Hey Mark, anything you think may Help, spout it out, this one should be running, read back a couple weeks this has been acting out.
Hey Mark, anything you think may Help, spout it out, this one should be running, read back a couple weeks this has been acting out.
Well, I think today was productive...the question is whether the car continues to behave tomorrow.
First off, those other gaskets for the float needle adjuster/set screw didn't work. The smaller one fit around the threads of the set screw(just barely) but the gasket isn't wide enough to cover the hole in the adjusting nut, so it wouldn't really seal anything. The larger gasket was too small to fit around the float needle at all.
I reinstalled the paper gaskets, after giving them a bit of lube, and reset the floats. For whatever reason I had no cascading fuel out the top of the carb today. I also backed off the idle speed screw all the way, then turned it back in about 3/4-turn. Then the car fired up, and with a bit of throttle feathering it eventually settled into an idle, albeit with a bit of surging.
I tried spraying carb cleaner around the base of the carb, and I think I might have a leak there, but with the surging idle it was not conclusive. One of the manifold/carb holes was stripped & I repaired it, so I'm not confident in tightening it any further than it is. Would it be a bad idea to use a thin smear of RTV on the carb gasket to help seal it?
I adjusted the idle mixture screws - they're as far in as I could go without the idle speed dropping like it was going to die. That's where I found max vacuum, so hopefully that's ok.
After letting it idle at probably ~300 RPM for about 20-minutes, keeping an eye on the coolant temp, and watching for leaks, I decided to shut it off. The main fan didn't kick on, although the secondary one did(the one in front of the condenser), so I'll need to do a bit more investigating on that.
I let the car cool down while I put the dash back together. The gauges still don't work, but I wanted to have it mostly together before I test drive it(eventually), or possibly take it to the autox this weekend.
I topped off the coolant and started it again. Once more it took a bit of work with the throttle before it settled into an idle, so I pulled it out of the garage. I needed to 2-foot the brake & gas to get it going without stalling, but it seemed fine otherwise. Although it died once after it was outside, I was able to get it restarted after a couple tries, and the idle actually seemed smoother than it was earlier in the evening. From then on it idled fine, however I did notice a small trans fluid leak. I was able to locate it at the radiator/lower trans cooler fitting, so I'll have to dig into that again too. After allowing it to come up to temp again, I backed it into the garage and called it a night.
Here's a vid from the first time it was running. You can clearly hear the surging, and I think possibly a vacuum leak, though it was on the passenger side so it's not the carb base(the repaired stud is on the driver's side).
After letting it idle at probably ~300 RPM for about 20-minutes,
300 rpm idle? That seems waaaaaaaaaaay low. I would be thinking 800-900?
In reply to NOHOME:
That's just a WAG, what does it sound like on the vid?
I almost feel like I can hear a vacuum leak when you bring the camera to the rear of the carburetor...but that could just be the venturis/air cleaner hiss I'm hearing.
Might be worth double checking all the ports there at the back of the carburetor.
In reply to ClemSparks:
There's only one large one on the baseplate. It's capped, and the starting fluid didn't have any effect when I sprayed around it.
I'd say that idle was around 450-ish and the surge is likely from a lean idle. Any vacuum leak you can hear usually will be large enough to prevent the engine from running (chased enough over the years I'm surprised I still have hair!). If it's a vacuum leak there will probably be one or two tiny ones. Try bumping the idle up a bit and back the idle screws out about 3/4 of a turn and see what the surge does.
I did hear what sounded more like a bearing howl though, possibly the air pump, alternator or a/c clutch. Easy to check, just remove the belt and spin the accessories. The one that feels "metallic" when you spin it is threatening to go. The early versions of the serpentine belt setup were notorious for eating bearings. My '85 Vette left me stranded twice that way because GM had not upgraded the bearings yet. That dinky little tensioner actually puts a huge side load on all the accessory bearings!
RTV on the fitting anywhere in the fuel system will be temporary only. Fuel and fuel vapors will break the compound down and turn it to jelly. I'm sure there's lots of good sealers out there but if you want something that will last literally forever, pick up a tube of 3M 5200. You can get it at most any marine supply store. It is impervious to gas, diesel, oil, water, fire, heat, cold, nuclear waste, it sticks to everything (I mean EVERYTHING!) and can only be removed with a chisel or grinder. Ask me how I know!
Cheers,
Mark
Oops, I just re-read what you wrote. I thought you had an intake fitting stripped. Disregard what I wrote about the atomic sealer. But RTV will not do the job sealing the carb gasket. If the carb base and intake surface are in good shape you shouldn't need to crank down hard on the flange bolts (or nuts, I didn't see if you had studs/nuts). They don't need to be gorilla-tight
In reply to B757Captain:
Thanks Mark!
I'm pretty sure the tensioner bearing is on its way out. The water pump & bypass pulley for the air pump are new, and the alternator was good - at least before I reinstalled it.
Don't let it go too long - mine let go just outside of Wagon Mound NM (pop. 250) one fine Friday nite. I'll never forget it cuz I had to stay the night there, rent a car to get home (Colo. Springs at the time). Wait til Monday morning, drive to Denver (one Chevy dealer in 8 state area had a tensioner) then drive back to WM to return the car and fix mine, then drive home. That night in Wagon Mound felt like the longest week of my life!
I abused the heck out of that Vette for 8 years before I sold it (at 185,000 miles) and other than typical things broken and fixed, the only parts of the car I considered weak were the single belt serpentine system (single failure point - any one accessory goes, you're stuck, can't even jury rig the water pump to crank pulley because the water pump is reverse rotation) and the rear wheel bearings. Other than that, everything worked when I bought it, everything worked when I sold it, and cosmetically the only thing bad when I sold it was the glass top was cracked. Back then the only real hotrod parts for the TPI was the Lingenfelter system but that was big bucks, plus I was racing then so I got my fix on the track. I just enjoyed the car! When you get it running well, you will too!
It's late here in Japan, gotta work tomorrow - mata ne!
Mark
Slight revelation: After trying(and mostly failing) to tighten the trans cooler line - I got it to turn all of 1/8-revolution, I hope that's enough - I tried firing up the car. It started about the same as it always does, the first 2 times when I tried letting off the throttle it stumbled then died. It restarted quickly, but eventually it died again with a slight backfire out of the carb, and wouldn't restart. I didn't think I'd burned through the second 5-gallons of gas yet, since it had only run about 20-minutes at a low idle on Monday, but I added another 1/2-gallon and tried again...still no luck.
Supposedly, the stock C4 fuel pump circuit allows it to turn on for 5-seconds or so at key-on, then it turns off until you crank the engine. However, this car has always had full fuel pressure from the moment the key is on - no idea why, but it's been consistent since I installed the new pump. Well, with key-on both fuel pressure gauges read zero. I turned the key off/on again, and still zero.
Unfortunately, this afternoon was apparently when my neighbor decided to run a tile saw non-stop, just across the fence from my garage, so I couldn't hear whether the fuel pump was running. By that point I felt like I was about to have a heat-stroke anyway, so I closed up shop...which is right when he finally finished sawing(after an hour & a half). So I tried the key one last time, heard the fuel pump running, check the gauges...and I was back up at 6-6.5psi.
So I'll need to do more troubleshooting to determine whether it's a pump and/or relay problem, or if there's an obstruction in the filter/line, but at least I know there's an intermittent fuel problem(among probably other things).
without rereading have you had the pump Out yet, they suck and are Known to be Intermitent, If It's Original It may Have the sock full of trash or just may want to go to the Recycler.
In reply to GTXVette:
Pump, sock, and filter are new. I also completely wiped the tank clean inside. Oh, and flushed the old gas out of the lines before I bolted on the carb.
Thinking about it more, for both gauges to show zero psi, then have full pressure after that, it's either a complete blockage - but one that somehow is intermittent(?) - or it's an intermittent problem with the pump and/or relay.
It seems unlikely it could have picked enough crud out of the (wiped clean) tank to plug the filter 100%, yet still settle enough to allow normal flow sometimes...right? Given that the relay is the only component I've not touched, I think I'll pull it tonight and see if I can pry the cover off to check the contacts.
well I thought that, the pump primes the system for 10 seconds or till pressure is achived then come on as needed when the switch is turned on.
In reply to GTXVette:
I know that's the way it's supposed to work, but my pump is on 100% once the key is turned to Run.
I pulled apart the fuel pump relay. It looked pretty good, but I hit the contacts with some light sandpaper, and redid the solder joints.
With a bit of testing I discovered a couple things: At key-on the fuel pump will usually run. This would fill the bowls and allow the car to start, but I had zero psi on both gauges, and the car died soon after. Also, even though the pump wasn't running I had ~11v at the pump connector. How sensitive are EFI pumps to low voltage?
I have the battery on my big charger now. I'm curious to see if the pump will remain on once I have a steady 12v+.
Also, in the process of troubleshooting I found out I'd have ~11v at the pump even though I was reading 0v from the FP fuse to ground on the battery. That doesn't make sense, but I'd need to see a factory wiring diagram for details.
Can you plug the return line so it Reads pressure, but that seems like that would shut the pump down until it needs more instead of it wanting to run all the time
In reply to GTXVette:
I could, but I've verified the pump isn't running when the gauges are at zero?
Straight wire the pump with a toggle switch for now. Same with ignition power. Isolate electrical issues from mechanical issues. Then, once mechanical are sorted, move on to electrical.
I spoke to the C4 expert, mr. Beachcomber. A minimum of 10.4 volts is fine to run the stock EFI fuel pump. He explained the circuitry 4 fuel pump relative to key start and oil pressure switch and the ECU. Give me a call and I'll explain what I gleaned from him as it's too lengthy for me to try to write
In reply to Ovid_and_Flem:
I was just reading about that over dinner. 
I've never had the oil pressure switch connected, yet I always had the fuel pump running with key on - until I cleaned the relay tonight.
In reply to Dusterbd13:
I'm going to jumper the relay so it's always on with the key, then confirm my voltage at the pump & its operation. If the pump continues to read 10v+ but doesn't always run, then I'm thinking it's on it's way out. I believe it had a year warranty though, so I'll have to dig through my paperwork & check.
If it isn't reading Oil pressure the pump turns off or just dosn't come back on after the computer tells it to Prime ..... I guess?
Slight progress. Based on a tip from Ovid_and_Flem I discovered the wires in fuel pump relay plug had pulled out of their sockets. Unfortunately fixing it still didn't resolve my problem.
I don't know why previously I always had voltage to the pump, but I'm pretty confident the reason I don't now is related to the fact the oil pressure switch is disconnected. I never found the connector for it when I reinstalled the engine though, so I'm going to have to get a little crafty. I'm going to see if I can find a circuit that's hot at key-on I can use to trigger the relay.
Does your fuel pump relay have a little wire tagged off of it like the one in the picture below ? (red wire taped to harness)
That's a test wire. You can jump 12v to that terminal and the pump will run. I thought TPI engines used them too (pictured is a TBI setup).
Dusterbd13 wrote: Straight wire the pump with a toggle switch for now. Same with ignition power. Isolate electrical issues from mechanical issues. Then, once mechanical are sorted, move on to electrical.
This should be your course of action.
In the car, power to the the fuel pump MAY be interrupted by operation or failure of: battery, ignition switch, oil pressure switch, fuel pressure switch, inertia switch, gear position switch, fuel pump relay, wiring, connectors, etc. Do you have a wiring diagram?
Hot wire the pump (with a toggle switch), and pump gas into a can to verify the pump, lines, filter, etc.
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