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| engine cranks, but won't start | Rate Topic |
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| Posted: 02-26-2007 04:14 am |
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1st Post |
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Ben Cecilia Member
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A couple of days ago I was driving around in SF bay area. The next day when I tried to start the Jensen to do some routine maintenance the engine would not start. So, I checked the following; 1.carb gets gas 2.replaced coil with known working coil 3.checked #1 spark plug for spark Thanks in advance for any info
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| Posted: 02-26-2007 08:47 am |
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2nd Post |
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Harkes Member 
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Hi Ben, assuming you have checked for spark and you indeed get a spark. Then all I can think of is your distributor and advance... Check your distributor to see if it the clamp/screw isn't loose and changed your advance. Do you run an MSD? I encountered a problem once. Engine cranked but wouldn't fire up. Turned out my white trigger line was poorly connected to the black wire (pertronix) in the distributor. Fixed the wire...and she started right up. So do check all ignition parts and check advance. good luck erik
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| Posted: 02-26-2007 11:24 pm |
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3rd Post |
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Ben Cecilia Member
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Hi Erik, This engine does not have the msd,I have checked the distributor cap for worn out parts and have found that's it's ok. I will pull out the spark plugs to see if they are fouled. Thanks again Ben
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| Posted: 02-28-2007 04:00 am |
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4th Post |
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LambandAndy Member 
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Ben, The ignition system has a "bypass" circuit for the ballast resistor that supplies a full 12V to the coil during starting. Should be a white/yellow wire running from the starter to the coil. Could have come loose. Andy 15223
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| Posted: 03-07-2007 03:31 am |
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5th Post |
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Ben Cecilia Member
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Hi Andy, Here are the following tasks the that I have done so far: 1.I pulled each spark plug to check for spark and they all produce a spark 2.I checked the carbs (stromberg's) and I can see fuel eventhough the back carb has a sticky needle Do I need to change the coil? , for bigger spark Thanks again in advance Ben
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| Posted: 03-07-2007 04:13 am |
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6th Post |
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Mark Rosenbaum Member 
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For an engine to run, you need:
Sufficient spark, at the right time. Verify that the spark occurs at the right time -- ideally about 8° to 12° BTDC though the engine should run (perhaps very poorly) if it's anywhere between 0° BTDC and 28°BTDC. The distributor mounting can sometime get loose and allow the distributor to jump free for half a turn before it re-engages. Also, certain distributor internal faults can give sudden timing changes. Try a replacement distributor cap. Try a replacement rotor -- and if you have one of the rpm-limiting rotors, make sure its sliding weight isn't sticking in or near the spark-disable position. Check the points gap and ensure it's about 0.015" -- too small, or too wide, and you end up with a weak spark that may light up a plug in free air, but which will not fire a compressed charge in the cylinder. Try a replacement condenser -- again, a fault here gives a spark that won't fire a charge in the cylinder. Proper fuel-air mix. You mentioned that the rear carb had a "sticky needle." If its piston-like vacuum valve isn't free to rise and fall, you'll have an uncontrolled fuel-air mix which is unlikely to support combustion. If you can see fuel dribbling into the carb throat, you have a leaking fuel inlet valve or sinking float, which in addition to messing up the fuel-air mix is also a major safety hazard. Both of these conditions, if they exist, would have to be fixed before you could expect the engine to run properly. A severe vacuum leak could also result in a bad fuel-air mix. From what you've described, it would be prudent to presume that you have several problems at once. If so, you will probably have to go through the whole troubleshooting process several times in order to be certain you've found them all. Please do let us know your results. Further advice and suggestions are available if needed.
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| Posted: 03-07-2007 03:21 pm |
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7th Post |
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Dan (Florida) Member
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I've had an unusual no start situation before and it may pay you to check if the distributor hasn't jumped out of its drive on the oil pump. There is a spring between the distributor drive on the oil pump and the distributor shaft that over time causes wear between the distributor shaft and the distributor housing causing the drive to move apart. Eventually the drive may just hop out of the oil pump end of the drive. If there is end play in the distributor shaft or the distributor isn't seated completely in it's drive housing you may jump time and stop. I fixed mine with an appropriately sized flat washer behind the distributor drive end and a close look at the seating of the distributor in the housing. HTH Dan Last edited on 03-07-2007 03:24 pm by Dan (Florida) |
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