Help!! Possible metering unit issue?

[Jim C1967]

Hi all,

I know that on forums such as this, contributors are encouraged to read past posts around the subject and I have done just this and have found similar issues, yet none which pertain to my particular problem and so I wonder if any of you can help.?

My dad who is 80 has rebuilt a 1972 TR6 he bought in Coventry ( we are from the great city!) over the past 3 years has now got to the point to start it. Over the past few days, and using the generous contribution of your  members have ensured the timing is correct and have measured pressure from the fuel pump to the metering unit. This is where our issues begin. When removing injectors, having established correct pressure at the MU, only inj 3 and 5 appear to be vapourising the fuel. The others are just dripping out. The injectors are new, as is the pump and the MU has returned from reconditioning. My question is , next steps? Bleed the injectors? Remove MU for recalibration? Or any other thing that somebody very experienced may identify? 
Apart from this, we currently live in North East Wales so if suggestions aren’t possible, is there any reputable garages that could possibly have a look, or indeed members which may be willing to have a look ( we would be willing to pay of course). 
many help /questions gratefully received. 

[John L]

Welcome!,

First of all make sure you have taken the power wire off the coil to stop any sparks!!

I think you will need to bleed the injectors that are not spraying properly, usually just by pulling on the little tip of the injector, or just by loosening the pipe fitting to the injector.

There isnt a lot of fuel being pumped at cranking speed so you will need to pull the choke out, to give the most fuel.

Let us know how you get on.

John

Edited May 18, 2022 by John L

[john.r.davies]

Agree with John!    A large catering coffee tin will take all the injectors, on their hoses, and limit the spread of sprayed fuel, for safety.

However, it can be difficult to keep track of which injector is working and which not, in the tangle in the tin.    I made up a rack, from a length of alloy sheet, that mounts each injector separately, catches the fuel and may be mounted temporarily on the top of the engine.

One more point to make -  pulling on that 'needle' on the business end of the injector should not be done with pliers, but with the fingernails - the needles are most delicate!

John

[astontr6]

When you fitted the injectors did you back fill the black injector pipes first??? If you did not you will have trapped a lot of air in the black injector pipes which can be difficult to remove. The correct procedure as per a CAV/Lucas Dealer, is to hold the black pipe vertical then squirt petrol from a Waso oil can down the pipe until petrol flows out then screw the injector on and bleed as normal. They usually start to squirt strait away? I have always done this and it has always worked for me! Cuts out all that frustration and aggro, plus all the cranking?

Bruce.

[Mike C]

And I normally bleed with the plugs out , distributor LT lead disconnected- it's amazing how quickly the TR engine spins and primes in this condition.

[John McCormack]

32 minutes ago, Mike C said:

And I normally bleed with the plugs out , distributor LT lead disconnected- it's amazing how quickly the TR engine spins and primes in this condition.

My method too!

[Peter Cobbold]

There is a active TRR group in North Wales, with one member with huge expertise in PI. Also Red Rose are just over the border. And there's TR Bitz.

I'm there too, but havent run PI for decades.

Peter

[zelrik]

I suggest you get a packet of 6 cheap disposable plastic Baby Bottles. 

Place the injectors inside & you can see whats flowing or not through the hose.

 

 

[Andy Moltu]

Keep cranking with a fully charged battery choke on (or to be more correct the maxim fuel lever) 

When you crank it over the voltage drops and with it the fuel pressure (This is why good connections are important).  It can take a bit of time to bleed the air out of the injectors. Some may bleed quicker because of the length of pipe and location on the metering unit. Additionally, whilst the injectors should pop open at the same pressure, minor variation in setting may mean one opens easier than another. Sometimes it’s bits of debris, perhaps from new seals that get in the injectors and stop them opening properly.

Take the injectors that aren’t opening properly off the pipes and blow them through with an airline. This makes sure they aren’t stuck, and if you have a pressure gauge on the airline it should open at around 50psi. An air bed adapter with the tip cut off makes a good seal for doing this job.(A foot pump will do too if you don’t have an airline but an airline with a pressure regulator allows you to turn up the pressure gradually to see the exact opening pressure). 

Heaving established they open you can reattach and try again.

Pumfords in Hoylake (are not too far away and used to be heavily involved with TR injection and presumably still have the expertise if you and the local members get stuck)

[john.r.davies]

4 hours ago, Andy Moltu said:

Keep cranking with a fully charged battery choke on (or to be more correct the maxim fuel lever) 

When you crank it over the voltage drops and with it the fuel pressure (This is why good connections are important).  It can take a bit of time to bleed the air out of the injectors.)

Very true, so in this situation, starting after rebuild or major works on engine,  I put heavy jump leads on the car (mine are actually starter cables), and connect them to a running modern.     This ensures that fuel pressure stays up as the battery doesn't get run down as much.

John

[Robert Price]

Had exactly the same situation with a TR6 on which I fitted an injection system, I could not get a fine spray despite my bleed efforts. So in the end I plugged them all in and tried to start the car, it fired on a couple of cylinders and within a short time gradually all fired up and it ran normally, so give it a try first before wasting lots of time and effort.

Rob

[astontr6]

On 5/20/2022 at 5:03 PM, Robert Price said:

Had exactly the same situation with a TR6 on which I fitted an injection system, I could not get a fine spray despite my bleed efforts. So in the end I plugged them all in and tried to start the car, it fired on a couple of cylinders and within a short time gradually all fired up and it ran normally, so give it a try first before wasting lots of time and effort.

Rob

 

On 5/20/2022 at 5:03 PM, Robert Price said:

Had exactly the same situation with a TR6 on which I fitted an injection system, I could not get a fine spray despite my bleed efforts. So in the end I plugged them all in and tried to start the car, it fired on a couple of cylinders and within a short time gradually all fired up and it ran normally, so give it a try first before wasting lots of time and effort.

Rob

Hi Rob!

That is why you have to back fill the injector tubes with petrol before screwing on the injectors.

Bruce. 

[CP26309]

I use a glass jar with a finger sized hole in the lid, and pop the offending injector through, to isolate it with the engine running.  When fitting new or reconditioned injectors I have always found they self bleed.

[CP26309]

On 5/19/2022 at 12:38 AM, zelrik said:

I suggest you get a packet of 6 cheap disposable plastic Baby Bottles. 

Place the injectors inside & you can see whats flowing or not through the hose.

 

 

But don't give them back to baby...One Petrol Head in a family is enough! ;-)