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Pete, Buick Technician
Category: Buick
Satisfied Customers: 28262
Experience:  17 years Buick Technician experience and training.
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91 buick century: going down the highway..fuel pump relay

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i have a 91 buick century 3.3l 6cylinder , it stalled on me going down the highway acting like it ran out of gas with a full tank. we have replaced fuel filter, fuel pump, fuel pump relay,fuel pressure regulator it still wont run. it starts runs a few seconds then acts like it runs out of gas. If you spray starter fluid in the air in take it will run as long as you keep spraying starter fluid. i appreciate any help on this as i am stranded 1300 miles from home.
thanks so much
sloan in south dakota

Hello,I will be glad to try and assist you with this,Welcome to Just Answer.


ok from what it sounds like here we know we have spark to the spark plugs or it wouldnt run at all,so we can assume the crankshaft position sensor is ok.

Three things I can think of here that could be at fault is either the camshaft position sensor,the sensors magnet in the cam gear,or the fuel pump module assembly wiring conector.

First the fuel pump module(the metal bracket that the fuel pump sits in in the tank,has wiring that runs from the module down to the pump,on top of this module will be a wiring connectot that runs from the fuel pump up to the module,pull this connector off and make sure the wiring terminals arent burnt,this is common once an old pump starts to draw to many amps it can heat up and burn the wiring terminals on the module in the fuel tank,if this is the case the wiring terminals will have to be replaced.To check this the module assembly with pump will have to be removed from the tank and the wiring connectors on this module and pump will have to be checked.

The cam sensor senses a magnet that seats in the cam gear,this tells the computer when to fire the fuel injectors to give the engine fuel,this cam sensor is located I believe just above the water pump,it has one wiring connector connected to it,remove this sensor(held in with one bolt) and use a mirror and flashlight to look inside the hole at the cam gear,then rotate the engine over by hand and you will see a spot on the cam gear that houses a magnet,look to see if this magnet is still in the cam gear,it may have come apart and fell out(this is very common on these 3.3 engines) if the magnet has fallen out then the timing cover will have to be removed,the cam gear removed and the magnet replaced.In most cases it ends up being this cam gear magnet,it sits in a plastic housing seated in the cam gear and throughout time and heat the plastic housing gets brittle and the cam magnet falls out,when this happens the cam sensor cannot recieve the signal to pulse the injectors to spray fuel in the engine.

If the magnet is in place(not just the plastic housing for the magnet but the magnet itself) then you could have a faulty cam sensor(this isnt as common as the magnet as I have had to only replace a few of these sensors before).One of these issues listed here could be the reasong why you arent getting any fuel.

If when you turn your jey on all the way forward just before you start the engine you hear a hum or buzz noise coming from the fuel tank for two seconds then you know the fuel pump is running and you can skip checking the wiring at the fuel pump module,if you dont hear this noise then it needs to be checked.Also a scan tool might show a fault code for the cam sensor if it does then you know you may have a magnet issue.We have replaced lots of these magnets before for this concern.


I hope this information helped,If you need anything else let me know,If you feel satisfied that I have assisted please click accept as this is how I get paid,positive feedback is appreciated,Thanks Pete.



Customer: replied 7 years ago.
ok new development. we were able to start the car this morning when it was only about 70 outside it ran good for almost 15 min then died. It is now doing the same thing it was before.previously when we were working on it the temp outside has been 100 or better my dad who is doing the work on it suggested it may be something heat related any help is truely appreciated. thank you so much for your time and attention to this.
if it started and ran until it got hot most likely the cam magnet is ok,it may be that the cam sensor itself is heating up and losing its signal,components will do this with wear and tear and age.Crankshaft position sensors will do the same thing and are very common on these engines as well but usually they will kill the spark and not the fuel.
Customer: replied 7 years ago.
need more suggestions, this 3.3 v6 buick engine does not have a cam position sensor, it is a burst fire not sequential. We have now changed out the throttle position sensor and the mas in addition to fuel pump,fuel filter,fuel pump relay, fuel pressure fix in any of it. It still will start as long as it is cool outside but as soon as the temp rises or you run it 10-15 min til engine is good an warm it dies just like you shut off the fuel. you can spray starter fluid in the air intake an as long as you keep spraying it keeps running... we are stumped
I dont have any more suggestions on this,thereis a possibility of 3 items here that could cause this,first and seen the most is crankshaft position sensor,second the ignition control module as it recieves the signals from allot of components to spark and pulse the injectors,and three possibly the engine computer(ecm),usually the computer wont cause this but it is possible,I would lean more towards the ignition module under the coil pack,this can heat up and fail and cause this exact failure.If you have a scan tool you can observe the rpm on the scan tool to see if rpm's are present when cranking over the engine when this acts up,if you have an rpm signal when cranking then most likely the crank sensor is ok,this would lean more towards a faulty ignition module.
Pete and other Buick Specialists are ready to help you
Customer: replied 7 years ago.
thank you for all your help. We have currently stopped working on this car as im out of time an money to fix it.