Too Much Choke

January 5, 2006

I have an '88 petrol Hilux with the 4Y engine. The problem is, the auto choke is not working right so the engine won't start (it is over choked). If you hold the choke flap open the engine starts fine, so I guess something is making the choke close up too much. Once you release the flap, the engine idles pretty poorly and is clearly seriously over-rich. When the temp has risen after a minute or two, a blip of the throttle causes the choke flap to flick to fully open, and the engine idles nicely.

Is there an endpoint adjustment screw to stop the choke flap from closing up so much? Or maybe the temp sensor is dodgy, any info would be much appreciated. I am slightly concerned that my main carb setting may be over-rich, as there seems to be no need for the choke at all in its current adjustment.

It was suggested to me that a manual choke conversion would be a good idea, does anyone know if these are available for this engine - I have looked around on the web but no luck.

January 5, 2006

I have an '88 petrol Hilux with the 4Y engine. The problem is, the auto choke is not working right so the engine won't start (it is over choked). If you hold the choke flap open the engine starts fine, so I guess something is making the choke close up too much. Once you release the flap, the engine idles pretty poorly and is clearly seriously over-rich. When the temp has risen after a minute or two, a blip of the throttle causes the choke flap to flick to fully open, and the engine idles nicely.
Is there an endpoint adjustment screw to stop the choke flap from closing up so much? Or maybe the temp sensor is dodgy, any info would be much appreciated. I am slightly concerned that my main carb setting may be over-rich, as there seems to be no need for the choke at all in its current adjustment.
It was suggested to me that a manual choke conversion would be a good idea, does anyone know if these are available for this engine - I have looked around on the web but no luck.
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I once had a AHem! Ford Escort with similar problems which were all caused by the automatic choke. I considered refitting a manual choke but ended up just constantly getting under the bonnet and dismantling the choke to reset the diaphram and then after a while sold the car! It sounds like the mixture is too rich and also a manual choke conversion would be a good idea after all no-one wants to sell a toyota!

January 5, 2006

Try these chaps https://www.milneroffroad.com/ they were reccomended to me but I've never had to use them just yet.

January 8, 2006

Thanks for the help. Milners don't list any carb stuff on their site, I will give them a call in the week. A guy who knows his carbs has advised me that the jets may have worn and are therefore oversized and providing too much fuel. Apparently some cars of this age use anodised aluminium parts in the jets, which is very hard wearing, but when it finally does wear through the jets erode away quite quickly. Perhaps that explains it suddenly jumping to a rich condition even off choke.

Best thing is to take the carb off and inspect it I guess.

January 22, 2006

Well I thought I would update on this problem. Toyotahilux.com list Weber carbs for the 4Y engine on their site, but I called them and apparently they can't get them any more. Anyway further investigation has led me to believe the carb may not be directly at fault, and certainly the choke is not to blame. After a few attempts to spin over the engine, it still won't fire, so I take out all 4 plugs and spin it over. Fuel sprays out of cyl 1 only. Cyls 2,3, and 4 are all dry (as are the plugs I removed, plug 1 wet). So only cyl 1 is getting fuel. Put the plugs back in, if it doesn't flood it will fire but on cyl 1 only, if lucky the rest will catch on after 5-10 secs of the engine running on cyl 1 and the starter combined. I can't understand this really, it seems I wouldn't have a problem if fuel was getting to the other 3 cylinders. If the engine still does not fire, removing plug 1 to clear the fuel out and retrying results in the engine starting. If the engine is warm, the engine starts as normal which is weird too. This engine has 16 individual vacuum controlled emissions systems on it, all mechanical which could be effecting this but I have tried to run through most of them and I can't see any links. Truck is at garage now to see if they can sort it out. Any thoughts on this would be much appreciated.

January 23, 2006

it take it they have checked all the compressions of all cyliders as the only thing i can think of is that clyinder 1 has compression and is creating a vacuum on the induction stroke and that the other clyinders cannot create a vacuum as the seal between the piston and the bore has been lost and therefore cannot draw the fuel air mix into them.

Sorry i cant be of anymore help

Steve

January 26, 2006

Thanks for your input Steve, good idea. Gladly it wasn't that nasty of a problem in the end! Guy at the garage reckoned that fuel in the cylinders issue was nothing to be concerned about. Dodgy connections to the coil proved to be the problem, seems I was getting intermittent and weak sparking - even though it looked fine when I checked it (always the way). Once the terminals on the coil were cleaned, starts instantly and actually runs better than it ever has since I bought it. Then on the same day, I was braking to turn into my road... BANG.. ruptured a brake line. Very lucky escape, had the steel lines replaced with coppers and now all good. Anyone with an older Hilux should definitely check their brake lines especially between the chassis rail and fuel tank, where you can't see them. Mine had been in a bath of salt and water for some time in that tight area :wacko: