91 Buick Lesabre

This car does not get driven much. Basically an extreme work beater. It sat for 11 months. Since getting it started up have had 2 problems.

  1. After driven a few miles it begins to run poor. Starving for gas. After a minute or perhaps a few mins it will run well again for a few more miles. Does this sound like a fuel filter or pump. Would a pressure tester tell me either way? Could it be a filter slowing down the pressure or a bad pump slowing down the pressure also? Filter is cheaper and easier to change. In the past I have found the pumps mostly go out they go out totally. Either way its a cheap fairly easy fix.

  2. More serious of a problem. For years it has had a finicky tranny that at times would not like to shift into the next gears until a higher rpm was reached. Sunday it stopped shifting into higher gears all together. I have 1st gear and reverse. I think it is the shift solenoid. One said to try some Lucas, maybe its sticking. I do not think this the case, but I could try it. It has proper fluid level.

I suspect your gas went bad.

As far as the transmission, when it first started having problems did you ever change the fluid?

Its new gas. the car has a ever so slight of a leak that over the 11 months it was empty and had to put new gas in. It only had a couple gallons in it when it was parked, if that.

Yes years ago when it started I changed the fluid and filter. Which did nothing to fix it.

Maybe its time to part from this dinosaure.

For the transmission you can pour a bottle of Trnas-Medic in for less than $8 and hope for the best. If it brings back 2 through OD have the fluid and filter changed if/when you find and repair the power loss problem.

As far as the stalling problem and not running properly my guess it’s bad gas I would try draining all the gas out replace the filter and putting fresh gas in it see how that works. As for the transmission I was having problems with my 99 Buick LeSabre with a funky transmission I put Lucas trans fix in it and it eventually solve the problem I did also change the filter and the fluid when I put the Lucas in. I wouldn’t spend any money on repairing the transmission on that car unless you can get it from a junk vehicle and do it all yourself. It’s not worth the aggravation as always this is just my opinion

Try some techron or seafome in the gas just for kicks.

which is better trans medic or lucas.

trans-medic is specifically intended for releasing sticky valves and softening seals which would possibly get your transmission back in operation. Lucas is mostly an STP type product that increases line pressure and somewhat swells the clutch friction plates. My last successful effort with a transmission problem like yours was a 2000 Cadillac that would only shift out of 1st gear if the lever was put in 1st and the car was driven up to a speed well beyond the proper shift speed and then upshifting resulting in a hard shift. I poured the snake oil in and after a few miles of cruising while stopping and forcing up shifts it began to shift on its own. I sold the car for the owner and the buyer was happy with the car, I saw her often in the neighborhood.

I can’t say that trans-medic works most of the time for problems such as yours but it’s likely that it has worked well in more than half my efforts. Of course when something is broken or worn out mechanical repairs are necessary. My old Ford F150 was chattering and dragging out shifts and the snake oil gave some short lived improvement but within 100 miles I was left on the side of the road waiting for a wrecker.

How about Sea Foam Hydra Trans Tune??? Sea Foam says to clean sticky valves and dry moisture.

At this point it probably does not matter what you use on this thing.

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what about sea foam hydra trans tune?

I’m not at all familiar with that product @knocksensor. But I have used several other Sea Foam products that did all that was expected of them.

I did a fuel pressure test on it. When I first hooked it up it was at 34 idle 36 revved up. My book is at a different location. I will be there by Saturday. It seems to me that is low. I took it off and then thought of hooking it up and letting it idle and see if it drops but the second time I hooked it up at was only at 20. I will let it sit for a while and see if it goes up over time.

I’m guessing that you need 45+psi. Replace the filter for now and see what the pressure is.

I looked in the book and it says 40-43 not running. I tested it not running and it barely went up, maybe 5 psi. also tested between filter and line to pump and it barely moved. Pump is shot. Also have a fix a broken rusty line. Would a high pressure hose work for that? Gonna have AAA tow it to the farm to work on it one day this month. It is not a priority whatsoever.

Exactly how many project cars are you currently working on . . . ?!

I’m just curious

Just one car.

As it warmed up I went back to working on getting this car running. Changed the gas tank, old was rusted out multiple leaks, fuel pump and filter. Now it runs ok.

It will not shift out of first gear. Reverse and first gear is all it has. Been looking up this shift solenoid, lockup solenoid, transmission solenoid, control solenoid, whatever they feel like calling it. One video said it could be unplugged if causing problems. One video said it would cause it not to shift. Is this something that is easy to get to and outside of the trany?

Another that it could be the transmission bands wont shift to next gear. Wondering what is the best type of stuff to use for that. Trans Medic, Lucas Stop Slip or Seafoam Hydra Trans Tune. Of those 3 which would be best to try before doing anything more?

Sea Foam

Helps fluid systems work smoother and last longer
Dissolves and liquefies harmful gum and varnish buildup in fluid
Cleans and lubricates valve bodies, shift actuators and solenoids
Safe for conventional and synthetic fluids
Will not swell seals or harm gaskets, O-rings, or clutch material
Helps to control moisture in fluid


Renews worn rack & pinions
Controls slack, squeals, hard spots & tight steering

Trans Medic

Helps eliminate slippage
Restores smooth shifting
Reduces wear

By any chance your transmission have a vacuum modulator?
I would check to see if it is getting vacuum.