fj40 backfires with Weber

[cruiserdood]

Holiday Greetings to all.


I've been trying to isolate the backfire and hesitation I've been getting on my 76 FJ. I've checked the PCV and connection and the fuel lines and all those seem to be in good shape. Previous owner replaced the fuel filter, fuel pump etc and it drove fine for the first six months...so this has been a rather abrupt occurance and has gone from bad to worse.

The problem occurs whether cold or hot. Anyone have any thoughts or suggestions on how to fix?

regards.

CD

 

[Downey]

Mechanics rule of thumb---backfires are almost always electrical!!!

 

[Michael Hanson]

Or the timing is off. Mike

 

[3doghouse]

Pretty sure both of you are saying the same thing, and I agree. Check/adjust timing.

 

[Pin_Head]

It would depend on what you call backfiring: whether it is backfiring through the tail pipe or carb and under what circumstances it does it, like deceleration or under high load.

 

[73tlcv8]

If it back fires out the carb during acceleration, it is leaning out - check your accelerator pump - or you may also have developed a vacuum leak, this might be evident by change in idle about the same time you noticed the backfiring starting. Check your manifold vacuum. I don't know the specs but someone else may.

 

[Colorado Boy-74-FJ40]

If it pops really bad on decelleration it could be an exhaust leak. mine did this until i replaced the intake & exhaust gaskets.

 

[F-junker]

ditch the weber...

 

[flash02]

ditch the weber...

x2..go for the Asin they work very well and it is what Toyota Engineers selected for there engine.

 

[Cruiserdrew]

Mine backfired horribly with the Webber on decel. It was one of many things I hated about it. To the Webber's credit, though, it still backfired very occasionally with a rebuilt Aisin Carb. The backfire was finally cured after a full desmog, and install of recurved FJ60 ignition.

 

[gettocruiser]

If it back fires out the carb during acceleration, it is leaning out - check your accelerator pump - or you may also have developed a vacuum leak, this might be evident by change in idle about the same time you noticed the backfiring starting. Check your manifold vacuum. I don't know the specs but someone else may.

x2

i understood backfire to indicate too lean a fuel mix