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View Full Version : am I getting too much fuel, or not enough???



nicklouse10
25-04-05, 02:00 PM
Hi all,
been searching the forum for the answers but cant find anything difinitive,
symptoms are;

The car dies when under hard acceleration, and then starts to kangaroo down the road, bunny-hoping embarrassingly for quite a while. The only way to drive it smoothly is to not take it above 4K in each gear, and increace throttle very gently gently

As it starts bunny-hoping, if you give it more throttle, or pump the throttle, it makes the situation much worse, often the car dies altogether and I have to come to a complete stop before restarting.
The quickest way to stop it from happening is to select 4th and ever so gently feather in the throttle. This has led me, to more or less rule out fuel starvation, and think it may be over-fuelling??

Iíve had the Carburettor, (Webber twin choke) stripped, and rebuilt it correctly. There is nothing wrong with the carb itself. It is running slightly rich though.

Iíve fitted a new electric fuel pump, and regulator.

The only thing I can think of, is the ignition timing may be off? But it has (cheap) electronic ignition? My next plan was to replace it with a set of points to see if this cures it?

I have read on here that the coil may be the culprit, and especially if it is mounted horizontally, as mine is, so I will replace that too.

Any other suggestions would be MOST welcome. I work away from home and will only have Saturday morning to fix this before setting off for Stoneleigh.
ps, have attached pic with new sidepipes, just got them on in time for Stones, and now this problem!

cheers all
Nick

h8jse
25-04-05, 02:10 PM
Nick


Don't if you have tried changing/renewing the HT lead yet? I have had the same problem in the past on a dare I say it "vauxhall astra GTE":whatever: and it done the same thing, after changing the coil, the ignintion pack located under/ near the coil, adjusting the timing and setting the co level some clever **** said change the HT lead, I did and it sorted it out!:thumb: hope this is of some help.

Jason

nbracken
25-04-05, 02:54 PM
Nick this sounds to me to be ignition related rather than fuel, and probably related to timing. It is easy enough to check. It sounds like the timing is not advancing with increased revs.

plod
25-04-05, 03:49 PM
Nick, had similar thing on mine. By complete fluke, the symptoms increased as I turned up to see auto electrician bloke. turned engine off and all light swere still one. Something was back feeding through the alternator I think it was and had a dodgy earth.

Hav eyou noticed anything strange when you've switched off? Did fan still run, was anything else turned on? I say fluke with mine as I'm sure I'd never seen the lights on when I turned off as I'd not driven it in the dark for a while.

grandadboats
25-04-05, 06:26 PM
A look at the plugs will tell you if it's fuel related. Black- too much, whitish- too little, brownish- about right.

Tony

h8jse
25-04-05, 10:11 PM
Nick

Hope you sort it, Let us know the outcome.

Jason

nicklouse10
26-04-05, 09:22 AM
HI Guys,
thanks for all the replies,
I have changed the HT leads and plugs last week.
I have not noticed anything staying on after I switch off, but I will double check.

nbracken; if the timing was not advancing with the increased revs, could this be a faulty vacuum advance pipe? sorry if thats way off the mark, Ignition is not my strong point, how would I go about checking my timing? I was planning on changing the electronic ingition for a set of points.

Nick

smash
26-04-05, 10:51 AM
Ignition problems will usually show under load conditions - could be the coil tracking if damaged. Is it affected by damp/rain? Would've thought starting would be an issue as well thought if this was the case.

50:1 outsider: You've not got a split diaphragm in the carb accel pump have you? Float definitely set right and you're sure the float chamber valve's not sticking?

nbracken
26-04-05, 11:24 AM
Nick you don't say what ngine you have but in summary yes, if your vacuum advance was not working correctly then your timing would be out when you accellerate under load and would cause the deterioration in perfoemce that you've noted.

To check timing is simple. Make sure you have your timing marks clearly shown on the from of your crank (white tippex works well). Then get a timing light - Gunsens sell a range, connect it as per the instructions and then point the light at the crank and increase the revs. On some models you'll get a read out of what your timing advance is on a digital display at various revs and you can compare this to teh settings that your engine is supposed to have.

If you don't have teh equipment or don't want to do this, just go into any decent garage workshop and ask them to check for you. Its a 2 minute job and provided you tell them what it is suppsed to be they can tell you soon enough whether you have a problem.

HTH

Nigel B

Purple AK
26-04-05, 07:49 PM
Nick.

I chased the exact same symtoms for six months. During which time I completely changed and upgraded the ignition system as I was convinced it was ignition related :mad: It was also the same with two different carbs, another reason for not thinking it was fuel.
The outcome and cure turned out to be fuel starvation caused by a blocked pump. I finally found this by removing the fuel line from the carb and pumping it into a jerrycan. What should have been a heathly 72 gals/per hour flow was a mere trickle. i know you have changed the pump, but have you checked the possibility of a blocked filter, collapsed hose or even an air leak (pre pump) that is restricting the flow.
Just my twopenneth HTH :thumb: