Another gmt400

[Jawzjeep]

Picked up another one. Makes 3 for me now. No pics yet. Barely took a look at it. Price was cheap. 88-91 based on interior and I'm pretty sure th400. C3500 with a canopy. Gonna do a quick once over and put it up for sale. No room in my life for something without a front drive axle haha.

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Oops. I forgot about 'street view' on google maps,
look at that!

 

[Jawzjeep]

Just realized I drove it home like this. Holy crap!

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Was the original owner. It's a 1990 and the maintenance record show his name from 1991. Paperwork shows a new engine installed in 2006 at 110,000 it has 190,000 now.

Also found this which was pretty neat.

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Found these in a box in the bed brand spanking new.

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[bucket]

That tire is impressive, lol.

 

[Jawzjeep]

That tire is impressive, lol.

I was underneath doing a little bit of inspecting when I saw it. Could not get my head away fast enough.

 

[HotWheelsBurban]

That tire.....whoooooa. WOW.....

 

[Jawzjeep]

I know this place is about Square bodies but my 90 is giving me some problems. I'm hoping that because it's TBI just like my Suburban the information crosses.

90 c2500, 5.7 w/AC. Runs rough after it warms up and the idle drops down. Exhaust smells rich. No codes..

I was doing some poking and prodding and testing and thought I found that my EGR vacuum solenoid had failed open. Went down to the parts store to get a replacement and it's not the same as what I have. The unit isn't the same and it doesn't have the same electrical connector. In fact the parts guy referred to it as something completely different. And the only option that he has for an EGR vacuum solenoid is the part that he brought me that doesn't have the correct electrical connection on it.

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This is the solenoid that is in my '90. Mounted in the exact same spot as my EGR solenoid in my 91 Suburban. Google Lens says it's a EGR solenoid. It has a 4 prong connection, but factory harness only uses three of the four. The large port has a vacuum line coming from here..

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And the smaller port went to the EGR valve itself.

I thought the solenoid from my 90 had failed because I was able to push and pull air through both ports at any time. But since the part guy is calling it something different I don't know if I'm actually testing it correctly. Since it has a vacuum line going directly to the EGR I assumed that's what it was.

My 91 Suburban has an EGR vacuum solenoid that looks exactly like the one the parts guy was trying to sell me with a little foam portion on the tip of a vent. It fits in exactly the same location as my 90s' solenoid and even has the exact same hard plastic vacuum line running from it to the EGR. My 91 has a two prong connector and so does the harness. So I can't even pull the one out of my 91 and put it into my 90 to see if it'll work.

This is the one on my 91 suburban noAC.

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I guess if I have to get the finned one then that's what I have to do. But at $150 ish bucks I'd really like it to be the other one.

Can anybody supply some clarity to what the heck is going on? Like what the difference is or why every time I look the part up it looks like the one I don't have?

 

[Sad Sack]

maybe the parts guy screwed up:

https://www.oreillyauto.com/detail/c/standard-ignition/engine-sensors---emissions/emissions---air-management/egr-valve-control-solenoid/7526524a7b60/standard-ignition-2-terminal-egr-valve-control-solenoid/std0/vs12/v/a/3054/automotive-truck-1990-chevrolet-c2500-pickup-rwd

Does that look like what you need?

That was what pulled up for a 90 c2500 2wd

 

[Jawzjeep]

That's the same one that the parts store guy pulls up with a two wire connector.

Mine has this connector

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As you can see the solenoid has four prongs but my factory wiring has three prongs so one isn't used

 

[Sad Sack]

That's the same one that the parts store guy pulls up with a two wire connector.

Mine has this connector

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As you can see the solenoid has four prongs but my factory wiring has three prongs so one isn't used

Does the old one have a part number on it?

 

[Ricko1966]

That's the same one that the parts store guy pulls up with a two wire connector.

Mine has this connector

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As you can see the solenoid has four prongs but my factory wiring has three prongs so one isn't used

Look at a Wells 2f1120. I think he sold you a DPFE valve Exhaust Pressure Differential Valve.

 

[Jawzjeep]

10068570 is Part number on the side. Is it just not coming up for the part guy because I'm calling it an EGR instead of the stupid exhaust pressure valve solenoid? Maybe it's just my language that was wrong I guess. Is it tested the same way as a regular EGR solenoid? Definitely testing $100 sensor before I just go get it.

What I can't seem to understand is why this one applies to my vehicle but all the rest don't. What's so special?

 

[Jawzjeep]

@Ricko1966 that's definitely it. Any idea why its there instead of a EGR solenoid or is it just the same thing with a different name? Off to find out how to test it.

 

[Ricko1966]

@Ricko1966 that's definitely it. Any idea why its there instead of a EGR solenoid or is it just the same thing with a different name? Off to find out how to test it.

I just looked at a 2f1120 sorry it's only 2 wires. Look at 2f1121

 

[Jawzjeep]

I just looked at a 2f1120 sorry it's only 2 wires. Look at 2f1121

Thanks dude, I caught that too.

Appreciate the help gents.

Wish it was the cheaper one... grumble, grumble

 

[Jawzjeep]

She's running like a champ now. Here's what I figured out

After seeing how expensive this stupid exhaust pressure differential valve is and having no codes coming up I went to checking miscellaneous sensors.

I confirmed my EGR valve is working and holding vacuum but pulled it anyway, cleaned it and put a new gasket. Then swapped on a new IAC that I had on the shelf and did the procedure to set it.

Started up nice and easy, coughed a little bit at first and then smoothed out. Idle dropped down like it's supposed to so I took her for a spin and everything seems to be working good now.

Unfortunately with no codes it made it a little harder to determine what was going on but in the end I believe my IAC was bad. Visually it looked pretty rough on the inside even after cleaning it a bit. And I swear the stepper motor never stopped trying to adjust it while in diagnostic mode.

I couldn't find much info on that exhaust pressure valve thing or how to test it. I just reinstalled it. If it's supposed to be tested like in EGR solenoid then it failed but seems to be working so that must not be the correct testing procedure. At this point I'm not going to scratch at the scab and leave it be.

Thanks fellers