Lean misfire

RSR 555 · Post by **RSR 555** » Wed Dec 04, 2013 10:51 pm

Bennie has a good point about the fuel.. make sure you check the rear fuel filter (and the front filter for that matter) and replace if it looks old.

Subydoug · Post by **Subydoug** » Wed Dec 04, 2013 11:36 pm

Re the intake gaskets, I never goo'ed any of mine. Just scrape off the old gasket material, get some fine emery paper rolled over some cold rolled square bar and sand off any high spots on both the mani and heads. Haven't had any issues to date, though If you have the right silicone, and you clean them up best you can, can't see it doing anything but helping the cause.

83wagon, how savage is the miss? Is it a quick sharp single stutter that occurs intermittently under load? Or is it like you turn the key off for half a second? Or is it like a shower of small stutters that all occur in one hit, but then stop as you let off?

My old hitachi had a clear window in the side of it for checking the float level. Makes setting and checking it relatively easy.

Still a bit concerned it may be an electrical fault given that altering the coil gave you different results. Some coils are picky on how the points act. I know that when I swapped from my old Bosch coil to the msd blaster coil by engine misfired and carried on like a pork chop, mainly because the points couldn't supply an adequate circuit for the larger coil to work properly, where the Bosch one was fine. I never did truly get rid or that misfire until I swapped to electronic ignition.

Regards

Doug

1983wagon · Post by **1983wagon** » Thu Dec 05, 2013 5:12 am

Yeah I cleaned up the surfaces with paper. I am always really fussy when it comes to that. It isn't a savage miss, after about half hour it will just be a small stutter maybe every 3 seconds when accelerating. (Doesn't matter how hard or soft you accelerate). Nothing at idle and nothing when I let go of accelerator. Purely just accelaerating. And yes my hitachi has a clear window too and it's sitting about half.. Is this correct?
Fuel filter at the front?? I have only seen one near the rear tyre? I haven't got one near my fuel pump like I think some people have.???

The more I look at it the more I'm thinking that it probably is a electrical thing. Electronic distributor sounds like the way to go I think.

Subydoug · Post by **Subydoug** » Thu Dec 05, 2013 9:04 am

Hmm, possibly, but in my experience usually electrical faults occur intermittantly during cruise, idle and acceleration.

Fuel starvation under load......hmmm... the first fuel filter to replace is down the back of the car. If you lay down on the passanger side of the car and look underneath the car just in front of the wheel well you should spot it. Mine is just an inline job with 1/4 inch barbs (I think! may be 3/8). Second fuel filter is in the engine bay. I dont know where they originally mounted because my fuel system has been changed.
Looking in your grampa spec thread I see you have the same fuel pump I used to have. When mine worked It put out around 3 1/2 psi of pressure and when the pressure dropped it kicked in. You may hear it pulse a few times when you first turn on the ignition but it will stop as the pressure comes up.

If all that works OK, it would be time to start looking at needle valve seats and float levels, and for crap or water in the carby bowl.

I doubt you have a jetting problem. Ive run my ea81 off the gauge lean and off the gauge rich. The only time you actually feel a miss is when you get a dramatic fluctuation in mixture, savagely when it swings lean and gentle if it swings rich.

You say the carby was recently rebuilt? well maybe the tired old fuel pump can no longer push the needle valve open properly because of the new spring or something like that.

I honestly cant remember about the float level, but half sounds good. Maybe someone else knows for sure.

Regards

Doug

1983wagon · Post by **1983wagon** » Sat Dec 07, 2013 5:43 pm

Thanks for the great response doug. Just changed the rear fuel Filter. Had a fair bit of crap in there. Didn't fix the issue but needed to be done. I can't see a filter anywhere in the engine bay. Maybe it's been plugged off? I have no idea.. Does anyone know where it usually would be from stock?

Silverbullet · Post by **Silverbullet** » Sat Dec 07, 2013 7:29 pm

The front filter is right next to the fuel pump near the wiper motor. There's a fuel line coming out of the pump directly into the filter and there should be a small pressed steel bracket bolted to the firewall that clips around the cylindrical filter. My ute is different to how my wagon was in that the filter has a vapor separator line on top as well, but my wagons filter only had an inlet and outlet. And for float bowl level on the Hitachi there is a small spot on the round sight glass at the 1/2 way line, that's the right level.

Forgot to mention when I had a shorting dizzy a multimeter with continuity buzzer is what helped me find the problem, best $50 I spent that week

steptoe · Post by **steptoe** » Sat Dec 07, 2013 7:29 pm

Brumbys had two, non Brumbys only had one I think

RSR 555 · Post by **RSR 555** » Tue Dec 10, 2013 11:32 am

The early MY models had the fuel pump up front but the later ones had them down the back. I can't remember seeing a filter up front on my 84 model wagon but it was definitely there in my 91 Brumby. Either way I'd fit one inline on the supply line to the carby, just to be safe.