Fuel pump problems

[japSW20]

hey guys havent been on here lately but i finally got my car to run,Ive noticed the pumps is loud,i mean i could hear it whining.So the other day i ran out of gas and i filled it up,i turn the key on and i hear the pump turn on then back off and from that day on it hasnt been pumping anymore From what i know its a factory pump.Anyone have anyidea what the problem might be? i traced a brown wire to the back but it has no power? my dad told me the pump might work be activated with ground instead of power?

 

[8tsixt]

check the fuse & relay if you have no power at the pump.

 

[2QUIK6]

So the other day i ran out of gas and i filled it up,i turn the key on and i hear the pump turn on then back off and from that day on it hasnt been pumping anymore

If you had the key/ignition "on" for very long after running it out of gas, you probably burned up the pump, they aren't designed to run without any fluid/gas being pumped thru them. You never want to run an EFI car out of gas for this reason. Check all the fuses in hopes that it burned a fuse before it burned the pump up, but if you are hearing the pump come on and shut right off, thats doubtful.

 

[Sam Colalillo]

Going off memory here so bare with me.

Start by checking the fuel pump fuse in the fuse panel in the car. Is it O.K.?

When the pump was cavitating it may have popped the fuse.

You have a fuel pump test lead wire on your Buick, you can supply power to this wire and the fuel pump will run if it is not bad. This wire is located behind the A.C. compressor next to the valve cover right above the header. Next to it will be the Tachometer test lead. I cant remember what color the terminal ends are on these two test leads but the fuel pump test lead should be a Tan wire with a white tracer. (Sometimes people plug these two leads together accidentally and their tachometers go bonkers). By supplying 12 volts to this lead the pump should run, if it don’t I think the pump is bad.

If it does then continue on.

Next check fuel pump relay wires. The fuel pump relay is the middle relay on the passenger side fender. One of the wires connected to this relay is a dark green wire with a white tracer, located in pin A1 of the fuel pump relay wire harness socket assembly. When you turn the key to the run position the ECM triggers 12 volts for two seconds to the Dark green wire with a white tracer. In order to check this wire for power you will need some help. Get your test light on this lead and have your assistant to the key to the run position, it should turn on the test light for two seconds, does it?

A tan wire with a white tracer is the power wire going directly to the fuel pump do you have power at this location? Remember unless you get the car running your only going to have power for two seconds after the key is turned to the run position.

The oil pressure switch can cause the fuel pump not to run, so after checking this stuff and you don’t determine your problem I’ll try to help you some more, if you post your findings.

 

[japSW20]

Going off memory here so bare with me.

Start by checking the fuel pump fuse in the fuse panel in the car. Is it O.K.?

When the pump was cavitating it may have popped the fuse.

You have a fuel pump test lead wire on your Buick, you can supply power to this wire and the fuel pump will run if it is not bad. This wire is located behind the A.C. compressor next to the valve cover right above the header. Next to it will be the Tachometer test lead. I cant remember what color the terminal ends are on these two test leads but the fuel pump test lead should be a Tan wire with a white tracer. (Sometimes people plug these two leads together accidentally and their tachometers go bonkers). By supplying 12 volts to this lead the pump should run, if it don’t I think the pump is bad.

If it does then continue on.

Next check fuel pump relay wires. The fuel pump relay is the middle relay on the passenger side fender. One of the wires connected to this relay is a dark green wire with a white tracer, located in pin A1 of the fuel pump relay wire harness socket assembly. When you turn the key to the run position the ECM triggers 12 volts for two seconds to the Dark green wire with a white tracer. In order to check this wire for power you will need some help. Get your test light on this lead and have your assistant to the key to the run position, it should turn on the test light for two seconds, does it?

A tan wire with a white tracer is the power wire going directly to the fuel pump do you have power at this location? Remember unless you get the car running your only going to have power for two seconds after the key is turned to the run position.

The oil pressure switch can cause the fuel pump not to run, so after checking this stuff and you don’t determine your problem I’ll try to help you some more, if you post your findings.

Well speeking of the oil pressure switch,i think that may be the problem,before the pump stopped(about a week) my oil pressure gauge just shoots up when i put I turn the caron,Im at work now but when i get back i will check,The car is a hot air so does it still have the lead? I will check the relay and brown and white stripe line for power.Thanks :biggrin:

 

[japSW20]

ok i went to the trunk and found the 3 wire plug that goes into the pump,i hokked up my test light to the brown with white stripe wire and turn the key on,no power,I went to my fuse box and the FP/INJ fuse was perfect,i went up fron to the relay on the pass fender and hooked my test light up to the green with white stripe wire and it had no power either I unplugged the relay,and there was 3 pins side ways and one horizontal ontop that was a red wire,that one had power with the key on

 

[Sam Colalillo]

Sorry, I assumed your car was an 86 or 87. I am not sure how things work on the hot air cars, but I’ll give you the basics on how a relay works. Pull up the attachment I posted in this response. This is a picture looking at the bottom of the relay (the terminal side of the relay).

Your relay should have the following numbers marked on it.
86 should be the ground
30 should be the power wire
85 is the trigger wire
87 should be the wire that runs your pump (when the trigger wire excites terminal 85 you should have power at this terminal)
87a has power when the trigger wire is not supplying power (not all applications have a wire connected to this terminal, you probably dont).

I assume you had power at the terminal marked 30, is this correct. Get an assistant and probe the other wires. Remember the pump is only going to run for two seconds, unless the car starts. This is to prime the system before the car starts. Now do you have power at any of these other terminals? I think you should be getting power to terminal 85 for two seconds after the car is turned to the run position.

 

[rodman99999]

The oil pressure switch CANNOT cause your pump not to run(unless the pump relay is bad). It's there as a back-up for the relay, and hooked in parallel. If the relay goes bad, the oil pressure switch bypasses it(as long as you have 4lbs of oil pressure). Not an opinion- a fact straight out of the factory service manual(page 6E3-C2-4). Oh yeah- the hot-air cars have the pump prime lead in the same general area as the intercooled ones. I used to use it to drain my tank all the time. A good way for you to find out if the pump is bad.

 

[Sam Colalillo]

The oil pressure switch CANNOT cause your pump not to run(unless the pump relay is bad). It's there as a back-up for the relay, and hooked in parallel. If the relay goes bad, the oil pressure switch bypasses it(as long as you have 4lbs of oil pressure). Not an opinion- a fact straight out of the factory service manual(page 6E3-C2-4). Oh yeah- the hot-air cars have the pump prime lead in the same general area as the intercooled ones. I used to use it to drain my tank all the time. A good way for you to find out if the pump is bad.

Yes you are correct, the relay and the oil pressure switch have to be bad in order for the fuel pump no to run. I should have been more speciffic in my first post. Maybe I was just getting tired of typing. Thanks for clearing that up. Am I correct on the wire colors I am having him check (he has got a hot air car)?

 

[japSW20]

ok guys went out and replaced the relay,went to the back plug before the tank and there is power in the brown with white stripe(always on with key ,doesnt shutt off) and the other wire (forgot color) has very weak power.I dropped the tank and tomorow im going to go buy a new pump and hook it up.Also another strange thing i saw is when i was pulling off the 3 fuel lines that go into the tank,one had ALOT of pressure(the widest hose) which i thought was weird due to the car not runin for a week

 

[Sam Colalillo]

Having that pressure is a good thing. When things like your injectors starting going bad they will leak down and you wont have good pressure. It is normal for a Fuel injected car to hold pressure.

The other wire you are referring to, is it the one that also connects at the fuel tank? This wire coming out of the sending unit is the one that is connected to the rheostat in your tank, it tells your gauge what fuel level to read depending on how much voltage it is receiving.

Hope this helps.

 

[japSW20]

Having that pressure is a good thing. When things like your injectors starting going bad they will leak down and you wont have good pressure. It is normal for a Fuel injected car to hold pressure.

The other wire you are referring to, is it the one that also connects at the fuel tank? This wire coming out of the sending unit is the one that is connected to the rheostat in your tank, it tells your gauge what fuel level to read depending on how much voltage it is receiving.

Hope this helps.

thats right,lol i completely forgot about the gauge.so 3 wires one would be power for pump,the other would be sending unit for gauge and the black one would obviously be black.what worries me is that now you say that it should only trigger the pump for 2 seconds but mine is fixed on as soon as the key is "on".thanksss!!! :biggrin:

 

[rodman99999]

Going off memory here so bare with me.

Start by checking the fuel pump fuse in the fuse panel in the car. Is it O.K.?

When the pump was cavitating it may have popped the fuse.

You have a fuel pump test lead wire on your Buick, you can supply power to this wire and the fuel pump will run if it is not bad. This wire is located behind the A.C. compressor next to the valve cover right above the header. Next to it will be the Tachometer test lead. I cant remember what color the terminal ends are on these two test leads but the fuel pump test lead should be a Tan wire with a white tracer. (Sometimes people plug these two leads together accidentally and their tachometers go bonkers). By supplying 12 volts to this lead the pump should run, if it don’t I think the pump is bad.

If it does then continue on.

Next check fuel pump relay wires. The fuel pump relay is the middle relay on the passenger side fender. One of the wires connected to this relay is a dark green wire with a white tracer, located in pin A1 of the fuel pump relay wire harness socket assembly. When you turn the key to the run position the ECM triggers 12 volts for two seconds to the Dark green wire with a white tracer. In order to check this wire for power you will need some help. Get your test light on this lead and have your assistant to the key to the run position, it should turn on the test light for two seconds, does it?

A tan wire with a white tracer is the power wire going directly to the fuel pump do you have power at this location? Remember unless you get the car running your only going to have power for two seconds after the key is turned to the run position.

The oil pressure switch can cause the fuel pump not to run, so after checking this stuff and you don’t determine your problem I’ll try to help you some more, if you post your findings.

Hi Sam- The "test lead" (actually: fuel pump prime) is a grey wire. It's behind the A/C compressor on an 86/87, but the 85's A/C is on the passenger side of the car. That may have been a tad confusing to a hot-air owner. The wire(grey) that he wants is on the driver's side on both cars though. Tan/white tracer is the correct color for the wire going back to the pump. When I bought my 87 'T' the tach and pump leads were hooked together(like you mentioned). Lots of confused people out there!!

 

[japSW20]

well back from the dead,i bought a new pump,put it in and while the tank was on the floor i plugged it in and it worked,it was late so i left the tank on the floor,went back the next day hooked everything up and no go im going to look for that lead,also i replaced the relay and theres still no power on the brown with white line

 

[artrenee10]

You might want to

check out some of my posts.....I am having damn near the same problem. No power to the tan line either.

I might have to replace the fuel tank hangar.....(Mike Dopkins you out there?)
Steve

 

[Sam Colalillo]

Start at the relay. Are you getting 12 volts for two seconds at the green with white stripe wire when you turn the key to the run position.

 

[japSW20]

Start at the relay. Are you getting 12 volts for two seconds at the green with white stripe wire when you turn the key to the run position.

nada

 

[Sam Colalillo]

O.K. No power to the green wire with a white stripe, this circuit is 465 on a 1987 Buick. Disconnect a battery cable. Goto the main connections on your ECM. One of the two socket assemblies connected to your ecm has pin marked A1. Next get your circuit tester out. Connect one end of you circuit tester to the A1 terminal on your ECM and the other the end of the Green wire at your relay connecter. Is this circuit good or do you need to repair this wire (did the circuit tester beep)? On a 1987 Buick The ECM triggers power to this green wire for two seconds. Refer back the Relay illustration I posted earlier, does this green wire connect into location 85?

I am hoping some one that has knowledge of the 85's will chime in, I would think your car would be similiar, only allowing power for 2 seconds.

Do you still have power to the red wire (actually should be pink with a black stripe) that connects to your relay, if you do not check you fuel injection fuse again.

 

[rodman99999]

It's important to remember: If the car doesn't START and RUN(ECM has to get reference pulses from the ignition module) within those two seconds, the power is cut to the fuel pump relay by the ECM.

 

[japSW20]

im going to check the ecm now,i did snap pics of loose wires i found under the hood?