Random Dellorto Flooding

PostPost by: JamesRattenbury » Fri Oct 15, 2021 8:40 pm

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?
1972 +2S 130/4, rolling improvement project.
JamesRattenbury
First Gear
First Gear
 
Posts: 23
Joined: 15 Jun 2019

PostPost by: mbell » Fri Oct 15, 2021 8:51 pm

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?
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
mbell
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 2692
Joined: 07 Jun 2013

PostPost by: ncm » Fri Oct 15, 2021 8:55 pm

Floats punctured??
ncm
Third Gear
Third Gear
 
Posts: 238
Joined: 02 Jun 2006

PostPost by: JamesRattenbury » Fri Oct 15, 2021 9:05 pm

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.
1972 +2S 130/4, rolling improvement project.
JamesRattenbury
First Gear
First Gear
 
Posts: 23
Joined: 15 Jun 2019

PostPost by: Craven » Fri Oct 15, 2021 10:09 pm

Check fuel filter for condition, not passing the odd bit of rust.
DHLADiags.jpg
DHLADiags.jpg (31.87 KiB) Viewed 1368 times
Craven
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1625
Joined: 14 Sep 2013

PostPost by: rgh0 » Fri Oct 15, 2021 11:18 pm

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
User avatar
rgh0
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 8815
Joined: 22 Sep 2003

PostPost by: JamesRattenbury » Sat Oct 16, 2021 6:58 am

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
1972 +2S 130/4, rolling improvement project.
JamesRattenbury
First Gear
First Gear
 
Posts: 23
Joined: 15 Jun 2019

PostPost by: RichardHawkins » Sat Oct 16, 2021 6:45 pm

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
RichardHawkins
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1206
Joined: 05 Jul 2008

PostPost by: JamesRattenbury » Sun Oct 24, 2021 7:26 am

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.
1972 +2S 130/4, rolling improvement project.
JamesRattenbury
First Gear
First Gear
 
Posts: 23
Joined: 15 Jun 2019

PostPost by: RichardHawkins » Sun Oct 24, 2021 3:44 pm

James,

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

Richard Hawkins
RichardHawkins
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1206
Joined: 05 Jul 2008

Total Online:

Users browsing this forum: No registered users and 15 guests