Rough Idle and a cracked floor. Please help

[hunterguy86]

Ok I've got a few problems with my 86 k5. 305/700R4/208.

1. The blazer idles really rough. Its idleing at about 550 RPM judging by the tach which is where it should be according to the sticker under the hood. I just replaced all the plug wires. The plugs, cap, rotor, and fuel filter are all new. I havent noticed any vacume leaks(I fixed the ones i did find). It seems to be running rich. I can smell fuel and the bumper is black where the tailpipes exit. If it is running rich would it make it idle rough? how do I adjust this? Maybe a timing problem?

2. My floor is cracked on the driver side along the rear bolt closest to the door. On that same side, there is a rust hole by the front seat mount bolt. how do I fix these problems?

Thanks for all the help y'all.

Dustin

 

[hunterguy86]

Anyone?

 

[shane74]

Ok I've got a few problems with my 86 k5. 305/700R4/208.

1. The blazer idles really rough. Its idleing at about 550 RPM judging by the tach which is where it should be according to the sticker under the hood. I just replaced all the plug wires. The plugs, cap, rotor, and fuel filter are all new. I havent noticed any vacume leaks(I fixed the ones i did find). It seems to be running rich. I can smell fuel and the bumper is black where the tailpipes exit. If it is running rich would it make it idle rough? how do I adjust this? Maybe a timing problem?

2. My floor is cracked on the driver side along the rear bolt closest to the door. On that same side, there is a rust hole by the front seat mount bolt. how do I fix these problems?

Thanks for all the help y'all.

Dustin

1. Check the EGR. You can check it by reaching under it and pushing on the diaphram. If it's bad, you should notice an immediate change in idle. Also, try pulling the EGR off and cleaning the passage. They often plug up with carbon. This causes the same issues you have.

The timing and fuel mixture is all controlled by the ECM. Not really much you can do to adjust it.

2. Get some 16 ga. flat plate and weld it up.

 

[Mad-Dog]

Justin, what type of fuel system do you have....?
Fuel Injected or Carbureted....?
I can't look at a '86 Blazer and tell what's under the hood w/o opening it....!

I'll take a wild guess and say it's got TBI, it runs rich so you gotta bad sensor.

It could be (coolant temp sensor) making the ECM think the motor is cold and running in open loop

If the ECM makes it into closed loop then the O2 sensor, Manifold pressure sensor, Throttle position sensor could all contribute to a driveability problem

Unless you know how to troubleshoot and test these components then ya gotta take er to a garage.

 

[hunterguy86]

Its got a rochester 4 barrel carb. I just rebuilt it a few months ago.
If I weld plate over the hole, what can I do to prevent it from rusting again? Just prime and paint it?

 

[shane74]

Its got a rochester 4 barrel carb. I just rebuilt it a few months ago.
If I weld plate over the hole, what can I do to prevent it from rusting again? Just prime and paint it?

If it's got a carb, did you check the timing? It sounds to me like an air/fuel mixture & timing issue. That said if you don't know what you're doing, take it to a shop you trust and have them look at it.

Yes, cut out all the bad metal, weld in the good. Primer seal it, and paint over it. Both inside the cab, and underneath.

 

[hunterguy86]

Thanks for all of the help yall. I'm gonna get on this stuff this weekend If its not raining. However rain is good its been really dry here lately

 

[Mad-Dog]

Oh ok.......the float level is probably too high causing a rich condition,
sometimes the float starts leaking and drops in the bowl causing the feul level in the bowl to rise too high making the engine run rich.
Or the needles are stuck in the raised position as a result of varnish built up on the outside of the plunger assy.
Probably due for a complete rebuild, should run fine afterwards.
Q-jets are rather complex for the novice, do a search on rebuilding carbs or quadrajets and you should be able to handle it.

As for the body work............it's not my specialty