Fuel types? Spitfire 1500 running terribly!

[Harveyzone]

Hi all,

Unknowledgeable amateur alert...

Background... After a long time off the road (a couple of years or more) I started up my Spitfire 1500 last week. After a bit of messing it eventually started and ran beautifully, but there was a bif fuel leak and a large pool of petrol appeared on the floor. I have now replaced large sections of the fuel line (see my previous thread) and all is well again. Or so I thought!

All back together again and started up perfectly, but after running for a few minutes it ran out of fuel (well loads had gone all over the floor).

So a day later and a gallon of fuel in the tank and I start it up again, but it is now running absolutely terribly - Lumpy and spluttering, and wont stay running on it's own.

8mm pipes all the way though, an additional fuel filter, and no leaks that I can see. The only other thing that I can think of is that I used e5 fuel, and the previous fuel would almost certainly have been pre-e10 'regular' unleaded. Would that have made this kind of difference and if so what do I need to change, or do I need to start diagnosis from scratch? 

Cheers,

Tom.

[glang]

Did you fully identify where and what the problem was with the fuel line Tom? I dont think the fuel is the issue now but, especially after a lay-up, its very common for debris from the tank or old fuel line to go into the carbs and cause the poor running.

Im not familiar with the type you have but would recommend getting into their float chambers and cleaning them along with the associated needle valves.

[Harveyzone]

Hi there,

Yes, I believe that the fault was in perished rubber joint, but I have replaced most of it anyway with new copper/rubber. There does not appear to be any leaking now from anywhere, not that I have been able to run it for long.

I have twin Weber 40 DCOEs (from a previous owner) on it . There is a fuel filter immediately before the fuel pump, and the line was not touched beyond this filter, so I would hope that it would have caught any debris etc from the old/new lines or tank, but I would not rule it out.

Cheers,

Tom

[Rutty]

I agree with Glang E10 as long as it is fresh is not going to cause the symptoms you have. Its most likely you have got debris in the fuel system after running out of fuel. Blow down the fuel line back to the tank incase its blocked. Check you float bowls and pump for debris and check you filters aren't blocked.

[Amy Wade]

I would also say it's unlikely to be the fuel, I always use super in my Spitfire, there are 2 reasons for using super they are;

1) Less ethanol (at least until the government decides otherwise)

2) The car was originally designed to run on 5 star petrol, super is as close as you're going to get without buying petrol from a racetrack. 

I would go for opening up the float chambers, the old fuel would have deposited a layer of lacquer as it evaporated. You may also find degradation of fuel line components between the filter & carbs has left deposits in the carbs causing blockages.

[Pete Arnold]

Your fuel problem sounds very like what I have recently experienced with my Vitesse, although the car had not been laid up for a long period.  The car started to lose power in the autumn and I did not seriously investigate the matter until March.

First the fuel pump (glass bowl type) was found to be sucking in air.  This was due to a leak around the rubber seal between pump body & bowl.  There were also some tiny pieces of what looked like thick paper in the gauze filter; later decided these were from the in line filter, near the tank in the boot, beginning to break up.

The new seal cured the ingress of air into the pump but the engine still would not keep running.  Made up a new pump using two bodies together with a repair kit.  Still the engine would not keep running despite proving that fuel was getting to the carbs at full bore.

Finally purchased a repair kit for the twin carbs (Stromberg CD 150s) and this cured the problem.  As with the pump there were some paper like pieces in the carbs but the main problem was that both the rubber diaphragms had stretched and one had a small split.

Car now running better than for a long time!

[Harveyzone]

Thanks all, 

So am I right in saying the regular (E10) => E5 change shouldn't make much difference to mix/timing (certainly not to the extent that it will not idle at all)?

It does sound like it is a 'muck in carbs' type problem, and I have disturbed something when doing the other repairs. Looks like I am going to have to learn about Weber DCOE carbs now! 😄 

Cheers,

Tom

Edited June 12, 2022 by harveyzone

[RobPearce]

Changing between E5 and E10 does not require any fiddling with anything. No change in mix or timing that you would notice in any way.

[Harveyzone]

39 minutes ago, RobPearce said:

Changing between E5 and E10 does not require any fiddling with anything. No change in mix or timing that you would notice in any way.

Cheers - I can discount that at least.

Tom.

[Harveyzone]

Hi all,

This evening was the first chance that I have had to look at this since the weekend, so I...

• Took apart and cleaned out the old in-line fuel filter. It was a bit mucky, but not terrible.
• Took the top off the carbs.
• Checked the carb filters - they look clear.
• Nothing of note in the float chambers. No obvious deposits or 'bits' and the valve looked clear and opens correctly.
• Nothing of note in the idle jets or adjustment screws. All seem clear.
• Nothing of note in the main jets. All seem clear.

So from a short visual inspection - nothing obvious.

So next I got someone to keep it running with their foot on the accelerator, and I, one by one, pulled the spark plug leads. Removing leads 1, 3 and 4 made no difference at all, but pulling 2 stalled it. I believe that it is only running on one cylinder.

Are there any more checks that I can do for elimination purposes? I have never taken carbs to bits before and am scared that I can do more damage than good. Is that my last and only option now? Any advice?

Cheers,

Tom.

[glang]

hang on, isnt this looking much more like an electrical problem now? Surely a faulty carb would only affect 2 cylinders not 3....

[Harveyzone]

3 minutes ago, glang said:

hang on, isnt this looking much more like an electrical problem now? Surely a faulty carb would only affect 2 cylinders not 3....

I must admit, when I did the check I was trying to work out which carb to look at in more detail, where along the the line the fault might be, and was suspecting 1 or 2 to be out and was mildly surprised (annoyed) when it was 3. This would suggest 2 or 3 separate blockages, not just one.

But similarly, what electrical issue would knock out 3 cylinders and not just 1 or all 4?

[ferny]

8 hours ago, harveyzone said:

I must admit, when I did the check I was trying to work out which carb to look at in more detail, where along the the line the fault might be, and was suspecting 1 or 2 to be out and was mildly surprised (annoyed) when it was 3. This would suggest 2 or 3 separate blockages, not just one.

But similarly, what electrical issue would knock out 3 cylinders and not just 1 or all 4?

Worn distributor, wobbly rotor arm, crap leads, coil breaking down, points worn or not set correctly, old spark plugs.

 

Of course, if only one cylinder is working after already establishing the fuel system is mostly fine then another fault could be the valves are worn or the head gasket is gone.

 

I'd check the ignition components first...

 

If you still really want to fiddle with the carbs you could try some Easy Start first too. That'd also test the ignition circuit and prove it's a fuelling issue.

Perhaps to give you more confidence, recently the Acclaim started mmisfiring on a return journey. It was fine on the way to the shops but returning home 20 minutes later it kept stalling and would only run on choke. I spent a day chasing the fault and checked everything I could - plugs, lead resistances, valve gaps, fuel pump and much more. The carbs haven't been touched in 40 years and the car was absolutely fine before so I had no intention of upsetting them if I didn't need to. 

 

I ended up stripping down the distributor and found a tiny crack in the magnetic ring thingy which then fell apart in my hands. I had to buy a modern replacement and it's taken weeks to get the timing right because it's a slightly different copy of the original part.

 

The point I'm making is that carbs don't just fail if they're working fine. Ignition components however do and can be a bugger to trace if you're not methodical and thorough. 

Edited June 15, 2022 by ferny

[Harveyzone]

Hi all,

I took an early lunch today as I wanted to have another look at this and do some more checks. As it happens I have a box of new parts for a service that I never got around to doing, so I went through the following:

• Put a spark tester on all plugs - all getting power.
• Fitted a new coil - no difference.
• Fitted a new distributer cap - no difference.
• Fitted a new Rotor arm - no difference.
• Fitted new spark plugs - Bingo!

The old ones look pretty coked up, all looking like this...

 

 

They are fairly old, but not very many miles on them. What does this mean? Not sure why one cylinder would still work though. I guess #2 was a little less coked that the others but it doesn't look it!

I also did a compression test whilst I had the plugs out - they all seem very low. Ranging from about 70 to 95 psi, but it is ticking over ok, if a little bubbly. Would it run at this compression, or perhaps my compression tester is inaccurate - (if I add about 50 it sounds nearer to what it should be - now I need a way of checking my compression tester!)?

 I will take go down the road later for a bit of a run to see if drives ok.

Anyway, thank you to everyone for you advice and pointers to get me to where I am now.

Tom.

[RobPearce]

WIth that much carbon on the plugs your spark will be tracking down the insulator and not doing anything useful. Number 2 may have been less coked up down inside where you can't see easily.

Those compression figures do sound very low but the engine probably would run at that, albeit not well. However, compression testers are not precision tools so the truth may be less bad. What I would say, though, is that with so much soot on the plugs you should be prepared for some head work. I had a 1500 engine (well, I still have it but when I got it...) that was so heavily coked up that, after standing for some time, the deposits on the backs of the valves fell off once started and jammed all the valves open. Something similar but less dramatic could result in enough valve leakage to explain your compression readings.

[glang]

Apart from apparent low compression I wonder if the mixture adjustment of the carbs is wrong. I havent got a clue with Webbers and in my view its a pity theyve been installed as I imagine they will have a tendency to foul plugs unless given plenty of welly....

[standardthread]

9 hours ago, ferny said:

If you still really want to fiddle with the carbs you could try some Easy Start first too.

 

 

WD40 also does the job

 

2 hours ago, glang said:

Apart from apparent low compression I wonder if the mixture adjustment of the carbs is wrong. I havent got a clue with Webbers

Still got a pair of HS4's off a MKIV for sale with manifolds

[glang]

Proper carbs, none of this Italian rubbish and almost as good as Strombergs😁

[standardthread]

1 hour ago, glang said:

Proper carbs, none of this Italian rubbish and almost as good as Strombergs😁

Prefer Strombergs, fitted to my Heralds and Standard, easy to tune and balance.

[Harveyzone]

2 hours ago, standardthread said:

Still got a pair of HS4's off a MKIV for sale with manifolds

Ok, I'll bite... what kind of price/condition? Are they pretty much good to go straight on?

Over the years, whenever I see some cheap ones for sale, I have been tempted to swap back to original carbs, but always decided against it - if it ain't broke etc...

[standardthread]

PM sent

[yorkshire_spam]

Aren't MK IV fitted with HS2 and 1500 fitted with HS4 ?

[standardthread]

2 hours ago, yorkshire_spam said:

Aren't MK IV fitted with HS2 and 1500 fitted with HS4 ?

Check this link http://sucarb.co.uk/

The tab on the carbs reads FX1122F (HS4's on MkIV's) There is also a link on the same site to cross reference different needles  http://www.mintylamb.co.uk/suneedle/

[yorkshire_spam]

7 minutes ago, standardthread said:

Check this link http://sucarb.co.uk/

The tab on the carbs reads FX1122F (HS4's on MkIV's) There is also a link on the same site to cross reference different needles  http://www.mintylamb.co.uk/suneedle/

http://sucarb.co.uk/cf/vehicle/list/?manufacturer=Triumph&vehicle=Spitfire

FZX1122 - Spitfire 1500.

 

[standardthread]

Good night