Back firing into aircleaner????

[brighty]

Just a quick one.... got a toyota 2F engine on duel fuel. Only when it's on petrol does seem to keep backfiring into the aircleaner..... when revs are at idle, then giving it a quick squirt to up the revs is when it happens. Once the revs are up it doesn't do it.

This car is not drivable.. no clutch or brake M/C atm (i'm getting the engine all good before I pull it out and into another vehicle.) So I can only test in the garage.

Anyone point me in the right direction???

[chimpboy]

Just a guess, but I'd say you may have too much advance - the fuel is burning while the inlet valve is still open.

Perhaps the engine is tuned more for gas than petrol.

Retard the timing a little bit and see what happens. Or just don't run it on petrol

[brighty]

Just a guess, but I'd say you may have too much advance - the fuel is burning while the inlet valve is still open.

Perhaps the engine is tuned more for gas than petrol.

Retard the timing a little bit and see what happens. Or just don't run it on petrol

Thing is, I'm gunna have to run it on petrol for a month or 2 after I put it into the other truck.... so it'd be ggod to get it going nice and smooth.

I'll retard it a bit and see how it goes..

[DamTriton]

You need to get some electrinic ignition happening. Some modules allow for switchable timing for LPG/petrol, although they are mechanically "anchored" at the distributor/block. All they do is set the ignition timing for LPG, then have a switchable delay, artificially "retarding" the ignition for petrol.

LPG installers/suppliers should be able to supply the unit, maybe upgrade to a full electronic dizzy too.

In the interim if you are only going to run on petrol for now, retard the ignition a few degrees (anywhere from 3-6 should be enough).

[mavzilla]

maybe your accelerator pump has dried out from running on gas and it leans out on hard sharp acceleration/ look down the carby with the motor of and make sure you see a squirt of fuel from the side or bingo it will do it every time cheers

[brighty]

maybe your accelerator pump has dried out from running on gas and it leans out on hard sharp acceleration/ look down the carby with the motor of and make sure you see a squirt of fuel from the side or bingo it will do it every time cheers

Had a look this morning.... got fuel coming in when accelerating(hard and softly) so don't think that is the problem.....

Will try to re-adjust the valve clearances now and see if it helps....

Other than that, I can only think of a carby kit/rebuild???

Any more thoughts???

[brighty]

ok, all valve clearances are now good.... id did help with the back firing a little bit, but still doing it.

Any more ideas????

[simkell]

have you checked the ignition timing. if all is good check to see if the balancer has spun giving you an incorrect reading whilst checking the timing.

[brighty]

have you checked the ignition timing. if all is good check to see if the balancer has spun giving you an incorrect reading whilst checking the timing.

How do I go about checking this????

[RaginRover]

have you checked the ignition timing. if all is good check to see if the balancer has spun giving you an incorrect reading whilst checking the timing.

How do I go about checking this????

You can use a vacuum gauge to see how the timing is or you can roll out plug 1 and then roll the engine around to TDC by hand and see where the balancer is in relation to where it should be. Ususally put a screw driver in the plug hole so you can tell when it is at top

Tom

[PK]

My Disco used to backfire and blow the airbox apart - put new plug leads on it.