Random Dellorto Flooding

[JamesRattenbury]

Hi all, I could do with some advise with an issue with my +2 130/4 with Dellorto DHLA40's that's driving me mad. What happened was one day a few weeks ago the rear carb started to flood into the air box, I took off the top plate of the carb, couldn't see anything wrong so put the top plate back on and started the car back up, but the issue had gone away...roll on a few weeks and about 150 miles and the issue came back, once again took the top plate off and put back on again and the issue disappeared. This continued and I've since tried replacing the float needle valve (did about 200 odd miles before the issue came back after this), checked the float height which was ok, but the issue keeps randomly coming back. Driving in traffic seems to bring it on quicker, but i'm still stumped and can't see anything causing it, plus the front carb is fine.

Has anyone got any ideas?

[mbell]

Have you checked the floats aren't leaking and taking on fuel? Could the floats be jamming and holding the valve open? What fuel pump are you running could it be supplying too high pressure?

[ncm]

Floats punctured??

[JamesRattenbury]

Thanks both, i'm running an original mechanical fuel pump. I will check for punctured/leaking floats tomorrow as I only gave them a cursory check the other day. I had discounted fuel pressure as the front carbs been fine and i've done quite a lot of miles between some of the times its flooded.

[Craven]

Check fuel filter for condition, not passing the odd bit of rust.

DHLADiags.jpg (31.87 KiB) Viewed 1691 times

[rgh0]

If the car sits for extended periods between runs deposits can build up on the needle valves as the fuel evaporates and this can cause them to stick open. I have had the same thing happen on my Esprit when it was not getting driven much due to covid lockdowns. I also found the car getting harder to start and not idling well due to deposits on the idle jets.

cheers
Rohan

[JamesRattenbury]

Thanks both, i'll take a look at those as well today, i'd be surprised if it is rust coming through as I put in a alloy fuel tank about two years ago

[RichardHawkins]

James,

As your front carb is trouble free, try changing components one at a time and see if the problem stays with the carb or moves with the component. I have not tried this with carbs but has been very useful with industrial chemical process machinery.

Hope this helps,

Richard Hawkins

[JamesRattenbury]

Thanks all for the replies and help, I finally got round to looking into the issue in depth and on the inside of the one of the floats there was some small damage i'd not seen before, a small part of the outside of the float had come away (how this happened I have no idea as its an odd place to be damaged). So i've swapped out the float for a new one (plus replaced the gasket) and so far so good, I did about 50 miles yesterday round the country lanes with a happy grin on my face.

After that I did take a look at the front carb float as well and noticed a previous owner hadn't set the float height right on that either, so even though I said the front wasn't causing an issue its now running better than ever.

[RichardHawkins]

James,

Glad you got it fixed, and thanks for telling us what the problem was.

Richard Hawkins