Metering unit and injectors first strt

[cookie]

Hi All,

 

Am in the (slow) process of complete restoration and have got to the point of wanting to start the engine.

 

Have read a few posts about bleeding injectors etc but have a issue I hope somebody can help with.

 

Powered the bosch pump, span engine (for a fair time) with no plugs but nothing at the injectors.

 

DIsconnected the fuel pipe at the injectors, still no fuel.

 

Disconnected an injector pipe on the metering unit, there was fuel there but it was just a dribble.

 

Should fuel squirt out of the MU with the pipe removed or is it supposed to be just a dribble.

 

Any thoughts on what needs to be done.

 

MU, PRV and Injectors refurbished by Neil.

 

Many Thanks

Dave

Edited August 12, 2015 by cookie

[John Bracher]

Dave, I had a PI saloon (yonks ago) that refused to start up after a long layup following being run out of petrol. (prize plum!)

 

In the diagnosis cycle, I found the PRV and the small inline filter in the MU inlet were full of 'mud'.

I took this to be the sediment from the tank bottom.

The PRV /line being clogged meant the whole (pretty much) of the pump output was going straight back into the tank, which threw me completely, as the pump was 'working perfectly'!!!

I 'guestimate' only @10% of the pump output was making it up to the MU end of the system.

 

May be worth a look??

 

Bleeding injectors takes a fair amount of cranking (you may flatten your battery, and make a load of petrol mess, so use a Hellmans jar with a 'just over' 'injector sized' hole in the lid) but they should pressurise/come to life eventually.

 

Good luck!

Regards

JB

[RobinTR6]

Given its all new you really need to check all components.

 

Check tank outlet for good flow, Bosch pump doesn't suck as well as Lucas so people usually fit bigger union from tank and larger pipe from tank to filter.

Ensure flow from filter to pump.

Disconnect pump outlet should be able to flow about 5 ltrs per minute and feed into bucket and turn on pump.

If you have decent output from pump but not at my then suspect pipework between them. There is a small filter in flexible pipe into My so check that.

 

Before you do any of this are you sure you have bled the system. Try turning ignition on with coil disconnected for 30 mins or so.

 

Been here a few times with new system , can take a few hours to bleed and time system. Even with injectors piping petrol I have had to spend 30 mins cranking, battery connected to another running car before she fired up.

[cookie]

Thanks gents,

 

Had a little play today.

 

Removed the fuel supply pipe from the MU, with the pump running petrol gushes out.

 

Reconnected the pipe and left the pump running for a short while.

 

1st Issue, With pump running and engine not turning, petrol started to drip from the joint between the MU and the Dist. drive.

 

2nd issue, with Engine turning over, Removed an injector and could feel pulsing but no spray. Removed the injector pipe from the MU, petrol there but no real pressure.

 

Any thoughts .

 

Many Thanks

 

Dave

[RobinTR6]

Progress, so sounds like the pump , prv, tank feed all ok(ish). The leak from the pedestal is probably the esals. There are 2 in the distributor pedestal where the behind the drive from the dixzzy to the MU. They dont cost much and are easily replaced (if you ginore the fact that you need to remove the pedestal and the MU to do them.

 

If you have pulse but no petrol I think more bleeding is required. Either plugs out and lots of turning over or plugs in, coil disconnected and ignition so pump running. This can be quick or in my case (with 3 different cars) a bit long winded. I have another go at bleeding first. Its also probably worth pulling the needle on one of the injectors which has a pulse and seeing if you get more than a drip of petrol. If needs be reove the injector fom the pipe and turn ove to check petrol is getting from MU to injector.

 

You could leave the dizzy seals till you know it all works or do these first as you may need to rebleed after removing the pedestal and MU...

[cookie]

Ah ok thanks, didn't realise the pedestal had seals.

 

Wish I had when I was putting it back together.

 

Oh well off to buy a couple, take it apart and refit. Hope fitting them is easy.

 

I hope there is nothing else I've missed in this area.

 

If these seal are shot would that have not helped the pressure at the injectors?

 

Thanks for the help

 

Dave

[Tim D.]

It could also be the o ring which fits between the MU and the dizzy pedestal.

Easier to change..

Tim

[RobinTR6]

The seals are a fiddle to get out, I used a dentists pick to ease them out, do note that they fit 'back to back', so make sure that you note their orientation when you remove the old ones. Refitting isnt hard just use something suitable to gently ease them back in. I'll assume you know how to 'time' the MU so that the correct injectors fire in time with the spark.

 

Let us know how you get on

[Andy Moltu]

Just checking did you put the little red plastic drive gear between the metering unit and pedestal? Presume it's there as you can feel pulsing.

 

Having established the pump is supplying fuel to the metering unit it is also reasonable to assume the prv is delivering fuel at sufficient pressure as it has been refurbished - if you have access to a pressure gauge check you have 100-106 psi. Repeatedly removing pipes and injectors lets air back into the system delaying bleeding.

 

To bleed the injectors - whilst cranking the engine over with the choke fully open, gently, and briefly pull on the nipple - this should let out the air and some fuel - do them in turn. An alternative is to gently tap the body of the injector but doesn't often work in my experience.

Edited August 13, 2015 by andymoltu

[astontr6]

Hi Dave!

 

Pull the dip stick out and see if the oil on it smells of petrol, from the leaking seals? If it does you should change the oil.

You should really put a pressure gauge into the fuel circuit by the M/U to check your pressure.

Lastly to help bleeding the injectors, you need to have a plunger oil can full of petrol, with a pointed spout. With the injector fuel pipes connected to the M/U disconnect the injectors in turn from their injector pipes and holding each injector pipe vertical back fill with petrol. When full replace the injector, this method pushes most of the air to the top and considerably cuts down on the cranking of the engine, tapping the injector and moving the poppet valve off its seat to get the injectors spraying.

 

Needless to say you have to be very careful when squirting petrol about, have a fire extinguisher handy! Also this is best done by 2 people!

 

Bruce.

[Topoff]

When you put the new seals in back to back make sure the drain hole in the pedestal is not covered.

 

Good luck with the bleeding, it will all work through in the end. Laurence.

[cookie]

Thanks for the help. New seals arrived today, will be fitting them in a week or so.

 

Fingers crossed that's one step nearer to getting the little project finished.

 

Will let you know.

 

Thanks

 

Dave

[cookie]

Hi All,

 

Got the first seal out struggling with the bottom one.

 

Is it possible to easily remove MU drive shaft by taking out the end thrust plate and the the outer seal.

 

Also notice there is a rubber O ring on the thrust plate, anybody replaced this before.

 

Or should I carry on trying to take out from the MU side.

 

Thanks

 

Dave

[cookie]

Managed to get the bottom one out with the aid of a very small drill bit and a couple of small self tappers, was locked in very well.

 

Just a matter of getting all back together, re timed, bled etc. Then there is the rest of the car to finish.

 

Dave