'94 K1500 Blazer 6.5TD help

[BlazerTurbo]

I just bought a '94 Blazer TD with 170,000 miles. The truck is awesome and runs great on the highway. We got about 17mpg on our first tank of fuel. We just took a trip up into the mountains in NW PA and had performance and exhaust issues. Power was disappointing and the truck struggled much more than it should pulling a 14' trailer up the hills. It also blew heavy black smoke while climbing the hills to the point that I have black soot down the side of the trailer. I assume it's unburned fuel. Even with that, we still got 12.5mpg while towing. This is my first diesel and I'm looking for a place to start without taking it to a shop. Glow Plugs? Turbo? The guy I bought it from had replaced many of the components but only did the easy side of the glow plugs. I have a feeling that's where I should start. Can anyone point me in the right direction? I'm in central PA in case there's anyone in the area that can help without raking me over the coals. Thanks.

[Robyn]

First off :D :D

Welcome to The Diesel Page

The glow plugs are only a cold starting aid and do nothing once the engine is running.

The 94 is the first year of the electronic injection system on the 6.5
Has the Check engine light come on? if so get the codes read and lets see what its telling us.
If there are no codes check to make sure the waste gate is working on the turbo.
This is the little arm assembly with the vacuum can on it over on the Pass side of the engine.
There should be about 15" HG at the little vacuum hose at the wastegate acuator.

If there is no vacuum there check the plastic lines that run to the vacuum pump and to the wastegate solenoid which is on the drivers side valve cover towards the rear.
The vacuum pump should be checked too to be sure its producing about 26"hg steady vacuum at the pump itself.

Be sure all the vacuum lines from the vacuum pump to the wastegate solenoid and to the wastegate actuator are all in good order and that you have vacuum. If the vacuum reading at the pump ( hook up gauge to pump only) is low and wiggly the pump is trash.

Give this a go and let us know

Robyn

[93_Burrito]

Got a few more central PA people popping up here... I'm in York county myself.

[Warren96]

Mine is a blazer also and when it blew smoke in the past ,it set a code in the computer.You dont have to take it to the dealer for this, if you dont know how, ask, it's easy ! Did you say ''raking over the coals''? Not on this forum.

[trbankii]

Welcome to the forums - just across the river from Harrisburg myself.

Robyn's information is a good starting point. With a bit more information the board should have you up to speed on your new truck!

[BlazerTurbo]

Thanks for all of your input. I'll try working on that this week to find out whats going on. The service engine light comes on intermittently. It doesn't come on all the time and when it does, its only on for 10-15 seconds and then goes out. I'll check the vacuum pressure and get back on to post my findings. Thanks again everyone.

[BlazerTurbo]

Performed a vacuum test and I'm ready for the next bit of advice. There is a steady 25" of vacuum at the pump. There is a steady 5" at the EGR. There is vacuum at the wastegate actuator but the needle bounces around wildly between 13" & 19". I also hooked up my vacuum pump to the actuator. It immediately drops to "0" after I stop pumping which leads me to believe that the actuator is bad. Also, the engine light does come on intermittently, for 10-20 seconds at a time, on the highway. It does not come on at all when driving around town. Thanks again for all of your help...I'm sure I'm saving a ton of $$$ with this forum. It's great.
:)

[JohnC]

Sounds like the diaphragm in the actuator is shot. You had the tester connected directly to the actuator, right? When the engine is running can you pull the rod out of the actuator? (It should be very hard to do).

It's easy to check the DTC codes on a '94. Do so and report back.

[BlazerTurbo]

Thanks JohnC. I read the codes and got 33, 39, 68, 78. I had a thought though...the guy I bought it from did some major work (heads, etc) just before I bought it. If he didn't clear any codes, some of them may be pre-existing. Would it be a good idea to clear the codes and start from scratch? If so, how do I do that? Regarding the actuator, I did have the vacuum pump hooked directly to the actuator. I can pull the rod out and it is somewhat difficult given the close quarters. Thanks again for your help.

You over in M-burg area, trbank?

[BlazerTurbo]

Can anyone help me out with the codes I found? Should I reset (how?) and then try again to make sure the problem wasn't fixed previously? Also, took some advice from this forum and pulled the rad shroud off. What a mess in between the rad and cooler. Cleaning should help bring the temps. down. Still need some input with the wastegate/actuator and codes. Thanks again.

[JohnC]

39 and 68 are trans codes. 33 is an EGR code. 78 is a boost code. These 2 are likely related to problems with the vacuum system.

To clear the codes:

(This doesn't work if the ECM is in the process of dumping the codes, so you may have to try several times)

Key off. Insert the jumper you used to read the codes. Key on, fully depress both the brake and throttle. Hold them until the check SES light flashes a code. If it flashes 12 only you're done. Release the pedels, pull the jumper and shut the key off in that order.

[Kick Ass Matt]

39 and 68 are trans codes. 33 is an EGR code. 78 is a boost code. These 2 are likely related to problems with the vacuum system.

To clear the codes:

(This doesn't work if the ECM is in the process of dumping the codes, so you may have to try several times)

Key off. Insert the jumper you used to read the codes. Key on, fully depress both the brake and throttle. Hold them until the check SES light flashes a code. If it flashes 12 only you're done. Release the pedels, pull the jumper and shut the key off in that order.

No key off first then pull out jumper...do it the other way bad things might result, although I wouldn't know what those "bad things" might be...

[BlazerTurbo]

OK; I got rid of the trans codes. Now I have 32, 33 and 78. I know that 32 and 33 are EGR codes but I don't think I have symptoms of an EGR problem. Should I start by replacing the 3 vacuum solenoids or should I do the wastegate actuator first? Thanks.

[Robyn]

I would make sure that the wastegate actuator is working right and or replace it.

The wastegate solenoid on the LH Valvecover can also be a source of issue.

Once you get the actuator fixed then try again. Your 78 should go away.
The computer senses boost in the intake and if its too high or low for a particular throttle setting it will set the code 78.

Good luck

Robyn