Old Petrol

[Ian Vincent]

This week/weekend I have had a graphic illustration on the effect of old petrol on starting a car.

 

For a variety of reasons at the end of last year i had to put the car (TR3a) away with a pretty full tank of fuel - basic Texaco unleaded.

 

Again for a variety of reasons I haven't been able to use the car much this year and it has been a pig to start. Last week I had a bit of time so I set out to re-tune it, after getting it started and warmed up, I set the mixture to what I thought was spot on and balanced the carbs, I then adjusted the points and set the timing. Result, the car was idling sweetly at about 600 rpm and picking up cleanly when I blipped the throttle.

 

Yesterday, I went to start the car and it would not start at all. I tried all my usual tricks - took the plugs out and warmed them up etc, but no dice. So I finally took the tops off the carb float chambers and filled them with fresh fuel bought the day before for the lawnmower - result, the car started instantly.

 

Today, I went out to start the car again to take it for a drive and get some new fuel - it wouldn't start again until after much cranking over and after warming the plugs, I got it to fire on one cylinder and slowly the others picked up. When I re-checked the timing and mixture - everything appeared spot on so I can only assume that it is the old fuel that is causing the problem.

 

Rgds Ian

Edited May 23, 2016 by Ian Vincent

[stuart]

Yep that`ll be the problem every time, any current fuel over 2 months old you will notice the difference especially starting from cold.

Stuart.

[Alec Pringle]

Never mind 2 months . . . . . just 2 weeks in the tank is sufficient to make a noticeable difference when measured on a rolling road. After 2 months the difference is, relatively, huge.

 

Cheers

 

Alec

[Ian Vincent]

Yep, that was it, just filled the tank with Shell V power and the difference was impressive; smoother to drive, more urge etc. I am expecting instant starting tomorrow.

 

Rgds Ian

[RogerH]

Hi Folks,

a few weeks ago an 80 year old chap down the road asked me if I could look at his mower as he couldn't get it going and he was puffed out.

 

It had fuel and went last summer. I pulled a couple of dozen times on the rope with no joy.

I pulled the fuel pipe off to make sure fuel was flowing - it was.

 

I then put some fresh fuel in and pulled another couple of dozen time - still no joy.

 

The chap suggested he dump it.

 

He took it home and left it in the front garden and told his wife what had happened. She agreed - dump it.

He went to the front garden and gave the little bu99er another pull and it burst into life. That must have been when the fresh petrol hit the plugs.

 

I was so close - I could have been a hero.

 

Roger

[marki]

So close.... Yet so far :-)

[john.r.davies]

Time before last I built an engine, I went high on CR, only just under 11.

 

And the first time I ran it, it pinked. Oh, gosh, do I have to run this with Plus octane booster every tankfuL/

But no! First fillup with new fuel and the pinking just went away.

 

John

[Ian Vincent]

Well my expectations of instant starting didn't happen.

 

I have driven the car a little over 100 miles since I filled the tank last weekend and adjusted the mixture until it is spot on (PS see my other post on that). I also have the timing exactly right (checked with a strobe) and although the car will start it takes its time.

 

I have to operate the fuel pump manually for one cycle to refill the carbs (presumably evaporation from a hot engine) and then when I press the button it will usually fire once on the first turn but will then require a significant amount of churning before it will fire again. At which point a leave it for about 10 secs and press the starter again and it will usually fire a couple of times and die. I repeat this cycle about three or four times before it finally catches and sputters into life.

 

I usually have the choke about half out during this process and once it has started it needs the choke out a fraction until it has warmed up, after that no problem and it will start on the button first time and drives sweetly, particularly at about 3000 rpm. When idling (at about 750 rpm) it starts to go lumpy after a while and needs the throttle blipped to clear it.

 

When I remove the plugs after a run they are the correct sandy colour.

 

Has anyone any suggestions as to what the problem may be?

 

Rgds Ian

[RobH]

Sounds like there is no problem Ian, just pull the choke all the way out - thats what its for.

[littlejim]

Sounds like there is no problem Ian, just pull the choke all the way out - thats what its for.

Like Rob, I have to start mine with full choke for the first bit. Starts easily.

[Ian Vincent]

Sorry guys, I have mislead you.

 

For my first attempt at starting I have the choke all the way out but after I have given it a long churn with no result, I set the choke to about half way and then start the wait 10 seconds process.

 

Rgds Ian

[RobH]

I used to have a similar 'problem' until I realised just how stiff the choke was - I thought it was open fully but I was only getting it about half way. Once I found that full choke meant the knob was 2 inches out from the dash, which required a really hefty pull, my starting problem disappeared. Could you be having the same experience?

[TR NIALL]

Have you checked how much the Choke Cam is moving when you pull the Cable also have you checked the position of the Choke Cam when the Cable is fully returned,you may have to much Free Play before the Choke Cam starts to engage.

[ianc]

Even in warm weather, I use full choke initially, but am ready to push it inwards almost immediately, the return amount being determined by ambient conditions. On a warm day, I can get it half way back within seconds.

With the engine warm, just a little choke gets the engine started immediately, but the choke can be pushed home as soon as the engine fires, whereas no choke may require some churning.

Ian Cornish

[Lebro]

+1

[MikeF]

It was choke adjustment for me

 

I used to have starting problems after long lay-offs, and attributed this to all sorts of things. After a particularly difficult starting session I really investigated carbs again and found my choke wasn't properly set up, general slop really - what felt like full out was only half out.. Now no problems. As soon as petrol hits the carbs it fires immediately. Needs one clothes peg (wooden in period) holding the choke out till temp gauge begins to lift and that's it.