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1992 LeSabre loss of power/missing and stalling


spinne1
05-24-2008, 06:41 AM
Hello, I have a 1992 LeSabre that is giving me fits. It has a rebuilt engine but most of the old ignition parts/old sensors, etc. It also has had the tranny replaced with a better one than what it had.

The car has two main issues:

1. When you punch the gas pedal it will stumble, miss, and almost stall. The only way to get going is to gently push the pedal. This is true in all weather, fuel tank levels, etc. It will do it at any speed. Power is lacking when the pedal is pushed reasonably fast.

2. When the fuel tank is below 1/4 full, the car will stall when going around right turns or when attempting to back up a hill (as in my driveway.)

My tests: it has new spark plugs. I haven't checked the plug wires yet. I checked the fuel pressure and it seemed fine, but it also idles fine and therefore I don't know the pressure under heavy load. I also replaced the fuel filter.

My plan: I plan to pull the tank and replace the screen, fuel pump, and possibly the fuel sender unit. I also plan to go to the boneyard and possibly pick up an ignition module, coil pack, some plug wires (if I find some that look excellent), and whatever else I can think of while looking at the dead cars. I will attempt to test some of my parts first, but honestly, the parts are so cheap where I go it is almost less trouble to simply replace them and see what happens. I know I can test some aspects of my parts but I'm not sure if I can simulate an "under load" condition to truly test them accurately.

What would you do in my position? I have a Buick Service Manual and can follow any of the diagnostics they have but I do not have a proper scanner, nor any other scan tools beyond a digital multimeter.

HotZ28
05-24-2008, 07:17 AM
Too many possibilities here to give any definitive answer. If you don’t have access to a scanner, you can only speculate as to what the problem may be. If you can get parts cheap, I would start with the MAF & EGR. This could also be secondary ignition, or fuel related; however, I would eliminate everything else before pulling the tank!

schofell84
05-24-2008, 09:42 AM
i remember having similar problems a few years back, it was fuel pump related. maybe something to do with the pick up?


i remember it stalling going around a certain hard right hand turn going to school everyday haha ... odd stuff.

vrmlbasic
05-24-2008, 11:41 PM
And here I thought I was the only one with this exact same problem.

I haven't changed my plugs or wires in a while, but I put on a new ignition coil so I doubt the ignition system, and the problem started to appear before I changed the coil out anyhow. I also have changed the fuel filter once after the problem started, and it still persisted.

Nothing like going down a tight right hand turn exit ramp that turns into a shared merge lane on a major road and loosings all power to make a day more exciting.

Maybe it is the fuel pump wimping out? That sounds like a good area to look, as the pita components to repair are frequently the ones that die.

Blue Bowtie
05-25-2008, 09:26 AM
Connect a fuel pressure gauge and determine if the pump can deliver proper volume at proper pressure. You mentioned that the pressure "seemed fine" but neglected to provide actual pressure numbers. 44 PSIG ± 3 PSIG is the required pressure with no vacuum at the FPR. With vacuum applied to the FPR, the pressure should be 37 PSIG ± 3 PSIG.

You can also pinch off the fuel return line to see if the FPR is leaking internally. A good pump should be able to produce at least 50 PSIG in this mode. You can also remove the fuel line and route it to an appropriate container. Operate the pump and see if it can deliver at least a pint of fuel in 15 seconds. If not, there is a problem with flow.

spinne1
05-26-2008, 12:13 AM
My pressure readings were all above 40psi but that's all I remember (it was about a year ago when I took the readings--this car has had this problem since I got it and I'm now getting serious about fixing it.) I will look into the further tests you suggest.

I went to the boneyard on Saturday and bought the following:

Driver's side powered mirror (don't ask, the wife did it--I GLUED it to the car which worked but it wobbles too much so I have to fix it right)
Driver's side sun visor assembly
Spark plug wire set
Coil pack
Ignition Module
Bracket for Ignition Module/coil pack
Throttle body metal with attached MAF sensor, TPS sensor, and another sensor.
Cruise control servo (it's been a little flakey lately)

I paid $66 with tax for everything. Not too bad considering the cost of spark plug wires alone new cost more than that for OEM quality. (and $200 for an ignition module, $120 for a MAF sensor, etc. etc.)

vrmlbasic
05-26-2008, 08:20 AM
This problem for me did not start until well over a year after I got the car, so I really think that it is some way electrical. Reading through the forum there are tons of posts of strange problems being caused because of grounding points being corroded.


The performance-oriented websites for the line of buick 3800 engines offer products to rewire the fuel pump as it is a rather known problem that when you floor the gas, the voltage to the fuel pump drops up to 2 whole volts. While that does not prove anything here, the electrical problems for fuel still exist with the later models, so I find it easy to believe that there are still electrical problems with our older fuel systems.
(though I can not see this explaining the right turn issue.)

Since our fuel pumps work perfectly fine (as far as we can tell) at idle and during normal straight-line driving, I hesitate to think that the pump itself is at fault. Replacing the fuel pump would help prove the electrical idea, but replacing the fuel pump on our cars does not sound fun at all. Buick's epiphany in regard to making the fuel pump accessable without dropping the tank did not come out until well after 1992 :(

BTW, does the infamous driver's door area ground point have anything to do with the fuel system?

(Edit: where would you find a scanner for this car? The best I've found is the paper clip lol)

HotZ28
05-26-2008, 08:29 AM
Wow, what a fantastic price on the parts! I hope something you bought will correct the problems! IIRC, the cruise servo cost 300-400 bucks new! Did you notice if the donor car still had the ECM? On the 91-95 GM cars, I have found that 90% of the time, problems with cruise control has been ECM related.

Just a little advice; replace one part at a time and go for a test drive; otherwise you will never know what fixed the problem.

spinne1
05-28-2008, 09:38 PM
Well, I've got the gas tank off and it's a good thing I did. I found significant rust with both the tank and the sending unit. In fact, the sending unit pipes all cracked and broke while removing the gas tank. They look like they are on the current Titanic. The pipes are very rough to the touch and flake badly with rusticles when touched. The ends of the fuel sender pipes are now frozen in the nylon quick connectors and thus I'll have to replace both of those with repair kits. Also, the sending unit was basically welded to the gas tank with rust. It took considerable pounding with a hammer to spin the holder piece off. When I got the piece off I found that the inner plastic in my gas tank was split and cracked and also broken. There were some broken pieces of plastic at the bottom of the tank. There is tons of sediment at the bottom of the tank too. More now that the opening is open and tons more rust particles fell in. The fuel strainer was very plugged/fouled with particles. I can see why it seemed starved when punched. Now I've got to figure out what to do with the tainted gas (a gallon or two's worth) and the old gas tank.

I bought a new gas tank, fuel sender unit, fuel pump (Delphi brand), fuel filter, fuel strainer, and soon new fuel quick connectors in two repair kits. This should solve most of my problem, I'm guessing (except my injectors could very well be clogged to some degree.)

I will install them this weekend and I'll report back.

vrmlbasic
05-28-2008, 09:43 PM
Well, it seems that the problem is catastrophic, as I was afraid. My ride is technically totaled, but I'm slowly working to correct that, and I have a _lot_ more than 2 gallons in there. Only 40 miles on the car before I was deprived of street-legal driving with her :(

(I never sucked the gas out because I figured I'd be sucking out crap from the tank, and your experience shows that there is crap--lots of crap--in the tank, and this way I have some gas to play around with)

Now I know what to expect when I get far enough in to work on that :(

spinne1
05-30-2008, 09:34 PM
Update: I've got the new parts and am in the process of installing them. I'm at a stuck point.

First, the bolts holding the fuel tank straps would not come off because the above clip thing broke from rust on both sides and I had to cut the bolts off with a grinder (45 min-1 hour each). Because I had no bolts for my fuel tank straps I went to Lowe's and bought some bolts/nuts/washers to hopefully fill the role of the original bolts. I dropped the bolts through the holes in the car where the straps connect and they hang down maybe 1 1/2 inches. The problem? I have the tank as high as I can get it even with shimmying it around and making sure the straps are in their "grooves" on the bottom of the fuel tank, but the straps are still about one inch from the bottom of the bolts and I can't figure out how to get them closer!

I'm starting to feel the only way to connect them will be to go the junk yard and get the original bolts/clips from another car. Why? Because the bolts are about 2 1/2 inches long and perhaps this is just enough to start the bolts and then the screw power will pull the straps tight. I am going to the yard tomorrow to hopefully get what I need.

I know I have the right straps because I checked more than one source of parts and the part number is right.

A second problem is that both fuel lines need repair at the tank end and Dorman's website as well as other websites all say that the 800-058 (3/8") fuel line repair kit is what you need for the inlet and outlet. Well, the inlet and outlet are DIFFERENT SIZES on the car, thus the 800-058 only will fit the outlet. Now I have to return one of the two 800-058s I bought and figure out what size to get for the inlet. Dorman's website should know better.

spinne1
06-01-2008, 12:54 PM
Update 2:

Finished the gas tank and fuel line repair and new fuel filter. Got it back together and put about 2 gallons into a dry tank with dry lines. Primed the pump several times. It started right up. Took it for a test drive and to get gas. Problem two with stalling around right turns on a very low tank is GONE!! Problem one, however, is unaffected. It still misses, lacks power, and stumbles. Now onto the ignition portion of my work. Also, I need to check if the PCM is bad or is getting bad information from a sensor or sensors. I also need to check the injectors if nothing else fixes it first.

spinne1
06-01-2008, 09:19 PM
Update 3:

Well, it is fixed.

I'm not sure what exactly fixed it. I didn't have the patience to fix one small thing and take a test drive, fix another, take another test drive. Therefore, it is one of the following things:

MAF sensor (I changed it)
Spark plug wires
Air filter (I removed until tomorrow when I buy another)
The sensor directly above the TPS sensor (I don't know what it is--but I changed it and cleaned the one put in)

vrmlbasic
06-01-2008, 09:38 PM
...or all 4 of those things. :(

Personally, my vote is the MAF if it had to be just one, but I also don't know what the mysterious sensor right above the tps sensor is; the only sensor in that region that I know is the Coolant sensor.

You have given me a place to start in solving my instance of this problem, and for that I thank you.

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