97 Blazer acting up need help

[jdrobbins]

Ok it will start and run fine for about 4-5 miles then it will act like it has water in the gas, runs very rough. If you let it set a while 30 min then it will start and run fine untill you let it cool all the way down. It just started it 5 days ago and has done the same thing every day. This is a rebuilt motor with 4000 miles, I was on vacation 500 miles from home when it started, but luckily made it home yesterday.

The very first code it threw was a MAF sensor, so took it off and cleaned with MAF cleaner.
Now it throws codes for crank and cam sensors.
I put a new fuel filter on it today.

Any help will be appreciated.

Thanks

[old_master]

What are the DTC's that were set in memory?
97 was a troubled year for ignition switches.
Have you checked fuel pressure and leakdown?

[jdrobbins]

New info.
Checked fuel pressure all pressures are good.

The codes it is throwing today are

339
341
440
1351

This is my wifes truck so I don't drive it much but it is still doing it almost the exact same time after you start driving. It will sit and idle for 30 min and not do it at all.

Today when I was looking at it it now seems to be electrical. When it starts to happen the tach starts jumping up and down and when it is really acting up the abs light comes on and the dash starts freaking out.

Thanks for helping

[old_master]

All of those DTC's indicate an erratic voltage problem. Sure sounds like an ignition switch problem.

Don't rule out fuel quite yet... what was fuel pressure with the key on, engine off, pump running? How long did it hold after the pump shut off?

[jdrobbins]

Ok, new info

Went ahead and changed fuel pump as it had a lifetime warrantee on it and didn't cost anything but my time.

No Luck - did not change anything.

Now I ordered an Ignition switch will be in tomorrow.

[jdrobbins]

Installed new Ignition Switch.

NO Change!!!!!!!!!!!

Any other guesses ???????????

[gotojojo]

Originally Posted by jdrobbins

Installed new Ignition Switch.

NO Change!!!!!!!!!!!

Any other guesses ???????????

I had a similar problem before with my Blazer missing and running rough. I was informed by an auto parts store to change the oxygen sensors, there are three and cost 50 + dollars each. This corrected my problem, it sounds similar to your problem.