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| Warm Start Trouble | Rate Topic |
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| Posted: 11-17-2020 10:12 pm |
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1st Post |
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Jagwire64 Member
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Back again. Still trying to understand this car. Car starts easily when cold with choke. Runs great. Very difficult to start when the engine is warm. I don't use the choke when warm (tried it no help). It would usually take 3 or 4 tries before it starts recently had to wait 30 min before it would start. Once it does, it runs rough for a minute or two then fine. PO removed the original airbox for foam filters. Also removed the Evap canister. My thinking is that i am getting to much fuel vapor from the hot engine so it won't fire. I'm installing a new Evap can...and an oil catch can and breather. Trying to match the original venting. PO has the valve cover hose going directly to the crankcase instead of the airbox. With no vent for pressure I assume that cannot be good. Though I am not sure this will solve my problem. I have also ordered some heat shields for the strombergs. Any other ideas. Thanks Tom
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| Posted: 11-17-2020 11:51 pm |
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2nd Post |
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pokeyjoe Member
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Sounds like its flooded. Residual fuel pressure getting past the needle and seats, maybe?
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| Posted: 11-18-2020 01:21 pm |
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3rd Post |
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Jagwire64 Member
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That was an issue that I rectified. The carbs have been rebuilt and seem to be operating properly...new fuel pump and pressure regulator. usually if i flood it ...i put the pedal to the floor and it will start. That doesn't help here. I acts like its flooded..not sure it is. I did read some about the Lotus 907 having warm start issues due to hot air in the engine bay. I know other people take off the OEM airbox because half the pictures on the web have it removed. I can't imagine every car is this difficult to start when warm?
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| Posted: 11-18-2020 02:42 pm |
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4th Post |
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Brett Gibson JH5 20497 Member
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I'm thinking that the positive crankcase ventilation that you mentioned might be a issue, if it's venting back into itself it's actually not venting. A heavy venting engine is best run to a canister or back into the carbs, one that doesn't vent so much, like mine, can be vented under the car. I'd also double check the choke disc's on the front carb to be sure they are not scored and allowing leak by. Just a couple of thoughts. Brett.
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| Posted: 11-18-2020 03:29 pm |
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5th Post |
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Jagwire64 Member
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The choke disc surfaces were a bit pitted. I bought a set of carbs with a cleaner choke surface, maybe I will try that next. What is the general warm start procedure? No choke, try starter....if no start... gas pedal to floor try starter? From owners manual. Last edited on 11-18-2020 03:37 pm by Jagwire64 |
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| Posted: 11-18-2020 05:54 pm |
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6th Post |
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noomg Member
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Jag, There's no warm start procedure other than a twist of the ignition key. When I hear hot start problems I think vapor lock. When you shut off the motor the temp in the engine compartment goes up before it starts to cool. If you've got an unprotected fuel line the fuel can vaporize making a hot start difficult. When fuel in the line vaporizes(before it's supposed to)it raises fuel line pressure making it harder for the fuel pump to supply gas to the carbs. When I first got my '67 El Camino it had hot start problems, I insulated the incoming fuel and fuel pump, I've had no hot start problems since.
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| Posted: 11-18-2020 06:08 pm |
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7th Post |
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Jagwire64 Member
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Vapor lock is my thinking...The fuel line isn't insulated. The steel line from the tank and coming up from under the car is not protected (i assumed they were all that way from factory) it is rubber line just before the carbs. Will try insulating that line. Thanks
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| Posted: 11-18-2020 07:28 pm |
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8th Post |
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Brett Gibson JH5 20497 Member
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For my 2 cents, I've seen a ton of Healey's and vapor lock on one would be a stretch.... can't hurt to try it though. If your confident in the carb re-build and adjustment, I would look at the electrical connections and grounds, heat can also bring on lose connections once the wires warm up and flex easier. I'm assuming that your ignition system is spot on. Brett PS: Float bowl level to high ???
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| Posted: 11-19-2020 05:40 pm |
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9th Post |
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noomg Member
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Brett, I agree, while Jensen-Healeys had many problems vapor lock didn't seem to be one of them. However the car is 45+ years old and who knows what changes POs might have made which could have had a negative effect. Insulating the fuel line is an inexpensive and easy fix, if it doesn't work you've at least eliminated one possibility. I've always been a big fan of when you're not sure what to do, do the easy things first.
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| Posted: 11-19-2020 07:15 pm |
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10th Post |
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Jagwire64 Member
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The ignition system seems to be set up correctly...it is a pertronix elec. I need to check the ignition wires.
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| Posted: 11-20-2020 02:54 am |
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11th Post |
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redracer Member
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Pertronix:: that COULD be the problem. Before you wrap the fuel lines, which I have NEVER seen necessary, put a set of points, condenser, and low tension lead back in and go from there. It may also be possible that your fuel mixture may be too rich, so an old CO meter would be VERY useful(I set the CO at 4-5% at 3000ropm, the "cruising" point). Newer spark plugs can clean up carbon rich mixtures, unlike the old plugs that came in out cars
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| Posted: 11-20-2020 07:19 am |
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12th Post |
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subwoofer Member
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Is it an Ignitor 2? And you are running the original tach and have connected the Pertronix per the instructions? Does it ever die while idling, for no apparent reason? Then you are experiencing the undervoltage lockout feature on the Pertronix. Run the red wire on the Pertronix straight to the battery through a relay and your woes will magically disappear...
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| Posted: 11-20-2020 08:53 pm |
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13th Post |
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subwoofer Member
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All you need for quick confirmation is a piece of wire to temporarily connect coil and battery positives when it is acting up. Another indication is if it always starts the moment you let go of the key when cranking.
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| Posted: 11-23-2020 07:19 pm |
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14th Post |
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Jagwire64 Member
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It is igniter 2...with the resistor i have 3 ohms. Never had it die at idle. it was only starting the moment i let go of the key when warm. No sound but the starter and when i let go it would catch (if it started at all) Did finally get the oil vent/catch can and evap can all plumbed and installed. Problem appears to have been solved. Got it up to temp...waited 30 min and it started with no trouble...didn't touch the accelerator or choke. drove it a bit and tried again at 5 and 10 min after shut off. starts like magic now. I can hear it firing before i let off the starter. Too soon to know for certain but the outlook is good. Will check the pertronix if the trouble returns. Thanks for all the help.
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| Posted: 11-23-2020 07:42 pm |
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15th Post |
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subwoofer Member
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My bet is still on the Pertronix, I spent a LOT of time fighting the same problem. But I have a Lucas Sport Coil and no resistor for hotter spark, so that may have made it worse. -- Joachim
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| Posted: 12-30-2022 02:51 am |
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16th Post |
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Darth V8R Member 
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Jagwire64 wrote:Back again. Still trying to understand this car. This is a very old thread, but I wanted to document an alternate response to this issue for other members on the board. The hot start problem is CARBURETOR related, not emissions, vapor lock or ignition. After the carbs heat soak for a while, they are hot enough to significantly heat the air passing through them during a hot start. The hot air is less dense, and contains less oxygen, and therefore needs less fuel to combust properly. The problem is that carburetors are stupid, and add fuel based on the VOLUME of air, not the density. That means during a hot start the mixture is pig rich, and difficult to ignite. Once the engine fires and enough cool air passes through the carbs, the carburetors cool off and no longer heat the air, and the density of the air increases, so the mixture leans out and the car runs normally. The Zenith engineers knew about this, and added a temperature compensator to the carb, but by now they are way out of adjustment if they are working at all. First, get the baseline mixture correct. Do NOT use the lift the slide method, it is much too sensitive to technique, and most people lift the slide way too much, so the engine tries to stall and the tuner assumes that the mixture is too lean. He then adjusts the mixture richer. This aggravates any hot start issues even though the car runs fine when cold and when cruising. Therefore use a color tune, CO2 analyzer, O2 sensor or plug cuts to get the mixture correct. Once the mixture is correct, the plugs will be a light tan color after a spirited drive with the engine fully warmed up. If this is not enough to solve hot start issues, you will need to adjust the compensators. These are the white assemblies on the side of the carbs, about the size of your pinkie finger. Make certain the carbs are at ambient temperature when adjusting them, they must not be warm to the touch. Remove the two small screws that hold the cover on the compensator. Do not lose them, they are number 5 screws, which you will most likely not be able to find at the hardware store (usually stores stock number 4 or number 6 screws, but not number 5). Under the cover is a bi-metal strip with an adjustment screw. The strip opens an air bleed to lean the mixture when the carb gets too hot, thus preventing a hot start failure. Tapping *lightly* on the black plastic plug at the end of the the strip with your finger, back off the screw until the plug can be felt to move when lightly tapped. Then tighten the screw until movement can no longer be felt and tighten the screw 1/8 turn further to preload the plug. Replace the cover and adjust the other carb in the same way. This will eliminate 95% of all hot start problems. It worked on my TR6, it worked on my TR7, and it worked on my TR8. All of them had hot start problems when first acquired. So try this before you go chasing ignition or vapor lock gremlins. Cheers, Vance Last edited on 12-31-2022 06:50 pm by Darth V8R |
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| Posted: 12-30-2022 06:38 pm |
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17th Post |
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noomg Member
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Vance, I had a feeling you'd be showing up here sooner or later. Congratulations on your latest acquisition and welcome to the asylum. You may know me as Sliproc on the TR7/8 message board. Looks like you found a nice clean stock late model steel bumper car. I know you're planning a full resto but judging by it's current condition it might be a good idea to get it running first and just drive it for a year or two. That may give you a good idea as to how much you'll want to spend on the resto. That's basically what I did, although it took me 25 years to get around to the actual restoration!
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