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TR4A running/fuel problem


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9 hours ago, eng622 said:

Interesting, I still have what looks to be two small lengths of rubber hose, one at the tank end the other at the front. But in front of that is a third rubber hose. There appears to be a small length of copper pipe from the front hose to the third one. The third one connects to the filter and then there is a fourth rubber one from the filter outlet to the pump.   

That is the standard layout if you look in a parts catalogue. As I said I have done away with the 2 rubber connectors under the car by fitting one length of metal pipe. At the rear end I incorporated a slight S shape to allow for movement. Works fine. At the engine end I fitted a cut off valve to the end of the metal pipe and then used a U shaped length of hose between the cut off valve and the filter. The U shape allows for any side to side engine movement.

The photo also shows where I have the coil on the wheel arch.

Keith

P4140902.JPG

Edited by keith1948
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Done some tests with a pressure gauge connected to the end of the fuel pipe going to the carb (no T fitting). So cranking get 1 1/4 psi which at one point went to 3. Engine started and ran for about 2 minutes with fuel in float chambers and pressure steady at 1 1/4.

With a single prime (engine stopped ) on release got 1 3/4 psi and with gauge off a big squirt of fuel into a jar..

Reconnected fuel pipe (float chambers empty) and started almost straight away.

This is telling me that there is probably nothing wrong with the fuel system during these tests but pressure seems low, not sure what SU carbs need and spec for AC pump.

On the  electrical side the dwell angle is spot on at 60 deg. Not going to be the spark plugs so maybe the coil. Condenser has been tested and run on other cars. Do not know what else to check.

It is only the successful bump start that suggests an electrical fault but still think there is a fuel blockage forward of the glass bowl, so can only be inside the pump. I think this because when it has stopped in the past several primes have been needed to get even a trickle out of the fuel  pipe. Having said that when it did start squirting out the car still would not start. The empty bowls test just shows you do not need to crank much to get started. In my case endless cranking has no effect. Perhaps I have more than one fault.     

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9 hours ago, eng622 said:

Done some tests with a pressure gauge connected to the end of the fuel pipe going to the carb (no T fitting). So cranking get 1 1/4 psi which at one point went to 3. Engine started and ran for about 2 minutes with fuel in float chambers and pressure steady at 1 1/4.

With a single prime (engine stopped ) on release got 1 3/4 psi and with gauge off a big squirt of fuel into a jar..

Reconnected fuel pipe (float chambers empty) and started almost straight away.

This is telling me that there is probably nothing wrong with the fuel system during these tests but pressure seems low, not sure what SU carbs need and spec for AC pump.

On the  electrical side the dwell angle is spot on at 60 deg. Not going to be the spark plugs so maybe the coil. Condenser has been tested and run on other cars. Do not know what else to check.

It is only the successful bump start that suggests an electrical fault but still think there is a fuel blockage forward of the glass bowl, so can only be inside the pump. I think this because when it has stopped in the past several primes have been needed to get even a trickle out of the fuel  pipe. Having said that when it did start squirting out the car still would not start. The empty bowls test just shows you do not need to crank much to get started. In my case endless cranking has no effect. Perhaps I have more than one fault.     

The correct operating pressure for an AC pump on a TR is 1 1/4 to 2 1/2 psi. Taken from Haynes manual.

Remember also that the effectiveness of the priming lever is dependant on where the engine is stopped. If the pump lever is already on the top of the cam lobe the priming lever hardly works at all, and sometimes you have to jog the engine 1 turn (half a turn of the camshaft) to get full stroke on the priming lever.

Ralph

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On 6/21/2022 at 9:38 AM, eng622 said:

Perhaps it is the pump. The glass bowl is always full and fuel clean but it is on the inlet side. When it has stalled using the priming lever does not give an instant squirt of fuel, takes several primes. It is an AC pump are these serviceable. What is there to check.

The AC pumps are very simple and easy to dismantle and check, in fact you don`t have to remove the pump from the engine. Disconnect the inlet and outlet fuel pipes, if you don`t have a cut off tap be ready with something to stop the fuel escaping from the inlet pipe. Undo the six screws on the top of the pump and seperate the top section of the pump from the diaphragm and lower body. There are two flap valves in the top section, one inlet and one outlet, check these are clean and operate ok  After removing any fuel try blowing/sucking on the inlet and outlet pipes, it should be possible to blow through the inlet but not to be able to suck through it, likewise the outlet pipe you should be able to suck but not blow. Inspect the diaphragm but if this was damaged the pump wouldn`t have operated at all and the sump would fill with petrol so I wouldn`t expect to find anything wrong with it.

If nothing else it will put your mind at ease if all seems OK.

Ralph

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Check the thin black wire that goes from the negative on the coil to the distributor. It has crimped spade connectors each end. Remove distributor cap and check the red wire that goes from the points to the plastic fitting that slides onto one side of the distributor and has the black wire connected to it. Again there are crimped connectors. I have had these come loose in the past (the wire inside the crimping) so I solder them onto the crimp these days.

Also check the crimping on the other wire that goes to the coil +

Keith

Edited by keith1948
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Point noted about hand priming the pump depending where the engine stops. 

Will take the top off the pump and do a continuity test with a meter on electrical circuits.

One point I forgot to mention. On the last run out where the engine stopped 3 times, after the first time it only traveled about 400 yds before stopping again, maybe because just on what fuel was in the float chambers.

Now on the third time it really was endless churning to no avail. By that I mean several churns each for quite a few seconds. Towards the end there was a hint that the engine might start (it did not) but noted a puff of fumes coming out of the front air cleaner. What does this tell you? 

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For what it's worth..,  a quick on-line check < here > of flow through a 6mm pipe, of 1m long, at 0.10 bar (approximately 1.5psi ) suggests an output flow rate of .278 litres / minute.  That of course equates to (..0.278 x 60 = ) 16.68 litres / hour = 3.67 gals (imp) / hr.  

It is of course easy enough to check these flow-rate figures (which were complied for bigger bores and longer lengths of pipe) by cranking the engine (with plugs out and the low-tension lead off the coil) with the pump's fuel pipe leading to a clean coffee jar for half-a-minute. After which you should see about 100ml to 140ml of crystal-clear petrol in the jar..    

As your pump's  1-1/2 psi pressure was recorded at cranking engine speed, then I'd think you can be reassured that your fuel pump is delivering more than enough fuel when the engine revs are higher.

 

If there's a constrictions in the pipe, limited flow through an in-line filter, or blockage at both  carb's float chambers (either at their connections in or their float-level valves not opening) then that's another matter. Those things eliminated, I would have thought you need to focus on electrical issues, and specifically something that effect all cylinders ..so not the sparkplugs or their own HT leads (where any failure would cause the engine to run on three cylinders).  

Pete     

 

 

Edited by Bfg
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On 6/17/2022 at 11:55 PM, eng622 said:

There is an inline filter before the pump. When it wont start when hot the filter appears to be empty.

I recommend you remove this filter (perhaps replace it with a piece of metal pipe with jubilee clips) to ensure the fuel is free flowing / the pipe is clear of debris (..rust particles from the tank for example).  NB. this pipe and the fuel filter should be full of fuel and so a large clean container is required to catch the petrol.

My reasoning is ; the fuel tank is above the rear-axle ..and so its fuel level is above the fuel pump. The petrol is gravity-fed to the pump, and then the pump lifts it to the carburetors.  Because the fuel is gravity fed to the pump.. it follows that the (supply) pipe from the fuel-tank to pump (and any in-line filter before the lift-pump) should always be full of fuel ..whenever there's sufficient petrol in the tank.   

 

Another way to check to see if this is the issue - is to drive the car until it stops, and then very quickly check the fuel filter to see if it's empty (having a torch / flashlight to hand might make it clearer to see).  Then open the fuel filler cap. There should be no vacuum in the tank (you might hear that when you open the cap).  A partial vacuum would be created by fuel being pumped out, and at the same time the tank having a blocked air vent.  Then check the in-line fuel filter again (..now the fuel filler cap is open) to see if the filter is filling up.  

If not.., then blow down into the fuel filler orifice. That may not be easy because the flip-open cap and its latch are sorta in the way and because of the reach to the filler, so you might want to have configured some way to do this before you do go for this test drive (..perhaps a plastic bottle or pot with a rim of the right diameter to seal around the fuel filler orifice, but with a hole in its bottom to allow you blow into the tank). The idea being to pressurise the tank slightly.. which will push petrol through the pipe (passed any restriction) to the pump.  Check the filter is full (or very nearly so) ..and see how easy the car starts.

NB. an in-line filter between the pump and the carb(s)  may often appear mostly empty, but not one which is in-line below the fuel's level.  It may have an air bubble within it but on the whole it should be mostly full of petrol.

Hope that helps.   Let me know how you get on.

Pete 

p.s. the car starting with a bump-start, may simply be because this in-effect shakes the fuel tank.

     

Edited by Bfg
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Update. Took the fuel pump top off and cleaned around the valves with a brush. Nothing obvious except the inlet valve has been replaced (see butchered around the staking). All LT leads checked for continuity and all ok. Started up and ran ok. Switched off to put the hood down and then to do a test drive. No, that did not happen it would not start, dead as a door nail. So looks electrical, checked the main HT lead and sparked ok. Then started to check each plug lead but on the endless churning noticed petrol pouring out of the rear carb float chamber. Bashing the side did not free up the valve. Took the top off and cleaned the valve and seat and rotated the valve a few times (how on earth do you remove the valve no spanner I have will get to the hex which looks 9 mm). Anyway put it back car started and no more fuel leaking. Seems to run ok so now will do the road test tomorrow. 

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2 hours ago, eng622 said:

Took the top off and cleaned the valve and seat and rotated the valve a few times (how on earth do you remove the valve no spanner I have will get to the hex which looks 9 mm

I used a 1/4" drive socket.  I think it is 5/16" 

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DISASTER - had to call breakdown 

I don't like calling them if I can fix at the road side. Morning test run after after sorting the float chamber valve leak passed all ok. PM run, put in 3 gallons of fuel all good for about 12 miles then a serious hesitation and luckily coasted to a  safe section of road.

Would not restart so went through some tests, fuel squirting on cranking, front float chamber full. Now electrical main HT spark seemed weak but still some spark at plug 1. Car would start after endless churning but would not keep running. Then it failed outright no more sparking from main HT. A local person helped  with a new coil to no avail. So taken home by breakdown service.

So those who said electrical fault look to be right, there was a fuel issue with leaking valve maybe fixed now. So it is not the coil and all HT leads checked out ok for resistance. Must be condenser, distributor cap/ carbon brush or rotor arm, cannot think what else. Have several classics and have had to replace 3 condensers in 18 months due to aftermarket **** but think the TR one is quite old and has previously been tested on other cars and ok. As said dwell gave 60 deg before these runs.

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Hi unkown TR owner with problems,

I'm old fashioned and wonder why you don't use common "Hello" and "Good bye" rules,

telling us nothing more than problems and not calling one of the members here on his name.

Ciao, Marco

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10 hours ago, eng622 said:

DISASTER - had to call breakdown 

I don't like calling them if I can fix at the road side. Morning test run after after sorting the float chamber valve leak passed all ok. PM run, put in 3 gallons of fuel all good for about 12 miles then a serious hesitation and luckily coasted to a  safe section of road.

Would not restart so went through some tests, fuel squirting on cranking, front float chamber full. Now electrical main HT spark seemed weak but still some spark at plug 1. Car would start after endless churning but would not keep running. Then it failed outright no more sparking from main HT. A local person helped  with a new coil to no avail. So taken home by breakdown service.

So those who said electrical fault look to be right, there was a fuel issue with leaking valve maybe fixed now. So it is not the coil and all HT leads checked out ok for resistance. Must be condenser, distributor cap/ carbon brush or rotor arm, cannot think what else. Have several classics and have had to replace 3 condensers in 18 months due to aftermarket **** but think the TR one is quite old and has previously been tested on other cars and ok. As said dwell gave 60 deg before these runs.

Change the lot. Parts are cheap so start afresh, good quality points and condenser  rotor arm and dizzy cap, check the earth braid from the moving baseplate to dizzy body.

The c--p parts is the reason I went electronic on all my classics and have not regretted it.

Ralph

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Hello Eng622 (what's your actual name?)

Fit a new coil but on the body not the engine (e.g. next to the horn). I use a standard coil. I had one of the 'uprated gold ones leak oil recently. I know you have circuit tested the black wire from the coil to the distributor BUT when it all warms up, a slightly loose crimp or break in the wire can then open up. You need a multimeter to test it hot. To play safe replace the wire itself. Check the spade connectors are making a good connection. Look for 'tracking' lines inside the distributor cap. Check the little red wires to the condenser. A 'wild card' might be a dodgy engine earth wire. This is positioned between the left front of the engine and the chassis turret. I have fitted an extra one between the front of the engine and the horn mountings on the body. The chassis to body connection is through the body mounting points and these don't always work that well. Replace the rotor arm. Make sure points have the right gap and everything on the contact breaker plate is secure. Then work your way back from the coil. Is the white wire back to the ignition switch ok. (wiring on my car seems to differ from the diagram in the attached link. The wiring in the small handbook is the one to go by).  Inside the distributor is a small black earth wire from the contact breaker plate to a connector under one of the 2 screws that hold the contact breaker plate in place. Check this wire is ok and the screw connection is good.

This is probably going to be a very simple fault when you find it. 

This wiring diagram in the link is not the same as the handbook. Mine follows the handbook.

Keith

http://www.advanceautowire.com/tr24a.pdf

Edited by keith1948
typo
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Along with Marco I'm also old fashioned, and sometimes wonder where common politeness and the courtesy of an address by name and perhaps even a 'thank-you for trying to help' now n' then, gets left behind on a club forum.  Anonymity has its place, but if your Christian, first, or nick-name is too anxious a prospect - then the use of a pseudo-name may be appropriate.  Even John Doe & Jane Doe have one of those !

I'll further add, that if you are near Ipswich, Suffolk then I would come across in my TR4A to give you hands-on / two heads together assistance. perhaps comparing the two cars and/or swapping parts across might get to the bottom of the problem.  I will respect your anonymity and privacy even if you are a professional restorer, a well know garage, a person of status, or a celebrity.  Personally I don't give a jot for any of that..  I, like many here, just offer an altruistic hand of friendship.  Feel free to PM (private message) me if you like.

p.s. many years ago ..when I was the designer, manufacturer and owner of a very-humbly-based (Citroen 2cv) kit car business - we received a letter expressing serious interest in our model range from a certain Duke of .........,  I naturally assumed the enquiry was from a public-house of that name :rolleyes: and replied with a copy of our brochure and a personal letter.  In short, the same politeness and genuine interest as I showed anyone.       

Pete.  

 

 

Edited by Bfg
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13 hours ago, eng622 said:

Then it failed outright no more sparking from main HT.  well that's progress ..insomuch as it really narrow things down !

Must be condenser, distributor cap/ carbon brush or rotor arm, cannot think what else.

Eng, my experience of condensers is that they work well, or they fail.  A failing condenser is quite apparent when prising the points open and the point's spark is a bright flash rather than a subdued sharp one.  I've personally not had one which only fails when the engine gets hot .. after 12 miles.    Likewise the distributor cap and rotor arm.  I can leave my car ticking over for 20 minutes and it'll get much warmer than when I'm driving along. This time of year the car's engine would be already hot much sooner than 12 miles.  Might I ask - what cooling fan you have on your car ?  And do you have any security immobiliser fitted ? 

As Keith points out many owners have moved their coil from being bolted onto the side of the engine block, across to being mounted on the inner wing / inner wheel-arch, which not only avoids directly-conducted heat from the block but also vibration.  The HT lead from that to the distributor cap, as well as the low tension lead and their connections within the distributor are prone to much the same heat and vibration.  They might also be prone to shorting out against the block, the metal fuel-pipe, or another HT lead. 

Engine earth wire is unlikely, because that would mostly cause the starter motor not to work.

A cracked distributor cap, unless really bad is more often only a problem in the damp. Very often it leads to a misfire on one or two cylinders but I wouldn't have thought a total stop.  A sticking carbon brush in the cap would again tend to work or not make contact.

Hope that helps,

Pete

 

Edited by Bfg
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Hi,

I have only just found this thread and I had the same problem for a couple of years. It was the condenser and DD supplied me with a new one. It was immediately an answer to hot starting. I keep two DD condensers in the boot and I have a special racing one for  a mini which is too large to fit in the distributor and is out in the fresh air mounted on one of the fixing screws for the coil. I think supplied by Swiftune ??

I understand that the foil used to make these condensers needs to be much longer than used in the cheap ones and my Swift tune condenser was over 30 quid. This is well worth the cost because it solved my problem  which was the same as eng622 on this thread.

Richard & B

 

 

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My name is Melvyn and thanks for all of the support so far.

Some tests today, It is not the coil as 3 good ones tried. Put a known good HT king lead to near a ground and flicked the points. There was a weak spark jumping about 1/8 inch. Tried another condenser that works (not one for this car) result the same. Noted that on flicking the points more and more there was then no HT spark but the points were now sparking more and it was audible. This tells me  that the energy to produce the  HT spark is being lost.  Then after more tries started to get a bigger HT jump so replaced the original condenser and still ok.

Now tried to start the car, lots of churning it tried to start, then eventually did lumpy to start with but after revving up/warming settled to a decent idle. So checked each plug with an inline neon and all ok. Then would not start again so not sure if a heat problem. If it is not the condenser it must be the points but checked the resistance when closed and less than 1/2 ohm so all good. All LT leads checked and less than 1/2 ohm. 

I'm stumped 

Melvyn

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It does sound perplexing Melvyn. One thing you could try when it won't start is to link the supply terminal of the coil directly to the battery.  Obviously you would have to remove that link to stop the engine again.  

I take it you have checked that the flexible lead inside the dizzy, from the baseplate to the body, has good continuity when the baseplate moves under vacuum advance? 

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Hello again Melvyn

Lumpy running at start up suggests uneven firing. So several things to check. If it were me I would now change the distributor cap, plug leads and lead from coil to distributor cap. I would also remove all plugs and clean them up and check spark gap. Make sure the HT leads are not touching each other or near to other possible earthing points. This will eliminate the HT side. You then know the coil and condenser is ok and so are HT leads and dizzy cap. Is the vacuum advance working on the distributor. If you suck on the vacuum advance pipe, there should be resistance and vacuum advance baseplate should start to move. If there is no resistance then there is a puncture inside the vacuum advance unit. You can get these separately but ensure you get the one with the push on or screw on fitting as per your car. If you have a spare distributor you could swap this bit over.

As Rob has said check the wire linking the baseplate to the screw on the distributor body and recheck the black wire from the -ve on the coil to the distributor.

We will await the next instalment.

Keith

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Wires on distributor checked out ok. Fed the coil direct from the battery. Test HT lead used and flicking points still gives a weak spark, sometimes 1/4 inch jump and sometimes nothing. Ordered points and condenser. Checked the coil P current around 3.5 A. Anyway it did start (coil via ign.) but runs rough but not all the time. Sometimes difficult to keep the revs up, other times just a small hesitation/misfire. Plugs checked and all the right colour considering how it runs. HT leads all have expected resistance.

So when it broke down it would not start and appeared to have no HT spark. Now looks to be an intermittent fault, perhaps it is the condenser, but as said did try another one and no better.  If a new correct condenser does not sort it do not know what else to try. No point in changing the HT leads or dist cap if still getting a weak spark when flicking the points. The king HT lead when flicking the points is a known good one. 

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I'm not sure that 'flicking' the points really tells you anything very useful. It is hardly consistent as a method, doesn't test a lot of the components and if the gap from the king lead to earth is wide, the coil is being over-stressed electrically as the HT rises much further than it will in normal use. It takes a lot more voltage to spark over 1/4 inch than it does over 25 thou, and that is stressing the insulation on the coil windings. 

 To me a better test would be to connect everything up but with the plugs out and resting on an earthed surface.  Cranking  the engine.  should show consistent sparks at the plugs.  That way you are testing everything - the points, condenser, dizzy cap, rotor arm, coil and leads. 

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