Front to rear fuel lines vs. fuel supply

[the edmundator]

If the front to rear fuel lines were the wrong internal diameter (i.e. too small) would this be likely to have a significant effect on fuelling?

I lose power after driving for a while, and it only seems to happen when the engine is under load (i.e. it is worse when driving uphill, or when accelerating, especially over 50mph). I also cannot get the engine to idle unless the choke (Weber, manual choke) is pulled out a bit to get the car to idle around 1500rpm.

I'm not sure whether this is a fuel supply problem, or if it's sucking in air - if it was sucking in air, would this be likely to be more of a problem when the engine is under load, or does fuel supply seem a more likely culprit.

I know an electric problem (e.g. distributor) is a possibility as well, but on the driveway there is nothing I can identify as being an obvious problem.

My front to rear fuel lines were replaced recently, with DIY items, and I wondered if it was possible these could be affecting things. I know the filler neck and tank have been rusty, but the problem isn't really intermittent enough to be dirt in the fuel system, and the filter looks spotless.

[Funky Diver]

So long as you're getting good pressure out of the fuel pump it shouldn't make a difference, in fact, it should actually increase the pressure going to the carb as there will be more restriction on the return line than you really need, basically ... the pump is going to shift a fixed volume of juice through, albeit possibly under a bit of strain, on each cycle.

The fact that you have to apply choke would say to me that there's definitely a fuelling issue within the carb itself.

Problem solving questions could be...

1. Have you tried adjusting the mixture?
2. What state are the plugs in? Running rich / weak / normal
3. Decent quality petrol? My car for some reason HATES Morrisons juice, yet Jet, Shell and BP it's just dandy.
4. The jets haven't been put in the wrong way around have they? I DID that when I first got my carb, and it produced CRUD performance. Unfortunately the "instructions" that come with the Weber aren't fab at telling you which is which, especially when you get a bag of bits to assemble, for jets n emulsion tubes, no wotnot...
5. Are the butterflies moving freely in the body?

Lastly... if it helps http://sciroccoregisterforum.co.uk/faq/ ... tructions/

[the edmundator]

Applying the choke only makes a difference to idling - it has no effect on the loss of power when that happens.

Other than the stalling the problems aren't new - I had exactly the same problems with losing power under load when I had the Pierburg. I can only assume it's not the carb itself that's the problem, but possibly an air-leak (vacuum or inlet manifold?), a fuel supply problem, or something that affects the spark under certain circumstances.

Petrol is V-Power, so I don't think that's the problem.

[ianaudia4]

Sounds as if running lean mate.
Also how old are the HT leads, dizzy, plugs and coil?

[Rusty dan]

Sounds very similar to my problems, it woul;d idle fine and sit there all day but when giving it the beans, the car would shudder, jolt and cut out.

My ignition timing was advanced 2 degrees when it should have been 6 degrees before tdc.

Set my timing by way of the flywheel, doing it by the cambelt was miles out.

Worth trying to wobble the carb to see if you have play in the flange gasket.
Also worth spraying a bit of brake cleaner or the like around air hose joints to see if the car picks up in running.

[Funky Diver]

aaaah.,.. ooooooh... what's the Carb gasket like in terms of integrity?

ie the fat rubber doofer that connects the carb to the inlet manifold, if that's knackered, when you inject beans, the carb get's a bit left behind and one of hte beans makes a nice air gap making the engine run lean as you like. Could be the issue... try pushing down on the carb (to compress the gasket) and then revving it by hand...

[markh]

Ive just started to have a similar problem with DARE Ed, yesterday it lost all power and died, it would only start again with full choke ( fitted a weber about 4 weeks ago, but have had no problems until yesterday) I got the short distance to where i was going and left the car for about ten minutes, when i came back it started and drove fine then about 2 miles up the road it did it again. Both times it happened i was driving up a pretty steep bank.
I had a quick look at it today, checked the fuel pick up in the tank, checked the tank for signs of water and checked the filters, everything fine. I checked the distributor cap and rotor and the terminals in the cap had pretty much burnt away, so fitted a new cap and rotor. Then i set the CO & idle on the carb as described in the Webber manual.
Things have improved and it only held back slightly on the steep bank near my house, it didnt die completely or cut out and i didnt need the choke, it just cleared itself and carried on running fine.
Im convinced its a fuel issue either an internal carb problem or faulty fuel pump rather than electrical, but i wont rule out a duff dizzy or coil just yet. I just hav'nt got time to look at it now until next weekend.

[go-for-it1]

Welcome to the club Mark!! Still chasing my problems also.
Rob

[markh]

Im gonna whip the Webber off this weekend Rob, an d strip it down, im hoping its just something simple like dirt in the carb !!!!

[go-for-it1]

Im gonna whip the Webber off this weekend Rob, an d strip it down, im hoping its just something simple like dirt in the carb !!!!

How'd you get on Mark?

[richlyons]

i fit my weber on the other day and it was running s**t, turns out i forgot to put the new manifold to head gasket, sprayed a bit of brake cleaner around and it picked up

so off came the carb and manifold again

[Funky Diver]

Which was the exact same issue I had when fitting my weer ... knackered manifold gasket, and it's quite a chunky mofo...

[markh]

Im gonna whip the Webber off this weekend Rob, an d strip it down, im hoping its just something simple like dirt in the carb !!!!

How'd you get on Mark?

Not had time to do it yet Rob.

[markh]

I seem to have cured the problem on mine. Took the Webber apart on wednesday and found a fair build up of crud in the both sides of the bottom of the float chamber, this was almost completely blocking the ports in the bottom of the chamber, so cleaned it all out with carb cleaner, removed all the jets and blew them through with carb cleaner. Put it all back together, and is been absolutely fine ever since, no power loss up hills or cutting out.
I can only guess that the tlting effect when going uphill meant the crud was moving and blocking the ports.

[the edmundator]

Well, now I have replaced/tried alternatives for:

HT leads (brand new)
Rotor arm & dizzy cap (brand new - old ones looked knackered)
Ignition amplifier (tried a different one)
Coil (swapped with known good one)
Weber carb (brand new, to replace Pierburg)

The same problem existed before and after changing all of these things.

Sat on the drive, the car idles fine, and revs away happily. I can't replicate the problem without driving.

There always appears to be fuel in the fuel filter, which is clean.

After driving a short distance (approx 2 miles) the engine will begin to struggle under anything but the smallest amount of load. If I am very careful and drive along with the slightest tickle of the accelerator, I can continue, although there is still a noticeable hesitation constantly. If I try to accelerate hard, the car splutters and dies.

I find it difficult to believe that the problem would be specific to the carb, since the same problem was present with the Pierburg and Weber.

Ignition-wise, the only thing I can think of that I haven't changed yet is the dizzy itself, but would it give rise to this kind of problem if it was on it's way out.

As far as the fuel supply goes, I can't really identify a problem.

I hate this car.