Absolute pig to start

tim wood · Post by **tim wood** » Wed Mar 11, 2015 5:22 pm

Hi, my 4.2 has always been a bit if a bugger to start after the winter layup.
Once started its generally ok for the season.

Over the years I have rebuilt the SU,s , fitted edis and the general engine condition is good - compression ok etc.

Today I started it for the first time this year and as usual it took a fair while, lots of churning with eventual catch.

I have a pressure regulator fitted. I fitted the gauge as a check and pressure was down to below 2 psi . Difficult to see but maybe 1.5psi. Could this be part of the problem or does anyone have thoughts.

Thanks
Tim

David Oslo · Post by **David Oslo** » Wed Mar 11, 2015 5:32 pm

I won't comment re the regulator, no experience to share. However when you say problems after winter layup and generally fine rest of season I immediately think of stale petrol, and more specifically petrol with high moisture content, e.g. condensation. It's a common problem over here with the cold climate in the winter, and can even cause carbs to freeze.

Anyhow, a bottle of 'condensation remover' (no idea if you can get that in the UK - however chemically it is isopropanol) into the tank is at least worth a go. Alternatively drain tank and refill (a bit of a pain...).

In the winter I always keep my classic cars (and boat) fuel tanks topped up to the brim, reducing chance for condensation in the tank.

christopher storey · Post by **christopher storey** » Wed Mar 11, 2015 7:00 pm

Tim : I have always found that unless started regularly, by which I mean 2 or 3 times a week, the Es require churning to get them going. The inlet tract is very large volume and really quite long. If I haven't had one of mine going for say a couple of months, I always reckon it will need at least 4 (and often 5 or 6 ) 10 second bursts on the starter with a 15 second recovery period between each attempt . I do know that CMC have a specific technique, which is to give a longish burst with choke and then full throttle ( I believe sequentially but I am not sure ) - the full details are somewhere on this board

EDIT : this was Heuer's post from an earlier time

"Andrew Turvey of CMC on starting an E-Type on a cold morning - "turn off the choke completely, push the accelerator to the floor and hold it there whilst cranking the engine over. Usually the engine fires-up, struggles asthmatically for five seconds then dies. Hopefully, it will then fire-up again using a little choke and less throttle". Why? "....... throttle flat to the floor is to add huge amounts of air to the fuel that has already been drawn into the engine. The air/fuel ratio becomes correct and if we have a spark - hey presto!"

What he's describing is fairly standard practice for starting a flooded engine, so whether it works if you haven't already flooded it I don't know

tim wood · Post by **tim wood** » Wed Mar 11, 2015 8:00 pm

Thanks both. At least I'm not on my own.

Tim

Tony · Post by **Tony** » Thu Mar 12, 2015 12:09 am

Join the club. Mine never starts after laying up over winter and can take about 10 goes to get stated. After that it start first time all season. I think they all do that or does somebody know better?

Moeregaard · Post by **Moeregaard** » Thu Mar 12, 2015 4:05 am

I'm with David on the stale-petrol thing. Automotive fuels are formulated with a relatively short shelf life, so any time a car is to be laid up for an extended period, you might consider adding a fuel stabilizing agent (available at marine suppliers) or filling the tank with aviation petrol (100LL), which has a much longer shelf life.

KingRichard · Post by **KingRichard** » Thu Mar 12, 2015 3:46 pm

Hi,

Never experienced it. Mine always starts within 3 seconds if stonecold and not started for many weeks before. On daily bases it starts instantly.

Even the first startup after the rebuild, it started in seconds after the choke was pulled out. We first gave it a try without choke out so oil pressure could build up to approx. 20 psi, which was after a minute or so. I also suspect fuel, but never experienced such here in Holland, even after 2 months not in use.

Richard

Post by **mgcjag** » Thu Mar 12, 2015 6:16 pm

Make sure u have a really good battery.....Steve

mystery type · Post by **mystery type** » Thu Mar 12, 2015 6:22 pm

I always turn the ignition on and let the carbs fill up with petrol before any cranking. seems im lucky, as my car always starts after a couple of turns.

Tony · Post by **Tony** » Fri Mar 13, 2015 12:54 am

If it is a stale fuel problem, would it not happen every time you start untill all the stale fuel is used up? I think it is more as Christopher stated and it talkes a lot of time for the fuel to Come through after being laid up.
It is strange nobody seems to know the definite answer. Is it a series 1 issue or do series 2 suffer the same problem?

PeterCrespin · Post by **PeterCrespin** » Fri Mar 13, 2015 1:55 am

I suspect it's a choke adjustment issue. A small maladjustment of the choke mechanism could lead to much less enrichening than there should be - which would have the effect of making it take longer for the mix to reach full strength. By any normal criteria cranking a fully-choked engine for as long as some report should flood an engine. The plugs of bad starters are usually dry, not wet.

If it were something as fundamental as the size of the intake runners then every car would suffer. Since some do and some don't, and the inlet passages are the same on all comparable cars, logic suggests a factor that varies between cars.

Tony · Post by **Tony** » Fri Mar 13, 2015 8:58 am

PeterCrespin wrote:I suspect it's a choke adjustment issue. A small maladjustment of the choke mechanism could lead to much less enrichening than there should be - which would have the effect of making it take longer for the mix to reach full strength. By any normal criteria cranking a fully-choked engine for as long as some report should flood an engine. The plugs of bad starters are usually dry, not wet.

If it were something as fundamental as the size of the intake runners then every car would suffer. Since some do and some don't, and the inlet passages are the same on all comparable cars, logic suggests a factor that varies between cars.

As you state Peter, there is the logic that all runners are the same, so it would suggest a coke, carb issue. how do you adjust the coke to make it richer?

Post by **mgcjag** » Fri Mar 13, 2015 9:20 am

Hi......I think that Peter is spot on with this, assuming that u have a spot on battery and ignition is set up ok....when i rebuilt my carbs and reinstalled them i followed the jag manual to set up up the carbs which includes setting the choke.....very easy to do just need to follow step by step....Nice little project for everyone who dosent have there carbs set up correctly.....Steve

Red Kite · Post by **Red Kite** » Fri Mar 13, 2015 11:13 am

Mine is the same.

Im not sure how an incorrectly adjusted choke will affect it. It struggles after a month off but fires up immediately after a week off, the choke is the same in both cases ?

PeterCrespin · Post by **PeterCrespin** » Fri Mar 13, 2015 12:57 pm

Good point of course Gerry. But the thing I like about cars and engines, as opposed to horses and dogs, is they don't get to participate in any decisions or problem solving. Many problems are binary - a wire is either connected or not. Some problems are more subtle - a wire may be connected but barely able to pass the required current. Some problems are multi-factorial - e.g. a wire may be connected but only able to work correctly provided it is not too hot and not damp and not being moved by an engine that only deflects enough in first or second gear. You get the picture.

There is no one-size-fits-all solution to poor lay-up starting. I prefaced my post with the words 'I suspect...' and did not offer it as the only cause nor even the most likely cause - just one that hadn't been mentioned and is often missed. I've had Jags that do the same. But then one also hears of E-types that start rapidly from cold with no choke at all - which is dodgy for a different set of reasons...

However, it is possible to work through every single factor methodically if we are motivated enough to play detective. Often it seems easier to put up with 'known' obstinate behaviour than spend lots of time and effort chasing things down but it can always be resolved eventually, if time and money are no object. You have to amass the greatest number of data points and try various theories to see which one fits best.

In your case it might be borderline float levels or some other adjustment that only deliver ignitable mixture when volatile fractions are still present in the fuel? Waiting 15 seconds for pump priming might help. Someone else's car might have a borderline ignition switch that collects condensation after a month or two, another might have dodgy choke adjustment etc.

Starting from first principles, if an XK is cranked for a long time and the plugs are not damp or there's no smell of fuel in the exhaust, I would deduce there is insufficient fuel to light off the engine. Maybe someone is opening the throttle (admiting too much air) or someone else has dodgy spindle bearings that only cause a problem leak at cranking speeds because running adjustments are set to work around it? Dunno, can't know, just throwing out pointers. Start with the easy basics then home in on the detailed specifics for each vehicle. My reason for dismissing engine architecture as a cause was to offer hope that it IS possible to get an E-type to start well and the inlet tract configuration is not an insuperable obstacle.

The first four stroke engine I ever rebuilt was a Triumph Tiger Cub. I couldn't get it to start (969 UTD where are you now?). After an hour of fruitless bump starting with two of us pushing like crazy, my friend was still keen and said "Engines sometimes need airing after a rebuild." I was sceptical but there was plenty of fuel in the carb and a fat spark correctly timed. I eventually noticed there was fuel mist behind the carb on the oil tank but the plug seemed dry. It was almost as if the engine was blowing through the carb instead of sucking. Which turned out to be the case as I had mixed up the pushrods at the rocker tips which are only a few millimetres apart and awkward to reach when refitting the head. As soon as I switched them the engine burst into life. I learned at 14 not to take anything for granted and check everything. The more elusive the problem, the more blind alleys you may go up but there is always a solution.

christopher storey · Post by **christopher storey** » Fri Mar 13, 2015 1:23 pm

Tony : I have both an S1 4.2 and an S2 4.2 and both are the same . I have over 50 years' experience of Jaguars going back to 3.4 and mark VIII and every one of them with carburetters, whether manual choke or the good old hisser ( I have only ever had one car with an AED ) has been the same. If used regularly, they are instant starters, but if left for a week or two, they require a good deal of turning over before they fire

As far as Peter's point about engine architecture not being a problem I agree with him that it is not a problem in a frequently used engine. However, there is no doubt in my mind that particularly on 4.2 manifolds if the engine has not been used for a while there is a very large volume to be filled with mixture before it reaches any inlet valve, and the gas speed over the jet is fairly low at cranking speed, hence it takes some while for the venturi effect to get going . This is why a majority of carbs have accelerator pumps to provide a priming effect without resort to the venturi effect, and a strangler flap as well to provide increased suction on the jet ,but of course this is not available on constant depression carburetters

jag68 · Post by **jag68** » Sat Mar 14, 2015 5:22 am

My old shop instructor said that the first part of gasoline that evaporated from storage were the light ends - by which he meant the shorter more aromatic molecules, and that it was these, when present, that permitted quick starts. I suspect that this evaporation is more of a problem in the float bowls than the gas tank, in particular if you store the car with a full tank - so starting with mostly old fuel in the floats is difficult. Once running in the normal course you're now on better gas in the float bowls. You'll find that giving it a shot of starting fluid (ether), just before the first crank will resolve the problem. That leads me to believe the the light ends solution is correct. I've owned my E type 42 years and it's always a hard start after storage.

rfs1957 · Post by **rfs1957** » Sun Mar 15, 2015 1:31 pm

My starting problems disappeared once I paid attention to getting unadulterated 12v to the coil. Cranking dropped the voltage so much that there was sod-all available for the ignition once it had struggled past the switch and w.h.y plus - in my case - a rather feeble white in the harness to the coil. Put a volt meter on it and be ready for a surprise. Always suspected that this explained why so many cars appear to try to fire up just as you stop turning the key ......

PeterCrespin · Post by **PeterCrespin** » Sun Mar 15, 2015 7:18 pm

Which in effect is exactly what Jag did with the S2 ballast resistor and relay system Rory, so you're not wrong. Not that I'm a particular fan of it, but still...

KingRichard · Post by **KingRichard** » Mon Mar 16, 2015 9:13 am

Hi Christopher,

That is a good explanation as why the engine starts instantly when regurly used and takes some times (in my case 3 seconds or so) to start after a few weeks of non-use. That was a learner for me.

Richard

christopher storey wrote:Tony : I have both an S1 4.2 and an S2 4.2 and both are the same . I have over 50 years' experience of Jaguars going back to 3.4 and mark VIII and every one of them with carburetters, whether manual choke or the good old hisser ( I have only ever had one car with an AED ) has been the same. If used regularly, they are instant starters, but if left for a week or two, they require a good deal of turning over before they fire

As far as Peter's point about engine architecture not being a problem I agree with him that it is not a problem in a frequently used engine. However, there is no doubt in my mind that particularly on 4.2 manifolds if the engine has not been used for a while there is a very large volume to be filled with mixture before it reaches any inlet valve, and the gas speed over the jet is fairly low at cranking speed, hence it takes some while for the venturi effect to get going . This is why a majority of carbs have accelerator pumps to provide a priming effect without resort to the venturi effect, and a strangler flap as well to provide increased suction on the jet ,but of course this is not available on constant depression carburetters

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