'87 TBI 350 Troubles

[Jims86]

Hmmm. have you looked at the injectors while its running? Have someone cycle the key on and off, for the fuel pump to run, with 10 second pauses in between, to see if the injectors are leaking.

 

[89Suburban]

Are you sure the timing is set correct with the brown wire off? Possible that the timing chain jumped at all?

 

[Jake292]

Are you sure the timing is set correct with the brown wire off? Possible that the timing chain jumped at all?

it is at the 2nd notch from the left on the plate that is attatched to the timing cover that shows the timing and i just replaced the timing chain that probably hasnt run for more than an hour

 

[Jims86]

it is at the 2nd notch from the left on the plate that is attatched to the timing cover that shows the timing and i just replaced the timing chain that probably hasnt run for more than an hour

try turning it a few degrees counter clockwise at a time, and see if it will fire and run on its own. sounds like you may have it too far advanced.

 

[Jake292]

shouldnt i move it clock wise to retard it? i have already tried it where it was all the way to the right on the tab thats attatched to the timing cover.

 

[Jims86]

shouldnt i move it clock wise to retard it? i have already tried it where it was all the way to the right on the tab thats attatched to the timing cover.

So you do have a timing pointer?I thought you didnt. it should be dead center on 0*
havyou opened up your distributor and made sure the picup coil is in god shape.

 

[89Suburban]

Should be set to zero warmed up at normal idle with brown wire unplugged.

 

[Jake292]

Thanks 89sub. Thats what i was wondering.

The pickup coil is brand new.

 

[Jake292]

What would the symptoms be of a bad spark control module? If the ECM was bad the injectors wouldn't be spraying right?

 

[89Suburban]

A bad control module would shut the truck down completely. Mine gave signs of it going, started randomly shutting off.

ECM going bad, you really don't see many reports of that. I thought mine was bad and swapped another one in and it was the same.

I would just start off setting the base timing correctly and we can go from there. I am assuming tour emissions/vacuum hose label is missing?

 

[Jake292]

Are you talking about the sticker on the radiator support? I'll reset the timing when I get home.

 

[Jims86]

All TBi small blocks are 0*, 454's are 4*
There are 2 items to worry about for ignition on an 87-92 tbi truck... The Ignition control Module which is in the distributor, and the Electronic Spark Control, which is mounted next to the throttle body....Later models had the ESC in the EProm chip in the computer.
There is a possibility that one, or both are on their way out, but IIRC, you said the timing was advancing off the scale when you plugged the timing wire back in? It is importannt that you check the injectors like I said earlier, just to rule those out, the we can check the ignition components...There is no way to check the ESC, but most good parts stors can test the ICM.

ECM gets pulses to run the injectors from the ICM, and the engine should run with the ESC unplugged, as it is only a knock filter, and sends timing retard commands to the ecm.

 

[Jake292]

The entire distributor is new including the modules that are with it l

The injector don't do anything when you cycle the furl pumps with the key

I had the distributor timed at 0* and there wasn't a difference; the timing mark was almost vertical at idle and it didn't change smoothly when I gave it throttle.

 

[Jims86]

The entire distributor is new including the modules that are with it l

The injector don't do anything when you cycle the furl pumps with the key

I had the distributor timed at 0* and there wasn't a difference; the timing mark was almost vertical at idle and it didn't change smoothly when I gave it throttle.

With the wire plugged in?

 

[89Suburban]

Autozone's website says they loan a fuel pressure tester:

http://www.autozone.com/autozone/ac...d-Equipment/Fuel-Pump-Diagnostic-Kit/_/N-25h2