Bob Holton

OK, Here goes. My baby is an 85 GS total stock. 78 k on i t. when cold ,it will run ok start ok some white smoke, careful accel no probs, push it to 4k and it runs out of poop. stop and swear a moment and it picks up and goes. when up to operating speeds,, it will run fine until you punch and hold it and at 50 or above and about 4krpm it doggs out and feels like I have run out of gas. does this even without punching it ,just strong acceleration. Back off and/or drop down a gear and it will pick up again after a looong pause. plugs are new, filter is new , sock in tank new. fuel pump is stock wired direct to hot side of front coil. I am not its first owner, the car was totaled by an ethnic college student who thought that cruise control meant hands off operation ,was professionally repaired. and inspected. Now my first thought is to replace the whole fuel line from tank to carb with a larger diameter , thus more flow. Pump and regulater ,pricey but maybe. are there any other places that flow could be restricted? filter at carb? Oh yes the carb has been professionaly cleaned by a good boinger mechanic. At this point I am about out of altitude airspeed and ideas, but dont really want to crash and burn. Sorry about the long post. thanks Bob

mazdaverx713b

iTrader: (91)

does it differ with the amount of gas in the tank?

Bob Holton

no quantity of fuel does not matter.

mazdaverx713b

iTrader: (91)

how many pounds of fuel are you running, meaning whats your fuel pressure set at?

Bob Holton

stock ,probbly 3.5/4

Sterling

"sock in tank new" -What does this mean?

"fuel pump is stock wired direct to hot side of front coil" -Is this according to someone's instructions here?

I suggest you change the filter again -0Just to eliminate it as a variable for 2 reasons; It's only a couple of bucks and some gas in yer eye, and people here can attest to changing their filters only to find the new ones were clogged only weeks later.
-But I don't think that's your problem.

Remove the larger diameter hose to the fuel inlet plubing of the carburetor, and let it flow into a pale when you turn the key on. You should have a good steady pour leaving little doubt about it satisfying the needs of your carb.
If it's even remotely questionable, then you'll have to measure the output.
You may have inadvertantly cooked your fuel pump with a non-stop, unregulated voltage that can fluctuate between 10 and 16 volts...A WILD GUESS on my part, as electrical systems are not my forte.

You mention "white smoke" which says to me right away that you may be experiencing the "rotten "O" ring thang"...the rubber "O" rings located in the intake manifold gasket may be on their way south, causing coolant to enter the engine.
Do a search on this, and it's a ten dollar fix good for another twenty years. (& no permanant damage is done to your engine, either.)

This could be helping to cough up carbon, but also keeping the exhaust cool if you've experienced loss of coolant. Which leads me to....

The possibility that your cats are clogged with carbon and gunk. Inside the cats are honeycomb screens lightly electroplated with platinum. These get gunked over with too much oil, or an over rich mixture, and renders them ineffective as catalysts in the changining of exhaust gases.
The gases will still pass through, though you may fail emissions. But the holes will get smaller and smaller in the screen as exhaust residue is deposited, eventually choking the flow of exaust.

-If the engine can't exhale, it can't inhale.

But start with the fuel flow first, then someone can help you check the exhaust situation. Perhaps in between, someone should help you check over the ignition just to make sure your plugs are hooked up correctly, timing set, etc.

Rx7carl

If your pump is wired to the coil (bad idea BTW) that means its in the engine compartment? Another very bad idea. The pump isint designed to suck fuel from such a long distance, its killing it and probably whats hurting your output under high demand. And running it off the coil is killing power to the pump and/or coil. Put the pump back where it belongs and wire it correctly.

Sterling, hes talking about the screen filter in the tank when he says "sock".

Bob Holton

Thanks for the help guys. The pump and filter are where they belong, the wire from the coil is ,(I think , someones idea to hear the pump run when you turn the key) I will look under the box in back to see what wires are available , Fuse's are ok now.Rod the cat? ehaust system is stock with 70K on it,except for muffeler.If I should have to go to a new pump , what do you and Sterling suggest,Carl? last check I was getting 22 mpg. and like the teenagers on here , at my advanced age I am sort of penny poor. Pump should not operate until engine starts right? wish Haynes had better labeled diagrams. Will check all this out. lonesomebob

All_Terrain_RX7

Except for the white smoke, I had very similar symptoms a few years ago in my stock '82 GSL. Replacement of the fuel filter corrected it. Moderate or better acceleration out ran the fuel flow. Engine would start sputtering. I could let off of the gas and the engine would resume normal operation. Highway speeds above 55 would also end up with sputter. As long as I stayed below 55, and accelerated gently, I could drive for at least 30 minutes (my commute) with no problems.

Sterling, RX7Carl, and others with more carb experience than me may have a better suggestion, but here's something to try. If you can see the windows on the bowl on the carb, you could make a run until the sputtering starts, and then pull over relatively quickly. Shut the fuel pump down, and look in the windows to see the fuel level. If you are "starving" the carb, the level should be low. If its at normal level that would suggest fuel delivery is ok. Low cost test no matter how it turns out.

I had an aftermarket cat clog up a few years ago. Response suffered throughout the RPM range. Just like Sterling said, if it can't exhale, it can't inhale. My work schedule caused me to just live with it a while. It got to where it would not even idle right. I was inspecting the intake side when I noticed the cat glowing.

Sterling

In theory that's a great idea, but unfortuneately the fuel flow from the pump is too fast for that to be accurate. There are other variables at work, as well, that could make this an unreliable test.

It would be really great if you could see the sight glass as you were driving.
Man, THAT would solve alot of problems!

purple82

Rig up a video camera!

Bob Holton

Cats? how do you suggest that I open it up? Replace ,with what? Today I ran it down to the 1/4 fuel guage mark and darn near ran out of gas. Filled up at2.12/gal god! I rember 15 cents /gal a looooong time ago. and it ran much better but still would goof off at 60.

Sterling

O-o-o-o-o-old man!

New rule...If a youngster like me can help a wise elder like you with your carb (...the only thing I know much about aside of metalurgy...), then you have to repay me with words of wisdom.
Deal?

Well, do they have emissions visual inspections there?
Replace your whole exhaust system with the most satisfying 750 bucks you'll ever spend on your car and get a Racing Beat header exhaust system.

Looks like V8Kilr is working on an exhaust system that may rival the RB, but for less, and that may be worth waiting for.

If you just want to replace the cats with a pipe, I don't know what to tell you...aside of the fact that you can purchase bits of the Racing Beat system individually.

Let's find out if you have other problems, first.

Bob Holton

Sterling ; I have been informed by my Grandchildren that words of wisdom ae not needed , as the younger generation knows all there is to know. Sounds like an echo from 60 years ago. My father smartened up so fast after I hit 20. Yes you have a deal, I just need to know the age gap?. Will start on Monday to see about the pump wireing, then the filter shows a few specks in the bottom, removing the tank is no stranger to me. how can I check the cat for clog? We do not have inspections here in MI. So what can I tell you? Bob

cdrad51

cat replacement pipe from RB = $110
shipping = $20
driving in an emissions free area where you can get rid of the cats = priceless

Tony Silva

I've had a similar problem on my 85 GS. I couldn't figure it out, till my dad suggested that maybe the carby's vacuum secondaries were getting stuck during driving situations. So I looked into that possibility, and sure enough that was the problem. Come to find out, it was the secondaries vacuum diaphram that had some how gotten a hole in it and was leaking a whole lot of air.

Tony Silva

chalk one up for the words of wisdom. My fathers.

Sterling

Highly unlikely that the Nikki diaphragm has a hole in it.
HOWEVER, VERY possible the secondaries are being kept from opening due to binding linkage, etc.

Bob Holton

Words of wisdom. Having a hole in a diaphragm can lead to paternity as well as loss of pressure or vacuume, and when found it is usually too late. There you go Sterling. Bob

Sterling

Too little wisdom too late, Bob!

Bob Holton

Better late than never for these young bucks on here. Know anyone that needs a louver? Will start at the tank and work foreward this week. with gas at 225/gal cant afford to drive it anyway. Bob