Hey All,

Just put my car back on the road today after completing an interior swap. Been sitting since June. It has the 305 TBI.

I noticed that the tank was low so i filled it up at Texaco. After spending $40 for 12 gallons of regular I headed on down the highway. A few miles down the road the problems began (and I live only a short distance form the gas station, so it ran fine for the couple of minutes it took to get there).

On acceleration: no stumbling or surging.....more of a lack of power.

Maintaining a steady speed: engine is surging....tachometer is jumping up and down.

In park or in drive with foot on brake: idles normally.

Check engine soon (service engine soon) light is NOT coming on.

This seems to be more prevalent at highway speeds than around town.

Bad gas? (what is the cure for bad gas, btw?)

Fuel filter?

Something else?


Thanks for reading!

 

.....but I will get it figured out anyway.

I noticed it happening around town today as I was driving. Mainly whenever the engine gets under load, climbing a hill or under light acceleration. Not a lot of rhyme or reason to it!

I put dry gas in the car, but it did not seem to make a difference.

Tomorrow I will jumper the test terminals of the ALCL connector to see if there are any codes stored in the ECM memory. I doubt if there is since the SES (Check Engine) light has not come on, at least that I have noticed.

Symptoms seem to point to a bad fuel filter or contaminated gas. I probably will change the fuel filter this week and may go talk to the gas station owners (I also buy my heating oil there as well) and see what they have to say about this.

I will keep posting to this thread in case anyone else is interested.

 

how old is your fuel filter?

 

I have never changed it. Car has just over 91000 miles on it.....and it has sat since June.

 

water in the gas? Ask the station to check the tanks (whether you'll get a refund and compensation is another matter..)

Mark.

 

bingo.

 

.....I bought a new fuel filter. Will install later on this week. Maybe tomorrow, who knows?

Talked to the owner of the gas station. Went pretty much as I expected. Assured me all was well. No other complaints received. Redundant filtering systems in place for water and sediment, between the tank and the pump and before the fuel leaves the nozzle.

They took my info and I let them know I would get back to them should I find out it was bad fuel.

Of course, they wanted to know what I meant by the term "bad gas". Generic phrase, to me it conveys either or all of these: substandard quality fuel, contaminated by one or more foreign materials, or has a high water content.

Updates to follow:

 

Replaced my fuel filter this afternoon. It did not make any difference....still exhibiting the same symptoms.

Notice-able at between 35 to 50 MPH attempting to maintain speed. The tachometer would jump about 250 RPM, up and down, which fits my idea of engine "hunting".

Hammer on it, and it hesitates at first, then takes right off. Sitting at idle or stopped in drive with the foot on the brake and it runs as sweet as can be. I do not get it.

Tomorrow or Friday I will attempt to retrieve any codes that there may be available via the SES. That should be interesting.

I am starting to wonder if it might be my O2 sensor instead......something like this happened on my Fiero, just not as pronounced. The codes, if any, will be the key.

 

doubt it's bad gas. If it were then you'd still have that "hunt" at idle.

It is possible that it is a slight higher RPM misfire. You would not notice it at idle because it's a high RPM misfire (or atleast a slightly above 1200RPM misfire). It's not too hard working for the spark to get to all the cylinders at idle. When you're accelerating you would not notice it.

All that I'd suggest, is a full tune-up and see where you're at (that's spark plugs, plug wires, dizzy cap, rotor, O2 sensor, fuel filter -done-, coolant temperature sensor, double check timing).

These are things you should have done every year or so.

After they're completed come back and see how it is

 

Well, I agree with you to a point.

I have had the car a few years, but have put less than 3000 miles on it since I bought it in 2002 or 2003.

I have new plugs and wires ready to put in, although I dread the thought of messing with all that smog crap to get to it all.

Last year I put in Hypertech coil, cap and rotor, as well as one of their "chips".

I believe I had a new coolant sensor put in when I bought the car.

O2 sensor I should have looked at while I was under the car this afternoon looking for the fuel filter.....I did find it!

I have never checked the timing......when cars quit using carbs it threw a mental roadblock at me!

SES never lit up, I will see what codes are in there (if any) to give me a clue. Good thing this is just my "good time" car and not transportation.

Thank you for the ideas and your reply.

 

Mine 92 350 TPI did the same thing under load TPI. Ended up being the Idle air controller IAC. But iam not fimular with TBI cars.

Bruce

USN Retired

 

You should check your TPS (Throttle Position Sensor.... check the board's write-ups for quick info on cleaning and setting it.

While you're doing that, you can do as suggested above by checking and setting the IAC

 

for the "no bingo"

sorry.

 

My Camaro is finally fixed after much neglect by me. I ended up putting in sparkplugs and wires a fuel filter and *** knows what else.

I took it to a GM dealership yesterday for their opinion.

They checked the EGR Valve and the Throttle Position Sensor but operated "OK". I also brought in my aftermarket computer chip (HYPERTECH THERMOMASTER P/N 122362) box that had my original stock computer chip in it. They swapped out chips and now everything works A-OK.

Not bad gas, just a bad chip. What a pain in the A$$.

Just thought I would post an update for those who may have been curious.....and thanks for the insightfull comments and suggestions!

Steve