The Real Bev wrote:
> On 05/09/2017 11:18 PM, Steve W. wrote:
>> Paul in Houston TX wrote:
>>> wrote:
>>>> Three years ago at the state auction I bought a 2006 Chevy 3/4 ton van with a 4.8
>>>> engine.It was in real nice shape and at the time I didn't need it so it has been
>>>> sitting outside in my yard. I realize this wasn't the best choice but I had no where
>>>> else to put it. There are a couple of things that you should know about this van. First
>>>> it was not started during the three years that it sat on my lawn. Next it presently has
>>>> a full tank of 87 octane gas that I stupidly put in three years ago before I parked it.
>>>> The battery of course was completely dead. I charged it at three amps for two days and
>>>> quite surprisingly it came back up and cranked the engine. The truck started right up,
>>>> another surprise.
>>>>
>>>> The problem is when you first start, except for a very slight shake the engine seems to
>>>> idle fine. if you goose it it seems to rev fine too. As soon as you shift it into drive
>>>> though the RPM's slow way down, the shaking gets much worse, (the engine even stalls
>>>> sometimes) the "engine" light blinks constantly and eventually stays on and when read
>>>> it's a "random misfire" code set on the OBD..g. I took it out for a short run today.
>>>> It seems OK on the flats but acceleration is "bumpy". It is missing and it really
>>>> almost dies on the hills.
>>>>
>>>> I've gotten all kinds of opinions as to what this could be. Of course the gas was one
>>>> thought. But if it was the gas would it idle fine in neutral with no load initially?
>>>> I've also heard plugs was another thought. But again if it was plugs same argument as
>>>> the gas? Then there is Mass air flow sensor, vacuum leak fuel filter etc. I hate to
>>>> think about shotgunning this problem. Does anyone have any thoughts on what this might
>>>> be and what steps I might take to isolate it. Thanks very much for any help. Lenny
>>> Clogged fuel filter, failing fuel pump, clogged cat.
>>>
>> Filter, pump and bad gas are all possible causes. I would bet on bad gas
>> and filter though. MAF isn't the issue.
>> The idle in neutral doesn't mean anything, that engine will idle just
>> fine when it isn't under load. Put it under load and it needs more fuel
>> but it's getting crap = no power.
>>
>> Drain the tank, you can jumper the pump and use it to push the old fuel
>> out once you disconnect the fuel line. Replace the filter and fill with
>> clean fuel. Bet the problems go away.
>
> How about whatever modern cars use to vent the gas tank? Our 68 Dodge
> van somehow got its hose kinked, which we discovered only after trying
> everything else.
>
>

The EVAP system on this one won't cause misfires unless the purge
solenoid has stuck open causing a vacuum leak. But the symptoms don't
match that problem.

--
Steve W.