hey guys,so i have been running a set of dellorto's on my 13b for almost 2 months now and have been loving it. however, my FPR gave out on me last Monday and fuel pressure dropped to 2psi while driving and caused the engine to cut out,popped the hood and seen the pressure gauge at 2psi. No big deal,i went to the locala advance auto parts and ordered a new holley FPR,unfortinitly,Advance and the local Autoxone,carquest and napa all just stopped keeping holley pressure regulators in stock less than a week before i need one. so i had to order one from advance auto and wait for it. unfortinily 2 days later when it arrived,it was the wrong one, so the waiting continues. i finaly get the right one and slap it on how i had it and adjust the pressure roughly to where it should be and turn the key over.with the fuel pump on building pressure i adjust to 4.5 psi the way i was running it (Carlos Gonzalos of GNS racing looked at my set up and recommended 4.5psi) and as the car starts up,it has trouble idling and shaking like crazy. i thought no biggie,its been parked all week and has carbon buildup,it'll be okay. so i finaly convince it to idle on its own and start checking out the engine/carb. i notice that teh front intake runner on the racing beat upper is freezing cold.almost to the point of burning so cold and the rear is at a normal cooler temp like it normaly is. so why is the front runner so cold? i lookl down the barrels through the velocity stacks when i notice that the front TB is dumping fuel like a facet and the rear is spraying fuel like it always has. i pull the cover off the float bowl to see if the float is sticky,it wase't. so i pulled the fuel jets out to clean thinking maybe some junk in the jets causing trouble...no difference. i pulled the carb off and started taking it apart. i got to the pump on the underside and it looks like it has been replaced before (the guy i bought the carbs from said it he replaced it,but didnt have a receipt or pics so i didnt believe him). i then double checked the o-rings on the jets,they appear fine.so im looking at this set up verry confused.im not sure whats causing the front tb to flood while the rear is working properly. please if anyone has any suggestions or ideas,any help would be muchly appreciated.oh also,after i shut the key off,the rear tb quits getting fuel,however the front tb remains to flood fuel for about 45 seconds or so before it finaly stops. the motor is 13b 6port in a 88 fc rx7,but since its a carb issue,everyone says to post in the first gen sections,thanks in advance

 

Done this to my car a few times, if you set the pressure too high and when you first turn the key to ignition and let the bowls fill up the pressure overpowers the floats causing the bowls to empty directly into the barrels via two small holes about 3/4 of the way up the central stack in the middle of the bowls where the main jets are.

1. 4.5 PSI is too much, 3.5 PSI is about the max that the floats can handle before they will overflow so chances are you were skating on thin ice for the few months the car worked.

2. Check your float levels and check the condition of the floats themselves, if they are pitted, flaking etc, you might want to look into ordering a new one, they are pricey and have to be ordered from England but can be done.

3. Ahhhh the wonders of the frosty manifold, it's all the heat being transferred from the manifold into the gasoline, kind of like when you get rubbing alcohol, brake cleaner, carb cleaner or gasoline on your hands and it feels cold? That and IIRC the manifolds are cast aluminum so they get cold as ***** anyway.

Hope that helps

 

how about creating a new paragraph per topic or at least use bulletpoints, and get to the point.

 

yea sry bout the continues typing without spacing or bullet points. i guess i didn't realize how much i had typed. so if the leaky bowl was caused from too much pressure,how come only one tb was leaking? i had replaced my fuel pressure gauge as i put the new pressure regulator on,maybe the old pressure gauge wasn't reading properly and then when i put the new fpr and gauge on,it was accurate and problems began.thanks alot Darren.im gonna slap the carbs back on and lower the fuel pressure and see what happens.

 

Atleast with my car the carb isn't perfectly level, IIRC it does sit slightly forward so the front barrel is the first to flood then the back one.

 

okay, so i got it all back and turned the fuel pressure down to 3.5 psi and tried turning it over,she was still flooded from earlier.i pulled the plugs and am in the process of cleaning them up.im letting them dry out and i'll try again later.

 

okay so after cleaning up the spark plugs and re installing them,turning the fuel pressure down to 2.5 psi,it's still flooding the front barrel. now though,it's flooding like a facet up to 2 minutes after shutting the key off and killing the fuel.i didn't visualy see anything wrong with the internals of the carb while i had it apart. i am completly stumped on this one. any ideas or suggestions will be extremly helpful. i am willing to attempt anything at this point.thamks in advance guys.

 

Where exactly is it flooding from? the inner venturi that hangs in the barrel or right infront of the throttle plates?

If the inner venturi that hangs down is where its flooding from then it's likely still overflowing

If its flooding from just before the throttle plates then it might be your accel pump check ***** or jets that are stuck open.

 

it's flooding from the inner venturi. it's like the venturi is a water hose just pooring fuel.it'll literaly leave a puddle inside the barrel. how would i check the to see if a jet is stuck open? i had pulled them out earlier today and cleaned them up.....

 

What you can do as a test to see if they are indeed leaking is to take the cap off the bowls, get some gasoline into a bottle or cup or something and fill the bowls up to the holes in the side of that central tower that can act like an overflow that drain down into those central venturi.

If you fill it up to the holes and nothing happens then you likely need to reset your float levels and make sure they aren't sitting too high and allowing fuel to fill up WAYYYY higher than they need to be.

If you fill it up to the holes and it starts flowing before you get to the holes then well...I'm not really sure whats goin on as that makes no sense.

Here's a great page that explains how the transition from idle to full throttle and how the fuel flows through the carb body.
http://www.motorcyclecarbs.com/Dello..._W168C1334.cfm

As far as how to set your float levels, in this thread it should be covered:
https://www.rx7club.com/forum/showthread.php?t=896075

I have school and work all day tomorrow but on Tuesday if you need me to take a few pics or make a video what to do then let me know and I'll take a swing at it

 

sounds like the needle and seat is bad/sticking if it floods at low pressure

 

my opologies. it is leaking from just in front of the throttle plate on the front barrel. i thought it was leaking from the venturi but i was wrong.my vision is a lil off and can't offord to get glasses at the present time.i had an extra set of eyes and they said leaking from just in front of the throttle plate. so that means...? i had pulled my plugs out again and this time i had tossed them into a pot and boiled them,cleaned up nicely. i actualy had the car running,idleing on its own and watching the fuel just leak into the barrel.

okay,so tomorow after school i'll check the floats again and test the bowl with a cup of fuel.after that i'll try reseting the float level to hope for a cure,that is if after reading the thread if it appears that the level is off. i know a couple of sites where i can order parts from,but i need to kno what to order.

thanks alot guys

 

You really want that fuel pressure to be 2.5 psi +/- .5 psi at the most.
Anything over 3 psi affects my idle which means the needle is not seating
well at that pressure.

If you've recently acquired that carb I would recommend getting a full rebuild
kit from dellorto.com and going thru the whole carb at this point.

BTW, in 90 degree weather my intakes are ice cold normally. So don't let
that fool ya. The length of that intake and the sharp curve make the gas pool
on the inner surface and cause a lot of cooling on the intake. Its the nature of
that manifold and this carb.

Below 45 degrees you have to be aware that icing can occur as well but once
its good and warmed up its not a big issue.

 

Replace the needle and seat.

 

does anyone know if the needle and seat are available maybe interchangable with any other carb? it's gonna take up to 2 weeks to come in from overseas and this is my daily driver. also,which needle and seat do you guys recommend? 1 site said to use the 3.5mm thats typicaly used for gravity bled motorcyvle carbs on a rotary engine. any idea what dell'orto origenaly ran on the racingbeat version?btw,i didn't get to try the fuel in the bowl thing as i was at school all day taking care of some financial aid paperwork and dealing with bs. thanks guys

 

I use a 2.5 in my weber. Should be about the same.

 

Order one from cb performance. Also check to make sure your fuel pressure gauge is accurate. I lean more towards fuel pressure issues than a bad needle seat. But it only takes a few minutes to check the float level. Also remember we need lots volume at low pressure and most malloy, holley etc after market pumps are designed to rum at higher pressures.

 

i've been on the cb perfomance page but they don't have it specified as needle valve and seat,they only have a listing for "needle valve (specify size)". is this the right part? or is it what they call a "float pin"? is that it,because that thing is cheap. on this site http://www.dellorto.co.uk/merchandis...artsectionID=1 they specify needle and seat but have 3 available im not sure which one is the correct one. any ideas?

 

Get the 2.50, it's the closest to 3.00 without going oversize. Many people have used that size with no problems. From the dellorto.co.uk site it's the part number below. See the .250 at the end of the part number, that is the size.

(13) DHLA Float needle valve and seat Part No - 8811.250 £10.95

Don't get the 3.50, it's too big and will flood. Unnecessary.

Be sure to set your float level and before you order, inspect your floats. If they have punctures, cuts or are horribly bent then order a new one with your needle and seat.