Hi all - first tech post forum.

My 85 12a, extendport with EFI and Haltech (EX6 I think) has been misbehaving in hot weather only recently. I´ve only had the car 6 months, so didn´t notice any problems till the summer.

Symptoms are:

After a while running just fine, especially if in stop/go traffic, engine starts to mis-fire and refuses to rev. When it does rev, there´s no power. So engaging the clutch stalls the motor.

Stopping the car and letting it cool down for a bit seems to make the symptoms go away - but sometimes not for long, especially if the poor driving conditions persist.

There´s no way the engine is over-heating. I have heaps of quality aluminium radiator and oil cooler - way more than should ever be needed.

Unfortunately, we´ve never been able to reproduce the problem in my mechanics shop.

I just had a heat shield fitted between the exhaust header and the inlet manifold. This seems to have made the problem WORSE! This afternoon, after 30 mins of perfect running at highway speeds, I took a sharp turn and the engine almost died as I hit the throttle out of the corner - similar symptoms. Then exhibited occasional cut-out under acceleration for the next half hour or more.

I am beginning to wonder if a new or better fuel pump setup is the issue. Others have suggested a cold-air intake box.

All ideas welcome. This car is well setup by the previous owner. My mechanic has known the car for years, and believes it´s a well put together package (he did the extend port - been in RXs for 30 years or so - so he should know).

Cheers - Mike

 

Did this happen on a left hand turn?
Does the fuel system have a surge tank?
What are the specs on the pump/s?

 

Sorry, but I'm not very familiar with Haltech systems. However, what are the chances that you are sucking something in the gas tank up against the pickup tube, causing intermittent clogging? Really, that's about the only thing that comes to mind right now.

Best of luck, and please post some pictures of the car (we love Aussie cars around here).



.

 

Yes - it was a left hand turn. Previously the suspected fueling problem had not occured on turns specifically, more seemed to be just general hot weather and standing still that produced the symptoms. A few days back it happened when I had the car parked while I answered the phone - the nose was pointed uphill - it sat idling for a few minutes, when I went to take off it stalled, and then exhibited the refusing to rev, and choking under load issue intermittently for the next ten minutes or so.

Sorry, I don't have specs on the pump - but my mechanic reckons it's heavy duty, and yes there is also a surge tank.

why would left turns be interesting?

Cheers - Mike

 

Fuel pickup tube in the tank is is on the left hand side. Since Australia didn't get the 84-85 fuel injected 13B, you guys don't have ready access to a 1st gen fuel tank with a sump cup, which was standard on the FI FCs. Most FI 1st gens that have a surge tank are set up with 2 fuel pumps. A low pressure/high volume one to pull fuel out of the tank and supply the surge tank. And high pressure FI pump to pull fuel from the surge tank to feed the injectors, returning the leftover fuel to the surge tank. Overflow from the surge tank then goes back to the main tank.

 

Thanks - interesting bit of information. I suspect I´m going to have to have a closer look at the fuel pump setup.

I was also thinking about the other suggestion of fuel blockage - I don´t think that´s the problem, as it would occur just as regularly in hot or mild weather. This is certainly some kind of overheating issue - we just don´t know what exactly is overheating. Also, the car has done some 300km+ runs in mild weather with no problems at all - from full tank to almost empty. So long as the weather is mild, or the speed high enough to encourage good airflow, the motor performs just fine.

The only conditions under which we´ve been able to re-produce the problem have been the combination of extremely hot days, and stop/go traffic with lots of idling.

Cheers - Mike

 

hey there, heres a few pics of what i've done im my 84 series 3. running a holley blue as the low-pressure pump, and a bosch 044 as the high pressure one, with a 2 litre surge tank, and -6 fittings for the low pressure/return lines and -8 for the high pressure feed lines.


heres the surge tank mountws in the boot on the right=hand side


you can just see the base of the holley blue in amongst the fuel lines, mounted under the car on the left-handside


heres the 044 under the car on the RHS.

 

Glad to see you put your Holley blue where I put mine, there is just no where else to locate that beast haha. That being said, I have no idea what is wrong with your car, but good luck figuring in out.

 

With your latest details, this leads me to think that the fuel pump may be vapor locking.

 

I'm reviving this old thread because I think I'm having the same problem. All Winter, not a problem, but two days ago, warm weather came back and bam - stalled out in traffic.

Getting spark, and starting fluid gets it going for a moment. Pump appears to be "on" but I suspect not pumping properly until 20 minutes or so after it cools. is replacing it the solution?

Suggestions on brands? i see on rockauto they go from $40 to $200. I know you get what you pay for, but I'm just a daily commuter, not a racer. Would the $50 model work just fine?

Pete

 

Nice looking low mileage GS there - same colour as mine, I just clocked 200 thousand kilometers though, so not as tidy.

The fuel problems seems to have been sorted in mine. We did three things in the end:

1) fitted high-volume fuel pump (mine has after market EFI, does yours?)
2) fitted a shield above the extractors, between them and the inlet manifold (I don't think this made much difference)
3) replaced the radiator.

The problem has not occurred again since the radiator change. The old radiator looked good, but in reality was a cheap import and had been leaking. I was lucky it never lost enough water to damage the motor (hopefully). We used a locally manufactured aluminium radiator - if I had been smarter, I would have sourced a brass or copper core from the US and used that. The brass/copper cores don't look as good, but they work better (provided you don't paint them), and as far as I'm concerned a cooling system is critical in a rotary so functionality beats looks anyday.

Good luck with yours.

Mike

 

Mike,
Thanks. I just updated my signature line, not having been here in a couple years, I've driven the car some and the mileage was a little off. Photo is still accurate, though.

I bought a fuel pump at rockauto yesterday, along with a couple extra fuel filters. My radiator is good, coolant has been changed several times in the 5 years I've owned it, and does not leak a drop.

No aftermarket EFI, the car is 100% stock except for the in-dash bluetooth car stereo and upgraded speakers.

I'll hope to get to this project soon, and will post the results once I've completed it for anyone else who's interested.

Thanks for your input!

Pete