Mechanic help needed asap..please.

[Dottefan]

Over the past couple of weeks my truck has started to backfire. I have a 98 2 door tahoe with a 5.7 liter vortec. Well Today, along with the master cylinder I went ahead and replaced the spark plugs and wires, and fuel regulator...but it still keeps back firing. It happens mostly when I take my foot of the gas, it starts to do it very rapidly, and its Idling ruff.. when I have my foot on the gas, it doesn't do it that much..it also acts like it wants to die on me every so often..I`m dropping it off at the shop tomorrow, not sure whats up with it..I `m thinking the compression is off, or the fuel pump..I also noticed that I had a hole in my muffler, while I was bleeding the breaks maybe thats the reason? I dont know...and Ideas ?

[Brock]

Probably not fuel pump. Sounds more like timing.

[Dottefan]

Originally Posted by Brock

Probably not fuel pump. Sounds more like timing.

Do you mean the timing belt? or is this something else ? and do you know how expensive this might be?

[SAUTO]

Originally Posted by Dottefan

Do you mean the timing belt? or is this something else ? and do you know how expensive this might be?

the hole in the muffler is probably just popping when you let off the gas and the unburned fuel gets there and ignites with the oxygen from the hole
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[Dottefan]

Originally Posted by JASONSAUTO

the hole in the muffler is probably just popping when you let off the gas and the unburned fuel gets there and ignites with the oxygen from the hole
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Would that cause it to Idle ruff also, and act like it is dying?

[PastorMikH]

Originally Posted by Brock

...Sounds more like timing.

ditto

I'm wondering if the timing chain jumped a tooth or two.

[Brock]

Originally Posted by PastorMikH

ditto

I'm wondering if the timing chain jumped a tooth or two.

I'm thinking more along the lines of it's not really out of time, but the 'puter thinks it is because of a haywire sensor or something.

[Dottefan]

Originally Posted by Brock

I'm thinking more along the lines of it's not really out of time, but the 'puter thinks it is because of a haywire sensor or something.

I`m thinking the same thing...or at least my pockets are hoping its just that lol.

[Simply Red]

Pinche Gringos

[Bwana]

Fuel pump, vacuum line, coil, water in the gas, etc. Start with the cheap stuff and throw in a bottle of "Yellow heat" and check under the distributer cap for any condinsation. You didn't get the engine wet at any point in the last week or so, did you?

[joemama]

Possibly spider injector.

[Simply Red]

Originally Posted by Bwana

Fuel pump, vacuum line, coil, water in the gas, etc. Start with the cheap stuff and throw in a bottle of "Yellow heat" and check under the distributer cap for any condinsation. You didn't get the engine wet at any point in the last week or so, did you?

yep, had that issue before with a Nissan 240 yrs ago. Yes to Yellow Heat.

Originally Posted by Simply Red

yep, had that issue before with a Nissan 240 yrs ago. Yes to Yellow Heat.

I don't believe Nissan has been around that long.

[Simply Red]

Originally Posted by Phobia

I don't believe Nissan has been around that long.

nice catch,

[Dottefan]

Originally Posted by Bwana

Fuel pump, vacuum line, coil, water in the gas, etc. Start with the cheap stuff and throw in a bottle of "Yellow heat" and check under the distributer cap for any condinsation. You didn't get the engine wet at any point in the last week or so, did you?

No water in the engine lol. I replaced the distributor cap today when I did the tune up and didn't see any water. It has new heads on it and a new intake manifold..but I did notice when I took the top of the fuel injector off that it was pretty dirty, didn't know if that was from the fuel modulator that I replaced being bad or not.