[juiced94fleet]

Ok, well I have posted a couple times on here my problems with my fleetwood, I need to know if anyone knows if there are any other fuses or relays for the fuel pump? The fuse under the hood is good, but it just doesnt seem to be getting power to the rear of the car to the pump itself, I replaced the relay on the firewall, I just cant find where else the problem could be, it just keeps cranking, Any help would be nice, Thanks.

 

[Katshot]

You SURE it's a fuel problem? Squirt some carb cleaner into the intake and see if it fires up. If so, my money is on the fuel pump itself. Very common issue on those cars. Plan on doing the sender assembly too while you're there.

 

[juiced94fleet]

This all happepened after I had put a new fuel pump in, The car would run before for a lil while then loose fuel pressure, so figured it was the fuel pump, so I changed that, everythings hooked up and wires are all good, now it wont run at all, just keeps cranking, All I know is that the fuse up front is good, but its at the back where its not getting juice, The wiring going to the fuel pump itself is not even working, (checked with test light) so its somewhere between the front fuse and the fuel pump? Any suggestions? Thanks.

 

[N0DIH]

Remember, if the engine is off, it will shut the pump down for safety. You probably need to set up, and cycle the ignition to get pwr back.

I would ohm out the pump at the tank first, don't trust test lights, use a meter. But always remember Kirchoff's Law, if there is no current flow, you will read B+, or in this case, battery voltage. Or GND through the pump's motor. If there is no load, the pump motor windings won't have any resistance to the current flow, giving you screwy readings that look good, but aren't.

If you are convinced that the motor windings are good and there is good electrical connections, run 1 of each wire (1+ & 1-) to the conn running to the pump by the tank. Connect each separately to the appropriate connections. It WILL start pumping if that works.

You should be able to measure the motor resistance (which will read very low resistance, like 5 ohms or less most likely) from the fuel pump relay output to GND. If you measure some resistance, I doubt I would even jack up the car. Apply B+ to the motor side of the fuel pump relay (with it removed), it should run.

The relay needs to be turned on/off. See what does it. ECM/BCM? Key? Fuse?

 

[ocjmakaveli]

since you say that the problem started right after you installed a new pump

It's possible during install the cables may have been pulled incorrectly causing a broken wire inside the insulation so it isn't seen or the connector may be damaged. The little pins inside the connector etc. may not be making contact.

You really need a multimeter those test lights can actually be bad for the car in some occasions.


Check the wires a couple of inches before the connectors.Just use a sharp razorblade and carefully take some insulation off.Don't forget to put electrical tape on the wires afterwards.

 

[Katshot]

All good suggestions. On top of that, understand a couple things about how the fuel pump works:
1. The fuel pump gets a 2 second shot of power at "key-on" to prime the system.
2. After the 2 second prime period, as I recall, the pump will not come back on until there is oil pressure (the oil pressure switch closes a circuit to the fuel pump relay). At least I'm pretty sure it works that way on that car. I'll take a look in my manual this morning at work for to verify that. It might also just be that the PCM needs to see a tach signal, can't remember which.

So when diagnosing this issue, you must understand that as soon as you turn on the key, you should get power to the pump. If not, don't even worry about cranking the engine. There is a spot that tends to have a problem in the wiring harness, it's directly under the back seat on the driver's side. The seat frame tends to rub through the harness right before it exits the body. Sometimes, it causes a short but sometimes it just creates an open in a circuit.

 

[ocjmakaveli]

All good suggestions. On top of that, understand a couple things about how the fuel pump works:
1. The fuel pump gets a 2 second shot of power at "key-on" to prime the system.
2. After the 2 second prime period, as I recall, the pump will not come back on until there is oil pressure (the oil pressure switch closes a circuit to the fuel pump relay). At least I'm pretty sure it works that way on that car. I'll take a look in my manual this morning at work for to verify that. It might also just be that the PCM needs to see a tach signal, can't remember which.

So when diagnosing this issue, you must understand that as soon as you turn on the key, you should get power to the pump. If not, don't even worry about cranking the engine. There is a spot that tends to have a problem in the wiring harness, it's directly under the back seat on the driver's side. The seat frame tends to rub through the harness right before it exits the body. Sometimes, it causes a short but sometimes it just creates an open in a circuit.

So to clarify the pump wil only receive power for about 2 seconds after the key is put to run? Then there will be no power there until the engine is running?

IF so then he cannot check the pump wires correctly unless he has someone switching the ignition switch back and forth while checking the wires correct?

If this is correct then that may have been his problem and he thinks that the wires don't have power getting to them.

Has he checked for fuel pressure at the fuel rail?

Also there is a possibility you have a defective pump...not impossible

 

[juiced94fleet]

Thanks for all the info, I have to get out there and try a few things, but as for pressure in the rail, should it spray out if it got built up from the pump working? Cause I have tried numerous times just to see what would come out, and usually nothing, but the last time I did it gas came out, but not a big amount, So would this mean something has to be going on there? right, And I thought maybe a bad (new) fuel pump too, so I returned it cause it had a lifetime, got the other new one in and same thing, Is there anyway to reset the computer or something, I have had the battery in and out during this, and wasnt sure if maybe something needed reset, This is driving me insane, this thing sat all summer and now its winter and still not running,

 

[turbocaddy]

did u do what the first guy said...spray carb cleaner down it's throat and see if it starts...that will eliminate the ign side of it....and you should hear the pump run for 2 seconds when u turn the key on...shut the doors and try to hear it...and u have to wait at least a minute or two before u turn the key again..check the pins in the black connector..they do pull out,they should be all even and level with each other in the connector

 

[Katshot]

Actually, as far as I know, there's no time-out between prime cycles. Every time you cycle the key, you should get a 2 second prime cycle. It won't provide a lot of fuel if you try to purge it at a line or some other opening, so don't think that just because there's not a lot of fuel when you open a line that the system's not operating correctly. The prime cycle is only meant to build system pressure so that when you crank the engine and the PCM sees a tach signal and energizes the injectors, there will be adequate system pressure to give a proper spray pattern at the injectors. That really doesn't require a ton of fuel.

 

[scurling]

When I changed the fuel pump on my 3.8L (Buick) Olds98, I got a fuel pressure guage at local Trak Auto (Advanced Auto, etc.) It will give you a positive reading on the fuel rails for pressure during engine cranking, and eliminate a lot of guess work. GMs have been working the same for a long time in the fuel delivery dept.

You could also open the line at the fuel filter, to see if the initial pump startup is working. It would give a small squirt.

The oil pressure issue that Katshot explained may also be the key to the problem, i.e., no oil pressure, no fuel pressure.....no start up.

I also had to prime the fuel rails every time I ran out of gas. The system doesn't like air in the lines. All I did was have someone crank the engine while I held the pressure guage attachment valve open with a screwdrive tip.

Good luck.

 

[Katshot]

Usually a couple of key cycles is sufficient for purging the system. Remember it's a looping system so air just gets pushed back to the tank via the return line if nothing else.

 

[juiced94fleet]

Well I sprayed some carb cleaner in it, and this was the first time this car has started in forever, so now I just have to look into a couple more things you guys have mentioned, but feels good to actually know its alive, somewhat, So any more info? And Ill keep you informed with what I do and how it goes, and thanks again for all this useful info,

 

[BCs71]

Every time you cycle the key, you should get a 2 second prime cycle.

This is the FIRST step you should perform to dignose the problem. This should be quick and easy and we haven't got a definite answer yet. Do you hear the pump running when you turn the ignition key forward?? Sound should be from the tank for two seconds and then quit....if you don't hear anything then there is no power to the pump and then you can troubleshoot from there.
If the pump DOES run, then there is power and then a fuel pressure check with a gauge is in order.

On the passenger side in the engine compartment is your main black box relay/fuse/convenience center. Right next to that black box is a small black female wiring connector with a single wire going into it. This leads directly to the fuel pump and if you supply the + (positive) side of 12 volts to this connector (jump it from the battery) you SHOULD be able to get the fuel pump to run.

If you cannot get it to run, then I would suspect that you have a wiring issue that occurred at some point.

Good luck, let us know how that little test works out for you....

And also for your convenience I have the 94 Fleetwood factory service manual pages for fuel system diagnosis and troubleshooting on the web already.....
http://www.imagestation.com/album/?id=4288362399

:cool2:

 

[ocjmakaveli]

I don't know if it's just me but in my 94 fleetwood I just can't hear the pump come on ever.

On almost every other car I've ever driven I can always hear the pump activate but on this caddy I have never heard it come on yet the car does start without a problem.

Juice just for kicks replace your fuel filter you never know.