Shortmoor Landy

Shortmoor Landy

Member
Originally had a problem with the Zenith carb running rich so went through the full strip down, lapped the mating surfaces then reassemble with new gaskets etc. actually did this on 2 carbs in case there was still a problem. Actually both carbs where great. Running very nicely. No more black smoke and much improved econony. However for some reason after about half a tankful of petrol (e10), I was getting a small bit of what looks like straw or paper blocking (inside) the main jet. Result was having to limp home on choke. This has happened in both carbs. I have two filters, the original glass bowl type plus one I’ve added which is an in line paper type. No change. Anybody know where theses bits are coming from? Are the gaskets inside the carbs disintegrating with the e10 petrol? Do I have to fork out for the e5 stuff? Any ideas would be most helpful.
 
Shortmoor Landy said:
Originally had a problem with the Zenith carb running rich so went through the full strip down, lapped the mating surfaces then reassemble with new gaskets etc. actually did this on 2 carbs in case there was still a problem. Actually both carbs where great. Running very nicely. No more black smoke and much improved econony. However for some reason after about half a tankful of petrol (e10), I was getting a small bit of what looks like straw or paper blocking (inside) the main jet. Result was having to limp home on choke. This has happened in both carbs. I have two filters, the original glass bowl type plus one I’ve added which is an in line paper type. No change. Anybody know where theses bits are coming from? Are the gaskets inside the carbs disintegrating with the e10 petrol? Do I have to fork out for the e5 stuff? Any ideas would be most helpful.
Click to expand...
It could be problems caused by the E10 petrol, maybe gaskets, or maybe just stuff it has dissolved from inside the carb passageways or fuel lines, ethanol is quite a strong solvent of some materials.

Try cleaning inside the carb thoroughly with carb cleaner, you can also have a look at the gaskets, and then trying a tankful of E5, or using the stabiliser additive with the E10.

I am not that familiar with Zenith carbs, we have Solex, and have been using E5 Super Unleaded, not had any problems.
 
O
Shortmoor Landy said:
Originally had a problem with the Zenith carb running rich so went through the full strip down, lapped the mating surfaces then reassemble with new gaskets etc. actually did this on 2 carbs in case there was still a problem. Actually both carbs where great. Running very nicely. No more black smoke and much improved econony. However for some reason after about half a tankful of petrol (e10), I was getting a small bit of what looks like straw or paper blocking (inside) the main jet. Result was having to limp home on choke. This has happened in both carbs. I have two filters, the original glass bowl type plus one I’ve added which is an in line paper type. No change. Anybody know where theses bits are coming from? Are the gaskets inside the carbs disintegrating with the e10 petrol? Do I have to fork out for the e5 stuff? Any ideas would be most helpful.
Click to expand...
 
Hi, thanks for your replies. Firstly I do use the truck 2 or 3 times a week on average 20 miles round trip. After having to clean the carb several times I added the paper filter right next to the carb. No change - after a couple of trips same problem. Changed the carb, same problem. I have redex lead additive in the tank but I do have an updated head to cope with unleaded. The next stage is that I’ve fitted a little gauze filter over the main jet. Seems to be running ok so I’ll see what happens. The final stage I guess is e5 but I’m such a tight a… that I begrudge paying the extra £3 for a tankful😬
Getting tired of having to split the carb and clean it out every few days.
 
If you have hardened valve seats then any additive is a complete waste of hard earned cash.. spend that on e10 instead.. it'll run better
 
Which carb has an in built filter under the big brass nut near the front of the carb? Has a small gauze inside

You can get a non paper filter to rule them out .
 
1692814251898.jpeg
 
Turboman said:
Maybe a problem with natural rubber parts. But I don't know if Zeniths have any.
Click to expand...
There is a rubber (?) diaphragm in the accelerator part of the carb. Don’t expect it to be natural rubber though. This diaphragm has a paper gasket either side of it. I believe the bits blocking the main jet are coming from inside the carb somewhere and this area is the prime suspect. Maybe the paper fibers are held together with some sort of resin that’s getting dissolved? Might disappear over time and in the meantime I’m hoping my little internal filter will do the trick. Filling up again tomorrow and will see how it does over the next week.
 
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