1990 Century Possible Fuel Pump Problem
CarDude225
10-25-2007, 09:34 AM
I have a beater 1990 Buick Century V6 3.3 with 146,000mi that I am about to sell. Asking $1000.
Anyway, I had someone coming over very interested in it and before they are suppose to come over I go to start it up, and it cranks but no start. :banghead: Strange. Add 2 gal fresh fuel: still no start.
I notice that when I turn the key from off to ign that I don't hear the fuel pump run for the few seconds that it normally does to pressurize the system. I verified no fuses blown, swapped fuel pump relay with another, no problem found.
On the fuel rail I take the cap off and push in the valve but no fuel or anything comes out. No sound either.
In the trunk I tapped into a gray wire I use to use to cut off the fuel pump power (for a car alarm) and hooked a 12v test light to it. Turn the key, the light lights up but still no start. Crank the eng, light lights up, no start.
I put an ammeter inline with the gray wire in the trunk. The circuit pulls 3 amps (not including the test light, obviously).
I also noticed near the fuel tank there is a tube that *was* connected. The rubber that joins the 2 tubes together has worn and the joint is separated. This tube goes to the right and I assume goes to the vapor canistor thingy.
The last time the car ran it ran fine and that was 6 days ago.
Here are my questions:
1) Does this sound like a siezed fuel pump?
2) What amperage should the fuel pump be pulling for this car? 3A seems low, esp. if the pump isn't spinning, which I assume it is not because I don't "hear" it. But something is for sure consuming 3amps.
3) Is there any safety issue with connecting 24v for a second or two to "boost" the pump to see if I can get it turning again, other than burning out the pump?
4) How hard is it to drop the tank? Can I use a floor jack? A new pump is $72 at the parts store.
5) Would the tube that has become separated cause the fuel pump not to run yet still consume 3 amps?
WHAT A PAIN! Thanks!!
Anyway, I had someone coming over very interested in it and before they are suppose to come over I go to start it up, and it cranks but no start. :banghead: Strange. Add 2 gal fresh fuel: still no start.
I notice that when I turn the key from off to ign that I don't hear the fuel pump run for the few seconds that it normally does to pressurize the system. I verified no fuses blown, swapped fuel pump relay with another, no problem found.
On the fuel rail I take the cap off and push in the valve but no fuel or anything comes out. No sound either.
In the trunk I tapped into a gray wire I use to use to cut off the fuel pump power (for a car alarm) and hooked a 12v test light to it. Turn the key, the light lights up but still no start. Crank the eng, light lights up, no start.
I put an ammeter inline with the gray wire in the trunk. The circuit pulls 3 amps (not including the test light, obviously).
I also noticed near the fuel tank there is a tube that *was* connected. The rubber that joins the 2 tubes together has worn and the joint is separated. This tube goes to the right and I assume goes to the vapor canistor thingy.
The last time the car ran it ran fine and that was 6 days ago.
Here are my questions:
1) Does this sound like a siezed fuel pump?
2) What amperage should the fuel pump be pulling for this car? 3A seems low, esp. if the pump isn't spinning, which I assume it is not because I don't "hear" it. But something is for sure consuming 3amps.
3) Is there any safety issue with connecting 24v for a second or two to "boost" the pump to see if I can get it turning again, other than burning out the pump?
4) How hard is it to drop the tank? Can I use a floor jack? A new pump is $72 at the parts store.
5) Would the tube that has become separated cause the fuel pump not to run yet still consume 3 amps?
WHAT A PAIN! Thanks!!
richtazz
10-25-2007, 01:38 PM
Sounds like your fuel pump took a dump at a very inopportune time.
CarDude225
10-25-2007, 07:07 PM
It is official; God loves me! :iceslolan
So I'm driving home from work tonight when it dawned on me that I should try reversing polarity going to the fuel pump for a brief moment to try to get the pump armature/shaft to swing. Then connect correct polarity.
So I used a spare 12 v battery, connected the pos to the car chassis, and connected the neg to the gray wire in the trunk going to the fuel pump.
IT WORKED! :grinno: :iceslolan The pump is working again! And yes, understandibly, the pump is on it's way out. But at least no grunt work here. I'll advise the prospective buyer of such.
There must be a bad "plate" on the armature and so if the armature stops while a brush is on that bad plate, then the pump won't start up again.
I also measure amp flow to the fuel pump while engine idling: fluctuation between 3.6A and 3.7A.
Good info to know...
So I'm driving home from work tonight when it dawned on me that I should try reversing polarity going to the fuel pump for a brief moment to try to get the pump armature/shaft to swing. Then connect correct polarity.
So I used a spare 12 v battery, connected the pos to the car chassis, and connected the neg to the gray wire in the trunk going to the fuel pump.
IT WORKED! :grinno: :iceslolan The pump is working again! And yes, understandibly, the pump is on it's way out. But at least no grunt work here. I'll advise the prospective buyer of such.
There must be a bad "plate" on the armature and so if the armature stops while a brush is on that bad plate, then the pump won't start up again.
I also measure amp flow to the fuel pump while engine idling: fluctuation between 3.6A and 3.7A.
Good info to know...
Automotive Network, Inc., Copyright ©2026
