Crosflow powered 7 - won't start
Discussion
Right, let us start at the beginning.
It was driven into the garage and you haven't been tinkering.
So things like the coil and the wiring hasn't been disturbed?
Has it got an electic fuel pump, does it make a sound when the ignition is on.
If it's a mechanical pump it'll take forever to drag fuel up from the tank. Mine with a mech pump used to flatten the battery before dragging fuel up to the carbs. Unscrew the two brass wing nuts on the carbs and see if there's any fuel around the emulsion tubes etc. If there's no sign of fuel you could try carefully pouring a little bit in there.
Electrics wise pull out a spark plug, reconnect it to the plug lead and lie it onto the engine. Spin the engine over and you should be able to see a spark across the electrodes.
If not you are probably going to need to remove the distributor to make sure the points haven't stuck closed. It's almost impossible to check them in situ due to the weber carbs.
But there's a spark and fuel it should start.
My main worry now is the fuel itself. Unlike petrol of old modern petrol has a very short shelf like now, apparently.
It goes stale and worse, turns into a jelly clogging upjets and tubes. (My 4 stroke strimmer has been sonically cleaned twice due to this.
Tony H
It was driven into the garage and you haven't been tinkering.
So things like the coil and the wiring hasn't been disturbed?
Has it got an electic fuel pump, does it make a sound when the ignition is on.
If it's a mechanical pump it'll take forever to drag fuel up from the tank. Mine with a mech pump used to flatten the battery before dragging fuel up to the carbs. Unscrew the two brass wing nuts on the carbs and see if there's any fuel around the emulsion tubes etc. If there's no sign of fuel you could try carefully pouring a little bit in there.
Electrics wise pull out a spark plug, reconnect it to the plug lead and lie it onto the engine. Spin the engine over and you should be able to see a spark across the electrodes.
If not you are probably going to need to remove the distributor to make sure the points haven't stuck closed. It's almost impossible to check them in situ due to the weber carbs.
But there's a spark and fuel it should start.
My main worry now is the fuel itself. Unlike petrol of old modern petrol has a very short shelf like now, apparently.
It goes stale and worse, turns into a jelly clogging upjets and tubes. (My 4 stroke strimmer has been sonically cleaned twice due to this.
Tony H
Skyedriver said:
R
My main worry now is the fuel itself. Unlike petrol of old modern petrol has a very short shelf like now, apparently.
It goes stale and worse, turns into a jelly clogging upjets and tubes. (My 4 stroke strimmer has been sonically cleaned twice due to this.
Of course check fuel supply and spark, but this is the most likely issue, these days: either the jets are blocked by fuel residue, and/or the fuel that's getting through is so stale that it won't ignite.My main worry now is the fuel itself. Unlike petrol of old modern petrol has a very short shelf like now, apparently.
It goes stale and worse, turns into a jelly clogging upjets and tubes. (My 4 stroke strimmer has been sonically cleaned twice due to this.
If the latter, there's a better than average chance that you've also now wetted your plugs, so they'll need either drying in an oven or (better) a fresh set fitting. Then clean the carb jets, drain whatever is left in the fuel tank and fill with fresh fuel, and you should be good to go.
You can get fuel stabilizer from marine chandlers and other suppliers, if you're planning to lay up again next year,, but it's probably better to simply run the engine regularly.
Skyedriver said:
My main worry now is the fuel itself. Unlike petrol of old modern petrol has a very short shelf like now, apparently.
It goes stale and worse, turns into a jelly clogging upjets and tubes
Hmm. My Seven sat idle for nearly 18 months and the "modern" petrol in it was just fine.It goes stale and worse, turns into a jelly clogging upjets and tubes
Received wisdom is that they've been progressively changing the composition of petrol over the years, resulting in it becoming much more of a problem: the fuel allegedly goes stale much quicker, these days.
Effects can also vary according to the source of the fuel in the tank (if from a low-volume outlet, it might already have been quite stale when you put it in), and how much fuel was left in the tank when you laid the car up.
Might also be an issue in combination with something else, of course: stale fuel or partially blocked jets, combined with plugs or other ignition system components that are past their best.
Effects can also vary according to the source of the fuel in the tank (if from a low-volume outlet, it might already have been quite stale when you put it in), and how much fuel was left in the tank when you laid the car up.
Might also be an issue in combination with something else, of course: stale fuel or partially blocked jets, combined with plugs or other ignition system components that are past their best.
I spent all morning cleaning out the carbs and the fuel filters. I also removed all the spark plugs and cleaned them up.
Still no joy.
I then decided to see if I could see fuel being sprayed into the carbs when I manipulated the throttle control springs. I imagine I should be able to see the spray through the chamber where the fuel filters are located. I could see nothing.
Would this be indicative of a fuel pump issue?
The one thing I didn't do was remove and check the distributor. On a twin Weber Crossflow the distributor is located directly behind the front carb and this really needs to be removed in order to get at the distributor. I just don't have the confidence to remove a whole carb and, more importantly, be sure I could put it back on correctly.
Still no joy.
I then decided to see if I could see fuel being sprayed into the carbs when I manipulated the throttle control springs. I imagine I should be able to see the spray through the chamber where the fuel filters are located. I could see nothing.
Would this be indicative of a fuel pump issue?
The one thing I didn't do was remove and check the distributor. On a twin Weber Crossflow the distributor is located directly behind the front carb and this really needs to be removed in order to get at the distributor. I just don't have the confidence to remove a whole carb and, more importantly, be sure I could put it back on correctly.
Eric Mc said:
I then decided to see if I could see fuel being sprayed into the carbs when I manipulated the throttle control springs. I imagine I should be able to see the spray through the chamber where the fuel filters are located. I could see nothing.
Would this be indicative of a fuel pump issue?
Were the float chambers of the carbs full of fuel when you took the tops off to clean them out? The carburettors have floats in them, with a valve that acts like the ball valve on your toilet cistern. Provided the fuel is getting to the carbs, and the float valves haven't stuck, the float chamber of the carburettor should be swimming in petrol... you can't miss it! If the float chambers are not full of petrol, then clearly the petrol isn't reaching them from the fuel tank.Would this be indicative of a fuel pump issue?
Are you on a mechanical or electric fuel pump?
Very basic faultfinding:
First, are you sure there's fuel in the tank?
Disconnect the fuel pipe where it enters the carb (direct it into a bottle or something to catch the fuel, and also disconnect the low tension leads from the coil, so you don't have a spark is a good idea!), then switch the ignition on. If you have an electric pump, you'll hear it operating, and fuel should start coming through the pipe and collecting in the bottle. If a mechanical pump, you'll need to actually turn the engine over using the starter motor.
If fuel isn't coming out of the pipe by this point, you have a fuel supply problem (no fuel, blocked fuel pipe, non-functional fuel pump).
Second: do you have a spark?:
Take a spark plug out and rest it on top of the exhaust manifold. Turn the engine over on the starter. You should see the spark plug sparking. If it isn't you have an ignition problem.
If you have fuel getting to the carburettors and a nice, strong spark getting to the plugs, then the problem is most likely to be with the carburettors (blocked jets) or stale fuel.
When I get this I check for sparks then if I have them I tip a tablespoon of FRESH petrol into the air intake, then have another go. If you have sparks then the engine will run briefly, pointing up the fact that you have a fuel problem. If it won't fire at all then you know there's a fault other than fuel.
I used to have a 2CV that would dry out its carb upon standing for a few weeks and refuse to start. A drop of fuel in the air intake would get it going for long enough to fill the carb and keep going. Without it you could be there for hours waiting for the fuel pump to wake up.
I used to have a 2CV that would dry out its carb upon standing for a few weeks and refuse to start. A drop of fuel in the air intake would get it going for long enough to fill the carb and keep going. Without it you could be there for hours waiting for the fuel pump to wake up.
Equus said:
Were the float chambers of the carbs full of fuel when you took the tops off to clean them out? The carburettors have floats in them, with a valve that acts like the ball valve on your toilet cistern. Provided the fuel is getting to the carbs, and the float valves haven't stuck, the float chamber of the carburettor should be swimming in petrol... you can't miss it! If the float chambers are not full of petrol, then clearly the petrol isn't reaching them from the fuel tank.
Are you on a mechanical or electric fuel pump?
Very basic faultfinding:
First, are you sure there's fuel in the tank?
Disconnect the fuel pipe where it enters the carb (direct it into a bottle or something to catch the fuel, and also disconnect the low tension leads from the coil, so you don't have a spark is a good idea!), then switch the ignition on. If you have an electric pump, you'll hear it operating, and fuel should start coming through the pipe and collecting in the bottle. If a mechanical pump, you'll need to actually turn the engine over using the starter motor.
If fuel isn't coming out of the pipe by this point, you have a fuel supply problem (no fuel, blocked fuel pipe, non-functional fuel pump).
Second: do you have a spark?:
Take a spark plug out and rest it on top of the exhaust manifold. Turn the engine over on the starter. You should see the spark plug sparking. If it isn't you have an ignition problem.
If you have fuel getting to the carburettors and a nice, strong spark getting to the plugs, then the problem is most likely to be with the carburettors (blocked jets) or stale fuel.
The fuel tank is about 1/4 full. It is registering on the dash fuel meter.Are you on a mechanical or electric fuel pump?
Very basic faultfinding:
First, are you sure there's fuel in the tank?
Disconnect the fuel pipe where it enters the carb (direct it into a bottle or something to catch the fuel, and also disconnect the low tension leads from the coil, so you don't have a spark is a good idea!), then switch the ignition on. If you have an electric pump, you'll hear it operating, and fuel should start coming through the pipe and collecting in the bottle. If a mechanical pump, you'll need to actually turn the engine over using the starter motor.
If fuel isn't coming out of the pipe by this point, you have a fuel supply problem (no fuel, blocked fuel pipe, non-functional fuel pump).
Second: do you have a spark?:
Take a spark plug out and rest it on top of the exhaust manifold. Turn the engine over on the starter. You should see the spark plug sparking. If it isn't you have an ignition problem.
If you have fuel getting to the carburettors and a nice, strong spark getting to the plugs, then the problem is most likely to be with the carburettors (blocked jets) or stale fuel.
I think the fuel pump on the 1600 Crossflow with twin carbs is mechanical.
The engine is turning over on the starter motor. It just won't fire up.
I can't really rest a plug on the exhaust manifold AND turn the ignition over at the same as my arms aren't long enough
It has to be said that highly-tuned (high compression, with large valve overlap) Crossflows can be a bit finicky to fire from cold, so the pouring-petrol-into-the-carbs trick doesn't always work.
As I've said above, it's also easy to kill your plugs by wetting them, if you give it too much fuel (either by pouring it in neat, or by too many pumps of the throttle pedal when trying to start it), so you need to be mindful of that, too.
If you've wetted the plugs, I find that you're better off fitting a new set of plugs than trying to dry them in the oven, but I appreciate there's a cost involved.
How high a state of tune is your engine in, Eric?
Supersprint (135bhp or above) starts to get a bit temperamental for cold starts if the fuel and spark aren't both spot on.
I used to have a 155bhp Crossflow that was a bit of a pig, from flat cold, to be frank.
As I've said above, it's also easy to kill your plugs by wetting them, if you give it too much fuel (either by pouring it in neat, or by too many pumps of the throttle pedal when trying to start it), so you need to be mindful of that, too.
If you've wetted the plugs, I find that you're better off fitting a new set of plugs than trying to dry them in the oven, but I appreciate there's a cost involved.
How high a state of tune is your engine in, Eric?
Supersprint (135bhp or above) starts to get a bit temperamental for cold starts if the fuel and spark aren't both spot on.
I used to have a 155bhp Crossflow that was a bit of a pig, from flat cold, to be frank.
Eric Mc said:
I can't really rest a plug on the exhaust manifold AND turn the ignition over at the same as my arms aren't long enough
Your arms shouldn't be anywhere near the plug (or the plug lead) - that's the idea of resting it on top of the exhaust manifold!If you're holding it at the time, you might well get a big enough belt of electricity (especially for an old bugger like you, and especially if you have electronic ignition fitted) to kill you!!
So long as you can see the electrode of the spark plug as you're turning the engine over, and the metal body (not electrode!) of the plug is in contact with some bare metal part of the engine, you should be able to see the spark as you stand beside the cockpit and turn the car over on the starter. In fact you'll probably hear it, too, if you have your hearing aid turned on - it sounds like the piezo electric clicking of the spark on a gas cooker hob.
No disrespect, but if you need to be asking these questions, I'm inclined to suggest that you need to get someone in who knows what they're doing.
Equus said:
Your arms shouldn't be anywhere near the plug (or the plug lead) - that's the idea of resting it on top of the exhaust manifold!
If you're holding it at the time, you might well get a big enough belt of electricity (especially for an old bugger like you, and especially if you have electronic ignition fitted) to kill you!!
So long as you can see the electrode of the spark plug as you're turning the engine over, and the metal body (not electrode!) of the plug is in contact with some bare metal part of the engine, you should be able to see the spark as you stand beside the cockpit and turn the car over on the starter. In fact you'll probably hear it, too, if you have your hearing aid turned on - it sounds like the piezo electric clicking of the spark on a gas cooker hob.
No disrespect, but if you need to be asking these questions, I'm inclined to suggest that you need to get someone in who knows what they're doing.
That's exactly why I'm asking. If I knew what I was doing, I wouldn't be asking.If you're holding it at the time, you might well get a big enough belt of electricity (especially for an old bugger like you, and especially if you have electronic ignition fitted) to kill you!!
So long as you can see the electrode of the spark plug as you're turning the engine over, and the metal body (not electrode!) of the plug is in contact with some bare metal part of the engine, you should be able to see the spark as you stand beside the cockpit and turn the car over on the starter. In fact you'll probably hear it, too, if you have your hearing aid turned on - it sounds like the piezo electric clicking of the spark on a gas cooker hob.
No disrespect, but if you need to be asking these questions, I'm inclined to suggest that you need to get someone in who knows what they're doing.
You don't need to be rude about it.
I will be getting a garage to look at it now as I recognise what I can and can't do.
CanAm said:
Eric,
Have you tried that wonderful Australian product, "Start Ya b
d" ? (or the less colourfully named British equivalents). Aussies swear by it!
^^^^^^ This ...A three second squirt of Eezistart into each carb and see if you get any signs of life .Have you tried that wonderful Australian product, "Start Ya b
d" ? (or the less colourfully named British equivalents). Aussies swear by it!If you do then the problem lies with the fuel, and or its delivery. With a bit of luck she'll fire up and continue running.
Try no choke and a smidgeon of throttle , and don't believe all that nonsense about engines becoming dependant on the stuff
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