we put a holley 650 cfm double pumper carb on top of a camden supercharger it runs great except it is hard to start when hot any sugestions

 

Probably getting vapor lock, a problem found on low pressure fuel lines and carb setups.

Try insulation on the fuel lines (in the old days on my old RA64 Carb'd Celica, we used a cover of nylon braid followed by a small heater hose to insulate so you had from the center out- fuel line, nylon braid, heater hose) and then re-routing them away from any heat source.

 

thanks man , will try!!!

 

well i have looked at all the fuel lines they seem to be up and out of hot areas, put a spacer between, the carb and the blower , now im going to try some heat fabric and place that on the bottom aspect of the carb below the floats , see if that may cool down the fuel abit.

 

well did the heat rap on the lines even on the bottom of the carb , and around the floats. it does a little better but im still at a loss. anymore thougths icemark.

 

The most common cause of flooding in rotaries is low compression, whether fuel injected or carb'd.

You could also have a weak ignition or worn/partially fouled plugs from a previous tuning attempt.

 

man i tell ya , im at a loss here , we checked compression both rotors at 120. so not a prob there, we have tryed setting the jets at different settings still no responce, the car starts on first crank, but after that it wil start but has a hard time. we have rapped the carb and fuel lines , thinking maybe theres some vapor lock going on , that help alittle. but still the car runs like its stock. now here we have a supercharger, with a holly 650 cm, header guded cat, holly fuel preasure pump. we took it for a spinn today rev to 7 grand , dropped the clutch and it took off like a old lady in a wheel chair race, the back dropped . but with all this in mind that ****** should have smoked the back tired like no tomorrow, we are thinking may its the blower. now threw my experience talking with people on here and where in from ,the blower should always show positine displacement, but it doesnt . when we flo0r it it does but at idle its showing vacum, now correct me if im wrong , but a blower should show positive displacment at all times. now with all that in mind please give me some inpute on what im doing wrong !!!! anybodys help is greatly needed. thanks rx7fromcal

 

it idles great when started, and holds a great idle all the time since we puts the carb on,now we are thinking the pullys is to big. not allowing the blower to spin fast enough on start up, and maybe the pully should be smaller so it wil give more boost and displacment on start up. tell me what you guys think.

 

and the hot start is still only when warm/hot right... not at any other times??

 

well , now it wont start again, my guys thinking, that when all this started it was with the map ecu, when it was hooked up . we are thinking that it shorted something out in the stock ecu, we have checked everything, and all checks out good . except for today we check the signal going from the ignition to the coils and its got a low signal, maybe there for making hrd for us to start, if that makes sence???? and that signal is controled by the ecu, and thats when all this crap started, so we are at a loss, going to the junk yard on monday to pick a ecu out of a car and see if thats it, who knowssssssss!!!

 

You're still running the ECU? I thought you switched to carb? So with a carb don't you run off a distributor rather than coils? Or are you running the ignition off the stock ECU and the fuel off the carb or something?

 

still runing off the stock ecu with the carb.from what i understand u can stil run a carb when still using the stock ecu

 

correct me if im wrong on this guys, im at a loss here.

 

ice mark to answer your question , it does it on first start up also, not just when its hot, im loading my shot gun as we speak to pump some buck shot up its ***, lol

 

How about upgrading to that new-fangled EFI whatsit...

 

No, a roots blower will NOT always show positive pressure. At idle the charger shouldn't be getting any air to compress, and should be bypassed. Do you have a competent mechanic who can tune a carb?

 

Ahhh, now we are getting somewhere.

what are you using for a fuel pump, Since it is happening when both warm or cold starting, I am thinking the fuel might be draining back

 

im usung a holly fuel pump, thats what we were thinking also that it may be draining back , but it seems to be getting fuel, but agian ill go back and check that again!!! im pretty sure its not because we have the return line plug so it wont do that.

 

sounds like too much damn fuel. what is your base pressure? dont go over 6psi on a holley and nothing under 3 or 4psi really. holley's are finicky creatures also, your floats really need to be dead on, make sure they are not too high and letting in way too much fuel. because it will run like that, but not crank. i had the same problem. and, check your idle screws...make sure they aren't turned out more than a couple turns. word..

-zac

 

preasures at 6 psi, thing was running the other day took it out for a spin . got back then it wouldnt start, im soooooooooo tired of working on this dam thing , lol. we are thinking somethings going on with the stock ecu , being that it ran piggy back on a map ecu for a bit , this is when all this **** started. so going to pick up a stock ecu at the junk yard to see what that does.

 

i still dont get why your ecu would affect this? but, give it a shot.

 

Should've kept the EFI, and found someone competent of installing/tuning your standalone (Wolf, wasn't it?)

 

na it was a map ecu, lol

 

Ah, think I confused you with snub.

 

no prob, id like to know how hes doing with his also.