99 le sabre hot no start

[Tech II]

What is the fuel pressure when the car is running?

[rachet16]

The gauge I was using said 25psi while the car was running

[Blue Bowtie]

That's about 10-15 pounds lower than the spec, which is 44 with the vacuum disconnected from the FPR and 37 with full vacuum.

Does the fuel system hold pressure after the engine is shut off? For how long?

[rachet16]

It held for as long as I was working on it I only left the gauge on for about 20 min.
The fpr says 51psi on the sticker. I don't see how the gauge can resd zero with the key on and the car starts right up!!! I tried bumping the starter on the recomendation of a friend who said maybe that was needed to initiate the pump relay :it still reAd zero until I started the car

[rachet16]

There was no difference in pressure readings with the fpr vacuum line on or off.

[Tech II]

There should be like a 5psi difference when you disconnect the vac line while the engine is running(higher disconnected).....

[rachet16]

Just did another fuel pressure test with a different gauge. It registered 15 psi with the key on 25 psi with the car running no change when I disconnect the fpr vac line . I left the gauge on and it bled down 5psi in 30 minutes.

[rachet16]

Just checked again pressure down to 14psi down 11 psi in 1 hour

[Tech II]

Fuel pressure should be around 40+ psi, while running or in a static test, not running....

Did you cycle your key to "on"(not to crank....do not start), off for 5 seconds, on, off for 5 seconds, on again to get max reading?

I don't know if you have plastic lines or rubber lines to the fuel rail...

If you have plastic, you need special shut off valves to test....

However, if you have rubber lines, use a rag and vice grips, and attach it to the return line(line coming off the fuel regulator)......now turn key to on(don't start), if pressure increases, you need a regulator.....may have to cycle key several times to get max reading...

[rachet16]

Cycled the key got 15psi. Plastic lines start the car I have 25 psi no change with fpr vac line disconnected while running

[rachet16]

Should I replace the fuel pump or try the regulator first???

[rachet16]

Where would I get the valves for testing??

[Blue Bowtie]

The FIRST thing to do is to verify that the pump is getting a full 14V with the engine running (12V KOEO). I've seen more than a few pumps condemned when the eventual problem is discovered as poor connections in the circuit (including grounds) causing low voltage. That equates to lower pressure. There should be a connector just to the right of the fuel tank where the contacts can be back-probed and voltage monitored.

[Tech II]

Blue is correct....you should check for proper voltage.....but that gets tricky....just using a voltmeter is not the answer, because you could have a voltage drop, and the voltmeter doesn't show it because of it's high impedance.......can do it two ways....attach a test light across your battery and note the brightness....disconnect the fuel tank harness, and attach the test light to the two leads of the harness to the fuel pump circuit.....turn key to on.....should light with same brightness as the battery, for 2 seconds(If you turn the key to the crank position it will be on steady).......if much dimmer then you have a bad connection somewhere......if you really want to verify actual voltage, you attach the test light to the the circuit AND, attach the voltmeter to the test light leads in parallel......this will give you the WORKING VOLTAGE across the fuel pump.....but I usually just go by brightness.....

I have seen a lot of bad grounds on trucks, but not on LeSabres......the other possibility is a bad fuel pump relay, where there is a voltage drop across the contacts from arcing too much(basically the relay is old)....so you can swap out a relay with the same number to see if the pressure increases, first....

But for the most part, I am suspecting that f/p regulator....there was a campaign for 1998 to 2000 LeSabres......call your local Buick dealer, give them your VIN number, and they can tell you if the campaign is still open on your vehicle(it's open if the F/P regulator was never replaced).....it won't cost you anything, and it's like a 10 minute job to replace.....

Unfortunately, only your GM dealer has these special valves to attach to your plastic lines to determine if the fuel pump is bad........

So, what I would do, is call the dealership first.....better yet, go to the dealership and ask them to show you on the computer, if there are any open campaigns on your vehicle, looking for TSB 03054B........there is a possibility, that the campaign is closed(sometimes closed after 10 years)....but you can check to see if it was done.....if it wasn't, then you can get one and install it yourself....very easy....do on a cold engine.....relieve pressure at the schraeder valve of the fuel rail, remove vac line, and remove the horse shoe retaining clip......grab head of fuel pressure regulator with pliers and slowly twist and pull out(have rags under the regulator base to catch spilled fuel)......look in base, sometimes the small o-ring stays in....remove......apply petroleum jelly to the new o-rings and install the new regulator....install new horse shoe clip(May have to push down on regulator to get clip to go into the grooves).......attach vac line....turn key to on several times to check for leaks.....then start car......

Now if fuel pressure is still low, and you have good voltage to the fuel pump, then in all likely hood, you need a fuel pump....unfortunately, this year, I don't think, has access to the pump through the trunk.....you have to drop the tank.....and that opens up another can of worms....rusted fuel lines from the sender can break/leak......when disconnecting the plastic lines from the metal lines, they can be a problem, and may have to be replaced....and then there are the fuel tank strap bolts.....sometimes when taken out, the weld on the retaining nuts break, and the bolt just spins.......all these things happen, if you live in an area that uses salt on their roads in the winter....so better hope it's not the fuel pump......

Did I make your day?

[rachet16]

Thanks Tech II ! Good info really helpful . You did indeed make my day. I'm really NOT looking forward to changing the fuel pump !!