| Author | Topic |
|---|
Location:
Melbourne
Registered:
September 2005
|
|
4A-C stalling on idle after drive
|
Tue, 08 November 2005 10:52
|
 |
got a 4A-C, new ignition leads, contact points, rotors, condenser, coil.. the works. Cleaned up the carbie as well. Carbie's float is fine (some people call them bowls or something), a bit stiff but nothing to worry about.
After a 15 minute drive (just cruising), when it comes to idle at a traffic light, the car will just stall. happens more with 91 RON and doesn't happen so much with 98 ROn. When this happens, the float in the carbie still has petrol but the fuel fliter has some fuel missing (the in and out lines at the top are dry).
it starts up again easily but there's a bit of bubble in the filter for the first 3 seconds or so.
1. What causes this stalling and how can i stop it? (suggestions?)
2. i understand old cresidas and old carbie engines with the fuel pump running off the cams have this problem i.e. fuel doesn't rise. It's a toyota problem and unavoidable? is this true?
3. any way i can make the 4A-C breathe better? it revs up to 6500RPM on high octane and 5500 RPM on 91 RON.
|
|
|
Location:
geelong
Registered:
August 2005
|
|
Re: 4A-C stalling on idle after drive
|
Tue, 08 November 2005 11:38
|
|
Yeah it sounds like it could be something to do with it fuel pump. I had a simaler think happen to my TA22, but it was a bit werse than that. With the TA the fuel pump wasnt pumpin propelly and when it was runing high in the revs for to long or when it was under load (using more fuel) the carby bowl would run out of fuel, then i just had to let it idol for a bit and i could go again till it happened again.
try pulling the fuel pump apart and clening it, dont know if it would help but then again i might 
|
|
|
I supported Toymods
Location:
melbourne
Registered:
June 2002
|
|
Re: 4A-C stalling on idle after drive
|
Tue, 08 November 2005 11:54
|
|
mine used to do this, i put a 4AGE in and the problem went away.
what do you mean it revs to 6,500 RPM on high octane and 5500 on 91 RON, 4ACs have no power anywhere, l;et alone above 6,000 RPM.
to answer you question without a search, you can make the 4AC a bit better, but you would be better off spending the money on ANYTHING else, as the motor has limited potential.
|
|
|
Location:
Melbourne
Registered:
September 2005
|
|
Re: 4A-C stalling on idle after drive
|
Tue, 08 November 2005 12:05
|
|
i reckon the 4A-C are under rated because it's a very sturdy and solid motor. simple to run, does the job of point A to point B and we have our fun in it. For what it is, it's pretty alright. May not be fast or have that much torque but it can do the things a GE can do just not as hard (which is good to learn with)
i'll try cleaning the fuel pump first, see how that goes. Apparently with 98 octane, since its a slower burning, when the engine stalls theres still enough fuel to "kick" it to keep going hence cutting to 500 RPm before going back to 900 again. with 91 ROn it stalls straigth away.
an electric fuel pump is an alternative. I plan to use the 4A-C until it's tired, but i'll build up a 4a-GE while wearing out the 4A-C. Plan is whichever comes first, complete the GE or wear out the 4A-C
|
|
|
Registered:
January 2004
|
|
Re: 4A-C stalling on idle after drive
|
Tue, 08 November 2005 21:01
|
|
|
you should of done a search on this forum as I have already documented how to fix this problem!! you will find on the front of the carby a diaphram casing(alloy) with a vacuum line going to it....block this line!! It will stop the mysterious stalling at idle associated with 4AC's.
|
|
|
Location:
Melbourne
Registered:
September 2005
|
|
Re: 4A-C stalling on idle after drive
|
Tue, 08 November 2005 21:44
|
|
| 170bhp wrote on Wed, 09 November 2005 08:01 |
you should of done a search on this forum as I have already documented how to fix this problem!! you will find on the front of the carby a diaphram casing(alloy) with a vacuum line going to it....block this line!! It will stop the mysterious stalling at idle associated with 4AC's.
|
i've loooked.. where is it? i mean the documented answer coz i've searched the forums and i'd have thought it's a common problem and discussed before but i didn't come across it in the search results. i searched "stalling" and "4A-C"
also where exactly is this diaphram? in front of the carbie is the bowl (float) and a bunch of lines. Is the diaphram a part of the carbie assembly? or just something with a line through it?
currently i've blocked the hot air tube and there's another vacuum on the left side that's blocked as well. (the hot air tube valve is broken.)
|
|
|
Registered:
January 2004
|
|
Re: 4A-C stalling on idle after drive
|
Wed, 09 November 2005 04:07
|
|
|
yeah this is a common problem with these carbs TRD_07, take the airfilter casing off, this will give you a better view of the carb. Looking from the front of the car towards the carb, you will see on the front left handside an alloy diaphram casing that is part of the carb, it has a vacuum line coming off it and going to a vacuum tree in the coolant outlet, when you find this one vacuum line just put a ball bearing in it. what happens is due to emission requirements under some conditions this diaphram opens an enrichens the mixture, when the carbs are old it opens at idle and floods the motor causing stalling. You will notice that your car starts immediately and puffs a small amount of smoke and then runs fine. I actually have a sprinter in the workshop now but don't have a digital camera! or I would take a picture, basically it's easy to find as it's the only part at the front of the carb(ie facing towards the radiator) with a vacuum line coming off it. Hope this helps, if it doesn't let me know and I'll try and get a picture for you.
|
|
|
Location:
Melbourne - NthSubs
Registered:
January 2004
|
|
Re: 4A-C stalling on idle after drive
|
Wed, 09 November 2005 04:19
|
|
|
can u replace the lift pump with a electric one? ie. 323/626 electric carby pump?
|
|
|
