brett vance

My rx7 is currently out of comission. But I have a problem involving a different vehicle. It's on a '96 pontiac Grand Am Quad 4. I own 3 vehicles, and the pontiac I drive 3 out of the four seasons. not winter obviously. Well since this last winter I've been experiencing a bit of bucking in the car, so I bring the car to the mechanic for the problem, he tells me that I've got sediment built up in my fuel tank. Clogging up my injectors. I've tried to get away with putting Cleaner upon cleaner (in the recommended amounts) in on fill - ups. The Check engine light will go off for a little but, but bucking would remain and like always the check engine light would come back on. I'm do for an inspection at the end of the month. My vehicle won't pass under the updated New York inspection laws passed this past summer. The tank has to be drained and cleaned. I can do it myself if I have the proceedure.

Any one who knows of the proceedure on dropping the tank and filtering the remaining gas, and cleaning the tank would be greatly appreciated.





Brett vance

Sinful7

How did he determine there was sediment in your tank? You should be able to siphon the tank (If there's no drain plug), then unstrap it, then slosh the remaining gas around and dump it out the filler neck.



There would have to be a whole lot of sediment in the tank to cause that kind of problem. Sounds to me like either your pump is bad (not uncommon for GM) or your fuel filters are toast. Maybe even the strainer filter in the tank.



If you have in-trunk access to the fuel pump ***'y, you may just try pulling it and seeing what you have going on in there. I have actually had dirt chunks fall into my tank from a FP change, didn't bother cleaning it out and it works fine. I've done the FP in my Olds Bravada three times over the last three years. One of the major causes of failure was linked to running a low tank level, where the pump has to work harder to get the fuel out.

brett vance

Ok. Your advice is refreshing in a sence, I'll have to take a look at the fuel pump assbly and see.



To answer the question of how he determined it was sediment. is That when I had purchased the car originally, It had been sitting for a at least a year Gagage keeped only being started to keep engine ok. The gas that was in the tank wasn't treated with stablizer. I found this out when I went to fill the tank up for the very first time, and went bucking down the street ulitimately to a stalled stop. Well it was my headache now. I had to get the vehicle towed to the machanic I bought it off of and, he who was a gentleman about it payed the tow bill, and gave me over $300.00 of free service on it. Replacing the coil packs, and having noticed that the car was bucking heavily on new packs, he opened the hood with me right there and plain as day we could hear a miss fire , so to find out it was missfiring in cylnder 2, and he didn't stop there, he asked me what kind of gas I used, did I put a treatment in and I told him 87 octane and no additives. Keeping accurate records he went and checked his logs and when the car came to him to sell off a man whom was sick and couldn't drive the one owner car anymore, thought his sone alraedy did the stable thing but was not sure.



Oh yeah, he took off the filter and it was caked with uglyness, put a new one on. Two weeks later the crap all over occurs again . No lie I went through a nother set of coils. Still with in the 30 days sales agreement free replacement, caked fuel filter, and the conclussion that this very well could be a tank sediment problem.



but if its not then like you suggested it could be a done pump. The vehicle was under a quarter of a tank when I bought , as I pulled in to the gas station I recalled that the near empty light just flicked on.

Sinful7

Yeah, severe bucking is usually caused by a bad fuel pump. To be sure, get under the hood and check the fuel pressure. GM typically uses a schraeder style valve on the fuel line. Your mechanic should've checked this FIRST, as it is a problem inherent in mid-90's GM vehicles.

Regardless of the issue, your problem is definetly fuel delivery, not spark. Is it MPFI or TBI? If it's MPFI and you're getting bucking, chances are that you're missing fuel from the source, not the individual injectors. Miss firing on one cylinder won't cause the bucking you're describing. A single cylinder misfire should simply trigger a CEL (Check Engine Light). Seeing as how this vehicle is OBD-II, the CEL should detect a misfire on that cylinder and trigger a code. If it's TBI, you could have another set of problems, including the TB injector assembly. Like I said, check out the fuel pressure, it should go to a specified PSI at ign-on, and stay steady for awhile. If it leaks down, your problem is an injector leak. If it's weak, the problem is the fuel pump. If it checks out, then you may have to investigate the sediment issue.. There would have to be an assload of water or contaminates in there to cause this kind of problem though, so I doubt that's it.