Suzuki Club UK

Not sure I'm out of the woods just yet, but this is definitely an improvement. I took it for a test drive yesterday and it's driving much better. Although still getting a bit of a fluttering idle when hot.

I took the air filter pipe off the carb and was looking down at damper piston to see if the fluctuations had stopped. It's still fluttering and when I lift it with a screwdriver it feels like the first 4mm of so of travel is not damped and only after that does the damper add some resistance. Need to figure out if this is normal.

When looking at the piston, I noticed that the sides of the carb between the piston and butterfly was visibly wet with fuel. I shut off the engine but left the ignition on so that the fuel pump was still running. I undid the 3 screws of the dashpot assy, lifted it off and found there was a puddle of fuel at the bottom of the butterfly.

It looks as though fuel is seeping up the jet. So either the float level is wrong or something isn't right on the bottom of the carb.

Will strip it down and double check float.

I'll add a video later to show what I mean.

Oh and I try to keep the birds nest of relays and wires out of shot in the engine bay. Too embarrassing, needs to be tidied up!

So I've checked the float height and it's correct. Reassembled the carb and it's still pushing fuel up past the needle. I've made a quick video to show what's happening.

https://youtu.be/UmBXcHA0lI8

Also, checked the two other SU carbs I have on the shelf and they have a similar amount of free play in the dashpot piston before the damper takes effect. So I expect that little bit of fluttering I was talking about is normal?

Can anyone suggest something to try? I'm getting closer to sending this carb off for a professional rebuild as I'm running out of ideas and want to be able to play as soon as we can!

I haven't actually verified that the new pump is putting out the correct 2psi pressure so I'll check that to make sure it's not the problem!

Finally found a few minutes to have another look at this, stuck the pressure gauge on the new pump just for a sanity check and it's bloody putting out more pressure than the old one!!
Showing just shy of 6psi when it should be 2.1psi!

No wonder it was pushing fuel past the jet.

Another few days of pissing about returning and ordering parts! So glad this isn't my daily driver at the moment

So I've opted to fit a malpassi fuel pressure regulator in the end. Set to just over 2psi and she's running loads better.

Pulls much better. Still a bit of fine tuning to be done, a friend has an AFR sensor so I'll give that a go some day to dial in the fuelling as best I can.

Oh and the dashpot fluttering has cured itself too, I reckon the excess fuel pressure was actually pushing it up and causing the fluttering.

Great news!

Thanks, was nice to get the wheels a bit muddy on a few local lanes today!

Always liked the vans. Looks spot on

d_r_1989 wrote: ↑

Sun Apr 11, 2021 9:31 pm

Always liked the vans. Looks spot on

Cheers, she's not show room but she looks good if you stand back a bit!

Just a pity about that dent in the left rear quarter, I need to get that straightened out sometime.

On the fuelling issues, I still have intermittent flooding happening! Drove fine for a few days and then started acting up big time the other evening. Whipped the dash pot off and puddle of fuel behind the butterfly again.

Rechecked the fuel pressure and still good at around 2psi. Reckon it has to be the float needle valve now, although the viton tipped one that's in there looks ok. I've ordered new needle valve and housing so will see if that helps! If that doesn't work I'll replace the float but it looks perfect and it's set correctly too.

Just arrived today, fingers crossed these will fix her up!