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Having a problem starting my Tr6 from cold when it sits for any length l was thinking it must be fuel drain back but not sure it has a non return valve are these common to fail or is it another problem l have ? Once its started it will start ok any help would be appreciated thanks in advance.

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Hi Richard,

Assuming it is a PI car then it is common for the injector lines to empty over time. Make sure your fuel enrichment lever operates fully as this needs to be fully open to fill the injector lines again and build up enough pressure to open the injectors. The technique for starting after a prolonged period is full choke and crank away. This usually means that at least you get oil pressure before it fires. Mine then starts on 2-3 cylinders with the rest joining in when they feel like it.

Mick

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2 hours ago, Mick Forey said:

Hi Richard,

Assuming it is a PI car then it is common for the injector lines to empty over time. Make sure your fuel enrichment lever operates fully as this needs to be fully open to fill the injector lines again and build up enough pressure to open the injectors. The technique for starting after a prolonged period is full choke and crank away. This usually means that at least you get oil pressure before it fires. Mine then starts on 2-3 cylinders with the rest joining in when they feel like it.

Mick

Hi Mick,

Thanks for the reply.

Yes it is a PI sorry for got to mention that little detail.

I am starting the car as you have described but if battery was down on charge it would pull the battery to the point of not having enough energy left to start as it is taking too long to fire on any of the cylinders but once it is warm no problem.

Not sure if there is a non return valve in the metering unit as well as in the fuel line?

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This happens to my car if I leave it for more than about a week. If I'm lucky , when trying to start after this time I can get it to fire quickly a few times on fuel that's retained in the system by starting with the throttle wide open - the short period of  firing seems to throw a few quick pulses of fuel into the injector lines-my engine then dies but restarts fairly easily thereafter.

Are you sure your enrichment lever on the MU is correctly adjusted?

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10 hours ago, Mike C said:

This happens to my car if I leave it for more than about a week. If I'm lucky , when trying to start after this time I can get it to fire quickly a few times on fuel that's retained in the system by starting with the throttle wide open - the short period of  firing seems to throw a few quick pulses of fuel into the injector lines-my engine then dies but restarts fairly easily thereafter.

Are you sure your enrichment lever on the MU is correctly adjusted?

 

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10 hours ago, Mike C said:

This happens to my car if I leave it for more than about a week. If I'm lucky , when trying to start after this time I can get it to fire quickly a few times on fuel that's retained in the system by starting with the throttle wide open - the short period of  firing seems to throw a few quick pulses of fuel into the injector lines-my engine then dies but restarts fairly easily thereafter.

Are you sure your enrichment lever on the MU is correctly adjusted?

When you say adjusted correctly do mean when you pull the choke fully out the lever on the metering unit is pulled right back as far as it will go?

Have heard many saying they have over wintered there car & first start up fired within a few turns so if the PI cars are set up right they should all do the same suely ?

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Yes the choke cable needs to move the enrichment lever on the metering unit as far as it will go. Pull the choke fully out, then push the lever to see if there is any more movement available. It is equally important that the lever returns to the stop with a small amount of play in the cable so that enrichment does no occur once the choke is pushed in.

I would find that hard to believe, it means all six injector poppet valves are sealed perfectly. This does not happen normally. Over weeks and months fuel evaporates and sneaks past the valves. Personally I don't touch the throttle on start-up, the choke cable sets a high idle which is enough to keep the engine at about 1500 rpm once it has coughed a spluttered a few times as the fuel lines fill up.

After a long lay-up the battery needs to be in top condition to turn a cold engine over fast with thick oil. Use a maintenance or smart charger over winter and it will help enormously.

Next time you have layed it up for a few months, please time how long it takes to first fire. Data, data, data.

Mick

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That and the gap on the MU cam is set at 6 to 8 thou. I've found that my PI engine is not a digital device like a modern car- it has a personality that has to be learned and understood.  I restarted mine today  after a month or so of coronavirus enforced vehicular isolation- it coughed after the second piston hit TDC- that's  always a good sign- then I had to crank it again for maybe 3 or 4 revolutions before it started firing again on 2, 4 then all  6 cylinders.

After that it had heaps of power driving around town and the nearby hills and stopped and started easily. If I want to use it tomorrow I know it will start straight away. Because that is what it does. 

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Richard I would also recommend a wiring upgrade working through a relay,  to the fuel pump if you are using a Bosch item. The original wiring just isn't up to the amps required to make the Bosch pump work. The current draw for a Lucas pump is approx. 3.5 amps which was fine as the original wiring was rated at approx. 8 amps. well the Bosch pump requires 13 amps.

Speaks for itself really. I did this for both my TR6's and the cold starting has been transformed.

Alan G

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How old is the petrol, the new E5 petrol does go off, if has been left for a time, may be worth getting out what's in there out and try some new 98 in.

If the injector nozzle o rings leak a bit, it will allow fuel to drain back thru the non return valves in the MU.

John

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2 hours ago, John L said:

How old is the petrol, the new E5 petrol does go off, if has been left for a time, may be worth getting out what's in there out and try some new 98 in.

If the injector nozzle o rings leak a bit, it will allow fuel to drain back thru the non return valves in the MU.

John

Going stale is a real problem with modern 98 octane  fuel. I added Stabil to mine yesterday as it won't get much use over winter.

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On 5/25/2020 at 8:34 PM, cp25616 said:

Richard I would also recommend a wiring upgrade working through a relay,  to the fuel pump if you are using a Bosch item. The original wiring just isn't up to the amps required to make the Bosch pump work. The current draw for a Lucas pump is approx. 3.5 amps which was fine as the original wiring was rated at approx. 8 amps. well the Bosch pump requires 13 amps.

Speaks for itself really. I did this for both my TR6's and the cold starting has been transformed.

Alan G

Hi Alan,

My pump is a Bosch unit & l have fitted a new wiring loom but guess that makes no differance  wiring is not one of my strong points what has be done to increase to 13amps ?

Richard.

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1 hour ago, Richard M said:

Hi Alan,

My pump is a Bosch unit & l have fitted a new wiring loom but guess that makes no differance  wiring is not one of my strong points what has be done to increase to 13amps ?

Richard.

Hi Richard,

Wire size s/b at least 2mm sq. rated at 25 amps or 3 mm sq. rated at 33 amps. PVC insulation, thin wall type, automotive grade.

Bruce.

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3 hours ago, astontr6 said:

Hi Richard,

Wire size s/b at least 2mm sq. rated at 25 amps or 3 mm sq. rated at 33 amps. PVC insulation, thin wall type, automotive grade.

Bruce.

Hi Bruce,

My new Wiring loom was bought from autosparks so l will have to check if this has wiring to fuel pump is of the thickness you mention.

As far as fuel leaks go l have no leaks or stale fuel in the tank & car runs fine once it is started & restarted from hot also only when sitting for a few weeks then l have the problem trying to restart from cold.

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19 hours ago, Richard M said:

Hi Bruce,

My new Wiring loom was bought from autosparks so l will have to check if this has wiring to fuel pump is of the thickness you mention.

As far as fuel leaks go l have no leaks or stale fuel in the tank & car runs fine once it is started & restarted from hot also only when sitting for a few weeks then l have the problem trying to restart from cold.

Hi Richard,

I suspect that your injectors are draining down through the O rings by the poppet valves or seats or both. You can easierly change the O rings, the difficult part is getting hold of them? The re-conditioners do not like to sell them on their own or refuse ! Use only Viton grade B only if you go else ware! I cannot remember the size required? A point to note is that BL modified the pump size wire from the summer of 1972 to the next size up. Derek  Graham will probably know the size?

Bruce.

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If you have an old ring take it to an industrial bearing supplier- they'll sell replacements in  Viton - and order in  if the size is not in stock. As Bruce says, most reconditioners will not sell their Viton components as spares.

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