Injector Problem

[Goswell]

No fuel coming out of Injector No 1 even if replaced with a known good one. With injector removed little or no fuel comes out of pipe. Have removed pipe at the Metering unit, no blockage and no fuel coming out of the Metering unit. Removed the union and again no flow of fuel. It sounds like a faulty Metering unit however all other injectors working well. Metering unit is fairly new and the cars performance was checked last summer with 105 bhp at the wheels. I'm wondering if it's a faulty union, ie valve stuck.

Any thoughts gratefully received

[tim_trinda]

The unions on the metering unit ( the bit where you connect the injector fuel  pipes) contain 1 way valves to prevent the fuel pipes emptying when the engine is not running. Remove the union for #1 injector and check that the valve has not stuck shut. I wouldn't have though its an internal problem with the metering unit as all the other injectors are OK.

 

Good luck

Tim

[Roger H]

Try swapping over pipes 5 and 6. - if the problem transfers to #5......

 

R

[Andy Moltu]

Have you bled the pipe?

With the engine running gently pull the "nipple" at the end of the injector a few times - this lets the air out & all being well once this is done the injector will open itself.

If you have already done this take the union off the metering unit & see if this is blocked.

[Richard Crawley]

Try swapping over pipes 5 and 6. - if the problem transfers to #5......

 

R

Roger I'me sure you meant 1 & 6!

But if the injector pipe is clear & the injector filter isn't blocked, try swapping over the no's 1 & 6 outlet unions to see if the fault transfers. Be aware that if you have an early metering unit with 'Dowty' seals you should replace these (after sorting out the problem) as they are not supposed to be re-used. The later units have 'O' rings & it's usually OK to re-use the originals.

[Goswell]

Thanks for the replies, does anyone know where to find out how the metering unit works, is there a web site. I understand the unit has shuttles that move back and forward blocking and unblocking the outlet pipes. If Injectors 1 & 6 share the same shuttle then the fault should be duplicated to some degree. Also does the unit need back pressure from the injectors to produce a flow of petrol ie if you remove an injector would you expect to see a jet of fuel out of the pipe.

A faulty union valve would seem an easy option however it's simply a small metal plate held in by a spring. To stick would need some serious gummy petrol. I suppose the spring could break and foul the plate, but I cant see anything wrong with the spring. Does anyone know if they do fail ?

[Richard Crawley]

If your metering unit is pumping fuel to 5 out of 6 injectors there is probably not much wrong with it. There is only one shuttle for all 6 cylinders & the unit itself is quite a simple, mechanical device - albeit machined & assembled to very fine tolerances.

Search back a few months in this forum & you will find a website link with two Lucas PI manuals; I can’t remember the links, can anybody else? I also downloaded them & have them in Word format so, at a push, I could “E” them to you but the files are quite large & the forum “E” mail facility does not seem to allow attachments so I will need your full “E” address to do this. Read theses manuals & it should explain quite a lot!

Try & understand a bit more about what is happening & then come back again if you are still having problems.

Also, do yourself a favour & get a manual, even a “Haynes” one would be a start.

Just a thought, have you removed the metering unit or distributor recently as this could put the metering unit timing out!

[Guest andythompson]

Try http://lucasinjection.com/

 

Good diagram and also some pretty rare info

[Guest andythompson]

Try http://lucasinjection.com/

 

Good diagram and also some pretty rare info

[Richard Crawley]

Thanks Andy, thats the one.

[Goswell]

Many thanks for the info, much more information than found in the Haynes or Triumph manuals. Nothing has been done to the car since a road test in the summer, and it was running fine a month ago but has not been used regularly since due to the weather.

[Andy Moltu]

Egil Kvalberg has some useful info on how the PI system works & can be modded & fault traced.

[Richard Crawley]

Egil Kvalberg has some useful info on how the PI system works & can be modded & fault traced.

Another very usefull document!

Am I missing something here (if I am please tell me!). Should this stuff not have permanent links on our site? we are supposed to be the premier TR club!

[john.r.davies]

All,

I have a similar problem - newly installed Pi engine, won't start, but will fire with QuickStart, so ignition more or less right.    No fuel from injector OR from fuel line without injector on turning the engine over on the starter.    Full pressure at meter and good back flow from PRV.  Meter correctly set (No.6 port just opening at No.1 TDC firing stroke).

 

Is the problem that the fuel system has not primed?   Will try A.Moltu's solution (above), but engine cannot run.   What is the priming procedure? Just flog the battery until it does?

 

All advice will be gratefully received - thanks!

John

[jemgee]

I read the item about priming the PI system. When I did an oil change I was concerned about the time it would take to fill and pump through the original horizontal filter bowl, so I pulled out the plugs and cranked over the starter expecting to see the oil pressure pick up off the zero after 10 or 15 seconds.

 

When nothing seemed to be happening after about 30 seconds I came to the conclusion that it was because the revs were so much lower than when the engine fires up and decided I was getting nowhere.

 

Whilst the manuals says it will prime on the starter has anyone confirmed it works?

[tim_trinda]

Richard CRawley - Posted on Feb. 10 2004,20:50 "Am I missing something here (if I am please tell me!). Should this stuff not have permanent links on our site? we are supposed to be the premier TR club!"

 

More and more replies to topics contain links to extremely useful and informative websites, I agree with you Richard some of these merit inclusion in the 'Links' part of our website. I'm not sure how to go about it though, e-mail to Chris Cunnington or webmaster??

 

Alternatively it might be a good idea to start a new topic 'My Favourite Link'!!

 

Tim

[tim_trinda]

john.r.davies - Posted on Feb. 10 2004,23:03 "What is the priming procedure? Just flog the battery until it does?"

 

John

 

There are many ways to skin a cat, or bleed the PI system this is how I did it.

 

I had to bleed the PI system on my TR6 after fitting new metering unit, injection pipes and injectors:

i) Charge the battery overnight.

ii) Remove spark plugs and remove power feed to ignition coil, no sparks required yet

iii) Obtain a tin with a lid in which 6 holes can be drilled to hold the injectors, I used a coffee tin

iv) Offer beer or money to someone to act as your assistant.

v) While your assistant operates the starter( 15 seconds then pause), gently tap an injector just enough to unseat the valve in the tip. I used the plastic end of a medium sized screw driver. Don't resort to using large spanners or hammers to 'tap' the injector - be patient. At first you will see a few bubbles, then a dribble, and if all is well with the injector will burst into life. Put the primed injector back in the container.

vi) Move onto the next injector, if you are lucky the may find that some of the other injectors have already primed themselves.

v) When you have 4 injectors primed, refit spark plugs and power to coil and satart the engine.

vi) Prime the last two injectors with the engine running. For these injectors I used a jar with a hole in the lid to prevent fuel spaying over the engine.

vii) And thats it? Well not quite.

vii) I left the car idling for 5-10 minutes and two injectors stopped working and needed priming again.

viii) The same thing happened on the first road test, two injectors stopped and needed repriming.

ix) The whole operation took a couple of hours before all was well.

 

Hope that helps

Tim

[john.r.davies]

Tim,

Thank you! That makes a lot of sense.

Just one explanatory, please - 'tapping the injector'.

Is that tapping the body, or the spike at the business end?

Best wishes,

John

[tim_trinda]

Is that tapping the body, or the spike at the business end?

 

John

 

Tap the body of the injector close to the business end.

 

Tim

[Richard Crawley]

John,

no criticism of Tim’s method intended & it’s ultra safe but here’s a much quicker version, as used by the original Lucas mechanics:

To prime the main fuel line from the tank to the distributor, turn on the ignition & loosen  the main fuel inlet union on the metering unit, then nip it up again when fuel shows. To prime the metering unit & injector leads, remove the coil +VE lead, the plugs & the injectors & place them on large piece of absorbent rag covering the air box or use an old baking tin; turn the engine over on the starter, no more than about 30 seconds at a time, then rest the starter to let the windings cool down. Do this until you see fuel spray coming from most of the injectors. Put the +VE coil lead, plugs & the injectors back in (make sure you loosely fit the injector keep plates or they may pop out when the engine spits back). Crank the engine; it will sp*t & f*rt a bit & then, hopefully, catch on a couple of cylinders. After a few seconds running, the rest of the cylinders should start to kick in, a few energetic blips on the throttle usually helps here. You can then go through & bleed each injector as necessary (see below). After a few minutes, it should all settle down & you should be running on all 6. Obviously, do not let the engine run for extended periods on only 2 or 3 cylinders as it’s no ideal, shut if off & go through the injector lead priming process again. The whole process should take no longer than about 10 minutes!

 

The recognised way of bleeding the injectors is to run the engine & remove them one at a time & very gently pull the spike/valve of its seating. The resulting flow of fuel will purge any air in the injector lead & flush away any debris, which may be preventing the valve from seating properly. You only need to pull the valve slightly off the seat to have effect & don’t apply too much force or you could find the injector spring pressure will need re-setting. Some use pliers but I prefer to use just use my fingernails as, unless you are superman, this way it’s almost impossible pull it hard enough so to upset the injector “blow off” pressure. You are looking for a nice, even cone spray from the nozzle, dribbles & uneven spray = injector O ring gone (easy to fix) or valve seat damaged (not so easy to fix). I use either a large piece of absorbent rag or an old baking tin to catch the fuel. Obviously, be careful & don’t spray fuel onto the hot exhaust but even so, it almost certainly won’t ignite, you need flame or a spark for that & don’t spray the ignition distributor or plug leads just in case it’s tracking to earth somewhere & don’t smoke!

 

You may have to repeat this process any number of times until it settles down, especially if you have been working on any part of the fuel system or if you leave the car without staring it for any length of time. I try & fire mine up once a week to avoid any problems.

[john.r.davies]

Richard,Tim,

With help and advice like that, my engine won't DARE not to start!

Thank you both - I'll report back (May be going to Cardiff this weekend, so later)

John

[Richard Crawley]

With help and advice like that, my engine won't DARE not to start!

Absolutely no problem at all: & if it don't start, I will state catagorically you have either overlooked something or there is something else wrong!

[john.r.davies]

SUCCESS!!!!!!!

 

Thanks to Tim, thanks to Richard, thanks to all.

Yes, churning the engine - I used my daily car and a set of heavy duty jumper leads to assist the 'native' battery - eventually does the trick.  I had the injectors sitting in a catering sized coffee tin that accumulated about a half a pint of petrol before I had even four injectors working consistently, and it took half an hour of churning, tapping and pulling to get that.    Then plugged in the injectors and spark plugs, quick flick of the starter and away she goes!

 

I thought afterwards: Presumably it's the air that must be got out of the lines and injectors.  If the injector pointed upwards, would it  purge more quickly than hanging them point down in a tin?  A "purging jig", to hold the injectors point up with a deflector to catch the spray and a drip tray to catch the fuel, would be a nice little project.  But I have lots else to do to the car first.

 

Thanks again!

John

[Richard Crawley]

Presumably it's the air that must be got out of the lines and injectors.  If the injector pointed upwards, would it  purge more quickly than hanging them point down in a tin?

John,

Great, glad to hear of your success but I am surprised it took that long to purge the system. Of course you are correct about the air thing & that's why I (& the Lucas mechanic I learned it from) hold the injectors high & point them skywards, either into an absorbent rag or well away from everything; it's much quicker but you can hardly sanction this as an "official method" in any manual. It's a risk if you are not "AWARE" of what you are doing & if someone happens to be smoking nearby. I have done it like this for nearly 30 years but accept no responsibility if, in the process, you torch your car, yourself, or your neighbor who happened to be lurking with a fag on the other side of your garden hedge.

[Peter Douglas Winn]

I am surprised that it takes so long to prime the injecters. I have never had this problem. I must point out that I do not try and use 5 year old injecters. The longest I ever had to wait was about 30 secs. I agree with the comment about holding them upside down, firstly you can see the spray pattern and secondly it is easier to flick the nozzle.

A WARNING about using various forms of Quick Start. Years ago I saw on the wall of the firm (that was doing a rebore on my old car engine) a poster. There was a picture of piston damage, a total wreck, explanation:- this was caused by using too much Quick Start. Without going into the technicalities Quick Start can overstress the pistons. So be warned!!!