Rich Running & backfiring

[machone]

Hello!

Just joined from the rushowners site. Having a few problems with my 1990 3.9l EFI motor. It didn't start after laying idle for 4 months. I changed the plugs, checked the Sparks and the voltage to the injectors - all working fine. Changed the plugs, charged the battery, changed the oil, got it started.

It seemed to run ok but at 3000 rpm, when the typhoon cam and rhoedes lifters are meant to give a bit more power, it seemed to bog down until a backfire or stall. This has got worse over the last day of driving although the power seems ok until 3000. She revs fine in neutral.

Any ideas? Thinking about changing temp sensor or idle valve - sensible?

[Ian Anderson]

First thing I would do is a reset on the ECU
Presumint it is hotwore EFI simply disconnect the battery for 30 seconds
Reconnect and try again

Ian

[kiwicar]

Hi
did you start it on fresh petrol or the stuff that had sat in the tank for four months? If it is the latter then drain the remains out of the tank, put some fresh in and blow out all the injection system, probably be worth taking out the injectors and dunking them in injector cleaner overnight.
Once that is done check for air leaks in the inlet manifold.
Best regards
Mike

[DaveEFI]

Hello!

Just joined from the rushowners site. Having a few problems with my 1990 3.9l EFI motor. It didn't start after laying idle for 4 months. I changed the plugs, checked the Sparks and the voltage to the injectors - all working fine. Changed the plugs, charged the battery, changed the oil, got it started.

It seemed to run ok but at 3000 rpm, when the typhoon cam and rhoedes lifters are meant to give a bit more power, it seemed to bog down until a backfire or stall. This has got worse over the last day of driving although the power seems ok until 3000. She revs fine in neutral.

Any ideas? Thinking about changing temp sensor or idle valve - sensible?

Temperature sensors generally fail open circuit. This would have the effect of setting the mixture for when the engine is cold, and not weakening it off as it warms up. They are easily checked with a DVM

The idle valve isn't going to matter much at high revs.

I'd check the fuel pressure after a long period on non use.

[machone]

Thanks to the advice here and the rush site I've got her running as before. Changed he plugs, the oil, the fuel and cleaned the injectors and apart from an occasional backfire she seems to be running well again.

Once in maybe 20 starts she doesn't want to - the starter turns but it's as if there is either no fuel or spark, I still have the fuel pump running but there's not even a hint of a bang. However, nice to be driving without the fear - overtaking once again!