1997 GMC truck issue.

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wtd

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southwest Mo.
My fiance and her 15 year old son own this truck. It has 29,353 original miles on it and has the 5.7L vortec in it. It originally was my fiance's grandfather's truck and basically is was given to the 15 year old son.

The other day her son got the truck stuck in the field. He was with two of his friends and was told to leave the truck alone and his older brother was going to get another truck to get it out. Instead of listening, they ended up getting the truck out but now the engine is missing in cylinders 2 & 8.

Supposedly one of the friends got in the truck and revved the engine up to redline to get it out and who knows how many times this was done.

The plugs, wires, cap and rotor were all replaced about 2,000 miles ago. I pulled the plugs in those cylinders and they look fine with no obvious cracks or damage to the tips. I pulled the cap off and all of the contacts look fine as does the rotor tip.

I pulled the valve cover on that side to see if anything looked abnormal but every thing looked fine.

My fiance's father is a backyard mechanic and did some research and said he found information that states that if you over rev this engine, it will mess up the fuel injectors in the spider and says that we need to replace the fuel injection spider.

My question is, what other tests do we need to do to figure out why we have these misfires and has anyone else heard that over revving the engine will cause a fuel injection problem on this type of fuel system? Thanks.

Wayne
 
Originally Posted By: mk378
Start with a compression test to check for mechanical damage.


After that, see if it still has the original Poppet style CSFI spider unit on it

If it does, it may have just been it's time

Those style injectors get problematic with time

You can drop in a replacement updated MPFI style replacement
 
It does still have the original style CSFI system since it's low mileage. It was running fine prior to the over revving of the engine. The valve springs on those cylinders look fine. I guess we can pull the rocker arms to check to see if the push rods are bent. They don't appear bent but you can't see the entire rod with them installed.

I will do a compression test to see what it tells us. Thanks for the suggestions.

Wayne
 
This is just sad.

The kid is going to destroy this thing have regrets the rest of his life after he grows up.
 
as stated, check compression. at first I thought the fuel injection suggestion was crazy - until the spider was mentioned - then I recall some discussion with a mechanic friend on this.
 
Originally Posted By: dlundblad
This is just sad.

The kid is going to destroy this thing have regrets the rest of his life after he grows up.


I doubt that since he doesn't appreciate much of anything. He doesn't even like the truck and wants one like his brother has which is a 2014 F150 crew cab 4x4.
 
Originally Posted By: Alex_V
Whatever it is, make the kid pay for it. It will keep the truck, but more importantly him, in better shape.


His mom has already told him he is paying for the repairs but even that doesn't seem to phase him.
 
Originally Posted By: wtd
Originally Posted By: dlundblad
This is just sad.

The kid is going to destroy this thing have regrets the rest of his life after he grows up.


I doubt that since he doesn't appreciate much of anything. He doesn't even like the truck and wants one like his brother has which is a 2014 F150 crew cab 4x4.


You have my condolences. He sounds like a real winner.
 
Originally Posted By: dlundblad
This is just sad.

The kid is going to destroy this thing have regrets the rest of his life after he grows up.


yeah, screw this, have the kid use his own money to pay a shop to diagnose and fix it. otherwise, the learning will never occur. can't afford it? no problem, truck stays parked. i would be much more appreciate of a beautiful low mileage gmt400 than this brat.
 
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Maybe offer to buy it as-is, for an appropriately discounted price. If kiddo doesn't like it he may go for an offer, though there is the problem of what he'd do with the money.

Since its apparently your problem anyway you may as well have a stake in it. If you keep and run it that'd be a lesson, otherwise you could sell and move on.

Of course this would be in a rational world. The real world has people in it.

EDIT: Sorry, not an answer to the question you asked. Nothing useful to add technically either.

I did once break the engine on an 1800 Marina trying to drive it home after the clutch had failed and it turned out to have broken a piston ring which had exited via the exhaust port, scoring the bore a bit and banging up the piston top which luckily was partly protected by lead deposits.

Replaced the ring and it drove OK for another couple of years until a spring hanger crumbled.
 
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I would have also loved to have a low mileage truck like that given to me at that age. It has been used on the farm so it does have scratches and a few small dents but it ran great up until this incident. I guess the next step will be a compression test. Thanks everyone.
 
Originally Posted By: wtd
Originally Posted By: Alex_V
Whatever it is, make the kid pay for it. It will keep the truck, but more importantly him, in better shape.


His mom has already told him he is paying for the repairs but even that doesn't seem to phase him.


Too bad. Such learning is hard to affect on someone when your perspective is the minority in their world and they've already established mindsets/habits to the contrary.
 
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