When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Rebuilt nikki carb stopped flowing fuel through venturis, lots green gunk buildup
After rebuilding the carb I had the car running and idling about 2 weeks ago (it ran poorly, probably because of the floats/fuel level/needle valves, but I have since fixed that). So yesterday, after getting the fuel level correct in the fuel bowl and getting the needle valves to seat properly I thought it would finally have it running right. I ended up not being able to get it started, so I changed the plugs today and it fires up... and promptly dies. I can keep the car running fine as long as someone sprays starting fluid into the carb otherwise it dies immediately. So obviously I have a fueling problem. There is fuel in the bowls but for some reason it is not flowing through the venturi. So I pulled it apart and found a bunch of green gunk (oxidation maybe?) on the jets, air bleeds, and needle valves. The brass parts in particular seemed to be the worst. Keep in mind this was completely clean and did not look like this when I put it together a few weeks ago. The previous owner said they drained the tank and replaced the fuel lines. The inline fuel filter right before the carb also looks fine. I've put about 3 gallons of fresh gasoline in the tank (and some premix) so the gas should be fine.
This also isn't just some discoloration. I can run my finger across it and that green gunk comes off and is 3-dimensional if that makes sense.
Anyone ever see something like this before? I showed my dad and he said he'd never seen this before. I left a piece of brass in some gasoline so we'll see if the same thing happens to that I guess. I do not want to rebuild the carb again until I figure out why it is getting all gummed up.
That crap (obviously) looks like something severely oxidized the copper in those brass parts. You mentioned rebuilding the carb recently - what did you use to clean those parts? How did you clean them and how did you clean the cleaner off after you were done? For example, I think that lye based cleaners (like Purple Power) are not supposed to be used on copper or brass parts.
If it were me, I would get those parts cleaned up as soon as possible. The longer they are allowed to corrode, the more base metal you will lose...
Best of luck getting it cleaned up and back to working!!!
I would check the fuel system. First thing would be the fuel filter. If it's full of crud then time to start looking at the tank and everything downstream from it.
I used one of those chemical baths for carburetors with basket that you use to dip the parts in. I'll be checking the fuel filter at the tank tonight. Anything in particular I should look for?
I have never had that happen to me after rebuilding a carburetor and I've done quite a few over the last 23 years. I think perhaps it was the chemicals that you used to clean the carb parts. Did you clean the parts with water and dry them with compressed air before reassembly? I would think that the chemicals were still on some of the parts or in the carb and were allowed to sit in the parts and were not washed before reassemy. That or the chemical bath was sitting in parts of the carb that that you did not blow out or forgot about. That's my guess.
I used carb cleaner after the chemical bath and then blowed it with compressed air. Ironically I didn’t use water because I was concerned about rust. I did leave some brass in the gasoline I had in the tank over a few nights to see what would happen and that oxidized too. The container wasn’t airtight and it was left outside much like the conditions of a carb would be in.
I also got a look at the fuel filter.
Looks like the PO changed it right before me. I do have questions about the fuel pump and another thing that had hoses cut.
Is this an oem fuel pump? Obviously I will be fixing the wiring. And what originally went here?
this is right behind the fuel pump.
since the brass oxidized in the gasoline I think I’ll pull the gas tank, flush it, and go from there.
I've put about 3 gallons of fresh gasoline in the tank (and some premix) so the gas should be fine
What kind of premix did you choice? In the 80ties i have had nearly the same in the race dellorto carb of my cross bike. I changed the very expensive 2 stroke synthetic oil to a other one. Not sure there will be a chemical reaction with the carb cleaner and the premix.
In case anyone finds this in the future here is what I did and it so far it has worked fine. Drained and dropped the tank. Sealed using POR15 fuel tank repair kit (it has some rust inside). Sprayed brake parts cleaner down the hard fuel lines and blew out with compressed air. Replaced all soft fuel lines including the fuel ventilation system. Also removed the fuel pump rollover valve and sprayed brake parts cleaner and blew it out with compressed air. Then I got a new fuel pump, replaced the fuel filters, and rebuilt the carb again and haven't had any issues.
10-03-21, 09:59 PM
that is one batch of bad gas!!!
