidence.

Any suggestions would be appreciated. I know that I need to check the diagnostic codes and will do so later today hopefully.

86GoldProject

I'd like to see you install a fuel pressure gauge and see what the fuel pressure is at when the car is acting up.. also since the fuel pump is so easy to remove on these cars if it were me I'd pull it out and see if the strainer on the pump is clean and replace it regardless since its obviously quite old and likely somewhat clogged also it's a very cheap part. Get the fuel pump gasket and a new strainer, remove the 4 screws holding the fuel door on and remove the 4 bolts that secure the pump, replace strainer and gasket, reinstall everything.

schrade

Vacuum leaks will prevent good atomization, and it will flood.

How's the idle? Loping?

bloard

The idle is pretty good except when it's in one of the "funk" stages, then it sounds about like it does when I forget to take the lawn mower off of choke.

I also forgot to mention that in my opinion it runs really hot. Not by the temp gauges in the dash but even after a very short drive everything just seems much hotter than it should or than I recall from before.

I drove it 3 miles to the muffler shop and after it had sat for 20 minutes, when we got it on the lift the entire exhaust system was still very, very hot which led me to think I might have a plugged cat. converter. (I worked at this muffler shop for years as a kid (my dad owned it) and know when an exhaust system is unusually hot). Gutted the converter and everything still seems really hot. The converter was more or less fine (but I can see better mileage and hp when its running right)

When if park it in the garage even after a very short drive you can feel the heat coming from car for a long time. Maybe these cars just run really hot and I have forgotten.

corvette kidd

rough idle, cutting out, step on the gass and get little to no acceleration. Fuel problem. I had this happen to me in my 84 in the mountains of Pennsylvania. Ha ha not good. I replaced the fuel filter on the side of the road and figured it to be ok. Ran ok. The car stalled out, ran rough, couldnt hold an idle without playing with the pedal. Luckily, I would pick up speed down hill to make the next climb. Found out the pump in the tank was pumping around 5 pounds of pressure. Not enough to keep the car going smooth or going at all.

Bad Fuel Pump. I did mine and the car ran smooth again. No problems since. good luck

bloard

Thanks, and you guys are probably right-on, but why would turning the car off an restarting help either a fuel pump or vacuum issue? Wouldn't the vacuum leak be constant and not only occurring after driving for awhile?

94z07fx3

I have a theory. Call it the Strawberry Milkshake Theory. You suck on a milkshake straw and one of the strawberry bits gets stuck on the bottom of the straw. But if you stop sucking it falls off and you can suck until it finds the straw bottom again.

The car sat with 1/3 tank. It rusted above the gas level. The rust started falling off since you've been driving it. Now the rust is on the sock. When enough collects to reduce flow you notice it. When you shut the car off, the rust falls away enough to allow flow again on the restart.

So get the strawberries out of your fuel tank.

(Many Bothans died bringing you this theory.)

bloard

I like the milkshake theory and have thought along the same lines myself. Anyone else think this should be the first step before I dive in? Oh, and could someone post the preferred procedure for getting the rust out... and keeping it from rusting further if that proves to be the problem?

3D-Aircrew

Every thing else sounds like fuel pressure but recall you still have that rotten varnish in your system.

I'm guessing both clogged injectors and fuel filters or sock. The hot engine is the tipoff. New injectors clog just as easy as old injectors if you run varnish through them. Properly working injectors are a must for cool engine.

I'd say the pump has enough time between when you power the ing and when you crank to pressurize for a moment enough to Run OK.

quiksilver458

I would also check the TPS voltage. I had a bad sensor that acted up intermittently. Checked voltage, replaced switch - worked like a charm.

94z07fx3

If a visual inspection reveals flakey rust then I would simply drain it down and sratch at it with a wire brush and scoop out the flakes with rags knowing that I might have to repeat this a few more times in the next few months.

If the rust is powdery and not flakey then forget about it. Powdery rust won't hurt anything.

If you just had to have that particular gas tank as opposed to one from vette2vette.net then you could research acids. Fill it with sulphuric acid and it will disolve the rust, for example. But then what are you to do with 20 gallons of acid? And what solution will neutralize the acid and leave a nice surface behind? Maybe there are services that do this on a regular basis.

If it looked likea doomed tank on my car, I'd have a local machine shop make me an aluminum box the same size with the same hole in the top for the access cover.

86GoldProject

so have you done as I suggested and pulled the fuel pump for inspection yet? It takes all of 10 minutes maybe.. My car sat for about 2 years before I got around to putting a new drivetrain in it. It had about 1/4th of a tank of gas. Before starting it I pulled the pump to find nasty varnished gas with rust chunks floating in it, I used a large magnet to get all the rust out of the tank that was floating in it, syphoned the remaining gas, replaced with fresh gas, replaced the pump strainer + pump gasket and r+red the fuel filter. Two years later still no problems. I suggest you do the same and go from there.

86GoldProject

Also you mentioned your whole exhaust system was hot which made you think you had a plugged cat. Your logic is flawed there, if your converter was in fact plugged up your exhaust system would hot up until the conveter, everything after that would be considerably cooler.

nate23

Just replace the fuel pump with a 1985 pump and then put an accel module in the distributor. It's cheap. It's easy.

Don't over intellectualize the 84. Its a simple system.

86GoldProject

So throw parts at it? Why not diagnose the problem first? I do follow the logic with the fuel pump though as this does sound like a fuel related issue. What is your reasoning for an ignition module? And why accel?

Frizlefrak

Diagnose and repair....throwing parts at a problem to fix it is fine if you're a millionaire, and have unlimited time to boot. For the rest of us, troubleshooting is the name of the game. Let's start with the fuel system, which is where I suspect your issue lurks.

Mount a fuel pressure gauge that reads 0-15 psi and tape it to the windshield so you can read it while you're driving. You can run a "T" fitting with clamps just in front of the fuel pump (near passenger front wheel well), as we don't have a schrader valve on our beloved crossfires.

I strongly suspect you will see your fuel pressure plummet when you step on the gas. If this happens, pinch off the return line with a pair of vice grips and repeat. I'm betting the same thing will happen, and then you can rule out the regulator.

If the pressure drops, you have a fuel delivery issue. If not, check for injector flow. One of the few nice things of owning a crossfire is that you can visually inspect injector flow by just removing the air cleaner and throttling the engine by hand....you should have a nice, misty, conical flow from each injector...and the volume should greatly increase as you throttle the engine.

If you have between 9-13 psi of pressure under heavy acceleration, and good injector flow, it's time to look elsewhere.

Run the fuel pressure test, post the results, and we'll go from there. I strongly suspect that you're $75 and 30 minutes from the solution.

mauitom

Did you check for any error codes? If it is truly running 'rich' code 45 will be set.

It's possible that the addition of fuel has nothing to do with your problem, but do check fuel pressure at the TBI's. Replacing with an '85 fuel pump and new screen will give you a nice performance pop, even if this is not causing your immediate problem.

Other possibilities include,
* IAC sticking
* Bad O2 sensor
* EST (code 42)
* Injectors sticking open

86GoldProject

so did you ever get it fixed?

onedef92

(Many Bothans died bringing you this theory.)

Mon Mothma like a ****...