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4.0l backfire


alexis29v

Member
Joined
Sep 19, 2010
Messages
14
Vehicle Year
1993
Transmission
Automatic
when my rpms reach around 2500 to 3000 my truck backfires. exhaust throws black smoke and flames lol. so that should mean to much fuel right? what else can cause it?
 
Thats, a tall order

Computor systems are self diagnosing we rely on codes to steer us.(there guide lines)

When you describe a syptom (back fires) 50+ possibility.

That called diagnosis by syptom, used as a last resort!

computors monitor them selves, if no codes. good possiblity its non computor related

they were not designed to be diagnosed by syptom,=ball buster

code reader.

alldata. on line manual $26 a year.will explain how to read code with or with out code reader

IF you have codes. you need wiring diagrams. sensor specs.

Then we can steer you. with out ball busting.. any questions
 
A lot of times a backfire is firing at the wrong time, so suspect the electrical system too... but flames and smoke could be fuel too. Is it throwing any codes?
 
when my rpms reach around 2500 to 3000 my truck backfires. exhaust throws black smoke and flames lol. so that should mean to much fuel right? what else can cause it?

I'd say possible timing problem or FPR is bad.

Have you checked fuel pressure or timing?
 
when my rpms reach around 2500 to 3000 my truck backfires. exhaust throws black smoke and flames lol. so that should mean to much fuel right? what else can cause it?

Low fuel pressure at the rail under demand can cause poor fuel atomization

Change your fuel filter before you do anything else.


If the timing is "off" on a 4.0 the engine is either F-U-K-T or a victim of demonic possession

for the former replace the engine.

For the later drain the coolant and refill the radiator with holy water.

AD
 
Fuel filter lean condition. no black smoke

could be, could be, could be, could be, could be , could be. one more could be.

$500 to $700 in parts, still the same, one more could be

how much do you wont to spend.?

change everything and you will fix the vech!

but you wont learn anything.

next time , It has an issue. 10 more could be .$700 later,

follow this,(A COULD BE. ) is a educated guess. or intuition from experience

If a part is suspected. you confirm IT by testing not replacing it.

Unless you like spending money and busting your balls
 
Last edited:
well i did change the fuel filter and spark plug wires and it didnt help. when i diagnosed it the computer said one cylinder was lean and one was rich well thats what the guy told me and it gave a 538 code also. i cleaned the MAF but i heard that can cause it even if i clean it cause it doesnt work but i dont want to just buy it and spend money without knowing.
 
code 538 . you did not do, your tests right insuffcient rpm
throttle movement in cyclinder balance
invalid balance

ITS saying, you f--ck-up the test


Get good info , on reading codes you just dont plug it in.

alldata will tell you how . other manuals onced learnt, its easy.

You have to help yourself some what, so we can help you,
 

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