Plugs
- Thread starter stina
- Start date
When you heat water on the stove, at what point do you see bubbles forming? Now with that in mind, consider what you are seeing in your fuel filter. Where are the bubbles coming from? What does that tell you is happening?
The level of fuel within the filter is not an indication of an impending problem. To me it does not sound like there is a problem with the fuel pump. The mechanical fuel pump will not work effectively when there is a combination of fuel and vapour before the pump. The engine will still run at this point but not very well. When there is full vapour before the pump, the engine stops.
Ron.
The level of fuel within the filter is not an indication of an impending problem. To me it does not sound like there is a problem with the fuel pump. The mechanical fuel pump will not work effectively when there is a combination of fuel and vapour before the pump. The engine will still run at this point but not very well. When there is full vapour before the pump, the engine stops.
Ron.
A wise comment from Dave Herns there!
Let's just run through all the possibilities first and then try to pick some likely ones to start with afterwards.
First up, an air leak into the inlet manifold on the engine side of the carburettors. Two possible sourdes for this really, the suction system to the servo and the carb to manifold gaskets etc. So have the rubber vacuum hose off the servo and off the manifold and check it isn't perished etc. Check that the white mushroom air valve on the servo is seated properly. Listen for any hissy leaks. You've had the carbs off recently to do the floats, haven't you? Check that they've gone back on properly and that all the gaskets are in good condition and properly sealed. Listen for any hissy leaks (I like that phrase - just invented it
).
Next ignition. Have the distributor cap off and just verify thet your nice new ignition module is bolted down solid as when you fitted it. Check that the vacuum advance unit is still working by having a good suck and checking that that moves the base plate. Check that the base plate rotates freely against the advasnce retard springs and returns to static position smartly. Is there a build up of crud on the lead terminals inside the cap. It must also be possible that the ignition module is fading away. The only way I can think of of testing that is to use some of those neon indicators in between the plug caps and the plugs. They are really graphic and give you that nice warm comfy feeeling that you really do have a spark.
Just to satisfy Ron, we'd better do some basic checks to be sure there's no risk of fuel vaporisation. Pull the coolant hose off the outlet from the carburettor tower and make sure you get deluged before you manage to get your finger over the end and put it back. Also check that the radiator really is full of coolant - I have known cars get an air lock between the rad and the header tank so that the header looks full when the rad isn't. Just to be doubly sure, run the engine at idle with the rad cap off for ten minutes or so, making sure that everything circulates as it should and there really are no airlocks in the engine. Do the final fill of the rad from the header tank with the main rad cap off so that you are sure there is no air in the hose between the two. My understanding is that this problem is immediate after starting the car? So there is absolutely no chance of the exhaust manifolds being hot enough to gice the fuel line a good boil as it runs down the side of the engine block underneath the right hand one? Best check that fuel line there is still tight to the block though and hasn't floated off closer to the manifold.
Then we are down to the fuel pump failing to deliver enough fuel. That could be caused either by a continuing problem with the pump, or by a blockage tank side of the pump or by an air leak tank side of the pump. I do like practical tests where you can see the result. How about taking the pump out of the engine and either keeping the proper fuel lines attached, or if yours are too stiff (ie original) rigging up some jury ones so that the pump is still connected fuel wise. Then pretend to be a camshaft for ten minutes and operate the pump lever arm and see what sort of effect you generate. I've never done this myself so I'm not sure what to expect, but if there were a blockage I think you might spot it. Likewise if there is a really big air leak, if you arrange the pump discharge into a pudding basin or similar you might see aierated fuel. I agree that you could be badly misled by what is going on in the fuel filter. So the next port of call after this is probably to start dismantling things. 'm sure I'd start with wanting to see what is going on around the fuel pick up in the tank, which means dropping the tank sender unit as mentioned previously. Fine if the tank is empty, a b##**#d if the tank is full. You could easily then finish up renewing all the fuel lines :shock: . So lets make sure you have already tried that reserve tap. The huge advantage of risking this is that the reserve system uses a different pick up in the tank and different ppie work all the way to the front bulkhead. So you can potentailly eliminate quite a lot of kit as not relevant.
So what would I do first? I think I'd go for the drawing air upstream of the carbs actions first. Then the ignition checks and the coolant checks, simply because they are easy and leave you with more certainty as you home in on the fuel system. When you reach that point, I'd definitely want to try the effect of using the fuel reserve system first. Then the pump test and then the tank sender unit.
Anybody else got any flashes of inspiration here?
Chris
Let's just run through all the possibilities first and then try to pick some likely ones to start with afterwards.
First up, an air leak into the inlet manifold on the engine side of the carburettors. Two possible sourdes for this really, the suction system to the servo and the carb to manifold gaskets etc. So have the rubber vacuum hose off the servo and off the manifold and check it isn't perished etc. Check that the white mushroom air valve on the servo is seated properly. Listen for any hissy leaks. You've had the carbs off recently to do the floats, haven't you? Check that they've gone back on properly and that all the gaskets are in good condition and properly sealed. Listen for any hissy leaks (I like that phrase - just invented it
).Next ignition. Have the distributor cap off and just verify thet your nice new ignition module is bolted down solid as when you fitted it. Check that the vacuum advance unit is still working by having a good suck and checking that that moves the base plate. Check that the base plate rotates freely against the advasnce retard springs and returns to static position smartly. Is there a build up of crud on the lead terminals inside the cap. It must also be possible that the ignition module is fading away. The only way I can think of of testing that is to use some of those neon indicators in between the plug caps and the plugs. They are really graphic and give you that nice warm comfy feeeling that you really do have a spark.
Just to satisfy Ron, we'd better do some basic checks to be sure there's no risk of fuel vaporisation. Pull the coolant hose off the outlet from the carburettor tower and make sure you get deluged before you manage to get your finger over the end and put it back. Also check that the radiator really is full of coolant - I have known cars get an air lock between the rad and the header tank so that the header looks full when the rad isn't. Just to be doubly sure, run the engine at idle with the rad cap off for ten minutes or so, making sure that everything circulates as it should and there really are no airlocks in the engine. Do the final fill of the rad from the header tank with the main rad cap off so that you are sure there is no air in the hose between the two. My understanding is that this problem is immediate after starting the car? So there is absolutely no chance of the exhaust manifolds being hot enough to gice the fuel line a good boil as it runs down the side of the engine block underneath the right hand one? Best check that fuel line there is still tight to the block though and hasn't floated off closer to the manifold.
Then we are down to the fuel pump failing to deliver enough fuel. That could be caused either by a continuing problem with the pump, or by a blockage tank side of the pump or by an air leak tank side of the pump. I do like practical tests where you can see the result. How about taking the pump out of the engine and either keeping the proper fuel lines attached, or if yours are too stiff (ie original) rigging up some jury ones so that the pump is still connected fuel wise. Then pretend to be a camshaft for ten minutes and operate the pump lever arm and see what sort of effect you generate. I've never done this myself so I'm not sure what to expect, but if there were a blockage I think you might spot it. Likewise if there is a really big air leak, if you arrange the pump discharge into a pudding basin or similar you might see aierated fuel. I agree that you could be badly misled by what is going on in the fuel filter. So the next port of call after this is probably to start dismantling things. 'm sure I'd start with wanting to see what is going on around the fuel pick up in the tank, which means dropping the tank sender unit as mentioned previously. Fine if the tank is empty, a b##**#d if the tank is full. You could easily then finish up renewing all the fuel lines :shock: . So lets make sure you have already tried that reserve tap. The huge advantage of risking this is that the reserve system uses a different pick up in the tank and different ppie work all the way to the front bulkhead. So you can potentailly eliminate quite a lot of kit as not relevant.
So what would I do first? I think I'd go for the drawing air upstream of the carbs actions first. Then the ignition checks and the coolant checks, simply because they are easy and leave you with more certainty as you home in on the fuel system. When you reach that point, I'd definitely want to try the effect of using the fuel reserve system first. Then the pump test and then the tank sender unit.
Anybody else got any flashes of inspiration here?
Chris
Hi Stina,
I have never seen Tesco fuel in Australia, so I am not in a position to comment never having used it. But having said that, in a properly maintained car, what is the common denominator? The fuel of course. Next time it happens, pull over and release the nut on top of the fuel filter. I expect you'll hear a hissing sound, bubbles will eminate and then just smooth fuel. Tighten the nut and drive on. In my case when I did this I could then drive for a time prior to it happening again. I am talking back in 1990 when Australian P6 Rovers fell like flies from vapourisation. Nothing before and then en masse. Lasted consistantly for two years, then just disappeared, no more vapourisation for over 20 years pretty much.
What I did in 1990 as a stop gap measure that worked a treat was to wrap the fuel filter with a piece of cloth and then redirect the windscreen washer tubing over to the cloth, securing it to prevent movement. Then while driving every now and then give the windscreen washer motor a burst, the water soaks the cloth keeping the filter and the fuel within cool. I had no vapourisation while doing this. Obviously though it is not a permanent solution, but it kept me moving in traffic going to and from work.
Give these a try and please lets know how it goes.
Ron.
I have never seen Tesco fuel in Australia, so I am not in a position to comment never having used it. But having said that, in a properly maintained car, what is the common denominator? The fuel of course. Next time it happens, pull over and release the nut on top of the fuel filter. I expect you'll hear a hissing sound, bubbles will eminate and then just smooth fuel. Tighten the nut and drive on. In my case when I did this I could then drive for a time prior to it happening again. I am talking back in 1990 when Australian P6 Rovers fell like flies from vapourisation. Nothing before and then en masse. Lasted consistantly for two years, then just disappeared, no more vapourisation for over 20 years pretty much.
What I did in 1990 as a stop gap measure that worked a treat was to wrap the fuel filter with a piece of cloth and then redirect the windscreen washer tubing over to the cloth, securing it to prevent movement. Then while driving every now and then give the windscreen washer motor a burst, the water soaks the cloth keeping the filter and the fuel within cool. I had no vapourisation while doing this. Obviously though it is not a permanent solution, but it kept me moving in traffic going to and from work.
Give these a try and please lets know how it goes.
Ron.
For how long it takes and what it costs, change the O ring in the reserve tap and then we can cross that off the list. If a short sighted clumsy person with big fingers like me can do it ,then most people should be OK
What about a crack in the fuel line that's letting in air but not letting petrol out ? Has the fuel line become unclipped underneath ?
What about trying a fuel can full of super duper petrol piped into the fuel pump direct to eliminate dodgy fuel/pipes in one go ?
Petrol tank breathers unblocked ?
I mentioned the servo hose as I had similar problems on my Corsair 2000E back in 1974
What about a crack in the fuel line that's letting in air but not letting petrol out ? Has the fuel line become unclipped underneath ?
What about trying a fuel can full of super duper petrol piped into the fuel pump direct to eliminate dodgy fuel/pipes in one go ?
Petrol tank breathers unblocked ?
I mentioned the servo hose as I had similar problems on my Corsair 2000E back in 1974
stina
New Member
Hi all todays installment .
First checked rad and carb tower coolant pipe . All o.k . Checked fuel lines and connections to / from pump under bonnet . nothing obvious wrong .
Started her up and it ran terrible from cold . I think this rules out vaporisation for the moment .
Things are obviously getting worse as it's un driveable now .
The fuel filter was full to start with then the level dropped but it always had fuel in it .
Any way out of desperation i took the carbs off again to see if their was anything obviously wrong .
The float chambers were full of clean fuel and nothing amiss . Replaced the carbs ( new gaskets again , had a spare set )
and started it without priming the float bowls to see if the pump did indeed pump ! Took a while but it started and ticked over rough . I cracked the fuel lines into the carbs while it was running and their was plenty of fuel getting there . I know "plenty of fuel" isn't a technical term but it was all i could think to do ( getting desperate )
I did think of doing as you said Dave and rigging up a fuel can but i'll need an old inlet pipe to butcher . Don't want to cut into original lines if i can help it . And tomorrow i will have a go at the reserve tap O ring . If anyone can talk me through that it would be great . Is it all done under the bonnet ? Do i remove that little screw on the side of the barrel i can see , disconnect the cable and pull the lever and barrel out ?
I am also starting to suspect ignition again . I have been through the lot as said before , but i'm starting to wonder about the coil as they can give intermittent problems , Correct or no ??? The coil has been on for 1000 miles , the one before that lasted only 100 miles and was replaced under warranty as a duff , could it happen again ? The Problem has got progressively worse . It does try to clear its self when you rev it .
May order a coil tomorrow as they're under 15 quid . just to rule it out .
Talking of which the coil was Simon BBC power spark to go with the ignition module . Does this sound enough money for a standard 12v coil ?
Sorry if i'm rambling , want to get it down while it's fresh in the mind .
More thoughts , opinions please .
Stina
First checked rad and carb tower coolant pipe . All o.k . Checked fuel lines and connections to / from pump under bonnet . nothing obvious wrong .
Started her up and it ran terrible from cold . I think this rules out vaporisation for the moment .
Things are obviously getting worse as it's un driveable now .
The fuel filter was full to start with then the level dropped but it always had fuel in it .
Any way out of desperation i took the carbs off again to see if their was anything obviously wrong .
The float chambers were full of clean fuel and nothing amiss . Replaced the carbs ( new gaskets again , had a spare set )
and started it without priming the float bowls to see if the pump did indeed pump ! Took a while but it started and ticked over rough . I cracked the fuel lines into the carbs while it was running and their was plenty of fuel getting there . I know "plenty of fuel" isn't a technical term but it was all i could think to do ( getting desperate )
I did think of doing as you said Dave and rigging up a fuel can but i'll need an old inlet pipe to butcher . Don't want to cut into original lines if i can help it . And tomorrow i will have a go at the reserve tap O ring . If anyone can talk me through that it would be great . Is it all done under the bonnet ? Do i remove that little screw on the side of the barrel i can see , disconnect the cable and pull the lever and barrel out ?
I am also starting to suspect ignition again . I have been through the lot as said before , but i'm starting to wonder about the coil as they can give intermittent problems , Correct or no ??? The coil has been on for 1000 miles , the one before that lasted only 100 miles and was replaced under warranty as a duff , could it happen again ? The Problem has got progressively worse . It does try to clear its self when you rev it .
May order a coil tomorrow as they're under 15 quid . just to rule it out .
Talking of which the coil was Simon BBC power spark to go with the ignition module . Does this sound enough money for a standard 12v coil ?
Sorry if i'm rambling , want to get it down while it's fresh in the mind .
More thoughts , opinions please .
Stina
Hi Stina,
Maybe there is actually more than one problem here, and they are overlapping thus making diagnosis more difficult. With the needles valves being different, I recall when I was rebuilding mine, the new ones were different to the old as you mentioned with yours. I reused the old original ones, never had a problem with them so why change them.. :?
If you wish to remove and replace the reserve tap 'O' ring, then yes to your questions. I did mine twice 20 years ago when I was chasing the vapour lock problem,..made no difference at all in my case. In reality I tend to think it would leak if there was a problem, but desperation calls for desperate measures.
You can rule in or out the coil by measuring the primary resistance.
Did you put some metho in the tank as I suggested to you previously? Water in the tank will see the engine misbehave pretty well right from the word go.
Ron.
Maybe there is actually more than one problem here, and they are overlapping thus making diagnosis more difficult. With the needles valves being different, I recall when I was rebuilding mine, the new ones were different to the old as you mentioned with yours. I reused the old original ones, never had a problem with them so why change them.. :?
If you wish to remove and replace the reserve tap 'O' ring, then yes to your questions. I did mine twice 20 years ago when I was chasing the vapour lock problem,..made no difference at all in my case. In reality I tend to think it would leak if there was a problem, but desperation calls for desperate measures.
You can rule in or out the coil by measuring the primary resistance.
Did you put some metho in the tank as I suggested to you previously? Water in the tank will see the engine misbehave pretty well right from the word go.
Ron.
ghce
Well-Known Member
Measuring the primary resistance will only tell you if the coil is no go ie hi resistance or low resistance however it will not tell you if it is breaking down in use, if you measure and find the coil resistance is in the normal range it still does not tell you if it is faulty or not, direct coil substitution is the only reliable method.
Graeme
Graeme
stina
New Member
Hi Ron . I think their is a couple of things going on here as happened before , Understand what you say about the needle valves , but it ran faultlessly on Sunday for 30 miles after i,d done them , the float chambers were full when i took the carbs off this afternoon also . Yes i splashed a drop of meths in the tank last Friday .
What your saying about the coil Graeme reinforces what i was thinking . They're so cheap it's gotta be worth a shot to rule it out . Worth having a spare anyway .
What your saying about the coil Graeme reinforces what i was thinking . They're so cheap it's gotta be worth a shot to rule it out . Worth having a spare anyway .
ghce
Well-Known Member
Have you tried the midnight under bonnet veiw to see if you have and high voltage flash overs?
Were it mine I would have a fresh set of new plugs to bang in as a test just to eliminate that aspect.
I tend to suspect low fuel levels in in line filters can be a red hereing as many cars seem to work fine with little evidence of a fill fuel filter.
Graeme
Were it mine I would have a fresh set of new plugs to bang in as a test just to eliminate that aspect.
I tend to suspect low fuel levels in in line filters can be a red hereing as many cars seem to work fine with little evidence of a fill fuel filter.
Graeme
arthuy
Well-Known Member
I will look and see if I have an old pipe end I could send down (def have one which I saw recently) you can put a hose on it.
You will get to the bottom of it eventually. Might be worth sticking to one line of faulting i.e fuel or electric until you are happy that they are fine
If you are going to try running it was a jerry can on the roof and gravity feed the carbs remember that the fuel pump will pump when the engine is running.
Good luck and hang in there.
Colin
You will get to the bottom of it eventually. Might be worth sticking to one line of faulting i.e fuel or electric until you are happy that they are fine
If you are going to try running it was a jerry can on the roof and gravity feed the carbs remember that the fuel pump will pump when the engine is running.
Good luck and hang in there.
Colin
stina
New Member
Spoke to the coil supplier today , seems they may of had a few failures of late . Hmmm . Hoping it turns up tomorrow , not done much today with that in mind . Did bite the bullitt and pull the fuel reserve , didn't leak , if it does i have the O ring so i'll have to do it . Made no difference to running .
Colin , cheers for the offer but i can get hold of one if i still have to go that route .
stina
Colin , cheers for the offer but i can get hold of one if i still have to go that route .
stina
stina
New Member
Hi guys . Since i last posted have had a bit of a night mare with the way it's running . It is undriveable at the moment . I have been through everything electrical and it is all new . the carbs have been on and off about 5 times checking and re checking everything . I have rigged it to run out of a can on the drive all to no avail . it will rev with the choke out without missing . From right out to right in ( lean to rich ) on the mixture screws makes no difference to the running . I even tried a borrowed set of carbs . I have put a new diaphragm and valves in the fuel pump . It all points to a low fuel level in the float bowls . My thinking now is although the pump does pump fuel , is it enough ? Pumping it manually off the car it seems strong , but i've been thinking , does it swing through the complete travel of the operating rod when driven of the cam on the engine . Have i rebuilt the pump but the operating rod is worn beyond being usable ? I have the loan of an electric pump tomorrow to see if that cures it . Don't totally know how i'm going to rig it up as i haven't seen it yet .
Any thoughts welcome
Any thoughts welcome
Hi Stina,
I would say that unless the mechanical fuel pump arm has a significant groove on the tip where contact is made with the eccentric lobe, then it is not too worn. Mine has almost no wear after all the miles it has done so I don't expect that to be the problem. There can be wear at the location of the locating pin, but once again it will be miniscule. Of course if your engine had been treated poorly with infrequent oil changes over its time prior to your ownership, then the wear may well be greater. Mechanical pumps can't really be tested off the engine.
If you disconnect the fuel filter and crank the engine over, you will see the fuel spurt out quite significantly, or at least you should do! That will tell you whether or not the engine is receiving a good fuel feed.
Ron.
I would say that unless the mechanical fuel pump arm has a significant groove on the tip where contact is made with the eccentric lobe, then it is not too worn. Mine has almost no wear after all the miles it has done so I don't expect that to be the problem. There can be wear at the location of the locating pin, but once again it will be miniscule. Of course if your engine had been treated poorly with infrequent oil changes over its time prior to your ownership, then the wear may well be greater. Mechanical pumps can't really be tested off the engine.
If you disconnect the fuel filter and crank the engine over, you will see the fuel spurt out quite significantly, or at least you should do! That will tell you whether or not the engine is receiving a good fuel feed.
Ron.