Mechanics

NOT STARTING OR STAYING RUNNING

1993 GMC Safari

Engine Performance problem
1993 GMC Safari 6 cyl All Wheel Drive Automatic 221, 72 miles

starting problems/doesn't stay running. Some days will start run for 4-5 mins then shut itself off cannot drive.
New parts by self or mechanics: distributor assembly, egr valve throttle position sensor, fuel pump, fuel pump relay, plugs, wires, coil

Fuel pressure 60psI at stop 58psi and holds Only code was 32 EGR and replaced it. Fuel injection unit was replaced 70 thousand miles ago.
Avatar
Jschnobrich
June 8, 2009.




Lots a miles on that puppy!

HAve you determined what is dropping out. Spark?

I assume the new distributor came with a cap and rotor?

Did you scope it to see if any irradic pattern is present?

Code 32 still present?

No car has not been on a scope since new distributor was put in yes all new assembly. Drove for 1-2 weeks left me alongside road. Called garage sat there for 20-30 minutes it started after a couple attempts. Ran rough had to slip it into neutral because of rough idle. Made it home. Never left the yard with it again. Attempted to start it again once and awhile it would start and I could move it around in the yard only run 4-5 min and it would shut off.

Today I put on a re rman ECU/PCM. Didn't make a difference. Put it on because the newer plugs were dark(rich Fuel mixture) but still fired when I turned the engine over. Seemed like good compression(timing?)
I went on to get at the wiring harness connector that goes into the Fuel regulator/injectors key on had 12.14 volts across the red and blue lead from ECU and the resistance on lead to Fuel reg/injectors was at 4 ohms.
As I mentioned earlier it had given the 32 EGR code and it was replaced. Somewhere along the line here fuel wasn't being burn't properly or too much was being injected fouling up the plugs. Is there a maff/map sensor, IAC or oxygensensors calling for too much fuel.

Thanks,
jim

Tiny
Jschnobrich
Jun 10, 2009.
HEy Jim,

Since powertrain management seeks to maintain or reduce emmisions, it will set codes that find something in error and is using other sensors input data to make changes to try to manage a problem. It then would set a code or codes for any incorrect data. Since the EGR code is gone and the no other codes exist, it takes us to a mechanical scenario rather than management. At least it is how I see it.

So I would think either weak spark or too much fuel as you say. Sice the CFI fuel pressure is good, I would lean towards spark or poor compression.


http://www.2carpros.com/forum/automotive_pictures/30961_nost_1.jpg


So I would say the next step now that the plugs are out. Is a compression & timing check before new plugs are put in. Spark did look like it could have been stronger with new coil & dist I figure the plugs are over saturated with gas. Maybe getting closer to finding out why the egr port openings were gas/oil wet instead of exhaust bone dry. Might be a couple days before I have time to get this done.

Are there nylon coated timing gears in this 4.3 W?

Thanks,
jim

Tiny
Jschnobrich
Jun 10, 2009.
Sometimes new parts are not functioning as a new part should.

I would confirm or eliminate the compression for sure while the plugs are out.

Hoping to get to the compression check on sat that left bank of plugs are a treat to get in and out. I seen you listed a ladder chart for testing, couldn't read it by the time I zoomed it up where it was readable it was to blurry. Maybe do it to silkplantplace@means. Net

Guess it's a timing chain distributor could have jumped out of sync. Thanks,
jim

Tiny
Jschnobrich
Jun 12, 2009.
I have more charts if needbe. YEah, the left side plugs are an engineering feat. Otta hang that bastard that approved that one.

I sent the diagram. To your email

So compression readings are all between150-154 psi. All plugs fouled #3 dripping wet.

Off for new plugs, will clear codes and start, re- test codes.

Thanks for the sentiments on the plug access factor a new 1" hole now exists threw the lower dog house rim allowing access to # 5 plug with 3/8 drive tools. Under the rug it's out of sight. Tired of the hassle.

Meanwhile what's causing the gas overload?

Ok back together now, no start, next step 5oz gas down intake turn over starts runs until gas fumes run out

I 'd say we are at step 4 on chart. I need to see if the light flashes. On step 5 I first tested 4 ohms charts states there should only be 1.6, will retest
AD

Tiny
Jschnobrich
Jun 13, 2009.
First two things on too much fuel is a bad fuel pressure regulator (but the spec is good..eliminates that) and a bad coolant temp sensor.


http://www.2carpros.com/forum/automotive_pictures/30961_cts_2.jpg



I would have thought a code for it would set, but it says here it may not.

Not sure on the nylon gears.

Well when I checked out the connector to the CFIunit the resistance is here and there. Reconnected it, started and I drove it for 14 miles idled fine at shut off. Restarted it twice.
Wife went to start it after 5-6 hours not starting. Today took apart the connector again no resistance moved the wires around didn't seem to jump on the ohm metere. Tugged on the wires alittle 2.0 ohms comes on reconnect connector it starts.

Either there is a problem at the connector or something inside the plenm.

Tiny
Jschnobrich
Jun 14, 2009.

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