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Help Engine wont start


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Hi Guys,

 

The engine was running one day and now won’t start.

 

I have a spark and fuel, it’s on electronic points. Engine turns over freely.

 

I have checked the ignition spark on the bench then on the car. Coil, leads, distributor all ok, I had a spark going to each plug on and off the vehicle. Distributor, electronic points, coil ,cap and leads were all new 2 years ago. Spark is a whitish colour.

 

Plugs are wet, fuel is getting as far as the carbs. Have tried entering fuel into the carb manually and easy start just to check but still no start. Diaphrams on rebuilt carbs look fine.

 

Compression readings on the engine rebuilt 1000 miles ago are 205 - 212 - 218 - 218

 

The timing hasnt moved...or at least the position of the distributor is the same and the bolt on the clamp is tight.

 

The white power feed to the + on coil shows 11.9 volts on sitting and 8 volts when cranking over.

 

I had loosened the dashboard to check the temp gauge but don’t think this has caused any issues and it worked while doing this, the ignition switch is lower down.

 

What else could the cause be or I can check please?

 

Thanks

 

Colt

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I found that one squirt of "Easy Start" is a great initial diagnostic tool before you get the toolbox out.

 

If the engine fires and dies then it means there is a spark and the timing is reasonable, the dying once the Ether is used up the indicates fuel problems.

 

If the engine won't fire then there is no, or very poor spark whilst cranking.

 

If the engine starts and then runs, it may have been flooded or the spark is poor.

 

If the engine starts but not all cylinders are firing then a bad plug / distributor cap.

 

 

Alan

Edited by barkerwilliams
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8v on cranking seems lowish. Is you battery on the way out?

Wet plugs suggests fuel is getting through. Dry over a gas flame, getting: wet with fuel does not end the life of a plug.

 

If you have a spare battery run a direct feed to the coil.

 

Are your body and engine earths ok?

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Certainly seems to be electrics.

 

Often, it's impossible to find the root cause (unless you have

specialist equipment/expertise) so the easiest way is to

replace plugs, leads, points, condensor, and distributor cap.

Fortunately, not too expensive, and useful to have backup

for these items anyway.

 

Last time I had a similar problem, it was plugs - even though

they were fairly new and showed no signs of any fault.

I've also had a fairly new coil fail, immediately after parking

after a run out (with no evident problems).

 

AlanR

Edited by TR 2100
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Fisrt try new Rotor Arm,

then remove elect ign and try substitute, or original points

Then dist cap

Chris

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Thanks folks. I will have to buy some points and try those.

 

I have charged the battery as it was dieing and will recheck the volts to the coil.

 

I did wonder if oil from the dashpots could get into the fuel easily hence stopping a spark? The level drops a bit and one of the diaphragms looked a little oily.

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IMHO you need to first test how strong the spark is FROM the coil.

Disconnect the coil lead from the distributor and hold the exposed metal end about 1/2'' to 3/4" from engine block, turning engine over with ignition on should show a STRONG spark.

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Hey Guys,

 

I charged the battery, cleaned the plugs and shook the inline fuel filter and it started, so not really any the wiser.

 

I checked the timing and this was ok based on 4 deg BTC (is this right for a fast road set up?)

 

It now starts but is running on really badly, like for 10 seconds running on. But 3 or 4 times it didn't run on.

 

I checked the timing again after a drive and it was spot on.

 

What other things can cause bad run on aside from timing as this must have something to do with the problem? Its quite a high compression head.

 

We didn't mark the position of the rotor arm when removed, if it were 180 degrees out I assume it would run really badly or not at all.

 

Could it still be engine earthing or arcing on the ignition system somewhere?

 

I have ordered a spare points distributor, leads and coil which I may swap over to.

 

Thanks again

 

Colt

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Running on when this does not normally happen can be down to fuel or hotter weather. Mine does it more often on Esso Suoer but not on BP Ultimate or Jet Super

and not on ordinary unleaded.

What fuel filter have you fitted?

 

Chris

Edited by potts4a
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My 4A will run on sometimes, I have an electric Revotec Fan fitted, the run on only occurs for maybe 2-3 secs if the fan is working when switching off.

Not sure if the run on is caused by the temperature or the possibility that the fan generates a current to the coil momentarily

Paul

Edited by Paul J
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My 4A will run on sometimes, I have an electric Revotec Fan fitted, the run on only occurs for maybe 2-3 secs if the fan is working when switching off.

Not sure if the run on is caused by the temperature or the possibility that the fan generates a current to the coil momentarily

Paul

 

I did have a bad interference of the electric fan with the LT to coil with the same symptoms as Colt described. I ran a live wire from the battery to the coil and it fired no prob. Then the problem started again and found out that the coil was fried - working intermittently - which I suspect was linked to the same interference.

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In the meantime, you can stop (not cure) running on by leaving it in gear and gently dropping the clutch as you switch off.

 

Tbh, even though I cured my running on some time ago (combination of over-advanced timing, plugs and fuel, if I remember) I still do it as a matter of course.

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Hey Guys,

 

Thankyou for the input. I wanted to try a few things before I replied.

 

I do have a Revotec fan, it wasnt causing any problems previously.

 

The fuel is fresh.

 

I fitted a new disti cap, rotor arm, disti clamp, HT leads and BP7HS plugs (replacing BP6HS) The old plugs were wet and a bit black.

 

It ran better on the new plugs but it is still overunning for 20 seconds.

 

On the hottest day of the year I needed full choke to start which isnt normal.

 

The timing has been checked multiple times.

 

Anything I've missed?

 

Thanks

 

Colt

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Diaphragms may look ok but, Try removing the damper caps, crank the engine and there should be enough vacuum to lift the pistons, if only one lifts then it's the disphram.

Needing full choke suggests that it may be running on one carb.

Chris

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