dies over 2500 rpm

[mean machine]

hello i have a 89 ranger super cab 2.9 v6 5 speed i started to have a problem when the truck warms up i had some bad gas 1/4 tank i added 1/2 tank of 93 gas and changed the inline filter but it still has the problem if u try to accelerate when u get to about 2500 rpm it bogs down like its flooding and it starts to pop and shudder if u continue to hold gas at that position it will stall out but if u leave up it will pick up speed again and act normal what could it be ? thanks in advance jason

 

[adsm08]

So you diluted fuel that was too old and stale to burn properly in your engine with fuel that is to resistant to burning to burn properly in your engine?

You do know that the octane rating is a measurement of the fuel's resistance to ignition and the higher the number the harder it is to get the fuel burning? Right?

Check your throttle position sensor as it may have a dead spot. Unplug your oxygen sensor and see if the problem goes away.

Oh, and empty out your tank and put some 87 in there.

 

[mean machine]

well the gas i bought was cheap as crap 87 and i put like 6 gallons of 92 on top of it and it started to act funny after i got the cheap gas oh and it will only do it under a load if u put in netural and it will rev all the way to redline with no problem it got me stumped and i have no check engine light on at this time

 

[adsm08]

So crappy cheap gas on top of stuff that is too rich.

I'd still empty the tank out and get 5 gallons of decent 87. Put some sort of additive, some BG 44K or something in it, and do the checks that I mentioned above. The stuff I listed can cause problems and not set off the light because the EEC-IV system was kind of stupid.

 

[db796]

If u drain the tank might aswell get a new fuel filter too.

 

[mean machine]

would a dead spot on throtle position sensor only show up after u drive for about 10 miles ? and i will try o2 sensor tomorrow if it warms up its 30 out right now . someone told me to check fuel pressure regulator but the thing is is that it just started this out of the blue after i filled up at a crappy 220 a gallon fuel station i already replaced the fuel filter .

 

[mean machine]

how do i check the throtle position sensor?

 

[mean machine]

UPDATE : today i went out and decided to loosen the gas cap it was really hard to get off but i took it off and drove it about 16 miles and it didnt do the sputtering and hesitating so it must be something to do with the cap or something please recomend what to check thanks jason

 

[adsm08]

TPS is checked by hooking an ohm meter to the pins on the sensor and slowly working it across it's sweep while looking for "dead spots" where the resistance changes suddenly and drastically with small amounts of movement or goes completely open. But I would not expect the TPS to only start acting up after 10 miles.

You may have a fuel pump issue as well if removing the fuel cap helps. The only other thing I can think of that I've seen resembling your situation was on a motorcycle. The owner rebuilt and re-jetted the carb and replaced a damaged fuel cap that had notches in the gasket. After the work it started to die at high RPM but would restart and run fine after a minute or so of being off and it would pop when the gas cap was removed. He figured out the cap was sealing too well and the stock fuel pump was pulling a vacuum on the tank and getting to the point where it wasn't strong enough to keep pulling fuel out of the tank. Notched the new cap's gasket and the issue has been gone ever since.


Since your gas cap is supposed to be able to seal the tank off completely I'd look into the fuel pump and the tank vent next. In that order.

 

[mean machine]

hey i found my problem it was a fuel pump going bad if i shut truck down when problem occurs and restart after a min or so it runs fine for awhile then it acts up again a mechanic friend said its the fuel pump or the pickup sock so im removing the tank to see thanks adsm08 i believe ur going to be the winner of this puzzle lol