Ever since I got my 91 convertible, I've noticed some sounds that I am concluding have to be from the fuel pump after I shut off the ignition. This is not what I'm used to with other EFI cars I've driven. I know about the 2 second fuel pump "pressure up" sound when you turn the key before cranking the engine. However, the sounds I'm describing is after I turn the engine off. Also, I have heard it for fairly long time after turning the engine off. I know you get used to hearing the sounds of the engine and related things in a car so it becomes routine for you. The thing that made me think this may not be normal is the one time it refused to start (no fuel). Today, I went to the garage to start it and not start. So I'm thinking it could be a fuel pump going bad. It may be completely dead now. I guess I should check to see if there is fuel rail pressure when I check it. I believe there is a Shrader valve on there. I have my FSM finally so I feel better about being able to find most stuff now.

One question I thought I was going to have seems to be in the FSM. It doesn't look like I will have to pull the tank. I think I can replace the pump thru the rear gas filler door. I was sweating that at first after looking under the car at the tank and the cable system holding it. I will give the GM engineers praise for designing it that way.

Have any of you had intermittent problems that turned out to be a dying pump? I have had this happen to me in two other vehicles. It drove me crazy until I finally traced it to that problem.

Were the sounds I was hearing before with the prolonged running of the pump possibly related to a pump dying slowly? I don't and didn't have a fuel leak.

Any input that helps clear this up will be appreciated.

Thank you,

WEK.

 

Before we go that far, lets put a noid light on the connections of the pump in the rear. That way we know if it is being energized or not. If not, your problem is elsewhere. IIRC, it is a fuel pump relay which energizes it when it gets a current. IDK if it is possible that the relay gets frozen in the "energized position".

 

If the pump is dead, it will get power in the connectors for 2 seconds and no more. If that happens and the pump doesn't prime the circuit, we have a dead pump

 

The fuel pump is the easyest I have ever done comes right out the top under the fuel door.

 

I may have a spare working relay. If I can find it I will replace the fuel pump relay and check. If I can't I can switch another relay (maybe horn) in the same area and try it to see if things go back to normal. Thanks. I had forgotten about the relay (duh!). That of course, is the first thing to check. I don't know if those can die slowly or act intermittently, either.

I'm so glad you don't have to remove the tank and therefore the rear bumper if the pump is bad. OMG!

I'll get on this in the AM.

Thank you,

WEK.

 

BTW: aklim, please explain the avatar. I'm sure you've been asked before but I have to know. I actually knew someone who looks very much like her.

WEK.

 

Before I go pulling the relay, it would behoove you to have someone turn it on and see if it primes or not. If the wires are broken somewhere, the relay might be fine but the power doesn't get to the pump. I'd go systematically from the back to the front and see if the terminals are giving it power before going anywhere. If you like you can hotwire it to pump and see if the pump is working or not and if it is, what pressure can it maintain.

 

Jenna Jameson the **** star.

 

**** star

 

Oh yeah. It's coming back to me now. That convention in Vagas, the autographed forehead, and then everything when blurry. Just kidding.

But seriously: I took the filler cap rubber housing out and tore it a little. There is a weather proof connector with three wires to the pump and fuel level sensor. I disconnected it as that is the only way to access it without splitting some wiring insulation. I have a purple, grey, and black. All the wiring I could see is in great shape not brittle or stiff. In the meantime, I cycled the pump with the ignition key. It activates and runs a few seconds each time. You can hear it a lot easier with it exposed. So I think it is working as far as the pump motor being energized and that probably excludes the relay as a problem, too. However, it does not exclude the pump since it may not be pumping anything. I've seen this happen quite often. It sounds great but does not pump.

So would you do the fuel rail pressure next? If that holds 40 to 42 lbs of pressure then I don't have a pump issue. In another thread antfarmer suggested a bad coil with this crank and no start scenario.

Getting ahead of myself.

Try again tomorrow.

WEK.

 

A forehead autograph isn't that memorable. OTOH, if she autographed the other head......

NO! That means you don't have leaks in the fuel pump circuit from the sock to the fuel pressure regulator. That does not say if the sock is partially obstructed. It certainly does NOT say if your pump can keep up. To test that, do a WOT run and see what the fuel pressure reading is. I like to pull the hose off and cap the nipple and do a couple WOT runs and see how much the fuel pressure drops especially during the run.

 

I think you are talking about placing a fuel pressure gauge onto the system and running it from idle to cruise, then some WOT events to make sure the pressure stays ~40 lbs. I have done that before on another car. It looks like that's where this little project is taking me. However, it won't start at this point. I am going to test the disconnected pump today with my battery charger to see if the pump will run, pressurize and stop with me standing close enough to hear any thing that may indicate a sick pump. It may tell me something or may not. I have access to it right now. Isn't the Shrader valve on the pump side of the regulator? So that also might tell me if there is pressure at the rail. If the pump is not pumping at all, that would diagnose it, I think? Looking for the obvious here.

Thanks,

WEK.

 

Yes just put your pressure gauge on it and turn the key then go from there.

 

Pretty much. You have to tape the gauge to the glass.

IF you try hooking up power to it, put a gauge and you can see if it can even generate the power. If it can, hook it back up and check the fuel pressure. If it is pressure, it should drop after the first cranks.

 

I had another thought about this. When you have done something different than is the normal routine, sometimes that contributes to or is the root cause of a problem when you may not suspect it. So yesterday, I pressure washed the engine bay. It's the first time I have begun to clean in this area. I did an initial spray down and then started the engine, used engine degreaser on some greasy areas, sprayed it down again. I avoided the alternator and distributor during this process. I left it open in the Sun to dry. Then I moved the car to the barn where it resides. The next morning it would not start. I hope this didn't have anything to do with the problem. I know this engine does not have the "Opti Spark" that people talk about. However, are there any other critical components that I might have flooded. I figured I was OK since it started and ran after I cleaned it. I just wanted to mention it. I will continue on the present trouble shooting path. Not starting is going to make it difficult.

WEK.

 

You do not have to crank the engine just turn the key on the pump will run for two seconds. And yes washing the engine very well could be your problem. If it was me if I had pressure I would put a fan on it and go think about what I have done.

 

OK this has been fun. But all good things have to come to an end.

I found the problem. The engine has an Accell HEI distributor which has that funky cap and the enclosed coil. I have never had one but I started getting suspicious when I saw that it only had one screw holding the cap down. I took the cap off: nothing seemed out of place so I started tracing plug wires and then the coil wires. When I touched the red wire from the battery (wondering if I was going to get lite up), it fell out of it's slot. I noticed a piece of tape wrapped around the connector. When I reinstalled the connector the car started. I believe this may also explain one of the two no starts I have had while I have owned the car (same symptoms). The other one where everything was just dead (no electrical) is still unexplained (maybe shifter position switch). So now I will have to fix this connector or replace the cap, not sure which.

So antfarmer was right whenever he mentioned a dead coil!!!

This brings me back to the original question. Is it normal for the fuel pump to cycle after you cut the engine off? I have been hearing these little buzzing sounds in different patterns coming from the rear of the car ever since I've had the car. I don't know what else it could be besides the fuel pump making those sounds.

Thanks for all your input on the possible fuel pump issue. I think it is OK so I will reassemble the filler cap/fuel door assembly. Now I know how easy it will be when it comes time to replace it. The hardest thing is getting that rubber boot out of the hole. I will show some pics of my misadventure with the distributor. I hope not to find any other surprises like that.

WEK.

 

AFAIK, it isn't. That brings us back to investigation. Safest way is to put a DVOM on the ends and see if it has power.

 

Good job with the noise at the back I would take a look at the power antenna too. The dead problem if the dash was lite up with no pump and no starter engauging try your other key after four min might be your vats.

 

I really thought I was done but after reading something in the FSM and remembering an event that occurred this afternoon, maybe not. The car failed to start again after me fixing the coil hot wire and moving it out of the garage.

There is a diagnostic chart showing a series of steps to diagnose a problem when a Code 54 is set. It is on page 6E3-A-79 Fuel Pump Circuit Low Voltage. In one of the steps it mentions "is the primary relay fuse blown". It shows different scenarios of a bad pump, relay, ECM, or ground condition. So I do seem to have a real fuel pump/circuit issue after all. It is intermittent. So there were two simultaneous issues: I fixed one. I learned that there is a secondary relay. It's way more complicated than fuel pump circuits I've dealt with in the past. It's even possible that the pump is causing the ground itself as it breaks down (if it is). So I won't be taking any long trips until I can diagnose where the problem is. I'm having a little difficulty with some of the terms. What is CKT? This could take a while. I'm repainting the inside of the fuel filler door and reassembling tomorrow. Then I will try to find the primary relay. I think it is in the same area as the amplifier on the PS under the glove box. I guess I have to remove the PS panel.

WEK.