alexdj125
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| posted on 16/1/08 at 11:37 AM |
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A very confusing starting problem
Hi, all. I've got a raw striker with a 1600 Xflow running on weber 40's. It usually starts ok from cold, even if its been left standing for
ages, however, when I've been for a drive and stop for fuel or something it doesn't like to start. It will hardly turn over like there is no
power, yet when I check the battery its fine. This means i always have to find a petrol station on a hill. Also when this happens, after trying to
start it for a few mins I find that the battery leads become warm. I have replaced the starter motor for a new one and checked the amount of power
coming through the starter solenoid and it seems to be fine. Like I say, only happens occasionally, and when its hot. I'm wondering if something
is expanding under the heat causing this? Any ideas would be greatly appreciated as its really getting to me! Thanks,
Alex.[img]http://locostbuilders.co.uk/upload/a676915-P111207_17.11[01].JPG[/img]
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britishtrident
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| posted on 16/1/08 at 11:42 AM |
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Ignition has too much static advance.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Pdlewis
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| posted on 16/1/08 at 11:43 AM |
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Hi,
I had this exact problem last year i found taking the negative off the chassie cleaning both contacts and re-attaching made an improvement. I also
put an additional earth lead to the engine on so it had one going to the block and one to the head
hope that helps
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ditchlewis
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| posted on 16/1/08 at 11:43 AM |
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i had a very similar problem, but it was solved when i changed the starter motor to a High Torque unit, not cheap.
other things, could the fuel be vaporising in the carb float chamber? so no fuel to pump into the engine
have you got a high compression engine?
it sounds so much like the problem i had but as i say it was cured by one of these
ditch
Could be as trident says, my brother in law played with the dizzy and now i have back fireing through the carbs.
[Edited on 16/1/08 by ditchlewis]Image deleted by owner
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r1_pete
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| posted on 16/1/08 at 11:45 AM |
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Yep, I'd go with over advanced, have you a modified distributor mechanical advance to compensate for lack of vacuum, or just set the static a
bit advanced? obviously dizzy is out of the question if you're running MJ or similar....
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BenB
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| posted on 16/1/08 at 11:46 AM |
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If it's fuel vaporisation the engine would still turn over..... Ditto too much advance on the timing.
I'd take off all the cables, clean the terminals and try again.
If that didn't work I'd replace the solenoid itself.... Unless the engine has been had its CR increased a standard starter motor should be
sufficient....
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BenB
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| posted on 16/1/08 at 11:47 AM |
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Unless anyone can explain why too much timing advance would stop an engine from turning over.....
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ditchlewis
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| posted on 16/1/08 at 11:53 AM |
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i had the compression ratio increased a lot and the standard starters i had only turned over very slowly. it was much much worst after a run wnen the
engine was hot then it would hardly turn over at all. the new starter has 200% more torque and used less amps.
the problem with starting a warm engine has not reoccured
ditch
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r1_pete
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| posted on 16/1/08 at 12:19 PM |
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quote:
Originally posted by BenB
Unless anyone can explain why too much timing advance would stop an engine from turning over.....
If ignition is too advanced, it will ignite the fresh charge of fuel/air mix too early, which tries to push the piston back down as the burn
progresses, not a problem once the engine is running, but during cranking there isn't enough momentum to carry the piston over tdc against the
burning charge. This happens when the engine is hot due to the better atomization of the fuel hence faster burn rate.
When advance is correct the charge ignites just before tdc, and accelerates to a full burn as the piston passes tdc, pushing the piston down the right
side of tdc. As engine revs rize the ignition is advanced to ignite the fuel earlier, as there isn't as much time between ignition and TDC at
higher revs.
Rgds.
Pete.
[Edited on 16/1/08 by r1_pete]
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BenB
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| posted on 16/1/08 at 12:21 PM |
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That's what I wondered- but wouldn't the pinking be obvious?
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r1_pete
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| posted on 16/1/08 at 12:25 PM |
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I'd expect some, but in a light car, the engine probably never works hard enough.
If the engine sounds ok and doesn't pink then the hi torque starter is probably the answer.
Take some tools out with you and back the ignition off a touch next time it happens, Zero cost option to find out if thats the problem.
[Edited on 16/1/08 by r1_pete]
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ditchlewis
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| posted on 16/1/08 at 12:31 PM |
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Please could you remind me of what pinking sounds like, could it be in the form of a carb back firle?
in which case i could play with the mixtures till the cows come home and will not get over the back firing and stuttering.
Ditch
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UncleFista
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| posted on 16/1/08 at 12:32 PM |
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If you're running megajolt, you can alter the map to give less advance under 500 rpm, it helped our starting no-end.
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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BenB
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| posted on 16/1/08 at 12:33 PM |
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One answer to see if it is that is simple- next time it happens and it won't turn over take off the supply lead to the coil. If then it will
turn over normally (obviously don't do it for too long else you'll flood the engine) it's the advance. If it still won't it
something else.....
Sound reasonable?
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David Jenkins
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| posted on 16/1/08 at 12:38 PM |
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quote:
Originally posted by ditchlewis
Please could you remind me of what pinking sounds like, could it be in the form of a carb back firle
I have a recording of pinking made with a mic attached to an engine - I'll post it here once my ISP decides to make my page available again.
 I think they've forgotten to feed the gerbils again...
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UncleFista
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| posted on 16/1/08 at 12:39 PM |
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quote:
<snip good idea>
Sound reasonable?
Sounds eminently reasonable to me 
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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r1_pete
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| posted on 16/1/08 at 12:46 PM |
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quote:
Originally posted by BenB
One answer to see if it is that is simple- next time it happens and it won't turn over take off the supply lead to the coil. If then it will
turn over normally (obviously don't do it for too long else you'll flood the engine) it's the advance. If it still won't it
something else.....
Sound reasonable?
Good idea, it really works tossing ideas round on here.......
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alexdj125
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| posted on 16/1/08 at 05:51 PM |
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Wow, really didnt expect this much help! Thankyou so much to everyone! It is a higher compression engine, and i'm using a lumenition and the
standard distributor, will this make the problem worse? I had the timing set up by a mate with a timing light gun thingy and we did it fairly advanced
I think as I've got quite a wild cam fitted. How do I set up the timing without a lightgun? The idea of the high torque starter sounds like a
good idea, i'll have a search for one! Also I'll clean all the negative connections and see what happens! Again, thankyou so much for your
help!
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Macbeast
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| posted on 16/1/08 at 07:40 PM |
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Ditch: pinking sounds like a metallic tinkling noise.
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