Leaky Injectors?

[Jersey Royal]

Richard

 

Weather in sunny Jersey, well isnt sunny. Been quite nice the last couple of weeks but the last two days its been sunny then heavy showers, just missed one the other day when out in the six top down, parked up in garage, then the heavens chucked it down.

 

Cactus needles, Sharp and very painfull from what i can remember. Sangria and paella,

 

Thanks for your advise on my continuing saga, i have ordered six new injectors, which i will fit, and then will know if i need to revisit Mu

 

Thanks Again

 

Guy

 

Will update once injectoers are fitted.

[Jersey Royal]

Hi All,

 

Update;

 

Recon injectors arrived this morning, all fitted, bleed, took car for run all ok

 

Got back and checked the injectors with ignition on no spark, and yes they still leak.

 

So looks like Mu off again

 

 

Cheers

 

Guy

[Jersey Royal]

Hi

 

Update.

 

Think i may have found the problem

 

Have taken of the four non return valves, and tested them. The brown book says to put pointy end into keroscene and blow through the other end, didnt have any keroscene so used water, three of them were ok and the fourth produced a nice bubble.

 

So could this one non return valve be the cause?

 

I should of checked them first time

 

 

Regards

 

Guy

 

Here is a picture of the rotor, is this how the bung seals should look, seated into the rotor?

 

 

 

I have checked all seals, cleaned and put back together, run up, still leaks, no joy. I await delivery of non return valve and hope thats the cause

 

Had a thought that maybe the bung seals were set in to far, so took of Mu for second time, and moved seals forward slightly, put back together for second time today. No difference

 

Edited August 20, 2008 by Jersey Royal

[John L]

The non return valve, just stops fuel draining back from the injector, so keeping the pipe full all the times. I took the spring out carefully, and rubbed the rubber disc on some very fine wet and dry paper, and it reomoved the ring where it had been seating. Check also the seat face in the bolt.

I presume that you have checked the fuel pressure into the MU? The return line is not kinked is it, giving a higher pressure?

I can only think that there must be too much clearance in the rotor parts, to allow fuel to all the injectors.

If the injectors are leaking then there is more than 50psi in the injector lines, which is then opening the injector tips.

No doubt you will tell us what fixes it.

Regards John

[Jersey Royal]

The non return valve, just stops fuel draining back from the injector, so keeping the pipe full all the times. I took the spring out carefully, and rubbed the rubber disc on some very fine wet and dry paper, and it reomoved the ring where it had been seating. Check also the seat face in the bolt.

I presume that you have checked the fuel pressure into the MU? The return line is not kinked is it, giving a higher pressure?

I can only think that there must be too much clearance in the rotor parts, to allow fuel to all the injectors.

If the injectors are leaking then there is more than 50psi in the injector lines, which is then opening the injector tips.

No doubt you will tell us what fixes it.

Regards John

 

Thanks John

 

Have checked fuel line pressure, and redone it all again today. Hardly takes me any time to get it off, refit check mu timing etc

 

So i can only think its some ware in the rotor itself.

 

I think the only fix is going to be send it off to a specialist, or buy a recon one calibrated to suit my engine. This is a real pain as prefer to drive the car the weathers great here at moment and the car is running brilliantly, having just fitted a 123 Ignition.

 

Thanks for all the replys

 

Guy

[Jersey Royal]

Update.

 

Having spoken to various Mu Experts.

 

My engine is fitted with a Fentune Supersprint Cam 320 degree duration, and calibration of the Mu was and is a pain, the Mu cant really supply sufficient fuel, so you will end up with lack of power some where in the rev range. Something like that anyway.

 

So , i could change cam out and put in a more friendly one better suited to the Mu, but i dont really want to take engine apart to do this as she is running very well.

 

Or if i fitted webers i could keep existing cam as is.

 

 

Doom and Gloom

 

Guy

[Richard Crawley]

It seems a shame (& expensive) to dump the PI & providing you can get to a point where the M/U is behaving itself, you can have it calibrated on the car on a rolling road by someone who knows how to set up a TR PI. This will give you a far better set up as the M/U can be finely tuned throughout the rev range; there are a couple of very good RR's over here but I assume there isn't one in the Channel Islands so you have the small logistical problem of getting access to one!

[Jersey Royal]

It seems a shame (& expensive) to dump the PI & providing you can get to a point where the M/U is behaving itself, you can have it calibrated on the car on a rolling road by someone who knows how to set up a TR PI. This will give you a far better set up as the M/U can be finely tuned throughout the rev range; there are a couple of very good RR's over here but I assume there isn't one in the Channel Islands so you have the small logistical problem of getting access to one!

 

Hi Richard,

 

To be honest i have only been happy with the Pi set up i have with the cam when i first bought the car and for the few years i drove the car before i got busy at work and didnt use it for a couple of years, it went like stink.

 

As a result the Fuel Injection system got gummed up and needed work with various garages including a Tr specialist, who like me where unaware of the cam fitted, have made adjustements, probably not for the better.

 

There is a rolling road over here, funny thing is i installed it years ago at Highlands College, New Enginering Block, as i understand it they have just put in a new one.

 

I feel that if i fitted webers, they could be set up overhere by someone with the knowledge and equipment i dont have.

 

There you go

 

Thanks for all the replys to this thread.

 

Regards

 

Guy

[JohnC]

Hi Guy,

It really is worth persevering with your PI - once you've got it set up it's pretty much maintenance-free (over the mileages most of us can afford these days, anyway).

 

As for the advice you were given, to the effect that the PI can't deliver enough fuel, I suggest you find another expert. OTOH, if your next step is to throw away the PI, then you have nothing to lose by tinkering yourself. Adjusting the max fuel stop really means removing the PI from the car (it's conveniently located below and on the engine side of the metering distributor). You'll need access to a rolling road or at least some kind of EGO analyser to check the result, and you will certainly throw out the calibration at other engine loads, but at least you can prove to yourself that the PI is indeed capable of delivering sufficient fuel. Even half a turn will bring a big increase in fuel. Sorry I'm not near my notes, but from memory I think half a turn gives something like 2cc per 1000 injections - about 4-5% increase.

 

If you do choose to go down the DIY route, then PM me. I'm not an expert by any means, but I have successfully calibrated my PI to run with a hot cam. Took several sessions on the rolling road, but I got there, and learned a few tricks along the way.

 

Cheers,

John

[k_raven_smith]

Hello again Guy,

If you would like to send the unit over to us, we have several sets of test figures , for different cam shafts. Its cheaper than a set of webbers.

Regards, Katie

Hi All

 

Quick question

 

Should the injectors leak fuel out when the ignition is on (ie pump in boot running only no spark)?

 

As all six of mine do, they do not rattle, fuel pressure is 100 through prestige new pressure relief valve.

 

Cheers

 

Guy

 

Well found out that the above isnt normal, and the injectors are most probably ok, and this could be due to internal seepage on the MU itself.

 

[Guest ntc]

Hello again Guy,

If you would like to send the unit over to us, we have several sets of test figures , for different cam shafts. Its cheaper than a set of webbers.

Regards, Katie

Hi All

 

Quick question

 

Should the injectors leak fuel out when the ignition is on (ie pump in boot running only no spark)?

 

As all six of mine do, they do not rattle, fuel pressure is 100 through prestige new pressure relief valve.

 

Cheers

 

Guy

 

Well found out that the above isnt normal, and the injectors are most probably ok, and this could be due to internal seepage on the MU itself.

 

What is the name of your company

[John L]

Guy

Could this be your problem as well taken from another quote yesterday.

 

I returned it to Prestige where Malcolm diagnosed a blockage in the shuttle bleed hole (I didn’t even know there was one). He fixed it but I had to pay for a new set of seals; no problems since in 4 years.

 

Regards John

[Jersey Royal]

Guy

Could this be your problem as well taken from another quote yesterday.

 

I returned it to Prestige where Malcolm diagnosed a blockage in the shuttle bleed hole (I didn’t even know there was one). He fixed it but I had to pay for a new set of seals; no problems since in 4 years.

 

Regards John

Unfortunately not, i had checked all the holes in the rotor and sleeve, took out shuttle and stops, there were fine.

 

Well spotted though and thanks for the post.

 

The unit is at a specialist, being checked and re calibrated in a last ditch attempt

 

Cheers

 

Guy

[Jersey Royal]

Hi All.

 

Mu is back, apparently the shuttle was pitted and problems with the datum track etc , it was also out of calibration.

Its nice and clean, and looks like new.

 

I have just finished fitting it and the system bleed itself. So all seems ok so far, i have yet to take it out of the garage for a proper blast. Its persitant presipitation(heavy) here at present. Weather looks ok for a go tomorrow.

 

Fingers Crossed

 

Guy

[pinky]

Hi All.

 

Mu is back, apparently the shuttle was pitted and problems with the datum track etc , it was also out of calibration.

Its nice and clean, and looks like new.

 

I have just finished fitting it and the system bleed itself. So all seems ok so far, i have yet to take it out of the garage for a proper blast. Its persitant presipitation(heavy) here at present. Weather looks ok for a go tomorrow.

 

Fingers Crossed

 

Guy

 

 

Hi guy,

 

glad you have nearly got it sorted out, you will be able to keep up now te he

[Jersey Royal]

Hi guy,

 

glad you have nearly got it sorted out, you will be able to keep up now te he

 

 

 

Ho ho ho. When i am finished messing around we will see my friend Have also adjusted my throttle cable as it wasnt opening to full chat.

 

Off to get a new set of plugs, my revs at idle are wavering a bit.

 

 

Cheers

 

Guy

 

The rains broke, so i took her out for a spin.

 

Well, what a difference in the cars acceleration, she pulls strongly in all gears, wheel spins in second and just does not stop pulling. The car does seem to be back to where she was years back when i first bought her, and prior to her two year lay up where i had to have Mu sorted out, it was done by a local Diesel Specialist overhere, i am told my Mu was set up to just below standard settings.

 

The Mu has been re calibrated to suit my cam By K Raven Smith, and i am very happy. Although i havent as yet checked for continious injection.

 

Pinky, you may recall i had some popping on overun, well thats all gone to.

 

Cheers

 

Guy

Edited September 9, 2008 by Jersey Royal

[Guest ntc]

Ho ho ho. When i am finished messing around we will see my friend Have also adjusted my throttle cable as it wasnt opening to full chat.

 

Off to get a new set of plugs, my revs at idle are wavering a bit.

 

 

Cheers

 

Guy

 

The rains broke, so i took her out for a spin.

 

Well, what a difference in the cars acceleration, she pulls strongly in all gears, wheel spins in second and just does not stop pulling. The car does seem to be back to where she was years back when i first bought her, and prior to her two year lay up where i had to have Mu sorted out, it was done by a local Diesel Specialist overhere, i am told my Mu was set up to just below standard settings.

 

The Mu has been re calibrated to suit my cam By K Raven Smith, and i am very happy. Although i havent as yet checked for continious injection.

 

Pinky, you may recall i had some popping on overun, well thats all gone to.

 

Cheers

 

Guy

 

Good news Guy

[Richard Crawley]

Ho ho ho.

Well, what a difference in the cars acceleration, she pulls strongly in all gears, wheel spins in second and just does not stop pulling. The car does seem to be back to where she was years back when i first bought her, and prior to her two year lay up where i had to have Mu sorted out, it was done by a local Diesel Specialist overhere, i am told my Mu was set up to just below standard settings.

 

Great news you’ve got it sorted, I bet your glad you persevered with the PI. The M/U is very akin to ancient diesel units but the problem with diesel specialists is they will almost certainly tend to set it lean. Some folks report 30+ MPG from a TR PI but it just isn’t possible & still get maximum power from the unit; if it’s returning more than 22 MPG urban or 25 -28MPG on extended motorway runs, your loosing some serious pulling power somewhere along the way!

 

Was that road test along the St Owens straight then?

[trfella]

Isn't popping on the overrun normally due to a rich mixture - unburnt fuel?

[Jersey Royal]

Great news you’ve got it sorted, I bet your glad you persevered with the PI. The M/U is very akin to ancient diesel units but the problem with diesel specialists is they will almost certainly tend to set it lean. Some folks report 30+ MPG from a TR PI but it just isn’t possible & still get maximum power from the unit; if it’s returning more than 22 MPG urban or 25 -28MPG on extended motorway runs, your loosing some serious pulling power somewhere along the way!

 

Was that road test along the St Owens straight then?

 

 

 

Hi

 

Well my happyness didnt last long, although car runs brilliantly, i have just switched ignition on no spark and i still bl**dy have continuios injection

 

What gives,

 

Mu recalibrated, new seals valves etc sorted, by specialist Have checked the return to tank its dribbling in there, i have even blown it through, cralled under car no kinks or anything in copper pipework . Also tried just connecting the rubber return pipe on the mu into a bottle ie not conected to tank, no difference

 

Prv is new type from Prestige, have tried my old standard prv, no difference

 

Recon injector.

 

Pressure before Mu is 100.

 

I almost give up now Something has to wrong

 

Any ideas before i go to the other side

 

Guy

Edited September 16, 2008 by Jersey Royal

[Guest ntc]

Guy

Did it just dribble into the bottle as well

[Jersey Royal]

Guy

Did it just dribble into the bottle as well

 

 

Yes it did Neil, i expected more of a gush.

 

cheers

 

Guy

[Richard Crawley]

What size should this pipe be?

Its 1/8” (or whatever), same size as the brake pipes; but don’t expect a gush, more of a steady trickle returning to the tank

Pressure before Mu is 100.

That’s a little low, I always aim for around 108psi but don’t go any higher; you don’t really want it dropping below 100psi at full chat or peak power could suffer as a result. This won’t really help your problem though!

Your problems with continuous injection is a bit of a puzzle; as far as I know the only possible causes are the rotor seals, damaged grommet seals between nose of outlet connection and sleeve or damaged inner ‘0’ rings on the Banjo connections. The only other possible cause I can think of is if the injector nozzle blow off pressure is set too low; I know the injectors are new/recon but it might be worth checking; they should be set to pop at 50psi. It may be worth striping them out & giving them a good clean, if there is a lot of rubber debris in there, it could be this is continually getting wedged in the injector nozzles making them dribble.

[paul gardner]

Just a thought, but have you checked that you have a clear return pipe from MU to fuel tank. If it is partially blocked, you may have too much residual pressure in the MU forcing fuel out of the injectors because it has nowhere else to go. Hope you solve the problem.

Yours

Paul

 

PS: Under idle conditions I would expect more than a trickle in the return pipe.

Edited September 12, 2008 by paul gardner

[Jersey Royal]

Its 1/8” (or whatever), same size as the brake pipes; but don’t expect a gush, more of a steady trickle returning to the tank

 

That’s a little low, I always aim for around 108psi but don’t go any higher; you don’t really want it dropping below 100psi at full chat or peak power could suffer as a result. This won’t really help your problem though!

Your problems with continuous injection is a bit of a puzzle; as far as I know the only possible causes are the rotor seals, damaged grommet seals between nose of outlet connection and sleeve or damaged inner ‘0’ rings on the Banjo connections. The only other possible cause I can think of is if the injector nozzle blow off pressure is set too low; I know the injectors are new/recon but it might be worth checking; they should be set to pop at 50psi. It may be worth striping them out & giving them a good clean, if there is a lot of rubber debris in there, it could be this is continually getting wedged in the injector nozzles making them dribble.

 

Hi Richard

 

Copper pipe is same size as brake line.

 

I take your point about injectors and blow off pressure being set low. I havent got the equipment to test this so have made a call to the Diesel Injection Specialist overhere, am sure he will check that for me.

It would be great if this was the problem.

 

 

Thanks Again

 

Guy