Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: Fotog on Wednesday,July 19, 2023, 01:34:08 PM
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I was driving the TC with mechanical fuel pump about a week ago and it started to run out of power and finally stalled-out altogether. One of those things where the further you opened the throttle, the worse it ran. Missing, etc. I'm trying to figure out what happened.
I was admittedly low on fuel. I wasn't going so far, and the gauge read between 1/4 and empty. I don't recall running it that low before, but I dipped it and there was about 3 inches in the tanks before I left the house. I had driven about 10 or 12 miles and was going up a hill when this occurred. I drifted to a stop on a side street. Turned the key, and it started and stopped in a few seconds.
I was able to check for a spark, and that was good. I re-checked the tank and had about 2 inches of fuel in the tanks. I thought that should be enough, but I don't really know where the outlet pipe is relative to the bottom, so had my wife bring me some gas. I didn't want to be too dumb about this. After filling, I had her crank it and could see fuel flow. It took about a minute before apparently the carbs were filled and it started. It sounded and ran fine; powerful, etc.
I drove it 1/4 mile, and the same thing happened. It died. After sitting for a couple of minutes, it started up again. Sounded and seemed fine. I drove it a few hundred yards, and the same thing. Poor running, low power, and ultimately stall.
I did this to get the car about 3 of the 7 miles to home, and finally had it towed the last 4 miles. The last time, after sitting a couple of minutes even, it didn't start.
I'm not sure what to make of this and how to troubleshoot it. It sure seems to be fuel flow related. I could easily replace the fuel pump which I don't mind doing, but I prefer to understand the symptoms and what could be happening if generally it benefitted from sitting for a few minutes. If fuel is somehow not getting to the carburetors, then I would expect that some significant cranking would be involved before it would start again, but that wasn't the case, at least until I gave up and had it towed.
Any ideas, especially about how to diagnose this, will be appreciated!
Vince
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The symptoms seem like it is the coil. It would be difficult for a fuel pump issue to cause what you described. You have two carbs so the float valve is redundant.
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Interesting. Given that the coil is basically a transformer, I would have expected it to either work or not, and the failure mode to be shorting internally after insulation breaks down.
Thanks!
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If way to lean, you will get the lean backfire through the carb at WOT. How is your tank internally? originally I thought mine was good enough until it plugged my pre pump filter to the point it would only idle. Not saying it's fuel but.
I know ignitions have issues when hot, cool down then work, get hot and don't
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Thanks, fellows. I'm not lean, pretty darned sure. No backfiring through carburetors. Not long ago I went to hotter plugs: NGK BP6ES vs BP7ES as they were fouling, a little wet too. I've only looked at one since, but it had a lot of carbon; no wetness. My Strombergs aren't adjustable. After some other todo's, I thought I should look into that, as maybe too rich. Seems like a lot of somewhat volatile PCs from the exhaust when running. I don't know if it's oil that gets through the valves or rich A/F ratio affecting the plugs. I think the tanks are fine, but I don't really know in detail. Another thing to investigate.
I just checked resistance of the coil though. I was lacking knowledge until now. Primary seems fine at 3.3 ohms, but the secondary is low at 8.6K ohms. Getting a new one on order now. I think Paul is right! I appreciate the response.
Vince
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A coil can fail intermittently. I always carry a spare. It's funny how I learned this. When I was 14, my father had a 1966 Shelby gt350h. (The one that is black with gold stripes) It was doing something similar to yours. I went with my father to the Ford dealer . They changed the coil and the problem was fixed. I am not saying that is the problem. But, it will eliminate one variable.
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Diagnosis is a methodical process where you test each potential problem area carefully until you find the issue.
Make sure the issue is still present. Then disconnect the fuel line to the carbs and point it into a plastic bucket/container. Crank the engine for 10 seconds. How is the fuel flow? (There will be a spec in the manual on fuel/time) Any crap in the fuel?
If it all checks out fine. Then look at your ignition. There can be a problem and still show a fat spark when cranking. Condensor issues can feel an awful lot like a fuel issue.
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When I was 14, my father had a 1966 Shelby gt350h. (The one that is black with gold stripes) It was doing something similar to yours. I went with my father to the Ford dealer . They changed the coil and the problem was fixed. I am not saying that is the problem. But, it will eliminate one variable.
I would have been 10, but we should have had one of those. We lived outside of Detroit then and dad worked in marketing for Ford. We got some new car every year, and had a series of Mustangs, but never one like that. Dad wasn't really a car enthusiast, not yet 40, with 4 kids...
John- Thanks for the suggestions. I'll try to be as logical as I can about this.
Vince
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My car had the same symptom when I purchased it, turned our the outlet of the fuel tanks were pluged with crud.
Easy enough to check.
Regards
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Change the coil for a 12v gold top coil. If that doesn't work, change the points and capacitor. If that doesn't work spray quick start into the carbs. If that works, you have a fuel feed problem.
Start with the most obvious and simple to fix, and then work through the list.
I went through the whole list, used a different type of quick start, it started first time, and starts easily thereafter, so I have no idea what the problem was. Fuel feed?
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If you replace the condenser, get one from Distributor Doctor. The Lucas branded ones currently available are junk. A few years ago I had an ignition issue that was hard to cure. I replaced the condenser twice with no improvement, until I heard about the ones being sold by Distributor Dr. I fit one theirs and the problem was cured.
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Thanks for all the suggestions. I drove the car the other day for about 10 minutes on nearby roads to confirm that the problem is still present, as JB suggested, but it was fine. The two differences from my previous experience were that I hadn't just recently (apparently) run out of fuel, and the the ambient temperature was cooler by 5-8 degrees F. It was in the low 90's when I had the problem.
I've been otherwise occupied generally since, but maybe tomorrow, a hot day, I will try again to duplicate the problem. I do now have a new premium coil, but haven't installed it yet.
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Could it have been vapor lock?
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I wondered that myself, but I haven't heard reports of that generally with Stromberg carburetors.... that I can remember. I don't think I have any experience with vapor lock, so I don't know if it's possible that it can temporarily resolve itself, like the symptoms I experienced. I've also probably driven in weather that hot before without a problem.
When I can get back to it I'll try to do some more investigating and see if I can find anything.
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This sounds very familiar. My car was in long term storage and after some reconditioning I was able to drive around the neighbrhood. I then attended a club even that was 10 miles away and on the way back it started stumbling. I was low on fuel and assumed that was it, but no. I could get a couple blocks and it would starve again. I found the fuel line from the tanks to the fuel pump was slightly blocked with sludge. I cleaned it out and blew back until I could hear bubbles in the tanks. Been fine for the last couple weeks. I plan on a more through tank clean and fuel line replacement over the winter. Hope this helps.
Mark
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Thanks, Mark. I'll replace the fuel line and filter as part of this process. Good idea about blowing it back too. I've got some things going on such that I haven't gotten back to it, but I hope to shortly.
Vince
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Here's where this stands: I replaced the fuel filter, located near the pass. side tank, just before the run up to the carbs.
I've driven the car about 15 additional miles, with no problems. I did fill the starboard tank (passenger side, that is) with fuel. I'm accustomed to it taking 5-10 minutes or something like that for the two tanks to equalize and the additional fuel to show on the fuel gauge. This time it was much longer, though I can't give a figure. I have not, but will replace the fuel lines. Maybe when it 'ran out of gas', I used all in the passenger side tank, and the crossover line wasn't able to supply the additional needed to keep running due to a partial block.
I have acquired a new coil, but haven't installed it yet. Will soon, but it seems that wasn't the problem.
One question: Will a supposedly higher-performance coil make for a better spark and thus less carbon fouling of the plugs? Not too long ago I changed from NGK BP7ES to BP6ES and they're still quite carbon-fouled.
Vince
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Changes to the ignition system to increase voltage output just increases the amount of voltage “headroom” you have. The plug will fire at the same voltage regardless. You can take advantage of the higher voltage potential by increasing the gap. That will raise the voltage at the plug. It will also cause the plug to wear more. This you can offset by fitting plugs with precious metal electrodes.
If you are still using points, then this is a bad idea. Larger voltage at the plug means more current through the points, wearing them quicker.
Rocking Pertronix? Fit a 3 ohm coil and open the plug gaps to 30 thou.
None of this will change your plug colour. It may help fire a heavily carboned plug.
I’m always leery of changing plugs away from the recommended heat range. Yes there are times you should do so but that is when your engine has been modified or is plain worn out. If it is stock then fix the issue. Don’t apply a bandaid heat range change.
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Thanks. I'll do some further investigation.
-Vince
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Back to the original issue- In conclusion, I ran the car out of gas. Farther below I’ll tell you why it didn’t run right after adding fuel. The gauge has little resolution below ¼ tank and I didn’t view it correctly: there is a parallax problem since it’s viewed from the driver’s position at a significant angle and there is about 1/8 inch between the needle and the scale behind it, so you really can’t read it very well until you move over to be directly in front of it… which is difficult if possible. Another problem is that the fuel outlet pipes in the tanks are located at the front of the tanks. If you start to go up a hill, fuel level will be lower in the front than the back of the tank and it will ‘run out’ when it’s low.
I replaced the fuel lines and filter, measured fuel level in the tanks with about a gallon of gas, and then again after all had dripped from the disconnected outlet hoses. I documented voltages and resistances from the level sending unit at different levels and generally got familiar with it all. But I didn’t find anything to be out of order. Fuel level in the tank with the level transmitter (left) went from about 3.5 inches to 1.325 inches, with a dip stick. Level shown on the gauge changed, but very difficult to discern the difference. I put that fuel back in, and drove about a mile and a half before I ran out again going up a hill. I thought the gallon or so that I put back in would take me farther, but not so. Now I know that once the gauge is clearly below ¼ full, I’m in danger of running out.
Regarding intermittent running after fueling:
My thinking was that the fuel comes from the right side tank, which communicates via a hose or pipe to the other (left, driver) side tank. Not exactly! The two are teed together near the right side tank with the outlet of the tee going up to the fuel pump, so at all times the fuel is supplied by both tanks to the fuel pump. Therefore, once you run out and you’re sucking air, it’s important to put fuel in both tanks to cure your problem. I initially had added fuel to the right tank only. Some fuel flowed to the other tank. I started the car and drove it a short distance before the left tank was again empty and I was trying to run on a mix of fuel and air again. If the car sat for a minute, it would re-start and go again for a few hundred yards before the same thing happened again. Dumb, but I got it now!
After my examination of the system, when I ran out the second time, I added fuel to both tanks. Once it made it to the carburetors, the car ran fine with no anomalies.
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Glad you got it sorted and yes, running low on fuel with twin tanks can be problematic because you don't precisely know where the fuel is.
I recall parking on a heavily cambered road and when I came out and started the car again, I had more fuel than when I parked.
Here's the Greta approved solution...
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Cars with twin tanks have problems when fuel level is low, and they are parked on a slope.
I parked my GT40 outside my local pub on a slope. It would not re-start after standing for an hour as the fuel had drained from the tank where the fuel was sucked by a powerful electric fuel pump.
Fuel gauges on old cars are very inaccurate from full to 3/4 full, and from 1/4 full to empty. They will not even register anything until you have about 4" of fuel in the left tank.
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I reported back in case my experience getting it to run without problems after refilling would be enlightening. It was a result of my habit of only putting fuel in one tank (right side) for the relatively modest amount of driving I do with it. It just didn't occur to me that I'd be sucking air from the other tank in short order if I followed my usual habit after running out. I hope some others learn from my experience.
4129, I wish I could say it had happened to me with my GT40 🙂.
And Gavin, I should follow the Greta approved solution, yes.
Vince
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Whenever I fill up, I fill up both sides to the top, as we have to put Super Unleaded into the car in the UK, and not all petrol stations sell Super Unleaded.
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4129, I wish I could say it had happened to me with my GT40 🙂.
Me too.
I'm not sure there's a more dangerous mental image than a GT40 parked outside the local pub and half a dozen tiinnies under the belt.
Thus I picture 4129R saying this – "Driver, bring the car around to the front." ;)
One side benefit to an electric fuel pump is the somewhat furious ticking sound as it fills up the carbs. I wait the three seconds till it calms down prior to starting the engine. It'll do the same manic antics if sucking air, too.
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"Driver, bring the car around to the front." ;)
I have not let anyone else drive it yet. The clutch pedal is difficult, you have to bend your knee rather than your ankle to operate it, or you stall it.
As with the Europa, side and rear vision are limited, and you cannot see over even slight brows on a road so overtaking is difficult on normal roads. Plus at night, you are so low you get blinded by even dipped beams.