Sportrak MYSTERY! Can anyone help???


Hi there
I have owned my 1992 daihatsu sportrak for three weeks now and i've had nothing but problems!

When the engine is cold it starts first time everytime and everything is fine and dandy until the engine heats up, once it reaches a certain temperature, it feels like the engine is being starved of petrol(even whith a full tank)when it reaches 3000-3500 revs. This happens in 2nd, 3rd, 4th and even 5th gear but 1st seems ok. I took it to a mechanic friend and he thought it was an electrical fault, so he checked the distributor cap and rotor arm, both of which needed changing, so he did so. However in the time it took him to fit them the engine cooled down again and it drove fine. Until the next day when i took it out again. Since then i've tried a few things of my own...
I changed the air and fuel filters and a load of crap was coming out of the old fuel filter when i changed it so i bought some good quality fuel system cleaner emptied the bottle into an almost empty fuel tank, let it settle for a bit then filled it up with petrol. I drove to a petrol station far enough away from my house so that the engine would be hot enough for the chugging to start and found that on the way home it was still chugging around 3000 rpm BUT it would work through it going up to 4000 before i changed up the gears. It did this all the way home but the following morning and for the rest of the week it ran perfectly, until i had to fill up again when the tank was almost empty again and lo and behold the dreaded chugging returned, but not as bad as before. Before when it happened it would get worse and worse, happening at lower revs until there was just no power there and i'd have to pull over, lift the bonnet and wait for the engine to cool down. now it just chuggs a little. Before and now, it used to only happen when i was going uphill, it didnt have to be steep but as long as its an incline and the engine is warm it will happen. I dont know what else to do so any suggestions are welcome.

Good luck with my mystery!

Filler cap or choke.

Check the fuel cap! Next time the engine is running hot and chugging, remove the filler cap. Does the problem disappear?
The fuel system is not vented. After a few miles travel when removing the petrol filler, the tank should hiss audibly. If the filler cap is of the wrong type/fitting badly, it could be the solution to your problem.
Failing that ... get the automatic choke checked.

Mace, Are you saying that the

Mace, Are you saying that the fuel tank/cap aren't vented or could possibly not be venting in this case ?. I'd have thought the latter, syptoms sound just like fuel starvation due to a blocked vent not allowing the fuel pump to draw fuel through once a depression has been caused in the tank.

Once worked with a guy who had his fuel tank sucked flat by a blocked petrol cap vent !


Have you tried removing the fuel cap whilst Sporty is giving trouble?
Have you check for a kinked fuel pipe, or blocked fuel pipe from engine to the fuel tank? The fuel system has a fuel return pipe from engine to the tank which could be blocked. There is also a 'check-valve' in the fuel - behind o/s rear wheel, close to the top of the rear shock absorber.
Do you have a CD Sporty Repair Manual? The section on Sporty fuel system is very comprehensive.

do these things have fuel pic

do these things have fuel pick up filters? might be blocked

opening the fuel cap will show not show if there is a fuel line restriction unless the vents are blocked also, however it might run a tiny bit better breathing more! but this might not be noticable

if there was that much crap in the fuel filter? have you cleaned the carbs? or is it injection? Could be leaky injector? be careful with injectors dont take them out and turn over the car, and injector can do just that inject fuel into you! get someone in the know to look at injectors!

when it chuggs, stop! take out one or more spark plugs if they are very light grey and look kinda hot, then it is fuel restriction.
if they are black and carboned a little then its not fuel.
the plugs are always the best way to tell if an engine is buring properly.
if it was electrical and the fuel is getting there and not burning, i.e. its not sparking or the timing is out (which could also be the problem) you would smell the unburnt fuel being chucked out the exhaust valves and burning in the manifold.
have you done a compression check hot and cold?
i would!!!!! it could be something like a valve not seating when it warms up! cracks in valves/valve seats cylinder heads, leaky head gaskets etc can open when warm and close when cold.

do the fuel cap thing
pull the plugs when it does it
do a compression check hot and cold
can you smell fuel
can you do a fuel pressure test? hot and cold?

anyone wana ride in my hovercraft!

Update, still having problems!!!

I took it back to my mechanic friend and he flushed the fuel system and found that there was a lot of rust inside the tank, that was contaminating the fuel. He cleaned the pipes and stuff and since it has only started to happen when the tank started sucking up the crap from the bottom of the tank when it fell below a 1/4 full. Now though its come back so I've tried the fuel cap test; result-hiss was heard. No problem there. I also checked if i could smell petrol when it happened, result- No. So the petrol isnt being burned in the manifold. I'll get the fuel pressure test and compression test done too this weekend if possible, but the mechanic friend took a look at the plugs first of all when i took it to him and said they looked fine. Does anybody know how much new fuel tanks cost? Im considering getting a new one to solve the rust in the tank problem! NE more suggestions in light of this recent developments would be welcome,
Thanks all,


Gavin, sorry to hear about th

Gavin, sorry to hear about the problems you are having I know exactly how they feel I am having the same problems which started a couple of days ago after a week of running sweet (just put back on the road).

Have you sorted yours out, and if so how?

Cheers Rob.

Other Ideas

Check the leads on the Coil are secure. I once had a problem caused by one of the HT leads just resting on top of the post rather than being secure, and it kept separating whilst driving causing the power to die intermitantly.

With all that grot in in the fuel it may just be worthwhile to check that the carb is clean internally. I know filters should stop the grot but I have had problems in the past (on other vehicles) where sediment had made it into the cabs.