1700 Crossflow inline fuel filters query

[HendrixsWhiteStratReturns]

Morning all

Just preparing to replace the fuel pump and blow out fuel lines on my car (as part of attempt to cure misfire) and think it might be worth putting a couple of inline filters in (one between tank and pump and the other between pump and carbs) to filter out any crud, although the tank is new.

Jus interested to see what other xflow owners use / any recommendations / links would be appreciated.

Cheers !

HWS

 

 

[Ed White]

I used to run a filter king on crossflows. Not so much for the filtering but the pressure regulating. each filter will reduce flow. You shouldn't really need them. Fuel is generally quite clean nowadays. I'd look elsewhere. What ignition system are you using. When does misfire occur? Where are you? Cheers, Ed

[HendrixsWhiteStratReturns]

Hi Ed

Thanks for posting - just had a look on Demon's site at the filter king - out of interest where did you mount yours ?

Re: the misfire there's a separate post on BC about the whole saga but basically;

 

Symptoms:

- car runs and starts perfectly from cold with an even tickover

- drives normally for 10-20 mins at all speeds, pulls well, smooth acceleration, no issues

- usually after 20 mins it starts to suddenly misfire at speed, eases off when I drop down to 50mph and then as soon as I try and accelerate it coughs and splutters and eventually grinds to a halt. Lots of popping and bangs through the exhaust. Wait 15 mins and set off and again and all runs well for a few miles until the whole cycle repeats.

Leads, plugs and coil (Bosch Blue) are all new and I am fitting a  new fuel pump in case it's that. Fuel tank was fitted brand new recently (and was thoroughly sluiced out before it went in). Carbs were checked over and all okay.

My car has an Aldon dizzy (103 FXY ULS) fitted with an ignitor. Looks oldish so I'm speaking to Aldon about having it tested and either refurbed/replaced to rule that out.

Some of the guys on here thought it might be air starvation/filler cap issue but I've ruled that out ...definitely seems to be either fuel and/or ignition issue.

Sounds like you are familiar with Xflows - any other thoughts gratefully received ?

It's a real pain in the arse - had to abandon an MOT test as the bloody thing broke down en route !

HWS

 

[Ed White]

Over fuelling? Are the plugs wet? My filter king was under the bonnet on one of the chassis rails. Funnily enough I'm fitting a crossflow to mine at the moment as a bit of nostalgia. Crazy I know but no-one ever accused me of being normal. Hoping for a good strong engine. 

Just because you have swapped all the bits doesn't mean you haven't got issues there. I've had new coils fail quickly, and old one's last donkey's years. Is the coil located somewhere warm. Any signs of fuel leaks?

Try running the car at night and look for any electrical arcs from leads etc. They will look almost like a smaller plug spark. 

Make sure the earth lead from the battery to the chassis / engine is tight and clean. Consider a seperate lead straight to a chassis point if connected to the engine. 

Have you had any feedback from Roger KIng of this parish? He's a crossflow god. 

You didn't say where you were located?

Cheers, Ed

[Ed White]

ps has it run well previously? What have you changed?

[virden]

Did you drill a small hole in the fuel cap to prevent a vacuum forming in the tank as the fuel reduces?

[HendrixsWhiteStratReturns]

Cheers for posting all - excuse me condensing responses below

Ed:

Over fuelling? Are the plugs wet? Nope

Has it run well previously? What have you changed? Yes it was fine, changed nothing.

Is the coil located somewhere warm. Nope - have felt it and it's not hot/overheating

Any signs of fuel leaks? Nope

Have you had any feedback from Roger KIng of this parish? He's a crossflow god. Yes, Roger very kindly posted a while back he thinks it could  be debris in teh fuel pick up and/or ignition...partly why I wanted to fit a filter once I've put the new pump in/blown out lines as a belt and braces job.

Just because you have swapped all the bits doesn't mean you haven't got issues there. I've had new coils fail quickly, and old one's last donkey's years. That's a fair point although I have tried 2 brand new coils, lead sets and plugs from different sources and the problem remains so it's unlikely

You didn't say where you were located? Sorry - Gulldford, Surrey

Thanks for tips on earth leads and arcing, will check...!!

Virden:

Did you drill a small hole in the fuel cap to prevent a vacuum forming in the tank as the fuel reduces? Yep, it's definitely not that.

HWS

[virden]

 Try putting the old coil back on, I was once supplied with a brand new but dud one, which cause symptoms similar to those described.  The car would grind to halt, then after  half an hour start on the button.

[HendrixsWhiteStratReturns]

Hi Virden

I do agree that it sounds like it's the coil (and that was the first thing I replaced when the problems started) but I've now tried 3 (the old one plus 2 new ones) and it's unlikely that they're all duff.

Appreciate the posts though. I'm going to press on and replace the fuel pump, stick a filter in, get the dizzy and igniter either refurbed or replaced and then see if that collectively cures it. If not then I've gone as far as I can and I'll have to book it into a local 7 specialist and get them to sort it.

Always prefer to try and do it myself as all goes into the memory banks for the future but demands of family and running a business mean that my scope for spending endless hours in the garage trying to get the bugger to run properly are limited.

Will post an update when it's sorted (either way).

[Roger King]

Assuming that they haven't changed the design in recent years, a Filter King is ideal as the only filter you'll need. You should set the pressure to about 2.5psi to keep the carburettors happy.

If the problem is with crud getting in the fuel tank pick up, a filter will be of no use. The problem we had was that a lump of sealant was blocking the actual inlet to the pipe, so the filter further down the line was located after the problem.

The coil is worth a look because the internal insulation could be breaking down as it warms up. The most extreme example I have ever seen was on a car that would misfire on right hand turns but be fine everywhere else. After a lot of frustration, we changed the coil and the problem disappeared; it seems that the insulation had broken down but required the g-force of right hand corners to move things just enough to cause a short.

[HendrixsWhiteStratReturns]

Hi Roger 

Thanks for posting, appreciate the extra advice. I know you mentioned the sealant issue on the other post - hopefully it's not that but its on my list to check.

In terms of the coil I'm almost certain it isn't the problem as I've tried 3 now BUT I've arranged to borrow a brand new, tested, Flamethrower coil to try it out and see what happens......belt, braces and string I guess you'd call it !

Cheers

 

HWS

[Duckpit]

Try the distributor cap

 

N

[OliverSedlacek]

You shouldn't put a filter between the tank and the pump, the pump wont like it. The symptoms don't seem right to me for fuel blockages as cooling down doesn't make a blockage go away. The times mentioned in your original problems suggest thermal issues.

You've probably done it, but have you swapped the rotor arm and coil lead.

If you've really swapped all the ignition components, you may want to check the alternator. I had similar problems and it turned out that the diode pack was breaking down intermittently once hot and 'spiking' the battery line. The spikes were upsetting the electronics in the ignition. Disconnecting the alternator (carefully) made the engine run flawlessly.

[john g]

I encountered the same problem a while back. During a service I replaced the plugs for new ones and had the same problem of a misfire after about 15/20 minutes. I replaced the 4 plugs and all was ok. You have tried the old coil, have you tried the old plugs? Just a thought 

[HendrixsWhiteStratReturns]

 

Cheers Oliver and John - alternator is pretty new but will check it, yes have swapped old plugs but no difference. Hope to nail the problem shortly.

[Mcalvert]

POSTED ON BEHALF OF TONY PASHLEY

Hendrixs…

I don’t know if you’ve been able to make any progress; if not, this may be of interest.

Do you have a mechanical fuel pump?

I experienced precisely the same symptoms that you describe in post number 3 above - even down to the car letting me down, likewise, en route to an MOT test (in my case, in the middle of five lanes of M25 in the morning rush-hour).

I, and several others, had convinced ourselves the problem had to be electrical but couldn’t fathom it out (this is on a Xflow/carbs/electronic ignition/dizzy/no EM). I gave in and resorted to ‘diagnosis by replacement’, swapping out as much as possible from my stock of spares - all without success until I finally removed the mechanical fuel pump. The movement of the actuating lever felt inconsistent and just a little ‘jerky’. It was not really clear to me how a faulty spring or diaphragm could be interacting with that particular time/temp/load cycle, but once I’d fitted a new fuel pump the problem disappeared instantly and entirely.

I’ve since switched to an electric pump, but for reasons unrelated to this failure.

Your case may be different, but hope you can resolve it soon.

Tony Pashley.

[HendrixsWhiteStratReturns]

Hi Michael, Hi Tony

Thanks for posting - yes I do have a mechanical fuel pump, looks original and I have a new on ready to go on.

My gut feel is that the problem is either with the fuel pump or the dizzy/ignitor. Like you, I have reached the stage where I'm just replacing what I can and hopefully by a process of elimination I'll find out what the problem is.

Everyone has been very helpful posting advice and suggestions based on their own experience - one of the problems is that the symptoms presenting could be any one of a number of things (all gradually being ruled out). I had hoped to crack the car this last weekend but family commits meant otherwise - hopefully this weekend will see me in the garage, mug of tea, five live on the radio, box of new parts to fit and surrounded by tools.

All part of the saga of ownership I guess - maybe I should write a piece for LF Michael ?

Working title " ARRRRRRRRGGGGHHHHHHHHHHHHHHHHHHHHHHHHHH (My life with a Crossflow)"

;-)

 

 

 

 

[Mcalvert]

Well... It's been rather too long since we have had any Xflow coverage in LF (mind you, I should probably declare a personal interest in the subject )  Best of luck with finding the source of the problem, and I look fprward to reading about it in what ever medium best suits!

 

[HendrixsWhiteStratReturns]

"....and then your Honour, my client could take no more and that's when he attached his Caterham 7 with a branch from a tree shouting 'Right .....I've warned you... I'm going to give you a damn good thrashing"  !!!!!

Court News - Guildford Circuit

 

:-) Cheers Michael will post (and write) when sorted !

[andy couchman]

Can't remember if I've asked but I had similar symptoms with my car when new. I had tightened up the nuts holding the carbs on and did them up too tight. I think if you do that, the floats effectively jam and eventually no fuel gets through. Changing to an electric fuel pump may help too and even release a tad more power?

Maybe try loosening off all carb bolts and then doing them up again and ensuring each is done up to the right level.

Worth a try?

Andy

[Clousta]

 

And if all that fails then may I suggest that you check your hose lines.  I broke down due to a split in the hose from the tank to the electric fuel pump.  It would suck in air and on hard acceleration the air/fuel mixture to the carbs was insufficient  to maintain progress.  Well, actually the car dramatically came to a noisy stop and after a wait I could proceed again for 30 seconds!  Repeat. The split wasn't visible except when on jacks and a strong light revealed a very slight dampness to part of the hose. On pressing the hose the split was revealed.  A smaller split or pinhole might cause a problem as the rubber warned up rather than on start up?

[andy couchman]

Good point. Modern petrol contains methanol (or is it ethanol?) that can damage rubber, so I guess bits could break up and cause the problem outlined. Modern fuel pipe is often thin plastic stuff that looks very weedy but it might be worth trying replacing the current pipe and see if it makes a difference.

[Jonathan Kay]

That's often said* about ethanol, which is now in various concentrations in quite a lot of "petrol" in quite a lot of countries. But methanol can damage rubber (and things like rubber).

Jonathan

* I once tried to track down what's actually known about ethanol concentration and various current "rubbers" but failed.

[Neanderthal]

Could the misfire be caused by fuel vaporisation? I'm sure that's why the previous owner of mine moved the fuel pump to the back of the car and also went solid state at the same time. Just a thought. Certainly would explain why it stops when it cools down.

[Englishmaninwales]

Alcohol resistant rubber/braided fuel lines that will fit between the mechanical pump and the twin carbs are available from Paul Matty.