Injector knock?

[Billman]

I recently replaced my vacuum pump because I thought it was making noise. It sounded like a rod knock. Truck has 60k on it so I thought it would be a good idea anyway. Well, once the truck warmed up, knock came back.

It's not that the noise is so bad, it's only at idle. Once your into it, you can't hear it. But sitting at a light drives me crazy.

This past weekend, I towed my trailer to the races.During the trip, with the cruise control on at 65, and beginning to climb a hill, it kicks out of overdrive. I always watch the passenger side mirror to see the exhaust. It doesn't smoke at all. But I did notice that after I fueled up at a rest stop while leaving the truck idling for 15 minutes, that it smoked like hell the first time it came out of overdrive in cruise.

My question is... Could I have a bad injector or injectors? Could this be the knock at idle I'm getting. 60k doesn't seem like that long for a set. I always use conditioner with every tankful, not great stuff but it is something.

The other thing I want to know is with a pump that has 15k on it, will Hi-pop injectors hurt it? If I have to go for new ones anyway, why not better ones? Has anyone seen much of a difference with them? Has this happened to anyone else?

Any insight would be greatly appreciated.

[charliepeterson]

I would short out the Injectors to find the one which is giving you the knock. With the engine running loosen up the Injector lines one at a time until the knock goes away. Give it about ten seconds at each Injector.

After 75,000 miles the Injectors don't owe you anything.

You're right in assuming if the Injector Pump might not handle the new Injectors. If the Pump has some miles , it takes a lot of pressure to open the High Flow Injectors. I would say do it. All the Injectors have the same mileage. If one fails the others won't be far behind. Even with stock new Injectors and a worn Injector Pump you might see issues when it's running.

Being a '97 you still have time on the clock for warranty?