When u changed gas filter did you happen to drain the gas into a container.
I would suspect water, had a similiar problem would idle for most part but as soon as put in gear would die. Put heet in it but way too much water in the tank for it to take care of.
changing gas filter found large amounts of water in it when drained into a glass.
Turns out taking bed off to drop gas tank the filler neck was totally weather checked etc.
you could take off out going gas line off then put appropiate gas hose on the end then using your ign key cycle your pump on a couple times.
or your selector valve maybe stuck if gas gauge moving hopefully puting the gas into the other tank. Dont know much about them currently working on a 86 with dual tanks.... might have to put a 4.0 in it bearings arent looking good.
while water ould be the culprit, all that is a little bit 2 much work w/o some basic diagnosis first
yes draining the tank is about the only thing that gets rid of the water.
might not be fuel related either....remove and test the TFI...(aka ignition module attached to the distributor housing .
check and clean grounds
like i said above, some basic diagnosis is required...jumping str8 to the tfi and grounds, while common problems, are not the correct way
first, try to replicate the problem. when the problem occurs, use a fuel pressure tester to test your fuel pressure at the shrader valve on the fuel rail...should be 35-45 KOE OFF and 30-40 KOE ON if i remember correctly, but certainly look the specs up to make sure. if there is no fuel pressure,
check to see if you can hear your fuel pumps running when you turn your key on. there is a fuel pump in your tank and one of the driver side frame rail behind the fuel filter. if the you cant hear the pumps run, that doesnt mean they arent running(most you can hear run, some you cant). see if the brown(EEC power) and green (fuel pump) relays are clicking over(located on the passenger side fender area by the air box). if they are, use a DVOM to test voltage out of the fuel pump relay - this will require a helper, as the ECM will only supply voltage to the fuel pumps for 2 seconds if the engine is not running. if you do have 12v coming out of the relay, check voltage to the inertia switch 0 its under the carpet on the passenger side foot well inside the cab. make sure its not tripped, make sure you're getting voltage to it, and backprobe it to make sure your getting voltage out of it. if there is voltage out of the intertia swtich it might be time to take it to a mechanic, as any further diagnosis tends to get more involved, finding the fuel pump plugs and what not.
if you did have the proper fuel pressure, check for spark. take a plug out, plug it into the spark plug wire, lay(or hold with insulated pliers) the plug on a ground pount or frame or someplace you can easily see, and see if the plug sparks. this will be easier to see at night...or if u have a spark tester use that, those are very easy to see. seeing as this problem tends to be intermittent, if you have no spark, it could be your TFI or your coil...but TFI's are very tempermental, and even when tested as good can still be bad. a coil test is easier...its pretty much the same as a spark test. unplug the coil wire form the distributor, put a screw driver in it, lay it someplace to ground, and have someonme crank it over to see if you see spark. you could also test votlage to the coil to see if thats correct, but you will need to get a book out to know the proper readings.
if you had proper fuel pressure and spark, and the truck is not starting, then i would start looking to what Mysticcook said about water in the tank, although some dry-gass treatment would help if water is in the tank(its stuff u put in your tank and it either isolates or evpaorates the water out, used commonly in old diesals and boats)
if you have fuel pressure and spark, and the dry gass didnt help, it could still also be water/moisture(albeit, a lot, so draining and cleaning the tank would be worth a try at this point) but at this point you would have to start looking at engine diagnosis, such as checking compression and leak down tests and what not. i wouldnt be to concerned about this unless you've had current or recent past history of running problems, excessive oil burning, lack of power(well, its a 2.9, so this is relative), coolent burning, etc
hope this helped.
EDIT: ...i've edited this 5 times already lol
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