'87 TBI 350 Troubles

[Jims86]

it was 180 out when i first stabbed it but im am sure that it is in the right possition because i pulled the #1 plug and felt for the comppression to blow my finger off the hole and the timing mark at the right location.

when the timing chain slipped it was back firing out the throttle body and the exaust so i think that it backfiring would mess the sensor up.

I havnt had time to replace the map sensor yet and probably wont until the new year.

It would be rare if it did, but then again, if it backfired with the throttle shut, it is plausible that it could have over pressured and torn the small diaphram in the sensor.

 

[bucket]

when the timing chain slipped it was back firing out the throttle body and the exaust so i think that it backfiring would mess the sensor up.

Ahh, yep that makes sense.

 

[Jake292]

ok so i put the sensor on this morning and still no luck.

It fired right up with the etc timing wire un plugged but once i plugged it back in it would stumble and die. it looks like it is putting the same amount of fuel in regardless if the wire is plugged in or unplugged. I checked the timing and it is right on with the wire unplugged but i couldnt get it to idle enough to check it with it plugged in to see what it was doing. the voltage is right on the map sensor though.

 

[Jims86]

ok so i put the sensor on this morning and still no luck.

It fired right up with the etc timing wire un plugged but once i plugged it back in it would stumble and die. it looks like it is putting the same amount of fuel in regardless if the wire is plugged in or unplugged. I checked the timing and it is right on with the wire unplugged but i couldnt get it to idle enough to check it with it plugged in to see what it was doing. the voltage is right on the map sensor no though.

Have you moved anything on the dist since this problem occurred? Wires. cap,rotor? it is real easy to cross 5 and 7. I am thinking that maybe something was messed with while checking before the MAP issue was dicovered.
Worth looking over. Make sure the Distributor has a good ground to the manifold.

 

[Jake292]

i did replace the entire distributer(cap, roter, etc) before the map sensor problem was discovered. just checked the wires and they are in the right place.

 

[Jake292]

also i checked the codes on the computer and it only shows rich exhaust....possibly flooding still?

 

[Jims86]

also i checked the codes on the computer and it only shows rich exhaust....possibly flooding still?

If the timing is so screwed up that it is pumping raw fuel through the exhaust, yup. Have you checked fuel pressure?

 

[Jake292]

i dont have a fuel pressure gauge

 

[Jake292]

Does anybody know if autozone loans fuel pressure gauges

 

[Jims86]

Does anybody know if autozone loans fuel pressure gauges

Best way to find out, is to call them. Also, when is the last time you changed the fuel filter?
Is your exhaust stock?

 

[Jake292]

it was a long time ago that the fuel filter was replaced.

 

[Jake292]

wouldnt it be running lean if the fuel filter was clogged?

 

[Jims86]

wouldnt it be running lean if the fuel filter was clogged?

Not if the ecm is opening the injectors to compensate. that Coupled with low pressure, leads to fuel drops instaed of spraying. It usually says lean if you try to give it throttle. It will also show rich with a Vacuum leak, which is another thing that commands extra fuel. Check for loose intake manifold bolts. ther is also a possibility that your intake gaskets are bad...old gaskets that are ready to go, usually dont stand up to a good backfire through the intake.

Unfortunately with OBD 1, you have to go through and do the things that May have not been done to figure out a problem. The ECM will tell you of a certain engine condition, but will not tell you about a fuel system problem, like filter, or the line at the fuel pump that likes to split...or a bad ignition coil, or secondary ignition problem....those are still things you have to physically check. The fuel issues can usually be narrowed down with the pressure gauge, which IMO, every TBI owner should have in the toolbox.

 

[Jake292]

ok i replaced the fuel filter this morning and still no change(wont idle with esc unplugged but runs fine unpugged)

 

[Jake292]

I checked the vacum coming from the intake and im getting 20 inches