1994 350 ci.

Here goes.....ran out of gas in my TBI truck (or so it felt like) and now it runs rough. I'm wondering if maybe I didn't run out and it just died as the result of something else. I added Heet (to remove potential water in system) and STP to clean injectors...and 10 gal. of gas.
Have replaced fuel, strainer (in tank), filter, plugs.
Have tested EGR, and fuel injectors and observed fuel flow at intake of fuel filter.
EGR: I removed and manually pulled a vacuum and observed the plunger moving upward and holding the vacuum for 2 minutes.
I also removed the air cleaner and observed the cone shaped spray streams into the bowls in the carb.
Don't know if the EGR is supposed to work this way.
I start the engine, it starts quickly and initially holds at about 1500 rpm.
Then the engine slowly drops to about 900 rpm and "falls off" (dies unless I catch it with the throttle/pedal)
When warm (after about 3 minutes ) it goes to dying right away. I can bring the RPMs up and keep it alive but it won't hold.
When I put it in gear it chugs spews and hesitates horribly.
Please help.
I read Vader's EGR document and it's great. I just can't get my truck to idle to test the EGR.
I take off the vacuum hose from the EGR and no change in engine behavior.
Rick

 

Check spark timing

Check fuel pressure

Check for a vacuum leak (high idle symptom)

Check/replace the IAC (idle air control)

Check/replace TPS (resistance should be smooth through the range)

Check/replace MAP sensor

 

Whitehawk,

Great info. I'll check the fuel pressure first because I checked the spark timing already.
I'll let ya know.
Rick

 

Sometimes, especially without a computer diagnostic, you just have to start replacing sensors (its always some stupid sensor!). If you are keeping the vehicle for a while, then I guess it is justifyable to put new sensors on. Don't get autozone brand sensors, I had a problem with an $80 crank position sensor and it would not work (tried learn mode many times with two different scanners), pissed me off.

This is assuming that mechanically, the engine is good ...because leaking intakes gaskets, jumped timing, and bad valves can't be fixed with tuning (not to scare you buddy, thats just worst case scenario).

 

Thanks again. I hear ya. The engine and everything was just cruising along at 65mph and then is just pff .. died. I didnt' even try to restart it. I just assumed it ran out of gas because the needle was on empty or near it.
It's when my wife brought me some gas and I restarted it that it got all goofy.
I'm going to measure the fuel pressure tomorrow and replace the carb gasket set (that gets trashed when you take off the TBI carb upper half to examine it). So I'll rebuild the pressure reg. and o-rings while I'm at it.
I still think (and hope) it's something in the fuel system.
With a hole in the strainer in the tank I'm almost betting it's the pump.
My next jump is the MAP sensor like you said.
R.

 

Checked fuel pressure by making one out of a simple water pump pressure gauge from Lowe's (*near the sump pumps for about 7.50) and some hose.
Gauge didn't even deflect to 4 psi upon initial test.

I thought, it should have peaked at about 20 or so.
Replaced it (2 hours) and it was in the tank. Bummer.
I used some ratcheting staps as a "buddy" lift to lower the tank even though it was empty.

Fired right up and ran fine.
So, replaced filter, plugs, upper end of carb 8 pcs. or so, strainer in tank,and all is now well.

Rick