VelvetKisses

ok so i have a 1984 rx7, 12a street ported, full raceing exaust with a header, quarter inch fuel lines, runing 2 psi fuel pressure, stock carberator but a holley air filter, all emissions have been stripped, the radiator fan is run on a seperat electric motor. ok

so thats a breif overveiw of the car, the problem im haveing is as follows, this morning went to start her up, turned over endlessley without a single pop indicating fuel igniting in the motor, checked the fuel lines, fuel was being pumped all the way to the carb. thought mb was no spark. pulled the pluggs, sparked beautifully. so at that point it apeared the problem was with the carb itself. its aproximately 23 degrees farenheit out, never had a problem starting in cold up to -5 f so i dont beleive the weather can be blamed. eventually though after about 5 mins of messing with it it started. i let her warm up till the auto choke kicked off, took it around the block and whenever exellerating in any gear around 1,200- 1500 rpms she hesitated, and twice when it reached 2000 she died. started back up just fine, only a touch of the ignition. so my question stands at this, is there potentially a problem with my carb? solutiions?

any help would be apreciated.

oh, the larger fuel lines might seem absurd running only 2psi, however i do have a 8 psi external raceing fuel pump followed by a fuel pressure regulator, so its not air pockets in the lines, woulda ran into this prob sooner if it was (project car so nothings as it will b when done)

VelvetKisses

ok, update already, not sure if its related, but my fuel gauge is on the fritz, its randomly reading between 3/4 and full tank. i have at most 3 gallons in the car. any help with the fuel gauge, related or not would be apreciated to

DivinDriver

iTrader: (15)

Stock Nikki carb needs fairly precise fuel pressure due to it's design, range being 3.7 to 4.7 PSI.

2.0 is considerably low. You may simply be running out of fuel in the bowls.

Try throttling up while watching your sight glasses on your carb bowls. If the level dips as you rev unloaded, you're starving on fuel.

Fuel gauge issue is most likely a failing sender, but could be an intermittent connection as well.

VelvetKisses

were running 2.0 because any higher it was flooding out below 3k rpms. ill try tweeking the fuel pressure more towards what u recomended, however this problem is recent and ive had it at 2.0 for about 4 months now without any problems. as far as the failing sender u recomended (parden me but i guess im still fairly new to some things) were would i look to find/ test to see if that is the prob? i apreciate the help man. ill keep u updated

Jibaro 12A

iTrader: (8)

Listen to this man. He knows what he is talking about.

DivinDriver

iTrader: (15)

The fuel sender is located on the gas tank, next to the fuel inlet. You get access to it by removing the rear fender liner on the left rear wheel. When they wear out, they generally develop dead spots. There's a testing procedure in the FSM.

As far as your fuel issue, that's a tougher one since it developed recently. Could be that the change in fuel viscosity with the cold temps was enough to make a difference - - or that your FPR doesn't like the cold and so is restricting delivered fuel. You might even have some ice in the lines from wet fuel. Checking the bowl levels will tell you if it's a problem with enough fuel getting into the carb. Then you'll know which direction to look.

I've heard tell that a lot of FPRs have trouble operating accurately at lower pressures, too. I don't use one so I don't have direct experience with them.

A Nikki flooding out at anything less than around 4.5psi might indicate a clogged return line, or a reverse-mounted check valve in the line, bad needles/seats, or some other issue.

VelvetKisses

ok so today i found a kink in the fuel line today, went ahead and replaced the section, checked the aftermarket fuel filter etc, not any of them. divin i think u might be on to something with the idea of ice in the lines, i did run it pretty low a few times, however i do beleive that running heat through it for the last 2 refills should have fixed that, im hopeing its fpr, tomorow im going to take the time to inspect the carb, make sure everythings ok with it. the bowls drop only slightly under throttle. ill also see if i can find/repair/replace the fuel sender.

DivinDriver

iTrader: (15)

One of the gents here had a photo-documented thread on removing/cleaning/replacing the FB fuel tank; the first part of it gives very clear photos of exactly how to get to the sender. Might help save you some time.

VelvetKisses

well i got to the sender, it was almost encased in ice, i thawed it out and now it operates normally.

DivinDriver

iTrader: (15)

That much ice inside the tank would lead me to think that your other problem might be getting complicated by a heck of a lot of water in your fuel, too.

Lot of ethanol in the fuel in your area? High-ethanol fuel is hydrophilic, and can undergo phase separation, especially in cold weather.

http://fuelschool.blogspot.com/2009/...l-blended.html

trochoid

iTrader: (6)

Very interesting info DD, never heard of Phase Separation. VelvetKisses, if you've been running the tank low frequently, the water can accumulate, freeze, then leave all the ice build up you found. I suspect your FPR isn't reading true @ 2 psi. Fill your fuel tank, add in a can of Heet and Seafoam, then park it in a warm/heated garage to thaw out. Before filling the tank, I would thaw the car out and drain the fuel tank to remove any residual water.