Ask David and Farrar: Technical Questions and Advice About Carbureting a DeLorean

[thirdmanj]

I never saw the nasty back and forth messages on the forum. All I know is I got a nasty PM from "Earl" this morning, I posted it for the world to see, and within an hour or two "Earl" had been banned. This truely is a Nazi forum.

I shoulda posted mine and Earl's pm conversation too. But I'm glad yours did the trick.

[stevedmc]

So stop posting here then if you object so much.

Huh? What are you saying I object to? I would have enjoyed seeing the drama.

[opethmike]

How is calling it a Nazi forum not objecting? Bringing Nazis into it is pretty severe!

[thirdmanj]

How is calling it a Nazi forum not objecting? Bringing Nazis into it is pretty severe!

Godwin's Law strikes again.

[dvonk]

Godwin's Law strikes again.

[stevedmc]

How is calling it a Nazi forum not objecting? Bringing Nazis into it is pretty severe!

Chad is a Nazi.

[Ashyukun]

Well, not to distract from forum drama, but...

I've not posted anything about it yet, but with the 850 mile drive down to DCS in a bit over a week (I'm going down early for a short vacation on the beach...), I thought it might be wise to put this down for others to think about/discuss.

Last summer I started having some weird issues with the car- it was intermittent at first, and then got worse to the point that it was undrivable when it would act up. It would idle halfway normally, but would then stumble and hesitate around 3500 RPM or if I tried going any higher. When it REALLY acted up, it would simply not start at all. I initially thought it was the choke, but no adjusting fixed it. I played with the mixture screws, and no luck there either. I consulted with Bill about it, but he was firmly convinced that it had to be ANYTHING but the carb that was causing the problems. Eventually I tracked down a shop with an expert on carburetors, and the car spent most of the winter months there (they didn't work on it nearly all that time, I just didn't push them much at all on it so they didn't prioritize it).

Eventually they worked out that they thought the problem was that the fuel pump (the standard Autozone low-pressure fuel pump) was putting out to much pressure and was forcing the carb to run extremely rich by dumping fuel down it (and the plugs corroborated this diagnosis). Some research found that the carb doesn't want much over 6psi, and the pump can put out up to 9psi or so. I had a few low-pressure fuel pressure regulators due to needing to solve a similar issue with a SBC in another vehicle, so I had the shop install one of those set to 6psi (mounted to the valve cover and in line between the fuel filter and carb)- and the car has run like a champ since then.

I figured it was something the others with the same fuel pumps and carbs might want to know- it's quite possible that I just have a really touchy carb or that I've just had pumps that have put out more than they should pressure-wise, but it's also possible this is something others might encounter. Thankfully it was a rather inexpensive fix parts-wise (and the shop didn't charge me that much more than an in-depth diagnostic fee).

[stevedmc]

I'm wondering if a rebuild would have solved the problem. The rebuild kits come with a new needle valve that has a small gasket attached to it. It is possible the gasket on your needle could be getting worn out.

[Farrar]

When my needle valve was not properly clipped, I had the opposite problem -- fuel would spill out so fast that the bowl would fill and the engine would die at idle. That was definitely my fault, by the way -- I wasn't paying attention when I put everything back together.

You could perhaps purchase a small adjustable fuel pressure regulator and set it to 6 PSI, which is what I am told the 2100 series carburetor prefers. I was thinking of doing that myself when I have $35 to spare on an experiment.

[dvonk]

i had a similar issue with fuel pouring out of a carb and flooding the engine after a rebuild... turns out the float arm wasnt properly adjusted and the needle wasnt seating fully; thus not sealing off the fuel flow.