Spark plug mystery

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2manyburbans

2manyburbans

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the truck had been running good for the last 4 months until it got colder out then it was constant hard starts last night the fuel pump acted as if it was weak I tapped it with a screwdriver started working just fine but as I drove the truck fell flat on its face miss firing and backfiring through carb like crazy im at a lost this spark plug is from the front driver side im gonna pull more and see if I can start there any help would be more than appreciated love you guys



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2manyburbans

2manyburbans

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passenger side very front
 
Vbb199

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Backfiring is a lean condition. The plugs also look a little lean.
You had to tap on the pump to make it come alive....


The pump is dying, and running the motor lean.
Replace the pump, maybe the filter too
 
Vbb199

Vbb199

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Side note we have the same color suburban.

Mines an 89. I assume yours is too.
Do you by chance have any spare body panels ?
 
2manyburbans

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Vbb199 said:
Backfiring is a lean condition. The plugs also look a little lean.
You had to tap on the pump to make it come alive....


The pump is dying, and running the motor lean.
Replace the pump, maybe the filter too
Click to expand...
After taping the pump yesterday the pump works like it should it fills up the filter "not very quickly" but it does and the truck sounds like it running rough and shaking pretty bad instead of a smooth rev it's like it bubbling kind of sound and my burb is a 85 and what panels are you looking for
 
Vbb199

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2manyburbans said:
After taping the pump yesterday the pump works like it should it fills up the filter "not very quickly" but it does and the truck sounds like it running rough and shaking pretty bad instead of a smooth rev it's like it bubbling kind of sound and my burb is a 85 and what panels are you looking for
Click to expand...

Im looking for a drivers front fender, same color as your truck
 
bucket

bucket

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Tapping on a mechanical fuel pump won't do anything.

Are you saying it doesn't always fill the fuel filter?
 
Vbb199

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Vbb199 said:
Backfiring is a lean condition. The plugs also look a little lean.
You had to tap on the pump to make it come alive....


The pump is dying, and running the motor lean.
Replace the pump, maybe the filter too
Click to expand...


Is this some aftermarket electric fuel pump?
Or the mechanical pump on the side of the motor?
 
PrairieDrifter

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Yep you have different plugs. I also vote fuel starvation. Pump, lines or filter.
 
Craig Nedrow

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Bottom pic is a hotter plug, and the burn pattern shows it. I have burnt a hole in two different engines because of a lean condition, just saying. Every electric pump i've had would fill a holly carb, both bowls in seconds.
 
3 Ton

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You can measure the fuel pump pressure. In a rare instance the valve can pop loose and plug the outlet.

ALL fuel pumps are chinese made and very bad for older rigs. Have your OEM on rebuilt, or do it yourself. Kits are out there.
and not chinese ones. Now & Then in Maine is your connection for fuel pump parts.

Backfiring IS a lean condition.
I missed where you said what type carb it is. So cant help ya there.
 
bucket

bucket

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3 Ton said:
You can measure the fuel pump pressure. In a rare instance the valve can pop loose and plug the outlet.

ALL fuel pumps are chinese made and very bad for older rigs. Have your OEM on rebuilt, or do it yourself. Kits are out there.
and not chinese ones. Now & Then in Maine is your connection for fuel pump parts.

Backfiring IS a lean condition.
I missed where you said what type carb it is. So cant help ya there.
Click to expand...

Again with the China thing...

Not all fuel pumps are made in China.
 
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