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Any experience with Carb no ECU engines here?


DavidB
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The ones that came in Bedford Rascals, Suzuki Supercarrys, Whizzkids, and SJ’s.
I’m having teething problems with my 1.0 engine - I rebuilt this a few months ago with new stem seals piston rings etc, I’ve put the cam in and the rods that the rockers slide onto. I made sure the put together was the same as the take apart but is it possible to put these in wrong so that the valves are opening incorrectly? I’m sure it’s impossible to do the cam wrong but my timing is spot on I think.

Its just not starting or even giving any intention of starting with fuel and spark but the timing may be out somehow even though everything is correct (belt timing marks distributor rotor arm points etc)

Theres also some bothering me with the coil. It gets hot as well as the ballast, with the ignition on and removing the dizzy from its housing sparks it (from the condenser on the side which is going to the + on the coil). With the ignition on I can turn the engine by hand and spark plug test lights light up without it running - which I’m sure isn’t right, or is it? It shouldn’t be getting hot anyway.

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  • DavidB changed the title to Any experience with Carb no ECU engines here?

Perhaps take the rocker off and observe which cylinders are closed in relation to where the rotor arm is as you turn the engine - if you've got fuel and a spark then unless there is no compression (or the spark is miles off) it should make a least a sad wump if not a proper bang.

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If you have fuel and a spark there should be a bang of some sort. Even if the timing was way out you'd get backfiring as exploding petrol escaped back out of the open inlet valves. Even with no compression there should be a bang of some sorts. 

Clutching at straws a bit but are you absolutely sure the petrol in the carb is going in to the engine not just straight back in to the return pipe?

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14 hours ago, Yoss said:

If you have fuel and a spark there should be a bang of some sort. Even if the timing was way out you'd get backfiring as exploding petrol escaped back out of the open inlet valves. Even with no compression there should be a bang of some sorts. 

Clutching at straws a bit but are you absolutely sure the petrol in the carb is going in to the engine not just straight back in to the return pipe?

That’s what I’m thinking, going to take the inlet off and check and then the head

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Just want to mention another thing

This thing kills batteries, apart from oil getting hot and ground wire doing the same, I’ve gone through three batteries. You can only crank for 20 seconds before it’s dead. I’ve got new ground wires and from past experience I’ve done the usual additions to the grounds that were there originally.

Coukd my starter be at fault with this?

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On 9/30/2021 at 11:31 PM, DavidB said:

With the ignition on I can turn the engine by hand and spark plug test lights light up without it running - which I’m sure isn’t right, or is it? It shouldn’t be getting hot anyway.

I am no mechanic but I would start with the basics on this one.  What you saw above sounds right - if you turn the engine, whether by starter motor or by hand, if the ignition is on and the ignition system is functional, you'll get a spark.  If the coil is getting hot it might be worn out. 

Do you get a spark when turning it over with the starter?  It sounds like you have a bad/loose/missing connection somewhere or a corroded cable somewhere on the ground circuit if a ground wire is getting hot as there is high resistance, might also explain the battery issue.  If it were mine, I would fix that before proceeding - perhaps this issue is preventing the ignition system from working when the starter is in use.

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Where did you check for spark? With the ignition leads against the engine block, or just at the point? And the second stupid question: are you 100% sure the ignition leads are connected the right way? After unsuccessful start, are the sparkplugs wet with petrol?

 

For "first start" after rebuilding my old dacia's engine, in early 2000, I towed it for about a half of kilometer in 3rd gear, with the ignition on, before it fired.

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Not sure about the grounding, everything looks right, battery charged over night doesn’t last long on first cranking, it even drained a brand new one. I took the inlet and carb off and checked everything, put it back together and spraying fuel into the carb port starts it. It won’t stay running though, but I’ll sort that later, I’ll have to sort this starting/battery issue first, and also new oil pump seal which is pissing out oil.

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3 hours ago, DavidB said:

You can only crank for 20 seconds before it’s dead.

Something not right there.  A new battery should be able to crank an engine for several minutes before it starts to falter.    I wonder if there's a monster draw somewhere that is killing your ignition during cranking.

Presume you've done the basics on this:  Put the timing cylinder at TDC between exhaust and intake, then rotate the engine two complete turns, checking to make sure that the inlet valve opens/closes at the correct time, the ignition lines back up (ish) at tdc again, then the exhaust valve opens/closes at the correct time.  If that's all correct, and you definitely have ignition, then a bleb of fuel down the intake should absolutely make it run.

Edit:  Just saw your last post properly... if it runs with fuel down it's neck, then the carb is definitely your issue.  1st port of call would be float chamber valve, then possibly blocked jets.

The battery going flat in 20 seconds of cranking is odd.  Can you get a clamp meter on the battery positive lead and see how many amps it's drawing under load?  That can be related back to the power of the starter motor to see if something is shorted in it.

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  • 2 weeks later...

I attached another earth from starter ground to the body and it starts instantly now. I did take the starter out before this so I’m not sure if I fixed something before that.

This engine is so smooth though, it starts as soon as you turn the key, even off choke. Unfortunately brand new radiator has a hole in it

 

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  • 2 weeks later...
10 hours ago, DavidB said:

New starter cured this, not sure what was wrong with the old one.

The new one sticks occasionally on the solenoid I think. Sometimes it starts but sometimes it sounds like it’s not engaging with a whirring sound?

The solenoid might not throw the pinion far enough to engage the crown wheel, hence the whirrrrr

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21 hours ago, goosey said:

From memory the carb on my old SJ413 was a vacuum controlled, over complicated nightmare, that got replaced with a Weber.

is the carb on the 1.0 engine the same ? 
 

No the 1.0 is OK, it's really basic manual choke, I've never had a problem with them on any of these F10A engines (touch wood).

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