New to me 87 Jimmy 4x4

[Jasonglh]

I picked up an 87 Jimmy from craigslist with a TBI 350 700R4 and supposed rebuilt transfer case and tranny. What was supposed to be a simple rear diff leak and broken speedo turned out to be a cracked transfer case from a new model Blazer with electric speedo output. It also had a bit of an erratic idle but did not show any trouble codes. Turns out most of the light bulbs and sockets were removed from the dash and now that is fixed.

I ordered a new correct np208 and speedo gear. Turns out not only was the speedo gear unhooked from the transfer case but also from the back of the speedo and the VSS sensor was not plugged in. I plugged it back into the speedo and got the speedo going as well.

At highway speed the truck doesn't seem to be working as hard as it did but doesn't seem to have as much power unless you really kick it down. The cruise still does not work. When the motor is cold it runs like crap until it warms up and does the usual smoking that is probably bad valve seals.

I have replaced the distributor cap rotor button and plugs but still have the erratic idle and crappy response especially when its cold.

 

[Jasonglh]

Forgot to add the belt was taken off the air pump and the cat is missing as well.

 

[496truck]

Check for any vacuum leaks? That's a good place to start. Always good to check the basics first. Sounds like the previous owner did some "tinkering" and now you get to play my favorite game called Find The F-Ups! I'm going through this same game with my own 87 Jimmy C-list purchase. My idle was high and the p.o. thought that putting a heavier throttle return spring would fix that. Turns out the Idle Air Valve on the pass side of the throttle body was broken. This may be something else to check on yours.

 

[MTNMIKE]

Also, test Plug wires ohm resistance, Timing, and like 496 said basics first!

Good Luck!

 

[Jasonglh]

Thanks for the replies.

No leaks I could find and the plug wires are ok. I swapped them with the plug wires on my boat and no difference.

I am off the next few days and will look further. Going to put in a new O2 sensor in also.

 

[mudboggink5]

So, where are the pics.

 

[Jasonglh]

Looks like I cant post pics yet.

Other than belt being missing anything else I should do with this air pump thats still other wise hooked up?

 

[496truck]

Does the air pump pulley spin free by hand or is it locked up. If it spins just put a new belt on it, it'll be fine. If it is locked up you should replace it depending on the emissions laws in your state.

 

[Jasonglh]

In Kentucky I think exhaust systems are optional. LOL

The airpump does spin freely but without a cat would it really do anything?

I did replace the O2 sensor and it does seem to run better at temp but until it warms up still runs like crap.

What is in the middle of that dash that sounds like a wind up clock?

 

[496truck]

Without the cat it is useless. You can remove it if it doesn't turn on the check engine light. Although by law you are not supposed to but it seems the cat is gone anyway so who cares right? You can remove the whole air pump system and plug the holes in the manifolds.

Mine runs crappy till it warms up too. Still working on that...

Haven't figured out the buzzing sound yet either. It's not the heater fan, I know that much.

 

[Jasonglh]

I ran down the tickng noise and found it's coming from inside the throttle body?

I took off the air cleaner and it's definately coming from inside the throttle body.

 

[496truck]

Ticking from the t-body would be the injectors. That is normal. To hear it inside the truck is not normal. Are they abnormally loud?

I thought you were talking about a buzzing noise from the center of the dash. I've got a wicked buzzing sound. Only when the truck is running. Key on/engine off no noise. Start it up and the dash buzzes. No radio, so I don't think it's ignition interference but I can't find the source yet.

 

[Jasonglh]

Yeah its definately coming from inside the throttle body and I can hear it in the cab with the truck running no problem. My exhaust is extremely loud too.

 

[mrgrim]

I was going to say the injectors as well but I have never had any that loud.

 

[Jasonglh]

I metered both injectors and resistance is 18 ohms each and from what I have read here it should be 13-16?

I'm guessing these are just worn out and that explains all the racket?