ItalianFedRotary

I'm having a problem with my dellortos. I'm running lean in my top end now. Before it was prefect pre my Autometer Air/Fuel gauge, three green and three yellow. I've rised my fuel presure and that didn't work. what else can I do to fix it? I'm thinking it might be a pluged main jet.

diabolical1

iTrader: (3)

what pump setup are you running? if everything is fine until you get upstairs, then it might be a volume problem. i mean, i'm thinking if you have an air/fuel ratio gauge, then you probably have a good pump setup, too, but i figured i'd start with the obvious, then work towards the less obvious ...

also ... check out www.gruntled.com

ItalianFedRotary

I don't know what the pump setup is at. I bought the carbs on line, and just through them on and they were perfect. All i had to do was adjust my idle mixture and that was it. How would I check that?

diabolical1

iTrader: (3)

oooohh ... well then, i'd start there.

if it's the stock pump, you will run out of steam by the time you get to around 5,000 RPM (and that's assuming that it's working perfectly) if lack of fuel at high RPM doesn't kill your first, then the Dells will kill your stock pump in time! it's that simple!

you have two main choices on pumps and i'm sure that people will argue back and forth as to which is better, but ... they both work, i can say that because i've used them both.

you can get a single high-flow, high volume pump like Carter or Holley (do a search in the forum to the part numbers) or you can get two universal replacement pumps (Facet, NAPA, etc.) and mount them in parallel.

carter and holley push ... like ... 7 psi
the others usually push between 4 and 6 psi

if you choose to go with the single pump, you'll need a lot of patience because you have to scale the pressure down ... A LOT. but you only have one pump and the volume is no longer an issue. the carter pump is cheaper than the holley (and everyone says its more reliable, but i can't say for myself) i use a carter with my Dell'Orto and my brother uses a Holley with his Holley ... both of us still have some fueling issues!

if you go with 2 pumps in parallel, then you will still probably need a pressure regulator, but you "SHOULD" have less headaches when it comes to tuning ... but don't take that as gospel!!!

either way ... check out www.gruntled.com and there is another site, http://personal.riverusers.com/~yawpower/access.html

both sites are very helpful (at least, i think so)

SilverRocket

EDIT: I was still writing when Diabolical posted, and I had pretty much the same ideas...

BTW, the Carter is supposedly much better than the Facets or whatever. There's nothing horribly wrong with the Facets, and I've seen them in action with good results, but there's no doubt the Carter is superior. It's also not too expensive and reputed to be the best option, so I'd go with that. I like mine a lot

Oh, and don't worry about tuning down the pressure, it isn't an issue. Took me a few hours to get my fuel pressure dialed in perfect, based on a bunch of experimentation with different settings and test-driving each one. Again, better to have the pump that flows the most. It'll give you more flexibility for the future if you ever want to throw in that ported 13B.

Anyways, I'm no expert, but here are my thoughts...

If you're running a stock or otherwise inadequate fuel pump, fuel pressure will fall off at high rpm and cause what you're describing. The stock fuel pump is located under a metal plate/cover, near the driver's side rear tire. An aftermarket pump should be mounted on the side of the framerail closer to the gas tank. RB also made some dual Facet pumps that mount in the stock location though, which they sold as an add-on for the Dellorto kit. Better check what you've got.

You should know that the stock pump is *entirely* inadequate for the Dellorto, and you shouldn't be flooring the gas for longer than 10 seconds or so if this is the case. Sounds to me like you gotta make sure what you have on there is adequate for the job, and upgrade if it isn't. A good setup that many of us run is the Carter 7psi Street-Race pump with a Holley FPR.

Also, you're saying you didn't rebuild the carb? In that case I'm sure this could be any number of things... better to rebuild it and start with a clean slate, that way you'll know what's going on in there.

ItalianFedRotary

Um..........well, the thing is, is that I have the Carter Fuel Pump, Aeromotive pursure reg. dialed in at 4.5 psi. I ckecked out www.gruntle.com and pulled the specs for my setup, Dellorto 48mm DHLA for a 13b 6port. ( I have an 84 GSLSE) And everything is what the specs are. BUT............the good news is that it's fixed now. what was happing, was that my charging system was fried. I was only push 12.5 amp out of my alternator and my O2 sensor, ect( everything else in the car) wasn't getting enough power, odvisously. So I got a new battery, alternator, starter, and it works just fine.

But on another note.... this morning I was going to work, and I stopped at a lightand it had just gotten to Normal Operating Temp. And it acted like it wanted to die. RPMs droped to about 500-600 from 1000 and once I got on the gas its sputted til about 2500RPM. What could that be? my Air/Fuel Ratio gauge stayed the same.
By the time I got to work it was fine, great pick up and smooth acceration. Wierd huh?


I know I should have rebuilt the carbs, but I didn't want to mess with them because I bought them with the intension to learn before i installed, but my FI system took a **** and they were sitting on my work bench. It took me a full weekend to get them in and running correctly. So I'm learing as I go. And there is a company here in Tucson, AZ that sells Polyurathan(sp) rebulid kits for them, for turbo applications. I'm just lazy and haven't bought it yet.

I've also talked with Paul at Yaw Power Products, I live in the same town, and the only thing he was able to help me with was general info, like what is on his web site.

But it's running good and strong now, just alittle wierd sometimes.
Also to see my engine it'll explain a lot. find my first post, " New to the forum." and i has my engine pic on it. I would have put it on this one but i can't find it now. So I'll take a new and put some place safe, like a burned CD.

SilverRocket

After it's first warmed up, and only if it's idling for a little while, mine will stumble a bit when I first touch the gas. I've heard of others' doing this as well, I wouldn't worry about it too much.

That's great that you fixed your problem!