'81 Celica GT Surging and Dying

JahLive · 03-17-2008, 09:20 PM

Quote:

Originally Posted by qldit

Good Afternoon richardk, shouldn't see that problem happening, must be getting expensive to run!

I would consider checking the actual float level, it is possible the fuel reservoir level is too high.

I don't know what the level setting for that carb actually is, but as a rule of thumb it is generally about a half inch from the top lip.

I like fuel pressure regulators being used, it often helps to stop surging of the float valve and helps to keep a more regular fuel level, but that is just an idea.

This is just a guess at what may be causing the problem.

Others will have different ideas.

Cheers, qldit.

Hello qltd,

i was hoping you might be able to help me with an issue i'm having with my 34DGEC?

i have an '81 Celica GT, 22R, Bosch Elec Fuel Pump, (Non-Dial/Not Mr Gasket) Tee Fuel Regulator W/return Set to 2.5, Stock everything else.

Fuel pump is right at the tank.

i took out the original mechanical fuel pump and installed the tee regulator.

all vac lines are sealed off accept smog, which is not hooked up.

HERE IS The ISSUE...

it starts right up no problem,

idles fine a little low when cold but right at 1100 when warm.

i usually let it warm up before driving.

put it in gear and ....

reverse is fine.
1st still good.

2nd gear it start to surge and die.
i push in the clutch and i can rev it up to 4000+
let the clutch out and surge and die.

then if i push in the clutch and don't rev it it dies.

i pull over and start it and it idles fine.

I ALSO NOTICE IT'S RUNNING REAL RICH.

WHITE SMOKE OUT THE TAIL PIPE.

vicious cycle.

please help.

sorry this post is so long but i needed to explain it all.

thanks

j

**qldit** · 03-18-2008, 12:10 AM

Good Afternoon JahLive, The description you make is actually symptomatic of fuel starvation but I can't explain the white smoke.

I would be inclined to disconnect the fuel line from the carb and ensure it can pump significant fuel into a receptacle from that point, you may need to use a bit of tubing properly fastened to the fuel delivery.

It should pump in the order of a pint in a minute or something like that order.

The pressure should be relatively good if you block the flow with your finger.

If the flow and pressure looks OK and in view of your description I would then suspect there is either a restriction in the fuel entry to the carb, the float valve is hanging, the pressure regulator is set too low, or the reservior fuel level in the carb is incorrect.

In the lower gears fuel stavation is less pronounced, but as soon as you shift into a higher gears it becomes very evident and won't sustain operation increasingly.

Now assuming the vehicle operated properly before you fitted this different pump there are some considerations, firstly the pump may unable to supply sufficient fuel, this should be determined by the check mentioned.

The next and most likely (in my opinion) would be that foreign material is lodged in the float valve which I think may be removed from the outside on that carb, if not you may have to dismantle the carb top and check it there.

Does that carb have a window on the side to check the reservoir fuel level, if not the normal kind of expectation is to maintain a level approximately a half inch or five eighths of an inch below the top.

A next check would be to disable the fuel pressure regulator possibly by blocking the fuel tank return line. It is possible the actual fuel pressure is insufficient to provide enough flow to the reservoir in a driving condition.

It should be remembered that some electric fuel pumps are designed for pushing fuel and others for pulling, but generally this does not seem to make all that much difference. You should get an idea from the flow check.

I suspect there may be some reason for that white smoke that may be determined doing these tests.

By the way we call Celicas, Sillycars here it has no bearing on their integrity.

Others will have different ideas.

Cheers, qldit.

JahLive · 03-19-2008, 09:01 AM

Quote:

Originally Posted by qldit

Good Afternoon JahLive, The description you make is actually symptomatic of fuel starvation but I can't explain the white smoke.

I suspect there may be some reason for that white smoke that may be determined doing these tests.

By the way we call Celicas, Sillycars here it has no bearing on their integrity.

Cheers, qldit.

Thanks For the info

i spoke to a weber tech this morning he is sending me a smaller jet set.

i live in higher altitude and it is possibly flooding out the carb with the original jets being for sea level vehicles. also explains the white smoke.

i have also read a few places that these carbs 34dgec you have to replace the jets in order for it to function properly.

hopefully that will fix it.

thanks again.

J

**qldit** · 03-19-2008, 04:35 PM

Good Morning JahLive, I gather that is not the original carb for that machine, actually a lot of those celicas were pretty "gutless" or "doughy" to drive but I never altered one because the critical nature of the systems in them.

I really didn't feel it was a carb kind of problem so much as all the antipollution stuff and the overall design.

I gathered that you weren't having any problem starting it after it cut out, which kind of circumstantially supported the starvation idea I had.

Yes high altitude causes funny problems and even more power loss.

I am not keen on under-jetting carbs because of the valve burning possibilities and higher cylinder head temps.

That will be an interesting execise.

Best of luck.

Cheers, qldit.

JahLive · 03-22-2008, 05:34 PM

Quote:

Originally Posted by qldit

Good Morning JahLive,

I gathered that you weren't having any problem starting it after it cut out, which kind of circumstantially supported the starvation idea I had.

Yes high altitude causes funny problems and even more power loss.

I am not keen on under-jetting carbs because of the valve burning possibilities and higher cylinder head temps.

That will be an interesting execise.

Best of luck.

Cheers, qldit.

The Jets Arrived Today He Shipped Them Priority At No Charge.
I Replaced The Primary Idle Jet With The .040 Jet (He Sent The Whole Jet Set)
It Seems To Be Running Very Well After Some Fine Tuning.
And The White Smoke Is Gone As Well.
Hopefully This Is It!!!

J

**qldit** · 03-22-2008, 06:36 PM

Good Morning JahLive, very clever, my congratulations.

One thing that really makes EFI systems attractive is the altitude correction, so it overcomes a lot of problems for people that commute between high and low altiude places in their vehicles where the old "carburooster" was a pain.

Thankyou for the feedback, you never stop learning this stuff.

Cheers, qldit.

03-18-2008, 12:10 AM	#2 (permalink)
qldit TSF Gearhead Join Date: Mar 2007 Location: Brisbane Australia. Posts: 592 OS: All Systems, mainly Linux	Re: '81 Celica GT Surging and Dying Good Afternoon JahLive, The description you make is actually symptomatic of fuel starvation but I can't explain the white smoke. I would be inclined to disconnect the fuel line from the carb and ensure it can pump significant fuel into a receptacle from that point, you may need to use a bit of tubing properly fastened to the fuel delivery. It should pump in the order of a pint in a minute or something like that order. The pressure should be relatively good if you block the flow with your finger. If the flow and pressure looks OK and in view of your description I would then suspect there is either a restriction in the fuel entry to the carb, the float valve is hanging, the pressure regulator is set too low, or the reservior fuel level in the carb is incorrect. In the lower gears fuel stavation is less pronounced, but as soon as you shift into a higher gears it becomes very evident and won't sustain operation increasingly. Now assuming the vehicle operated properly before you fitted this different pump there are some considerations, firstly the pump may unable to supply sufficient fuel, this should be determined by the check mentioned. The next and most likely (in my opinion) would be that foreign material is lodged in the float valve which I think may be removed from the outside on that carb, if not you may have to dismantle the carb top and check it there. Does that carb have a window on the side to check the reservoir fuel level, if not the normal kind of expectation is to maintain a level approximately a half inch or five eighths of an inch below the top. A next check would be to disable the fuel pressure regulator possibly by blocking the fuel tank return line. It is possible the actual fuel pressure is insufficient to provide enough flow to the reservoir in a driving condition. It should be remembered that some electric fuel pumps are designed for pushing fuel and others for pulling, but generally this does not seem to make all that much difference. You should get an idea from the flow check. I suspect there may be some reason for that white smoke that may be determined doing these tests. By the way we call Celicas, Sillycars here it has no bearing on their integrity. Others will have different ideas. Cheers, qldit.

03-19-2008, 04:35 PM	#4 (permalink)
qldit TSF Gearhead Join Date: Mar 2007 Location: Brisbane Australia. Posts: 592 OS: All Systems, mainly Linux	Re: '81 Celica GT Surging and Dying Good Morning JahLive, I gather that is not the original carb for that machine, actually a lot of those celicas were pretty "gutless" or "doughy" to drive but I never altered one because the critical nature of the systems in them. I really didn't feel it was a carb kind of problem so much as all the antipollution stuff and the overall design. I gathered that you weren't having any problem starting it after it cut out, which kind of circumstantially supported the starvation idea I had. Yes high altitude causes funny problems and even more power loss. I am not keen on under-jetting carbs because of the valve burning possibilities and higher cylinder head temps. That will be an interesting execise. Best of luck. Cheers, qldit.

03-22-2008, 06:36 PM	#6 (permalink)
qldit TSF Gearhead Join Date: Mar 2007 Location: Brisbane Australia. Posts: 592 OS: All Systems, mainly Linux	Re: '81 Celica GT Surging and Dying Good Morning JahLive, very clever, my congratulations. One thing that really makes EFI systems attractive is the altitude correction, so it overcomes a lot of problems for people that commute between high and low altiude places in their vehicles where the old "carburooster" was a pain. Thankyou for the feedback, you never stop learning this stuff. Cheers, qldit.