Engine Running Issues

[Duckie]

Hi,
I have a Stag and since Feb 12 have been doing it up - mainly bodywork and getting it on the road. Since passing the mot, daily running issues are plaguing me.

I've got problems getting the V8 engine revving properly. As soon I put any real pressure on the accelerator, the engine stalls or drops in revs. Pulling out the choke seems to always aid the engine picking up but struggles to idle equally without. Warming up is a problem, backfiring is frequent and the choke doesn't appear to help that much though without it, the engine simply doesnt run. I can seemingly 'build' revs by working up the pressure on the foot pedal. Once revs are built the engine feels like its pulling back on itself as though it is saying no I dont want to go.

I have been having carb problems though I thought I'd sorted these. I took off the main throttle linkage to do the haynes carb setting up exercise and the engine simply stopped. Trying to get the engine to run evenly without the linkage is a major headache. I have got it better but the idle running screws needed to be turned in quite a few times and by hand revving the RH carb revs freely but the LH seems to hold back. If I have isolated this to the LH bank - what would be causing it to hold back and not rev freely?

I'll come back to the auto transmission leak, pdwa brake fluid leak and the auto transmission leak in separate posts!!

Feeling flustered!!

Any help from the Forum's seasoned experts would be gratefully received!

[Stagdad]

Have you checked diaphragms on the carbs for splits,blocked or split breathers , ignition timing and incoming fuel filter for being blocked as a start and then I would go through and set the carbs up step by step as in the manual.
cheers Steve

[jleyton]

Steve just beat me to it - I was going to say that the original Triumph ROM has a surprisingly good and easy to follow guide to setting the carbs up from scratch.

Re your future problems , your PDWA shouldn't leak. No fluid should get to the plastic PDWA switch itself - there are seals either side of it on the shuttle.

A belated welcome to the Forum btw.

Cheers

Julian

[davidf]

"by hand revving the RH carb revs freely but the LH seems to hold back. If I have isolated this to the LH bank"

Just for clarity, the LH carb does not feed the LH bank of cylinders. If you look at the manifold, you can see it crosses 2 and 2. Also, there is a balancing hole in the manifold between the section from each carb, so with the linkage removed, you can actually run the whole engine from one or other carb.

[Duckie]

Have you checked diaphragms on the carbs for splits,blocked or split breathers , ignition timing and incoming fuel filter for being blocked as a start and then I would go through and set the carbs up step by step as in the manual.
cheers Steve

Yeah I checked the diaphragms and one wasnt seated in the right way round so changed that with a good spare. Breathers are worn but seem ok - I'll renew these as a next step. Ignition timing is 16 deg btdc on lumenition electronic ignition - does that seem ok? Incoming fuel filter has been replaced and since dismantled and cleaned out along with blowing out the fuel pipe back to the tank with an airline. Needle valves were sticking so renewed them for uprated type, fuel then coming through and replaced the bottom cover seals while at it. On with setting up the carbs and have set the idle screws as best I can anyway given the idling problems. Next job was to complete the fast idle settings and then complete the process. Setting the carbs to run the engine on tickover without the linkage on is still problematic though need to do a fresh rerun to see how it goes from cold start up.

[Duckie]

[QUOTE=jleyton;273266]Steve just beat me to it - I was going to say that the original Triumph ROM has a surprisingly good and easy to follow guide to setting the carbs up from scratch.

Re your future problems , your PDWA shouldn't leak. No fluid should get to the plastic PDWA switch itself - there are seals either side of it on the shuttle.

A belated welcome to the Forum btw.


Thanks Julian,
I have a pdf of 498 pages of the stag repair manual - is that the same as the original rom? PDWA valve leaking at the switch point? Sounds like the seals have gone, I think I got a repair kit a while back - is it possible to use eezibleed kit on the stag??

[Duckie]

"by hand revving the RH carb revs freely but the LH seems to hold back. If I have isolated this to the LH bank"

Just for clarity, the LH carb does not feed the LH bank of cylinders. If you look at the manifold, you can see it crosses 2 and 2. Also, there is a balancing hole in the manifold between the section from each carb, so with the linkage removed, you can actually run the whole engine from one or other carb.

Noted, I'll check this out during next garage time. I wonder why its pulling back then?

[jleyton]

[QUOTE=Duckie;273293]

Steve just beat me to it - I was going to say that the original Triumph ROM has a surprisingly good and easy to follow guide to setting the carbs up from scratch.

Re your future problems , your PDWA shouldn't leak. No fluid should get to the plastic PDWA switch itself - there are seals either side of it on the shuttle.

A belated welcome to the Forum btw.


Thanks Julian,
I have a pdf of 498 pages of the stag repair manual - is that the same as the original rom? PDWA valve leaking at the switch point? Sounds like the seals have gone, I think I got a repair kit a while back - is it possible to use eezibleed kit on the stag??

Hi, Have we got a proper name for you ? (I don't really want to say 'hello Duckie'

Anyway, there were a few different versions of the ROM but one of the ones I've got is a 498 page PDF so I guess that's the same as yours. If so, you want Page 116 section 19.15.02. You'll see that it starts off with the words ' the following operations assumes all adjustments to be incorrectly set' so I reckon that's a pretty good place to start from !

This is Drew's picture of a dismantled PDWA so you can see that the seals on the shuttle should keep the fluid away from the switch and the only place it should be able to leak would be at one of the brake unions. I've never needed an eezibleed - bleeding has always gone simply for me . Nb to the left of the brass body you can see the home made tool required to lock the shuttle to prevent if from sliding when bleeding.

Good luck.

Cheers

Julian

PDWA dismantled.JPG

[stag157.7]

sounds like a carb piston problem
do they both rise and fall at the same rate
you have got oil in the dashpots

alan

[jbuckl]

You already got some good pointers here.

Heres my 2p:-

Diaphragms & carb piston operation can be checked for raising & lowering smoothly with the air filter & elbows off. #1 check.

static Ign is 12 degrees before tdc no 2. #2 check.

Fuel delivery is sometimes compromised by poor pump delivery & or poor 12 v supply to the pump, sometime due to resistance at the fuel cut off / inertia switch contacts. #3 check.

If electronic luminition, suspect whole system!!!!! , fit aldon ignitor or similar.


If the dizzy is not electronic, check condensor, normally non start if if its failed in closed condition, normally points burning if its failed in the open condition.

Checks 1-3 will probably give a root cause.

Use an analogue meter to check fuel pump voltage.

Let us know what you find

[Duckie]

[QUOTE=jleyton;273303]

Hi, Have we got a proper name for you ? (I don't really want to say 'hello Duckie'

Anyway, there were a few different versions of the ROM but one of the ones I've got is a 498 page PDF so I guess that's the same as yours. If so, you want Page 116 section 19.15.02. You'll see that it starts off with the words ' the following operations assumes all adjustments to be incorrectly set' so I reckon that's a pretty good place to start from !

This is Drew's picture of a dismantled PDWA so you can see that the seals on the shuttle should keep the fluid away from the switch and the only place it should be able to leak would be at one of the brake unions. I've never needed an eezibleed - bleeding has always gone simply for me . Nb to the left of the brass body you can see the home made tool required to lock the shuttle to prevent if from sliding when bleeding.

Good luck.

Cheers

Julian

[ATTACH=CONFIG]28156[/ATTACH]

Hi,
Yes its Tim.

We are talking the same manual and I like the assumptions so that's good! I'll print out the page to follow on next garage stint.

"home made tool required to lock the shuttle to prevent if from sliding when bleeding" - not really sure what this means or what the tool does? Where does the shuttle go? I presume the shuttle is the torpedo bit with 2 seals on?

[Duckie]

Hi Alan,
Yes and yes, I checked those things today.

[Duckie]

#1 check completed today.
#2 check - next garage stint, looks like I need to be altering the dizzy a bit.
#3 check -pump is original type and wasn't working right a few weeks back so I put the spare on and seems much better - still weak? Could be I s'pose - will check. No inertia switch currently fitted both wires just twisted together into a connector block!

Dizzy is electronic.

Thanks for this - I'll come back hopefully later in the week more likely to be sat am tho'.

Tim

[jleyton]

Hi Tim,

Yep, the 'torpedo' is the shuttle and it normally sits centrally. The front and rear brake circuits are separate. If however you get a loss of pressure in either front or rear circuit then the shuttle moves across and, in so doing, earths that switch that illuminates the dash warning light. But the other circuit still operates ok.

When bleeding, it is essential to prevent the shuttle from moving and that hand made tool is inserted instead of the switch to prevent the shuttle from sliding.

Hope that makes some form of garbled sense but come back if I can explain any more.

Cheers

Juliuan

[Duckie]

When you say bledding has always gone easy for you - have you had someone else helping or is there a nack to doing it on your own? I heard recently from someone that you could just open the bleed nipple and it will self bleed - is this true or just BS?