1998 454

[dkh_524]

My truck shut of on me one day after coming to a qwick stop on some slushy roads and only started and ran long enough to get into a parking lot. I have had a guy been looking at it who fixes it when ever I had a problem. He can't figure it out other then the motor being shot. I have fuel and spark the pressure on the fuel is where it should be. All it does is crank. He and some others think it shot due to the compression test I'll post a pic if the numbers.

In the past I had a hard start problem and replaced everything like the fuel pressure regulator and the fuel injectors replacing the injectors fixed the problem for about over a year. Just recently it did have that problem again but it would start. Once in a blue moon when I would shut the truck off my fuel pump would make a loud bang sound witch has been going on for some time.

I also have a friend that is a gm tech and he thinks I am fine but he doesn't have the time to look at it.

So I got some techs that say I am screwed and need a new motor. Then I got another that says I am good and just need to look at it but he can't find time to.

I need some more options on what I should do or a problem to check. Thanks.

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[CrustyJunker]

Unless that thing was banging around before it shut off, I doubt it's just "shot," all of the sudden. How many miles are on it, big guy?

 

[SCOTTYINWV]

I would seriously be looking for a new engine pulling that one for some machine work and rebuilding.

If the performed the compression check correctly, That's no Bueno.

 

[dkh_524]

It has 214,000 miles on it. It was running good and no over heating or smoke also if that means anything. Has anyone done a rebuild on one and what was the $

 

[CrustyJunker]

Yeah, agreed the compression numbers don't look fabulous, I've found similar results because of poor quality compression testers. Not saying this is the case, but I wouldn't say likely. Any check engine light?

 

[SixSpeedSS]

Poor quality compression tester or plugged air intake not allowing air into the combustion chambers.

How was it performing right up to where it quit? If the performance was good, then I would say those numbers are not correct. Keep in mind an engine is an air pump. I would re run the compression test and make certain the throttle plates are open with the air intake disconnected to get as much air in as possible while using a quality compression tester.

Typically low compression won't just 'occur'. The compression will gradually degrade over time. Obviously compression is an important element of an internal combustion engine, but it should still run with those numbers you show. Not great, but it should run.

Check engine light on? Plug a scanner into it? Check fuel pressure? At the minimum I would check the shrader valve and see if you get a pfft/spray of fuel. Are you sure you have spark? These 454s have injector issues too.

 

[steampunk1375]

I would check fuel pressure for sure, loud bang from the fuel pump sounds catastrophic.

Also did you look for spark? A failed ignition module can shut you down. I don't have a lot of experience with the 454's but I've been down the 'it quit and won't start' with quite a few makes/models.

 

[dkh_524]

Sorry it has taken awhile to get back. I havnt been able to get to it lately but hopefully soon. The day it stopped running it was running fine no issues with power. I did however checked the pressure and the checked for spark and they where both good to go. But I have been second guessing on the spark.

a week or two before this happened I did have a check engine light on but it went away.

A few years ago I change the fuel injectors with the bosh ones and did a tune up.

 

[Kevinx]

Pull the plugs, add a table spoon of oil to all 8 cyls. Slowly pull the fuel pump relay, and bump the starter around for a couple of revolutions. Then do a compression test. Your new injectors may be leaking, and washed the cyls down.
If that doesn't work, try un bolting the cats on the inlet side, and try again. A melted cat will wreak havoc with a compression test.
Make sure it's done with a good tester.
Just another thought. If the engine to chassis ground strap breaks. The plugs will see a big blue useless spark, but it won't fire the mixture. Long term cranking can pump out the lifters, and drop compression

 

[dkh_524]

Well the good news is my truck is now running. I towed it up to another friend that works at a gm dealer and he worked on it. It ended up being the coil. It was good going in but coming out it was bad. Also replaced the starter due to it started smoking when we were trying to find the problem.