Jump to content

Starting a warm TR6 PI


Recommended Posts

Interested in people's techniques for starting their TR6PI when the engine is hot (i.e. been sat for 15 mins after a decent run) or been sat for a few hours on a hot day. I've had my car since 2013 and it's a very nice car in excellent condition. And it has the "underslung" throttle conversion from a well known source.

 

My car, a '73 PI, starts perfectly from cold with 3/4 choke most days and some light work with the throttle pedal. It's an excellent 'from cold' starter.

 

However... when warm, things get more interesting ....

 

1. After a 20 - 40 min run and say, after refuelling, it will start only (but reliably) with a quick and meaningful depression of the 'gas' pedal on turning the key. It won't start just by turning the key and a gentle nonchalant pressure of the gas pedal to the 1/3 or 1/2 mark. No. It needs to be "fired" back into life with a good squirt of fuel and will start robustly. Makes petrol station staff jump ! I quite like it (is that bad of me ?)

 

2. After a longish run, though, on a warm day, and after being sat there in the carpark for a few hours, the car definitely needs coaxing with a bit of choke and some exploration of the gas pedal.

 

It's been serviced religiously, and the PI set up and set up again and admittedly runs very well indeed, but come to starting on a warm/hot day and it is always interesting. Usually it is 3 - 4 goes to get the car running and it reluctantly starts despite good pressure, good alternator, plenty of battery power etc.

 

It's not a car that you can just relaxedly turn the key, apply a bit of gentle pressure and it bursts into life. Nothing like an MGB or any other comparable classic. Nope... the PI needs working to start when hot.

 

Judging by the MANY road tests I've read over the years, this seems to be the "devil in the detail" flaw cited by the car test reviewers with the PI, which most owners then and now experience(d) in some form or another.

 

Tough question, but is there a universal workable solution or is it the price we pay for owning the PI ?

 

 

ps: and don't say "carb conversion" unless you've done it and it changed things. I haven't driven it up any mountains either so that's an unknown too.

 

 

 

 

 

 

Link to post
Share on other sites

Alex I have to ask the topical question …………….do you have stainless braided injector lines ??

Link to post
Share on other sites

Years and years ago my Dad had a nearly new 2.5Pi saloon and it still had on the windscreen a see through sticker with Triumph's starting instructions for the car, I seem to remember something like .. from cold:- use the choke, do not touch the throttle pedal ..... hot start:- press the throttle pedal down 1/3rd of the way and crank until it starts .. or words to that effect.

When you think about it, with with the throttles closed while starting there will be maximum vacuum at the metering unit and consequently minimum fuel supply to the injectors.

Link to post
Share on other sites

For mine...

From cold: about half choke and a touch on the loud pedal. (Although I still have the original twin cable for the choke I have backed it right off preferring to use the pedal.)

From hot: just a dab on the gas pedal as it always fires straight away.

 

Must concede though. Until recently I still had two braided fuel hoses on cylinders 1 and 6 (don't ask), I bought it like that and never bothered to change them. However replacing them with the nylon type has improved the initial cold starting especially if left for a few days.

Link to post
Share on other sites

Mine starts from cold on full choke and when it starts (first time is usual) choke in to half way 2/3 minutes than all the way home.

 

Hot starts no choke, leave for a few hours (ambient temperature regardless) full choke then when started choke fully home.

 

They all have their idiosyncrasies.

Link to post
Share on other sites

Hi Alex, in short hot starts in my view and experience should not be that tricky.

Fyi, a hot start after short stop, less 5 mins, is straight away, just a tickle of throttle if any.

 

Longer hot stop, say over 45mins, mine seems to have the odd habit of fires on say 3-4 cyl instantly (a small ' brmm') but difficult to keep running. Nearly always stalls, on 2nd attempt is apparently lifeless for 3-4secs cranking then starts on about 4cyl and the last 2 join in after a second or two. This can be either no choke or say half choke seems to make little difference and about 1/4 throttle.

This is reliable if odd behaviour..!

 

So I think they all have ideocyncracies... This is a 69CP car, lumenition, refurbed injectors & Lucas pump, new nylon pipes, MU untouched for many years, 20+?.

Cheers, J.

Link to post
Share on other sites

Shaun,

I think heat soak is a factor, but do you refer to Alex B, or my description... Or perhaps both?!

Cheers, J.

Non return valves on your metering unit more like.

Stuart.

Link to post
Share on other sites

throttles open 1/2 - 2/3rds and crank

 

Hot engines will mek mixture richer, as air is thinner

so thinner air is not as much air going in as cold air

 

hence open throttles t, balance oot the richer mixture due t,thinner air

 

M

Link to post
Share on other sites

Hi JamesStag,

 

I was originally referring to Alex B question.

 

Heat soak be eliminated by fully opening the bonnet immediately after a run then checking starting performance after a similar duration parked?

 

 

Stuart, would a non-return valve that 'lets by' present more of a starting issue after the engine has cooled from a substantial run whereby the engine bay has had the opportunity to gain substantial heat? Or would one expect the symptom to be similar no matter what the previous engine bay temperature got to?

 

Shaun.

Link to post
Share on other sites

Hi JamesStag,

 

I was originally referring to Alex B question.

 

Heat soak be eliminated by fully opening the bonnet immediately after a run then checking starting performance after a similar duration parked?

 

 

Stuart, would a non-return valve that 'lets by' present more of a starting issue after the engine has cooled from a substantial run whereby the engine bay has had the opportunity to gain substantial heat? Or would one expect the symptom to be similar no matter what the previous engine bay temperature got to?

 

Shaun.

Irrespective of temperature they would slowly leak pressure back over time.

Stuart.

Link to post
Share on other sites

Hi Shaun and Stuart,

Thanks both for replies. Shaun ok, but actually given Stuart's comment i think both myself and AlexB should have better hot start performance...

 

Stuart thanks for your advice. For info I've discussed my car with Neil F before (previous niggles with Lucas pump, now finally resolved I think, perhaps confirm that after next hot summer drive!).

I recently contacted Neil about my cold and hot starting. He said to refurb injectors first as they were likely leaking back, but I must say once done the starting is not much better. However the WOT performance seems to have improved. General car running and smoothness has always been good.

So now it seems the NRVs at the MU need replacement or new seals. Guess Neil still best man to speak to? I'm quite capable mechanically so can I service these myself?

 

Many thanks, J.

Link to post
Share on other sites

Hi Shaun and Stuart,

So now it seems the NRVs at the MU need replacement or new seals. Guess Neil still best man to speak to? I'm quite capable mechanically so can I service these myself?

 

Many thanks, J.

Looking at an old banjo bolt NRV at the moment, you would be in to Ship in a Bottle territory trying to replace the seal, (goodness knows how it's done!), the other NRVs could be done but they would be a bit of a trial and you may well alter the spring tension getting the seals out, better to leave the whole lot to Neil and start with a completely new set.

Cheers Rob

Link to post
Share on other sites

Modern petrol is very aggressive let alone the 'E' factor! If your MU is more than 5 to 10 years old I would exchange it for a re-con unit! Reason if the seals in the NRV are leaking there be may others seals that are also starting to disintegrate or swell up, so you have to work out what is the most cost effective route! I had a problem 3 years ago with 6 re-con injectors where the poppet valve 'O' rings failed in 3 months due them being old stock by only 24 months and could not with stand the current petrol of the day. When I approached the company who re-conned them which was not the supplier that supplied them to me. They replaced them all FOC! They said that they had stopped using black 'O' rings 2 years ago and that they s/b green which was a much higher grade of Viton to with stand the current blend of petrol.

 

Bruce.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.