First thing I would have investigated is the fuel odor. Could be loose banjos or bad gaskets allowing air into the lines. Depending on which pump is in there, it could be the pump. I once had intermittent problems caused by the tank screen fragmenting and partially obstructing the dip tube.
The fast way to eliminate ignition as a problem is to hook up a timing light with the induction sensor on the main coil lead. If the pertronix is failing, you’d be able to see the missed sparks. For fuel, the first thing to do is to fix the leaks, should have been first priority anyway. If your not running better at that point, the fuel pump can be tested with a pressure gauge (should be 2-4 psi. the carbs will tolerate up to 6 psi, but better to stay in range) , and the flow rate can be checked by replacing the fuel line with a temporary hose leading to a gallon bottle and seeing how much it can pump in 30 seconds. S1/S2’s require at least 15 GPH.
I’ve had the float needles stick both ways. The old rubber ones mostly stuck open, and fuel shot out the overflow tubes. But not always. My newer Gross Jets have stuck closed, as they gummed up with today’s gasahol. It caused the issue the OP describes. I had to rebuild them last summer, after ten years or so of operation. It’s such an easy job, and even easier to test with a hammer.
I had to give up on Grose Jets, they’d stick any time the car was idle for a length of time. But those problems weren’t intermittent. It would be every spring dust-off, tapping on the float chamber tops with a mallet. Threw in the towel and went to viton needles, which seem less prone to this problem.
If any of the needle valves was stuck open or if a float was sunk, he’d be seeing fuel pouring out of the overflow tubes and the pump would run continuously.
Once again, thanks for all the advice. I’m working through all these suggestions……
When I took the dashpots and pistons off the other day, I observed that the needles appear to be made out of some sort of brass-like metal material. Today I attempted to see if the float bowl needles were sticking. I tapped on the float overflow tube top bolt and nothing seemed to change but I’m going to work more on this trajectory.
When I lift up the pistons one at a time by the lift-pins, the other two carbs are not really able to keep the car idling, but when trying this test, I did not disconnect the throttle connections. I may have to repeat this with the carbs separated. I did notice that when you lift up on one piston, the engine tends to sag. My research suggests that overall, this might suggest I’m running lean??? However, after replacing the plugs, you can see how black they are after only 20 miles. I am convinced there is more progress to be made with the carbs. Stay tuned…
I noticed one way I can keep the car from stalling on idle if to choke it. That seems to avoid the most sever idling-quitting instances.
One thing that seemed to help was replacing the fuel filter. Now when driving, the warm car doesn’t stall upon return to idle after being exercised. This is definitely an improvement. But I’ve taken it out twice since replacing the fuel filter and the overall PROBLEM is still there (car starts terribly and will barley run at low speed under power producing frightening carb backfires.)
I also still have to address the gas smell I noticed this summer and I think I should check into what’s going on with the fuel pump. There is probably a connection there. I’ve also noticed my gas “mileage” on 93 octane 10% ethanol gas isn’t so hot at 15mpg or so. I took everything out of the trunk. There looks to be some wetness above the tank, and the smell is acute, but there are not obvious LEAKS. (See trunk video)
The videos…
Anyways, again, thanks to everyone for their advice…
That’s a fuel pump, I don’t recognize the brand, is there a marking? So here’s the thing. You have a lot of seepage at the top of the tank. What I would do is order a new gasket, new bolts, new copper washers , new banjo washers, and a new tank strainer. Pull that mess out and reinstall with the correct hardware. The bolts on the tank are BA standard if memory serves, one can only hope those screws were tapped with the correct size. I’d also replace those spring clamps. They’re probably fine, but maybe not.
I’m pretty sure that the stock configuration was two copper washers under each of the cover bolts.The major vendors may offer a bolt and washer kit for the tank.
FWIW, despite this method being in every manual on the topic, it has never once proved reliable for me. Within a fraction of a second of lifting any piston on my car, the rpms start to fall and it starts to stumble. But my plugs never look lean. Neither do yours. They look fine.
A better method, used by many here is to cup your hands over the pipes and feel for “chuffing”. A condition where it makes a little dry cough. If it’s just on one pipe then it will be that carb that is slightly lean. If both pipes do it, suspect the middle carb. Turn in the suspect mixture screw 1/8 turn to richen it, rev it and let it settle. Then feel the exhaust again.
If you feel no chuffing at all, and your hands are getting black spots or you sense the rpms rising and falling, suspect a rich condition. Lean out all 3 screws until you finally get a chuff. At that point enrich and inspect again.
I believe only the fuel level sender is the weird BA size screws with a blind thread. That is why 2 washers are required to get a seal while just crushing the gasket. It’s a lousy tolerance stack. The pickup plate is 10-32 screws. If the fuel pump is suspect you should check the fuel pressure and/or replace the pump. In my case I drilled the blind BA threads through and tapped to #6-32. Then used sealer on the threads.
I do the same as this. Also can check for big variations in temperature between the front and rear three this way - a differential in mixture. Then I go for the laser thermometer at the same relative spot on the exhaust manifolds as a final check.
I’ve never had any success with the lifting pin method. I did see a video from University Motors on YouTube where our hero used a 3/16" screwdriver at the carb throat: rotated the screwdriver and lifted the piston. It looked a wholly more controllable and repeatable method. Yet to try it though. Paul.
Lots to share, but I NEED SOME IMMEDIATE ADVICE as my car is dead 20 feet from my driveway. Bottom line, the fuel pump is not switching on.
This happened first this afternoon when I zipped out for lunch to see if the new Holly 12-426 fuel pump solved my overall problem. After a massive effort to start, the car ran fine. Then after 15 minutes, it quit. No fuel pump coming on and no fuel in glass-bowl. I left it there all afternoon and at 6pm just before I pulled out my tools to reinstall the old fuel pump, I thought I’d try starting. Bingo, started right up.
Tried to make it 15 minutes to home but had to stop moving to get it into first to get up my steep driveway. (I knew not having a first-gear synchro was gonna come back to bite me.) The car went dead. No fuel pump clicking. Tried again 90 minutes later, no fuel pump clicking and no gas in glass bowl. I’m guessing if I wait a few hours the fuel pump will start working again as it did this aftenroon? I tapped on the pump to no avail.
Suggestions on getting my car to start one last time with this fuel pump to move it 50’ uphill into my garage? Or should I just put the old pump back in at midnight in the country-dark?
Unbelievable…
The good news is, I think this is definitely a fuel problem.
Looking at the specs for that FP 4-7psi isn’t that just outside the requirements for SU or Storms? Is the pump getting dead headed and overheating possibly? Just think outside the square here, one other option I take it the tank is venting OK? Had a guy on a hill climb who was experiencing fuel starvation, ended up towing him off the motorway, got him to my house and after a while we went back out to his car and turns out his dad had fitted a new petrol cap W/o vent. This was causing a depression and the pump was unable to draw fuel.
Maybe smack it with a hammer? Works with a worn out SU fuel pump with sticky contacts. Good for a couple hundred miles at least.
And if that doesn’t work, pull the cover off, which will expose the contact points. File them lightly with a nail file. That’ll get you maybe 500 miles…
I put one of these Facet type pumps in my E when the original pump started having vapor lock type problems. Where did you mount the Holly ? At first I spliced in the Facet in the opaque lines up at same level as the original pump but seemed like was having trouble pulling fuel up out of the tank to that level sometimes. I then moved it down lower to same level as the tank. Has been working fine for several years now for my 2 ZS carbs. I have been using same type pump trouble free in my Cosworth Vega when I put dual Weber DCOE’s on it in 1989. They are easy to splice into the fuel hose and plug into original wires and you might be able to find locally to get you home. Just a thought.
If the pump isn’t working, you either:
a) have a broken pump or
b) poor power electrical connection. (check it with a tester lamp at the terminal on the pump) or
c) poor grounding. (remove and clean the grounding point screw or however it is done) or
d) over-pressure on the carb side of the pump, due to blockage or
e) poor suction side on the tank side of the pump. (this is less likely, because you would at least hear the pump trying)
After five hours of waiting last night, I had to get the car off the road. At midnight it was still dead. Checked to find there was no power to the fuel pump. I rigged up pos/neg leads from the battery, the pump immediately started clicking, the glass bowl filled up, the car started right away, and I drove up the driveway and up and into the garage.
This morning I reconnected the pump to the car’s fuel pump power wires just to see if by chance the car’s “pump power lines” had mysteriously “come back…” Turned the key and bingo… click click click…
So at least PART of my overall problem is with the power being supplied to the fuel pump. It isn’t a fuse because a fuse wouldn’t blow and then come back plus this morning, I checked the #4 fuse for continuity and it’s fine. The PO even labeled the wires going to the #4 fuse!
So what the heck could be going on? Is there some kind of “safety feature” that turns off the power to the fuel pump when the car is warm, but not “supposed to be running” like after a collision or something? Sounds unlikely… hell, this car doesn’t even have hazards!
By the way, the Holley I installed is the 12-426 and it’s rated to 1.5-4psi and 25 gph. Should be perfect for the 6cyl with the SU’s, no? I put it on the front of the trunk-well where the old pump was which is about 1" vertically above the level of the fuel tank.
You have not proved that. You just as likely have a problem with power “leaving” the pump. I suspect you have a grounding problem. See my post of a few minutes ago.
That almost sounds like an intermittent electrical source.
Other than that… could there be some “gunk” that got sucked into the pump and is jamming it? ( really reaching for straws here)
LLoyd
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