4AGE dying at idle then refusing to start *updated*

[rollaholic]

the car - 1983 AE85 trueno with complete AE86 mechanical transplant, though the fuel pump is an external one currently residing in the engine bay.

the problem - three times in the last couple of months, i've been sitting at an intersection with the car idling happily, then all of a sudden revs drop, then it sounds like i've lost a cylinder - application of throttle at this point results in strangled sounding rev increase for a few seconds, then it drops away to nothing and refuses to fire again.

the first time after sitting for 20 minutes it started and i drove it for approximately 6 weeks. the second time i decided i had better do something about it. checked spark and fuel, both appeared to be ok - though i wasnt able to check the flow of fuel directly since i didnt want to leave it flowing while i ran back to the engine bay, but there was defintely fuel coming out of the return line. had coil pack and igniter checked by auto electrician, igniter was declared healthy, they reccomended i change the coil pack since it turns out whover did the engine conversion kept the old 3A points type coil. i duly replaced the coil with something more appropriate, and this morning it died again after a couple of days back on the road.

i had originally thought it might have been water from the heavy rain getting into something, but the second occurence was on a dry evening. the first and third times were both at about the same spot - just after getting off the motorway on my way to work in the morning. the second time was after the car had only been going for about 5 minutes.

after towing my car back to work this afternoon it started first pop, which was very annoying since its hard to work out whats wrong when everything is working. im tempted to replace the fuel pump almost regardless, A because its in an annoying spot, and B because it looks old and worn out.

though i'd see if anyone had any other thoughts, or experiences of similar problems.

cheers!

edit - i should probably mention that the radiator fan is manually switched by the driver, for a couple of reasons i wont go into. i dont think the problem is caused by overheating though, since i tend to err on the side of caution with my switching.

[Ae92typeX]

Ever had a new fuel filter? I'd try that before a pump, cheep enough.

[rollaholic]

yeah, not a bad thought, i'll do that. im kinda hoping to work out whats wrong with it before i drive it again though, because when it craps out its a real pain in the ass.

(no kidding! hehe)

[Santa'sBoostinSleigh]

does it steam out the exhaust?
checked the oil/water for levels + milkyness?
could be BHG - when it gets hot, it expands and may be letting water into the cylinders

[importcustoms]

ill put my money on a stuffed fuel pump or blocked fuel filter

[rollaholic]

i'm 99% sure its not the headgasket, oil and water are normal, and levels only dropping by the amount leaking might try and find time to put the headtester on it tomorrow. im leaning towards fuelling issue myself at the moment, going to replace the filter for a start and drive it till it breaks down again, see if i can get something more definite out of it while its not going.

/sigh!

[rollaholic]

well, after the last breakdown i spoke to an auto electrician who said these cars often suffer from an ECU fault. i gave him the ECU and he got it checked, apparently there was some fault and so it was repaired - despite the expense i felt it was a better option than replacing it with another secondhand item of unknown quality.

the car has been fine for a week or ten days, till it did its old trick again last night. once again it was in the pouring rain, and once again it started again by itself after 4 or 5 hours of sitting - and once the rain had stopped too, incidentally.

im starting to feel like it is associated with water getting in somewhere, despite my earlier misgivings. whats the stuff in the picture below, next to the ECU when its wet water sometimes pools below that stuff - im not 100% sure on where its coming from yet. could this be the source of my problems?

[WeirdGTi16]

This sounds like Distributor fault - had same problem with AE92. Ended up replacing distibutor as fault inside dizzy wiring. Dificult to diagnose because intermittent fault. So Auto sparky needs to check when engine dies

[Lith]

Yeah I was going to say that, I'd put 50c on it being a dizzy.

[ollieboy]

They also sometimes leak oil through the dizzy which gives similar problems.

[Lith]

The RPM pickup in the dizzy craps out over time.

[rollaholic]

interesting, i have a dizzy from a smallport, will it work with my bluetop ok? i know the plugs are different...

im planning to put the smallport into the car eventually, but while i get the rest of it up to scratch it would be nice to keep the bluetop going a bit longer.