92 4.3L starting and stumbling problems

Well, let's see... My truck truck is very hard to start. If it has been left off for some time (i.e. a few hours) it will take approx. 6 seconds to start. It will crank and crank and then just start right up. If I turn it off for maybe 10 minutes it take less time to start. The longer I wait the longer it will take to start (up to a few hours...) My other problem is when I am driving the truck will stumble while accelerating quickly or being put under a heavier load. it is most apparent when going up hills or having the truck in a high gear at lower r.p.m. I have done many things to it...

Replaced items...
-spark plugs and wires
-dist. cap and rotor
-ignition coil
-throttle position sensor
-oxygen sensor
-fuel filter
-fuel pump
-fuel pressure regulator
-egr valve
-replaced battery with an optima red top
-starter (old one was getting ready to die)
I have also rebuilt the rear axle, clutch and replaced the flywheel.

The timing (at idle) is dead on (0 deg.)the plug wires have the propper resistance and the plugs are gapped propperly. I'm clse to my wit's end. The only things I can come up with are either a problem with the vacuum advance or perhaps there is play in the dist. shaft. I would like to know if anyone has any ideas. Thanks.

Hey,
I had the same thing happen to my truck a week or so ago. I also tried most of the things that you did. It ended up being the ignition control module. It is located right under the distributer cap. If you take it off and take it to an auto parts store, they can check it for free. If it is bad, it was only about $30. this is a good thing to check before you keep throwing parts at it that it doesn't need. Hope this helps, Jimmy Dager

I'm hoping you didnt do most of things just recently to try to fix your problem. Unless you are fairly certain what the problem is and how to fix it, do not throw money away pretending to be a mechanic. Most instances it will be a lot cheaper to take it to a mechanic and let them fix it than throwing all sorts of unnecessary parts into it until you get the right one. Just my $.02

I went ahead and toook out the ignition control module and tried to have it tested. I was unable to find anyone who would and decided to replace it since it appeared to be in rough shape. It didn't fix the problem. Also, everything I have replaced thusfar have been components that were about to go bad anyways so the money I have spent so far has not been a complete waste. Thanks for the input though.

It could also be a weak coil or pickup coil.

I put a new set of wires and plugs on mine and had to carry the wires back and get better ones. The ones I had were bad.

AC plugs??

I dealing with a stumbel when going up hill,talked to a freind who works at a goodyear and he told me to start with my mass air flo ,take tube apart and sho.t carb cleaner in tube and senor and clean real good let air dry real good,then he said if its still doing it get tourqe converter looked at might be slipping, i have done almost eveything you have done to so lets hope ,if you fix problem and its not what i told ya let me know so maybe i can fix mine.

If the fuel pump relay goes out the truck will not start until it gets full oil pressure. This can take anywhere from 4 to 10 seconds. The relay on your 92 is located on the firewall on the passenger side under the t shaped black plastic cover. New one should be about 12-16 bucks.

I found a buddy with a code reader and found out that the fuel pump relay had gone bad after all. I replaced it and the truck starts really well now. However, the stumbling problem is still there and I am still working on that. Thanks for the help and I hope this helps you all.

There is no mass airflow sensor on your 92. The stumble could be caused by the IAC (idle air control) on back passenger side of throttle body. This generally will not set a code. The other culprit could be the MAP (manifold absolute pressure)sensor. This also will not generally set a code. Since you have a friend with a code reader you could check to see if these two are operating at the correct millivolt ranges before buying new ones.

hetfield, put a vacuum guage on your engine and see if you have a vacuum leak. tbi's are known for sucking the base gasket in or also an intake manifold leak. which will make it start hard or stumble. also try plugging the vacuum line to the charcoal cannister and drive it and see if that helps. later, toivo