4 hours ago, Turbobandit said:

 

That’s just an inline  fuel filter. Don’t run it with your original injection pump switched on, even with a t piece. I tried this and it just sprayed fuel out of the bowl overflows as the pressure is still too high.

Having the Pump after the send/return loop might also behave a bit weirdly, I don’t think the return line is screened at all either so you’ll likely suck a lot of crap from the tank into your pump that way.

How long did you try the pump for? My bike pump takes a while to prime after fitting as they don’t pull very well, I have to crank the engine for a bit several times until the fuel actually reaches the carbs. One advantage of the clear fuel filters is that you can see them fill up. 
if you can mount your pump as low down as possible (lower than I have) it might help things 

Fitted my new manifold along with cbr600 carb rubbers today. It runs a lot better and the vacuum at the trumpets is noticeably much stronger. 
However it’s still revving itself up to about 3K rpm seemingly at random with no throttle input or anything, popping slightly from the exhaust. 
It’ll Rev much better on the throttle now the idle jets are clean,

Sprayed carb cleaner around all boots, manifold and servo connection and it doesn’t seem to change.

When it does this I sometimes get fuel coming out of the overflows too. I stripped the carbs yesterday and cleaned all of the jets, needles, float valves etc so I’m at a total loss.

 

anyone got any ideas? Going to try richening it up with the pilot screws tomorrow as I’m guessing this is a lean condition of some kind

cheers!

If fuel is overflowing it is too high in the well.'

Excess pressure, dirty needle valve?

 

 

yes popping is usually lean, but can be unburnt fuel.

 

If you hold a piece of paper loosely at idle at exhaust does it make regular movements away?

If it is sucked onto exhaust or misses a beat you might have one weaker cylinder that needs richening or unblocking. Infrared thermometer should read the same on all exhaust manifold branches. If one is only 90 and others are over 200 you have found the bad guy.

 

Does engine temp make a difference?

Some ECUs add more ignition advance while the engine warms up and makes 

setting up fuelling a moving target. Let it get warm with bonnet closed.

 

Strong spring on the throttle flaps and cable?

Have you balanced the flow?

Edited 22 November, 20205 yr by dvderlm

1 hour ago, dvderlm said:

If fuel is overflowing it is too high in the well.'

Excess pressure, dirty needle valve?

 

 

yes popping is usually lean, but can be unburnt fuel.

 

If you hold a piece of paper loosely at idle at exhaust does it make regular movements away?

If it is sucked onto exhaust or misses a beat you might have one weaker cylinder that needs richening or unblocking. Infrared thermometer should read the same on all exhaust manifold branches. If one is only 90 and others are over 200 you have found the bad guy.

 

Does engine temp make a difference?

Some ECUs add more ignition advance while the engine warms up and makes 

setting up fuelling a moving target. Let it get warm with bonnet closed.

 

Strong spring on the throttle flaps and cable?

Have you balanced the flow?

Might have to replace the needle valve, it’s been cleaned several times and seals fine when I blow into the lines. 
The head itself gets quite hot but right now I’m having trouble getting it to operating temp as it’s just revving like mad. I can even take the choke off after maybe 30 seconds of idling and the revs will dip then go back to either running lumpy or fast.

Oddly enough then putting the choke back on kills the engine? 
 

Throttle springs are all strong, will give them a clean though. They’re currently balanced according to my old leaky manifold, I’ll have to give it a go now it’s sealed better but again hard to get it running at idle to do this.
Could imbalanced throttles cause an engine to idle at normal speed then suddenly just run away with itself like this?

Unbalanced throttles usually gives a shaky engine, rather than regular small pulses on the flywheel.

 

But It's really hard to get mixture correct if one cylinder is doing the most work, because the piston next in ignition sequence will have a strong induction stroke when the current one does its combustion stroke. This can get into a rare resonance where a pair of cylinders (in inner and outer placing) push the no load engine faster as each reinforces the other. Easily spotted by removing a spark plug lead in turn and restarting on 3 cylinders to spot the strong man.

 

Racing idle is normally a vacuum leak sign. If there's no vac leak, throttle plates may not be closing sufficiently, or fuel level is too high or idle jetting too big.

 

If it's running very hot it is usually lean, but can be too much fuel at idle.

 

Take out a spark plug and look whether it is bright white ceramic (lean)

or sooty (rich) or oily (timing wrong). 

On 23/11/2020 at 11:20, dvderlm said:

Unbalanced throttles usually gives a shaky engine, rather than regular small pulses on the flywheel.

 

But It's really hard to get mixture correct if one cylinder is doing the most work, because the piston next in ignition sequence will have a strong induction stroke when the current one does its combustion stroke. This can get into a rare resonance where a pair of cylinders (in inner and outer placing) push the no load engine faster as each reinforces the other. Easily spotted by removing a spark plug lead in turn and restarting on 3 cylinders to spot the strong man.

 

Racing idle is normally a vacuum leak sign. If there's no vac leak, throttle plates may not be closing sufficiently, or fuel level is too high or idle jetting too big.

 

If it's running very hot it is usually lean, but can be too much fuel at idle.

 

Take out a spark plug and look whether it is bright white ceramic (lean)

or sooty (rich) or oily (timing wrong). 

Thanks for that, put new rubbers and a proper intake gasket on today, along with a rough bench balance of the butterflies.  It'll now idle and warm up to the point that i can take the choke off.  When i do this however fuel starts leaking out of the overflow and the emulsion tubes on carb 2 (i think? Tubes on the top of the carb adjacent to trumpet.)

The float valve seems to work fine when i blow down the fuel line.

Is there anything that could cause this that ISN'T the float valves?   

Really frustrating as other than leaking fuel all over the exhaust i'm ready to get the vac gauges on there and start setting it up so it's driveable 😞

thanks!

 

(Also reminded myself to go and get some new plugs/smaller socket as the new manifold doesnt give me enough room to get a socket in there lol)

• Hole in a single float so it sinks slowly.
• Float rubbing on side wall.
• Float hinge damaged.
• Dirt at valve.
• Worn needle valve tip or seat.
• Damaged body gasket.
• Excess fuel pressure. You are using a carb bike pump, not injection bike pump, right?

Clamp the fuel line with a bolt and jubilee clip, temporarily to reduce flow.

Consider a low pressure regulator if that helps.

 

Are you still using a T joint? Blow compressed air down fuel return line to tank and check it bubbles. 

 

 

I found a diagram of fuel and vacuum tubes I think but not exploded diagram of insides so I can't tell if they are emulsion tubes. Guess they are Keihins.

I am a Weber amateur enthusiast not bike-carb guru. 

 

Appear to be alternative ways to pressurize the float bowls. Maybe with rammed air not just atmospheric (the pipes top right 38 45 48 49, where do they connect?).

Surely only atmospheric is needed when not moving or below 100mph.

 

 

 

 

cheers, I’m sure the pump is a carb one, pressure is much too low for injection and same model year etc as the carbs. I’ve had it running without fuel leaks before the change in manifold so I’m dead confused, it’s just the one carb doing it; unlike when it was all four with the old high pressure fuel pump.

T piece return is disconnected as it just made my pump run constantly and never get to pressure and switch off.

 hoses in the top right might go to the float bowl drains. What’s leaking on mine is like a cluster of brass tubes by the throat of the carb, air jets or something?

 

By the way, when you suggest clamping the fuel line, is this for diagnosis or can you use that as a permanent method to reduce fuel pressure?
Might try it to get my car useable, depending on whether NRP have got the right bits in stock today. live round the corner from them thank god 

11 hours ago, dvderlm said:

Clamp the fuel line with a bolt and jubilee clip, temporarily to reduce flow.

Consider a low pressure regulator if that helps.

Just for diagnosing. 

 

Try turning key to running, but don't start engine.  

I'd expect motorbike pump to run for a bit until wells full (replacing any evaporated) and then cut off when needle valves close (just like toilet cistern).

 

See if pump shuts off when you fully clamp the hose (or kink it 180 degrees).

 

Brass tubes at highest point sounds like air correctors(except a little odd for it not to be filtered airflow. Dell'orto have a very fine screen and and twisty passage to the air correctors but they are covered). Air should be sucked in there. Fuel should not come out.

Edited 25 November, 20205 yr by dvderlm

5 minutes ago, dvderlm said:

Just for diagnosing. 

 

Try turning key to running, but don't start engine.  

I'd expect motorbike pump to run for a bit until wells full (replacing any evaporated) and then cut off when needle valves close (just like toilet cistern).

 

Brass tubes at highest point sounds like air correctors. Air should be sucked in there. Fuel should not come out.

Yep the pump does that for a couple of seconds. After draining bowls it takes a few goes of this to fill them again and get the engine started, however I think this is because it’s wired to the original injection pump circuit which obviously work at a much higher pressure.

When actually cranking and running the pump runs as needed like it should. 
 

Ive had another look at the float needles and the spring pistons on most of them are stuck in the down position, particularly the leaky carb. There was also a fresh load of gunk in the seat and threads of the main jet holder that could’ve been leaking, I think the bulk of the fuel was coming from the corresponding air jet on top for this. 
 

Ordered some new float valves which should be here tomorrow and sort the problem!!! fingers crossed.

cheers

Success!

New float needles sorted it. Attempted to balance the throttles with guns on carbalancer, it seems a bit crap though so don’t know how precisely I’ve done it. 
Took it for a spin and it’s driveable, albeit extremely slow. Think it’s pinging sometimes at high revs/wot.

 

The one thing I’m confused about is the revs are often hanging, I’ll get up to a speed and it’ll just coast at that speed without engine braking. When I brake or bring the clutch up the revs drop back to normal (ish)

Takes ages to go back to idle after blipping the throttle too, return springs seem fine (snaps shut when I pull from the engine bay) 

One step forwards. Hooray.

 

Maybe throttle linkage at pedal or through chassis or bulkhead.

If the inner cable is worn or frayed it'll stick in some positions.

 

Or just too much idle power.

 

Get it idling below 900rpm when fully hot. Or it'll pull the car along at 20+mph in high gears with no feet touching pedals, when it should slow to about 5 or 8mph and be near stalling.

 

One horsepower can pull a laden cart faster than you can walk.

 

 

... and try a differential carb balancer.

Hard to find in shops. Must be too expensive.

http://www.powerchutes.com/manometer.asp

 

 

Edited 27 November, 20205 yr by dvderlm

There's another very small chance possibility for engine speed not slowing.

 

The carbs were already worn enough that needle valve/seat did not seal (about 200,000 miles?).

The throttle plate edges might have worn where they touch the barrels, letting too much air past. But it's Honda carbs, so I'd expect really long life.

 

On Webers you can get replacement plates. I have never ever needed to.

The fixing screws are steaked, so they cannot fall out, which makes them hard to remove too.

 

You can, in theory,  file a chamfer on the correct edges of removed plates and refit so they rotate past any barrel wear point. Never done this either. Keeping it round scares me.

 

The shaft seals for the throttle shafts might be leaky too: you found no vacuum leaks. So ignore this.

Though actually a vacuum leak, unlike manifold gasket leak, worn shaft seals are not near any idle or progression holes and very small area, usually of little importance, just needs a tiny bit more fuel. Not the case for a turbo conversion.

1 hour ago, dvderlm said:

There's another very small chance possibility for engine speed not slowing.

 

The carbs were already worn enough that needle valve/seat did not seal (about 200,000 miles?).

The throttle plate edges might have worn where they touch the barrels, letting too much air past. But it's Honda carbs, so I'd expect really long life.

 

On Webers you can get replacement plates. I have never ever needed to.

The fixing screws are steaked, so they cannot fall out, which makes them hard to remove too.

 

You can, in theory,  file a chamfer on the correct edges of removed plates and refit so they rotate past any barrel wear point. Never done this either. Keeping it round scares me.

 

The shaft seals for the throttle shafts might be leaky too: you found no vacuum leaks. So ignore this.

Though actually a vacuum leak, unlike manifold gasket leak, worn shaft seals are not near any idle or progression holes and very small area, usually of little importance, just needs a tiny bit more fuel. Not the case for a turbo conversion.

Interesting, took it for a further drive today (including very short stretch of motorway,) its WAY down on power and definitely pinging at higher speeds. Wot gives no extra power apart from more noise

Doesnt like idling below 900, with the injection system on it only idled at 900 anyway. I have a feeling this is probably part due to balance though.

Im 99% certain its not running rich, the exhaust has never smelled of petrol even on full choke, could tell when the old injection system was warming the engine up as it absolutely stank on cold mornings.

 

I'm tempted to drill the main jets out, at least temporarily, smallest bit i have is a 1.5mm though, so would be (bodgey) 150 jets. Current jets are 140 and 138. Reckon this is worth a go? Don't fancy driving it to a RR and pinging my engine to death on the way. 

 

Ordered a 90 degree cable guide to help the throttle pull in a straight line, as the throttle operation is definitely mushy regardless of whether its sticking or not lol

Cheers!

Hey rusty 

Is your distributor a vaccum type ? 

1 hour ago, Turbobandit said:

Hey rusty 

Is your distributor a vaccum type ? 

Nope, i'm currently using the stock 6n distributor and ecu, just with all plugs on the manifold/injectors disconnected. Is yours a 6n? I don't think im getting any variable ignition advance with the tps and MAP sensors disconnected, which is why some people use the vacuum ignition from earlier polos. 

Edited 27 November, 20205 yr by rusty
spelling!

Rusty I’ve been doing some research for mine and I jumped first and bought a vaccum distributor but have since found out if you connect your map sensor to the vaccum of your inlet your ignition will advance. The TPS only controls Tickover . Mine is actually a Skoda felecia fun 1.6 AEE which I’m doing the conversion on . I’ll be connecting the map sensor first hopefully tomorrow I’ll be doing this and get it running . 

This should stop it being so flat and also stop the picking 

1 minute ago, Turbobandit said:

Rusty I’ve been doing some research for mine and I jumped first and bought a vaccum distributor but have since found out if you connect your map sensor to the vaccum of your inlet your ignition will advance. The TPS only controls Tickover . Mine is actually a Skoda felecia fun 1.6 AEE which I’m doing the conversion on . I’ll be connecting the map sensor first hopefully tomorrow I’ll be doing this and get it running . 

Ah Bollocks that makes a lot of sense, i had the option of getting balanced vacuum lines when i had my manifold made and didn't want to fork out extra at the time.

Well done finding a felicia fun though, absolute dream car. Can people really sit in the back of them? 

I’m not fitting a balance bar mate I’m connecting mine together off the vac take offs and teeing from them to the map sensor . Will do same job as a balance bar . Can’t sit in the back of mine mate as mine is a bit ratty lol . Rear seats removed and bulk head welded in . Matt black slammed to floor on borbet wheels and side exit exhaust . Want the bike carbs on it not to try and help it move a little more hahaha it’s so slow 

11 minutes ago, Turbobandit said:

This should stop it being so flat and also stop the picking 

Might try running it off a t piece on the brake servo connection, with a fuel filter before to smooth out any pulsing? Any chance you've found anything relating to this as i'm sure i've read about it before, just cant find it again 🙄

Don’t use the vaccum from the brake servo as the vaccum will change every time you brake . I’ve been watching videos on YouTube and googling like mad to find answers and pretty much sure I’ve found them as this aeema to work . If I can get mine running tomorrow on carbs then I’ll let you know how I get on or if you try it let me know what happens . Also in the owners manual it says the TPS only controls Rickover which only leaves the map sensor to

Control ignition timing 

Just now, Turbobandit said:

Don’t use the vaccum from the brake servo as the vaccum will change every time you brake . I’ve been watching videos on YouTube and googling like mad to find answers and pretty much sure I’ve found them as this aeema to work . If I can get mine running tomorrow on carbs then I’ll let you know how I get on or if you try it let me know what happens . Also in the owners manual it says the TPS only controls Rickover which only leaves the map sensor to

Control ignition timing 

Yeah thats what i was thinking, might have to fit some vac takeoffs, tapping holes gives me the absolute fear though.

My haynes manual got leaked on in the boot before i fixed my open air so all the useful pages for this have unfortunately turned to paste haha. Interested to see how you get on!

As long as you take the manifold off and drill and tap you will be fine and cause it’s alumnium it’s quits soft . I’ll let you know how I get on tomorrow mate and hopefully will have some good news . I’ve bought a fuel pressure regulator gunna try that and if not see if I can mount the pump by tank and see if it will pull the fuel through the original pump .