98 K1500 issues

[allg32]

OK couple of issues with my truck. It stumbles or misses on hard acceleration will throw P0330 code occasionally. I think this issue is the fuel pump. Checked my pressure and its around 52-55 at idle but only goes up to about 58 when I hammer it, this is just sitting in the garage in park and it will backfire occasionally thru the intake. Timing is good. MAF is good haven't checked TPS yet
The other issue and the one I am more worried about is when I am driving and go to accelerate to pass someone. When I stomp on it it will just rev and not really go like it should. If I just slowly accelerate it will drop down and go but still not like I think it should.

Any ideas?

[speedygonzales]

Your fuel pump appears to be fine.

300's are nearly always ignition. There is no 330. The closest is 336 for CKP. They are known to be trouble.

However, (you didn't tell us which engine) I'm going to fill in the blank and assume you have Vortec 5.7.

These engines go through caps and rotors like Hitler through Poland. In fact just the other day I parked mine and next day boom no start. When you have a missfire on a Vortec. Start with the cap and rotor. Day after Xmas was a hold up till I got to Napa to replace the funked up parts.

You would do good to pull plugs and look at them while you're there.

[allg32]

Yes it is a 5.7 vortec and its a 0300 not 330. New cap and rotor and distributor.. Went to pass somebody this morning, accelerated and nothing happened, backfired then all of a sudden it took off like a scalded dog. Really acts like a carbureted truck that needs more fuel. Its got 207K miles, think the timing chain may be wore out?

I will check plugs this weekend

[speedygonzales]

300 is cylinder missfire. Look for the exact number like 304 will be cylinder #4. You can also unplug and replug one plug wire at a time until you find the one that causes no change.

[speedygonzales]

Originally Posted by allg32

Yes it is a 5.7 vortec and its a 0300 not 330. New cap and rotor and distributor..

Did you do the cam retard process when you put in the new distributor?????? I don't believe a mis timed distributor will give your symptom cause mine was mistimed for years before I realized it needed to be timed. But one less monkey in the wrench. You know?

[allg32]

I've had the code pop up a couple of times but then the CEL will go off and may stay off for a week or more. It always comes up as random misfire. But the issue is always there
Yea I have a buddy with a scanner so I had him set the timing.

[speedygonzales]

If the same cylinder is misfiring, the plug should indicate it by being fouled. Or at least more fouled than the others.

You can then try swapping out the plug and the wire to see if that eliminates it. If those 2 things don't fix the misfire, you have no choice but to then change the cap. It couldn't be the rotor since that is common to all cylinders.