delight024

Just thought I'd add a thread to an already growing epedemic of 4.3 fuel problems. All my problems as well have started since running low on fuel. After getting gas, within 20 miles I no longer can drive my new (to me anyways) 1990 astro rs. We have so far replaced or rebuilt the following: fuel filter, air filter, o2 sensor, fuel injectors, fuel pressure regulator and tested the fuel pump. I then hopped on the ol' faithful internet and have came to the conclusion that we could try 100+ things and the problem is still going to exist. People with the same problem have replaced far more to get no where. We've had 3 different mechanics come look at it to no avail. The computer says nothing is wrong - no codes at all. Out of all the threads of "fuel problem" has anyone actually fixed the problem?
My symptoms exactly mirror: http://www.automotiveforums.com/vbu...ad.php?t=212039 .
I'm beginning to believe that no one has an answer. What we have troubleshooted is that in the throttle body there is injector A and injector B as well as plug A(for the injector) and plug B. When watching the injectors while cranking the motor injector A squirts and injector B sort of drips. Obviously we replaced injector B. No difference. So what we did was take plug A and plug it into injector B. Lo and behold, now injector B squirts gas and injector A drips. We have traced and retraced all the wires for wear and tear. Again, this all started VERY soon after being low on gas which is what makes us want to believe it is the fuel pump and I burnt it out or something. We've checked it 3 times and everytime the key is turned on (not started) the pump kicks on and fuel begins to flow. PLEASE... if you have any suggestions I would much appreciate it. I have read every thread on this subject so far as well as other research and have came to the conclusion that until someone can say "THIS is your problem" I am not pouring any more money into this piece of S#$%!! Thanks for your help.

UPDATE: Today I tried unhooking the MAP sensor and it tried to run a little better. Going to replace it tomorrow.

enginetune

There are three important things to consider. First is if the fuel pressure is not correct, nothing else will be. Second is to make sure that not only the fuel pressure is correct, but that the volume is correct also. This requires a special gauge made for the test. Indications of incorrect flow to the injectors could be a weak pump, restricted filter or feed line. And third, in all of my experience, what fixed the last vehicle will probably not fix yours. Each cause of no start needs to be looked at with an open mind by the numbers or one can guess is carreer out the door.
My thoughts on this condition, make sure the pressure is within spec. This includes not being to high. A resriction in the return line could cause a serious problem as well. If you can trade the injectors plugs and the problem follows the wires, don't put a MAP sensor on it. Get a good test light and check for good current to the injector that has the problem with key on engine off. Compare to the good one. Checking with a meter will show 12 volts but if there is resistance in the wire, a load such as a test light will need to be applied to the end of the wire. The computer supplies the ground to open the injector. This is called pulse width. It is recommended to use a "noid light" to check the ground circuit or fifing timme of the injectors. I have used a test light with similar resistane of an injector connected to both power and ground of the injector lead (replace the injector with a light). Do both leads one at a time and make sure they both flash at the same rate and brightness when cranking. I think you have a combination of troubles. Running out of fuel extended the working load of the computer and a weak link broke. You need to look at a wiring diagram for the injector circuit to understand a little more about how the current gets to the injectors. The driver in side the ECM can be isolated with little effort. A meter should almost always be used when checking wires. Breaks can occur inside the insulation and won't be seen. The tests I mention here should help to pinpoint a specific area of the wiring or ECM Or Pin damage. A round pin with a sleeve over it to make a connection, Could the sleeve have gotten bigger due improper assembly? Or a pin not straight? Or the wire backed out of the connector? Or somebody 7 years ago poked a hole in the wire, checking for God knows what, and now it has corroded? The possibilities are many, pick a spot at the end in this case and work back to the source.

delight024

Thanks. We'll try that probably tomorrow. We checked pressure and it seems to be fine. It's so frustrating. Thanks for the suggestions.

grapony

I'm with enginetune on this one, Sounds like a bad injector driver. Try another ecm. Be sure to check the resistance of both injectors and make sure theyre pretty much running the same. A shorted inj can screw up a driver.

__________________
14 year auto tech from AL. Ask if you need some info.

comp

what did you find ????

delight024

We've given up for the moment. Just too much money invested in a vehicle we only had for a week before this happened. Maybe after superbowl...lol. Thanks for the suggestions, keep em comin!

comp

let us know