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She just cuts out!

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Help!!!! its nice out and my esprit is broken;o( Started the car at the weekend and really had to pump the accelerator to get it to going, as soon as I lift off it just cuts out.

Its almost as if theres not enough fuel getting through..

Things i checked:

1) I thought it may be the fuel pump but I can hear a whirring sound when the ignition is turned on.

2) Battery is new and there is plenty of life there, checked all the fuses and nothing has tripped out.

3) Fuel was pretty low so filled her up to just under half a tank

Any ideas on what else I can check? Free beer on offer?

Rgds

JK

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Stuck fuel pump?

If you have an SU type fuel pump near the base of one of you r tanks it probably has corroded points and/ or stuck diaphragm armature. Points, simply take the tape off that seals the rubber cap, remove rubber cap and drag some very fine wet&dry / sand paper (200 grit or similar) through between the two contacts. Diaphragm armature, may move itself free if more fuel is applied, it will help get sufficient pressure to do it.

Quick check to see if that's the cause is to carefully remove the fuel supply pipe somewhere near the carbs, taking care to not spill fuel/ get it in eyes etc, use a suitable container (petrol can?) and have somebody turn the ignition on (make sure they also know how to turn it off) for a few seconds, see if fuel flows.

I'm suspecting fuel rather than spark as it runs for a few seconds.

Edited by andydclements

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It's not an SU pump on the 85 turbo, it's an inline electric jobby.

Could well be fuel still though as your filter may be blocked possibly.

Would be worth popping off the supply hose to the pressure regulator, sticking it in a bottle and seeing how much fuel is being pumped. Should be gushing out the hose, if it's dribbling then your half way to finding your problem.

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If it's a similar in-line one to the Excel then a sharp tap with a small hammer freed that up, and it had been ticking for ages with no fuel movement before the impact.

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LOL Andy

Its not the ticky ticky SU type mate, hitting it will do little to improve it's performance. It's an inline electric fuel injection type pump, if it's whiring then it's working.

If your on your own and you want to do the test at the pressure regulator then turn off the inertia switch in the boot, switch the ignition on, then you can switch the pump on and off on your own with the switch in the boot.

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The Excel isn't an SU one, but it still responds to gentle persuasion. :rolleyes: Admittedly when I was trying that I was thin along the lines of kill or cure. If it didn't start to work I was going to need a replacement one, so....

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Thanks for your help guys, there is some great tips in here and disconnecting the pipe to the fuel regulator sounds like a plan, if it dribbles then "Houston we have a problem" .Ive attached an image below I'm assuming its connection 4 that needs to be removed is this correct? You may guess from this post that I'm a novice;o)

Thanks for your help

JK

post-4320-127110105285.jpg

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What you should really do is disconnect '2' insert a tee piece with a pressure gauge and check you get approx 4 psi. Failing that, disconnect '2' and see if you can fill a jam jar in a few seconds.

Probably worth changing the fuel filter as a precaution. Also remove the jet covers and make sure all the jets are clear.

Steve

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Ok

4 is your fuel supply

3 is the return bleed off back to the tank

2 is the supply to one of the carbs, theres another identical one behind 1

1 is a pressurised air supply from the boost pipe which ups the 'on boost' fuel pressure accordingly

To check the pump is working and the filter is not blocked, remove pipe 4

If you want to test the regulator remove pipe 2, or it's sister connection behind 1

I'd start with 4 if it was me.

There's a big filter under the car slightly bigger than a can of coke. That's the main filter.

Also remember there are small fuel filters inside the fittings as the pipe enters each carb, it's highly unlikely either of these are blocked but I guess it is 'possible'

I don't know the flow rate of the pump but it does deliver a large volume of fuel, it will be obvious if there is a problem with it or the main filter.

I guess if the fuel delivery is good your next step would be carb float levels, but these should nit really change at all unless the fuel pressure starts to drop off.

Your a little way off this stage yet though! :)

Edited by Simon350S

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Firstly, I'd check the fuel flow as described above...assuming that's OK, pull the tops off the carbs and look inside at where the fuel levels are. Initially..is there any fuel in there? Could be the float needles sticking shut. Then remove the jets and inspect them, and blow through as required...modern fuels seem to evaporate and leave varnish behind which blocks the jets, especially if the vehicle hasn't been used for a while. The "slow running" jets also cover the fuel supply over the intermediate range, and the jet in the very bottom of the assembly gaets restricted by the varnish build up which gives all sorts of misfiring. I finally had to clear mine with a piece of calibrated guitar string!! There must be some sort of solvent that works on the varnish stuff but I haven't found it yet....

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MEK, Methyl Ethyl Ketone did the trick on my old hd6 SU carbs, gets the goo right off, we use it as a solvent in aircraft industry but it could be hard to get...

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4 is your fuel supply

3 is the return bleed off back to the tank

2 is the supply to one of the carbs, theres another identical one behind 1

1 is a pressurised air supply from the boost pipe which ups the 'on boost' fuel pressure accordingly

I've always said you're a little backwards! :) What would Freud have to say about that?!?

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There must be some sort of solvent that works on the varnish stuff but I haven't found it yet....

There are aerosols of carb cleaners which will dissolve it or you can use plain old cellulose thinners & a brush. :)

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First thing i'd check is that all the leads are pushed home on the dizzy, mine kept cutting out and it turned out to be the centre lead was not pushed fully home, it had been disturbed.

My fuel pump whirred etc, you may be causing a load of work for nothing more than a loose lead.

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I'm not sure about your part of the world, but if your wanting to go with the MEK suggestion, most home improvement stores have it in the paint section. My local improvement store has it near the paint thinners. Use caution though as MEK can also be used as a fairly effective paint stripper! I'd imagine that you'd probably get similar results using Acetone which tends to be pretty widely available wherever beauty supplies are found.

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I tried paraffin, acetone, white spirit, cellulose thinners, MEK, alcohol, methylated spirits, ether, nitromethane, methanol, amyl nitrate and nitro benzine.... but drew the line at hydrochloric acid. Nothing managed to clean out the very small hole in the idle jet itself...it was very difficult to inspect the inside of the jet, I tried magnifiers and even a microscope, to no avail. The only way to find out was to drive the car..and I had this horrible part throttle misfire at around 2,500 to 3,500 rpm. In the end, I decided to measure the inside diameter of the jets using a piece of old guitar string I calibrated with both a micrometer and a digital vernier caliper. I can't recall the figure at the moment, and I'm too lazy to go down to the workshop and consult the manual and my associated notes...but suffice it to say that the piece of calibrated wire wouldn't go through the jets. I sat in front of the telly that evening slowly reaming out the jets, very gently,using the same piece of wire. Nothing "brassy" came out, but quite a bit of "varnish" type stuff. Reassembled the carbs, drove the car..perfect. And still is, now.... At the last Model Engineering Exhibition I bought an ultrasonic cleaner, so if it happens again I'll combine solvent with ultrasonic agitation and see if that helps!

Edited by molemot

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I second the idle jets being clogged if it won't run when you let off. I have a snowmobile that 2 years in a row that had one carb's idle jet would gum up.

That E10 ethanol mix gas they run lately (at least in the US) will do this when stored a while (some claims are a shelf life of 90 days max). Evidently current formulations start to separate out and gum up/gel in a much shorter period of time and the fuel stabilizers should be used in storage (something called phase separation). I knew this year just what the problem was and where to go and clean it out with a tiny wire.

http://www.daybreakfishing.com/ethanol-fuel.html

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Yippee she's running again.!!!!!After running through the various posts on here I’ve now sorted it.thumbup.gif

I checked pump and fuel supply, as fuel delivery was good I thought carb related sounded a good bet . As I haven’t a clue on carbs I invested in the book "How to Build and Power Tune Weber and Dellorto DCOE and DHLA Carburettors" with a view to checking jets and floats as suggested. After reading the post on checking the leads are pushed home on the dizzy I thought it’s probably worth checking all the spark plugs before I start pulling stuff apart, on inspection they were pretty grubby so replaced all 4 and she started 1st time. .....Nice

respect.gif Thanks for everyone who posted, I now know a lot more about how my car works and the useful fuel pump checks and the book on carbs will all come in handy for next time.

Thanks

JK

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Another proof of the old adage "No matter how much you are convinced it's carburettion, it'll turn out to be ignition!" Glad you got it sorted..and without pulling it all to bits!! Always try the simple stuff first....

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