Fuel Pump next?

Ian Donkin · Post by **Ian Donkin** » Sun Nov 21, 2004 7:03 pm

My 2.4T (with CIS) still won't pull above 3,500 revs...

I've changed the distributor cap, points & rotor arm, fitted new plugs, air & fuel filters, numerous fuel lines, adjusted the valve clearances, changed the oil & filter (unlikely to have any impact) and today replaced the distributor vacuum hose.

The car starts well and runs evenly at tickover, is very responsive when I blip the throttle and pulls nicely at low revs. However try as I might to climb up to the redline (even down a steep hill in second gear!), I just can't get above 3,500 - 4,000 revs maximum.

If I depress the clutch and floor the throttle (rather brutal I know), I can almost get to the redline, but certainly not the rev limiter and it won't sustain high revs even with this treatment.

The fuel pump is without doubt noisy and 'gurgles' somewhat when I turn the ignition on - is there any way I can check to see whether this is my problem before spending the best part of £200 + VAT on a replacement?

Nick Moss · Post by **Nick Moss** » Sun Nov 21, 2004 9:54 pm

Have you checked that the fuel is getting to the pump: gauze in tank, no sh1te in fuel lines, no trapped or kinked lines?

Barry · Post by **Barry** » Sun Nov 21, 2004 11:27 pm

Ian, my car is doing just the same, runs more or less O.K. upto 3200 revs, but won't go beyond, tonight blipped it in workshop, sure enough it will go further without load. The interesting thing is that mine is an E engine running on Zeniths. I have pretty much ruled out fuel (known carbs, tested fuel flow rate (102 LPM) and pressure all post filter etc etc) See
http://www.ddk-online.com/phpBB2/viewtopic.php?t=3966 for adventures so far. Despite recent static testing I still suspect C.D. unit breakdown, as there are several internal elements to the unit that become more and more stressed as the revs increase. Later this week a friend is bringing his oscilloscope up to try some dynamic testing on the car. I am currently considering converting to a multiple spark discharge (MSD) system. I am pretty used to diagnostics, my father is a licensed avionics engineer, and the friend with the scope designs industrial electronic circuits. So far we have all been beaten by my Poxy Porsche!!

My feeling was to continue on ignition, as like your car, the revs still would not rise, even downhill, yet the car has plenty of pulling power at lower revs: therefore less likely to be fuel? If you have an old analogue dwell meter, and a strobe light, worth hooking both up and watching what happens when you hit your 4 grand 'limit'. Also worth pulling plugs again, are they all the same? if so you know the problem is not down to a couple of cylinders. If they are carboned up might well be ignition (plenty of fuel, but incomplete combustion). Anyway I will probably order up this MSD system tomorrow anyway (like the idea of the technology) and will report back ....

domo1977 · Post by **domo1977** » Mon Nov 22, 2004 9:26 am

Guys

As you correctly say if the CD unit is at fault then the weakened spark will probably be getting 'blown out' at higher revs under load. A easyish way to check this and possibly provide an interim fix is to close up the spark plug gaps to something closer to that of a car that does not run CDI (cant remember the exact gap, check Haynes manual).
Thinking being that the distance a spark can jump is a product of the voltage available, at higher rpms the coil has less time to charge between sparks so less voltage avaiable (CDI unit was introduced to reduce this prob). Therefore if you reduce the gap it has to jump, it will operate to higher rpms with a weak spark, downside is that combustion isnt as good at low rpm/high load and you can get plug fouling (another reason CDI with bigger plug gaps was introduced)...... but it would be worth a try to get you out of a hole and prove a point!

that my 2pennys worth anyway
hope it's of some help!

Dom

Ian Donkin · Post by **Ian Donkin** » Mon Nov 22, 2004 9:47 am

Barry

I've been reading your posts with interest as it seems we may have a common problem (then again, the two may be completely unrelated)!

I've noted what Nick suggests and hope it's not at the tank end (although I'll have to check that also), but I do have it in my mind that it's either advance related, or lack of sufficient fuel delivery (and I completely filled the tank with fresh fuel before starting this journey).

I pulled the distributor cap off yesterday and sucked on a piece of fresh tube attached to the distributor vacuum advance to check this is working and it appears to do so.

I'm also going to verify this against my friends results with the vacuum advance he sees in his 2.4T engine; whilst I only get a few 'minutes' of advance, 15 'minutes' = 90 degrees, so I suspect all is well here. I didn't however check the manifold is generating vacuum, but it must be or surely it would run like a dog (I will check this also).

All my spark plugs are brand new (as are all other service items); the old ones were the same spec [Bosch] and had no wear, but were very sooty and it's going in next week for the mixture setting up correctly. As the guy that's doing the mixture has a rolling road (and you don't get many of those in backwaters such as where I live!), he'll be able to test it under a full load too.

I can also get access to a strobe light - haven't used one of these since I was at University and owned a Beetle! so before taking it in next week I guess I'll be able to check the ignition timing and make sure the distributor is generating the necessary advance.... if all is well it'll be back to the fuel.

I also put up a post yesterday about gear ratios as I'm not sure whether my rev counter is a little lazy, or the T spec car is long geared and knowing what speed I should be going for a given amount of revs will help me to eliminate this from my investigations. I do know that this can't be the only problem as I'm sure that my car should do more than 40 mph in second.

I'll keep you updated with progress.

Barry · Post by **Barry** » Mon Nov 22, 2004 6:38 pm

Just to let you know, I ordered a MSD 6A ignition setup today, should be with me tomorrow (Tues). Hopefully will be able to fit by end of week, and give an update. By the way, I'm sure your rolling road guy will have some sort of ignition analyser, and should be able to get a 'scope picture of the coil (transformer) output. It might well show a breakdown of output (disturbed output signal) as the revs go into your 4K area. Interesting the plugs are carboned, suggests plenty of fuel, rather than starving?

My travels have taught me one thing, these thirty year old C.D. units actually contain a high number of componants that do actually degrade with time. E.G. the main capacitor has a 'self heal' design that helps stop total internal failure, but each time it 'heals' the performance reduces. There are other parts that can become overworked as the revs rise because of a gradual decrease in performance over the years. It would seem they do not always suffer a fatal, catastrophic failure, and can die a slow mis-firing death!

Out of interest, apparently our age cars have rev counters that are contact breaker driven. By implication this can mean a) Faulty contact breakers may be indicated by fluctuating rev counter, or b) A faulty rev counter can disturb the contact breaker signal to the ignition. I tried mine disconnected to see if if changed misfire. Didn't.

Of course having spouted on about ignition for weeks, we all know that I am going to fit my shiny new MSD, go up the road to be greeted with same old misfire.

I can almost hear the laughter already.

Barry · Post by **Barry** » Thu Nov 25, 2004 6:28 pm

Now received the MSD ignition box and coil. Not fitted it yet, but has given me something else to check: they recommend 8.5mm helically wound H.T. leads. These are required for 'high powered' ignition systems to reduce/elliminate the potential for electromagnetic interference causing ghost signals to interfere with the ignition unit. What occured to me was that the H.T leads supplied (to me at least)as 'standard' leads are solid core e.g. visible strands of aluminium/copper wire running straight down the lead (the worst for producing EMI). Our C.D. ignitions are actually nearly as powerful as modern systems, so surely the lead requirement would be the same. Therefore I am now up-grading my (six week old) leads to Turbo leads that come with full shielding.

It maybe worth checking that if you have conventional leads, that they are well away from the L.T. wires (contact breaker, and both small coil wires). Also make sure the king lead from the coil is not resting on a plug lead, and that ajacent firing leads don't run together.

Just a thought .....

Barry · Post by **Barry** » Sat Nov 27, 2004 5:34 pm

Unit is now fitted, story over here: http://www.ddk-online.com/phpBB2/viewtopic.php?t=4098 and has led to a rev happyish (well its only done 150 miles!) engine. Certainly will climb round the clock O.K.

Food for thought: still yours will probably be something completely different now Ian.

Ian Donkin · Post by **Ian Donkin** » Mon Nov 29, 2004 1:06 pm

I am pleased to be able to report some progress following a session at the local workshop today although it's not fully sorted yet.

As I suspected (it wasn't exactly difficult to spot), the mixture was way too rich and this has now been adjusted (although this was not altoghether straightforward as the mixture screw was very tight - near seized - and needed working loose first).

I'd also 'cheated' when I bought the car and adjusted the screw on top of the throttle lever to get her to tick over as the hand throttle wasn't (and still isn't) working - I now know this wasn't a very clever thing to do...

Anyway, with the above sorted, CO2 at tickover is not much above 1.5% and my engine appears to run fairly cleanly as HC levels are around the 200 ppm mark.

The timing was adjusted to the correct 5 deg ATDC (previously it was bang on TDC) and everything was recheked. Whilst the car now revs far better, without load and at full throttle it wont go above 5,600rpm. I also know for definite my rev counter is not reading correctly as at a steady 4,000 rpm on the test guage, I'm seeing 3,000 on my rev counter.

On the road it pulls much better and will rev further, but still won't find the rev limiter.

I think I need to follow in Barry's footsteps... watch this space for an update later.

Ian Donkin · Post by **Ian Donkin** » Fri Dec 03, 2004 6:15 pm

Good old Barry

- he pm'd me earlier this week to suggest a couple more things to check out and I am delighted to report that with the tacho feed disconnected from the points I have a very 'growly' 2.4T!

I can't believe that it only has 140BHP as it pulls very hard right through the revs, only getting a little wheezy approaching 60mph IN SECOND. Grab third and it's off again, only this time the inclement weather and lousy road conditions deterred me from finding out how much more than 75 it'll go in that gear.

I thought CIS was supposed to be an unresponsive system, but it feels really alive. I've booked a session at the local workshop again next week to recheck the mixture now the ignition seems to be sorted and then I plan a power test on his rolling road.

Anyone know where to send my VDO tacho for diagnosis / repair?

Nick Moss · Post by **Nick Moss** » Fri Dec 03, 2004 6:37 pm

I have had a 2.4T CIS and a 2.4T MFI recently and the CIS car felt better to me. It ran cleaner and felt like it had more power too.

impmad2000 · Post by **impmad2000** » Mon Dec 06, 2004 11:01 am

Ian,
I can look at the tach if you are not in a hurry. Since I am looking at Barry's CDI, I could may be test the two out together.

Let me know if interested.

Cheers

Ian Donkin · Post by **Ian Donkin** » Wed Dec 08, 2004 8:06 pm

Thanks for the offer Tim - I'd be happy to let you have a look at it.

I'll send you a pm.

Ian Donkin · Post by **Ian Donkin** » Thu Dec 09, 2004 4:22 pm

Update following return from the garage today.

With the rev counter disconnected, the timing had altered by a full six degrees from where it was set only a week or so ago

. I have no idea how the rev counter could cause this, but I'm sure there will be one or two on the forum who will be nodding appreciatively as they read.

That means in two visits to the garage it's had around twelve degrees of advance dialed out!

Anyhow, following this and a resetting of the idle speed (it was ticking over too fast again) it was time for a run on the rolling road...

Not sure how much power is likely to be lost through the transmission on an old car like mine, before running it my tech suggested as much as 25%, so when I saw somewhere around the 100 bhp mark appear on the dials (it's not a fancy computer controlled rolling road, but an old Sun piece of kit), I was pretty pleased

.

So now I'm going to use it whenever the weather permits, keep it topped up with oil and if it breaks I'll rebuild it. Hopefully it will get through next summer and give me plenty of enjoyment before the planned rebuild I had in mind when I bought it.

If you see a scruffy powder blue '72 2.4T (as opposed to Barry's fine example) being driven around and about next year, chances are it'll be me.

Enjoy!

hot66 · Post by **hot66** » Thu Dec 09, 2004 5:11 pm

Will be good to see it out on the roads.

I'm pretty sure we will bump into each other next year at some point ( not litrally though !! )