Have you got a shit pump or something?!

No it's not. I just can't see what I'm doing wrong. I have read every guide, picked everyones brains and recreated the T-piece method as other people have and it's no better. It will go along for a while, but any longer than a few seconds at what and it splutters and dies. I'll have another go tomorrow and check if the float bowls are dry. They were with the old carbs, so to make sure it's the same issue, I'll need to check them. No good throwing more diollar down the shitter to get no better results.

Another boring update

How far are you away from me?

The pump was brand new and when not connected to anything it pumps plenty of fuel. I think too much is going down the return, hence thinking a restrictor in the return line may help to remedy this

Max, I'm not sure exactly, but Sheffield is a way. Hot to be at least 3 hourish!

hmm... You need to try some sorta return restriction i think as you say. Maybe a regulator or something?

If you haven't got one lying about, clamp a set of molegrips lightly on the return line and have a play about adjusting them.

It's difficult to adjust as the problem only come about when the car has the throttle open for a few seconds. I think I'll find a a small tube to put inside the fuel pipe to reduce the diamter further, something like the take off from a fuel filter ought to do the job

There should be a brass tube in the return line, does yours? It is like an inner sleeve where the rubber hose ends and the plastic hose begins.

Nope, I have either lost this, or the car never had it. What's its function

Also, what side (OD) are peoples fuel lines? Mine look tiny, and there's no difference between feed and return. Wondering whether this is causing a lack of flow

Well i found the brass restrictor in a piece of pipe i had cut off. This is now inline with the return. I have also plumbed a second clear fuel filter inline just before the carbs to monitor flow to the carbs. Idling, its fine and on short bursts of throttle, it stays full. But when on s few seconds of throttle under load, the car still stutters and dies. At this point, the float bowls are practically empty, pointing to fuel starvation. However the inline filter stsyd full.

So basically the bowls are almost running dry when the throttle is pressed for extended periods as it will tick over all day long at idle. What would cause this? The inline filter stays full at all times, so it would appear the pump is supplying sufficient fuel, but there's something happening between the filter and the float bowls (this part of the tract is just piping though, so has limited potential for problems). These carbs have significantly smaller float needles (despite being a larger choke size) compared to the other carbs, but both sets of carbs have given the same symptoms so can it be this?

Upon further testing it seems that when the fuel filter (the 2nd one, before the carbs) is full, the car runs worse, as if there is a block somewhere between the filter and carbs, starving the engine. When fuel is just dribbling through the filter, the car runs much smoother and picks up revs much better. When the car dies, bubbles come up from the carbs and through the filter. I think there's an air lock somewhere in the pipework or in the float bowl. Maybe one of the air jets is blocked? I'm not too sure and rapidly running out of ideas

Have you tried running the pump not connected to the carbs and seeing what flow you have coming out of the t piece? Glad you foud the brass tube, I suspected last night it may be missing if you'd done new lines and not realised it was there.

Yeah cheers for that. Pump is flowing about a 1/3 of a litre per minute, so should be plenty. It's weird as it also prefers to run with the choke open, even when warm. Then it just dies altogether no matter what I do. Mixture screws have been tried and 2, 2 1/3 and 3. All give the same problem.

What carbs are they? CBR 600s?

What jets are in them? Its a 1.6 AEE right?

are the fuel bowl vents all open and not blocked for sure Simon and is the pump pumping the correct pressure

it needs to be 4-6 psi doesnt it for the carbs just thinking that maybe the pressure of the pump isnt enough as when your what it could cause back pressure in the float bowls closing them and the pump isnt giving out enough pressure to force fuel back into them and so its just going down the return still even though its restricted

hope you get what i mean as this could be a possibility couldnt it

Nope, that makes sense Pete. It's just dribbling through the second filter, so I wouldn't be suprised if there isn't enough pressure to force the floats open. I think I'm going to sack the facet off and go for a motorbike pump. That way I can fuck the return off and be rid of that variable. I think all the vents are open. They were when the carbs went on, but I guess they could have gotten blocked since.

Jim, yep 1.6 CBR600 carbs. 36mm chokes with 160 mains and 38 idles. I'm going to get a range of jets too, but thats for when its running correct

1/3 of a litre a minute? That seems nothing I'm sure my bike pump would manage at least 2 litres a minute?

Thats what was going into a jar at the carbs, so some would have gone down the return. But i was suprised with the lack of flow, especially since it was unrestricted. When I checked the flow of the return a while back it was gushing out, so I've always assumed the pump was ok.

if you were closer you could of borrowed my facet to try to rule that out as my deffo works fine ran my carbs perfect

what bore are your fuel lines mate

Edited 25 November, 201213 yr by StinkyPete

The facet was brand spankers. Fuel lines should be the same as yours were. It was an early one, about 5mm i think

1/3 of a litre per minute is really not a lot. Mine's on the original injection pump with the t-piece, having no issues at all.

Sounds like fuel starvation though. Also, I drained the tank on my dad's bike the other day, used a length of a pipe and a filter - only because it gave me enough length to reach the tank - no other reason for the filter.

Anyway, once i took the pipe off the tank - bearing in mind the filter is still attached and open to atmosphere, as is the other end, the filter stayed full of fuel. No flow, no pressure, still holding fuel.

Wouldn't come out if I shook it, either.

Why not just cable tie a fuel tank onto the bonnet and what the car with the carbs being fed by gravity?

My filter doesn't drain either, but thats due to the system being pressurised. It's the same reason you can turn a glass of water upside down over someone's head.

Just ordered a bike pump. That way I know all the pressure will be going to the carbs, and not down the return. God knows why I can't get this relatively simple system to work. Believe me I feel like a spazz.

i changed my fuel lines simon to ss braided ones that had at least an 8mm bore so very big compared to standard polo ones as they are 8mm o/d

I thought about doing that, but there's always going to be the restriction at the outlet of the fuel tank

Not convinced on a low pressure pump AND a tpiece?

Are you asking a question?

If not, who uses a low pressure pump and T? I'm going to bugger the T off and run the bike pump as it should be used. Fuel in, fuel out and that's that.

Are you asking a question?

If not, who uses a low pressure pump and T? I'm going to bugger the T off and run the bike pump as it should be used. Fuel in, fuel out and that's that.

Is there anyone you can take it to around you simon?