Petrol FJ62 flat spot

[Flying Briar]

I've just bought an FJ62, 3F engined Cruiser and am having a brain wrecking time of trying to get rid of the hesitation / flat spot just on accelleration and at around 1500 - 2000 rpm. The carburetor has been rebuilt and vacuum diaphram for the secondary replaced. I was also experiencing problems with the distributor and had to replace the vacuum advance module as the diaprhram was punctured. The problem is nowhere near as bad when I bought the vehicle but is still a niggling one. Timing is also spot on.

Has anyone got any ideas ? Could it be the polution / vacuum control gear that is associated with the carburettor ?

[stets]

i had the same problem, i replaced the little inline cone filter at the base of the carby, it worked on mine

[bad_religion_au]

check that you got the right vac advance/retard modual, there are about 4 different ones that all fit the 2f/3f dizzy. make sure it's setup properly, make sure your dwell is set right.

change your fuel filters (can't hurt and costs about 2 bucks). and check for vaccum leaks (spray WD40 around the intake manifold, and vac lines while it's idling, if the idle goes up, you know you have a leak)

[Flying Briar]

check that you got the right vac advance/retard modual, there are about 4 different ones that all fit the 2f/3f dizzy. make sure it's setup properly, make sure your dwell is set right.

change your fuel filters (can't hurt and costs about 2 bucks). and check for vaccum leaks (spray WD40 around the intake manifold, and vac lines while it's idling, if the idle goes up, you know you have a leak)

Cheers mate. The vacuum advance module is a new aftermarket replacement so I'll track down a genuine one as I now believe the units are different for the auto and manual. Manifold gaskets are fine and I did the leak test on everything associated. Interesting thing with the distributor vacuum module is that Nardek were 2 months before they could supply one at $90 (or a complete new distributor for $200), Toyota were $150 and 3 weeks and the mob in Vic supplied the new one I now have for $54.

All filters have been replaced.

I also have (as it would seem) high vacuum pressure in the fuel tank when I open the cap. Is this normal ? Could it be a contributing problem

[stets]

high vaccuum pressure in the fuel tank can be an issue if it is too high, but you shouldn't have a large vaccuum unless you are running an elec fuel pump, if you are still running a mechanical fuel pump i would suggest, getting a replacement fuel cap. on the other hand if you plan on doing a lot of water crossings keep your old cap as it is a very good seal, that way water does not get into your petrol tank

[Flying Briar]

high vaccuum pressure in the fuel tank can be an issue if it is too high, but you shouldn't have a large vaccuum unless you are running an elec fuel pump, if you are still running a mechanical fuel pump i would suggest, getting a replacement fuel cap. on the other hand if you plan on doing a lot of water crossings keep your old cap as it is a very good seal, that way water does not get into your petrol tank

Cheers Stets, it's funny when I take the fuel cap off. It sounds like a bunch of drunk footy players in the tank. A big slurp noise (inrush of air) with a great gurgle immediately following. It runs the standard mechanical pump and the vehicle only has 150k on the clock.

[bad_religion_au]

get one of those emergency temporary fuel caps. put that on and take it for a spin. if the problems solved, you know that it's the vaccum in the fuel tank that causes it

(personally i'd be fine doing the test without a cap, but most would frown apon that)

most likely your breathers/ tank vents are clogged with crud, so a clean out of them will fix the problem without replacing the cap.

[Flying Briar]

get one of those emergency temporary fuel caps. put that on and take it for a spin. if the problems solved, you know that it's the vaccum in the fuel tank that causes it

(personally i'd be fine doing the test without a cap, but most would frown apon that)

most likely your breathers/ tank vents are clogged with crud, so a clean out of them will fix the problem without replacing the cap.

BR - Tried the test without the cap. Still runs the same. I'll double check the breather lines but this 60 series has hardly seen any off road work for the lines to block up with mud & crap. I knew the old bloke I bought it off. I think the problem this vehicle suffered was not getting thrashed once in a while.

[bad_religion_au]

didn't think it'd be the cap, but worth a try.

have you checked if the dizzy has any side to side play? i had a similar problem intermittantly when the distributer chewed it's bearings on the shaft?

[Flying Briar]

didn't think it'd be the cap, but worth a try.

have you checked if the dizzy has any side to side play? i had a similar problem intermittantly when the distributer chewed it's bearings on the shaft?

BR - I'll pull the dizzy out and check. Like I said this Cruiser has had an easy life and hasn't got the mileage on it to have many worn parts but I could understand the counter weights probably being seized up. I enquired about one of those HEI DUI electronic distributors.I asked whether the vacuum advance modules varied on the standard dizzy and he said no. Toyota prescribed a different one of the Auto though !?

[stets]

the auto does have a different advance module from memory

[Les Addison]

Hi Flying Briar. Usually flat spots are fuel related problems. The 2F & 3F engines were prone to this for a couple of reasons, the first and main cause is that the accelerator pump is not working properly, remove the top of the air cleaner from the carby, dont start the engine, look down the air horn and jab open the throttle, there should be a squirt of raw fuel injected from the squirter nozzle near the top of the venturi. If this doesn't happen or the duration of the squirt is not long enough it will cause a hesitation or flat spot. The cause of this could be that the steel ball has not been put back in the pump bore, or the pump leather plunger is not working properly or damaged . The other cause can be the inlet manifold heater plate is cracked or missing, which will cause the manifold to run too cold and not atomizing the fuel enough. The other thing that this plate can do if it is broken, will fall into such a position that it partially blocks of the exhaust pipe causing very eratic and poor performance . They also had a problem with main jets that were too small by about .002". But check those two out first. Hope this helps. Les

[Flying Briar]

Hi Flying Briar. Usually flat spots are fuel related problems. The 2F & 3F engines were prone to this for a couple of reasons, the first and main cause is that the accelerator pump is not working properly, remove the top of the air cleaner from the carby, dont start the engine, look down the air horn and jab open the throttle, there should be a squirt of raw fuel injected from the squirter nozzle near the top of the venturi. If this doesn't happen or the duration of the squirt is not long enough it will cause a hesitation or flat spot. The cause of this could be that the steel ball has not been put back in the pump bore, or the pump leather plunger is not working properly or damaged . The other cause can be the inlet manifold heater plate is cracked or missing, which will cause the manifold to run too cold and not atomizing the fuel enough. The other thing that this plate can do if it is broken, will fall into such a position that it partially blocks of the exhaust pipe causing very eratic and poor performance . They also had a problem with main jets that were too small by about .002". But check those two out first. Hope this helps. Les

Cheers Les, I've rebuilt the carburetor with a Nardek brand kit that supplied a new pump bore steel ball and I replaced the pump plunger. The accelleratot pump is working well as I've had my head over it a few times. I even checked the bore of the accellerator pump for any snags and it is fine too. I had everything soaked in a carburetor cleaning agent to get rid of any carbon / varnish build up and all vacuum and jet ports are clear.

The inlet manifold heater plate is interesting, I'll definitely have a look at that. The vehicle is a "Dog", to drive when it is cold but I've accepted that due to unleaded fuel !? The Cruiser is fitted with extractors (before I bought the vehicle), do you think it may have been likely that this plate could have been removed when they were fitted? Also those extractors give off some heat. I've gone close to scolding my hand when adjusting the carburetor sometimes. This heat no doubt radiates through to the inlet manifold. Thanks again mate.

[Les Addison]

Hi Flying Briar, If it has extractors the heater plate is not there ,it agrivates the problem specially when they are cold, the inlet manifold used to bolt on to the exhaust manifold with the plate sandwitched in between. some other engines use a hot water system. It is many years since I have messed around with 2 and 3 Fs. From the factory they used to run the jets on the lean side,which caused valve burn outs and were subject to flat spots, bore out the main jet .002" larger , this does not efect the fuel economy and usually fixes the problem, also they go much better. The carby on these models was also noted for not being set up properly as far as lever and link adjustment in sync to throttle opening. It is possible to set them up with ordinary tools and specific drill sizes while working on the bench. If I can find my old set up file I will post it for you . Les

[Flying Briar]

Hi Flying Briar, If it has extractors the heater plate is not there ,it agrivates the problem specially when they are cold, the inlet manifold used to bolt on to the exhaust manifold with the plate sandwitched in between. some other engines use a hot water system. It is many years since I have messed around with 2 and 3 Fs. From the factory they used to run the jets on the lean side,which caused valve burn outs and were subject to flat spots, bore out the main jet .002" larger , this does not efect the fuel economy and usually fixes the problem, also they go much better. The carby on these models was also noted for not being set up properly as far as lever and link adjustment in sync to throttle opening. It is possible to set them up with ordinary tools and specific drill sizes while working on the bench. If I can find my old set up file I will post it for you . Les

Cheers Les, I'll take the main jet out tomorrow and get it drilled by a machinist at work. Any other information would be much appreciated.

[Les Addison]

Here is a simple way to adjust the settings on 2F & 3F Toyota carbs without the need of angle gauges.
Secondry throttle valve angle 28 deg, use # 56 drill, gap to edge of throttle valve plate & venturi throat. Primary Throttle Position, use # 68 drill.
Choke Breaker 38 deg, use # 27 drill.
Fast Idle use # 55 drill .
Primary throttle opening begins to touch secondry actuating arm at 7/16" measured at jet side of throat. Bend small tang to adjust. If flat spot still exists drill out Primary main jet .002".
Use in conjuction to instructions in worshop manual. The # drill size gaps, give you the angles of the the throttle plates. Les