Intermittent no power to fuel pump and gauge reads empty
 

I have a 1999 saturn SL, and have an intermittent problem usually when its cool or cold out. For some reason the fuel pump will randomly stop working and fuel gauge goes to empty. I have checked the interior fuse panel for the F5 problem, and have power to the fuel pump relay. Although when it exhibits the behavior, and I turn the key on, I get no power to the fuel pump relay trigger connection. I've tested at the backside of the interior fuse panel for the DKGRN/WHT wire that feeds the trigger, and when its exhibiting the behavior I get no power there, but when the key is on I get 12v at the PCM connector on what I believe is the correct DKGRN/WHT wire.

This isn't only a cold start condition, as it can happen when driving, and will cut out and back on, sometimes immediately, and other times after a wait.

I have searched and searched everywhere I could find for answers, but have come up completely baffled.

Has anyone else had this issue, or know where else I can look?

I had another account on here a couple years ago and asked, but got banned after 2 hours for what it says is "inactivity" even though my account was only a couple hours old. How active do I have to be to not be banned permanently for "inactivity"?

Also, sometimes I can leave the key on with park lights on and it will work, other times it will not. But it will also just cut off when running like that as well, so I'm not sure if that helps or not. :(

Does it have power locks/key fob? Maybe a problem with immobilizer but just guessing that if it's a regular sl it probably wouldn't have that. Sounds like the connection is being interrupted at the pcm if you have power to relay but lose trigger. Either that or there is a bad/frayed wire en route to tank. I'll have to pull out the old fsms and see if I can scan in a wiring diagram.
Does this wire that your testing go/come from a fuse to the relay and how are you testing it. It's been awhile since I've been behind one of those panels

It doesnt have a fob, just the key. As far as I know the wire on the back of the fuse panel that isn't getting power does not have a fuse before it, and where I'm testing at the pcm is through the back of the plug. From what I have found, the wire from PCM is DRKGRN/WHT, but there are actually 2 different DRKGRN/WHT wires on 2 different plugs coming from the PCM, and I'm not 100% certain I'm testing the correct one.

I thought maybe something with wiring back to tank, but if its not even getting power to trigger it would rule that idea out I would think.

I'm testing with multimeter and probing the connector.

Definitley sounds like a shortage somewhere. Trace the wires back as much as you can.
I would assume the bundle of wires runs through the car as it does with the Ions.
Any rips/tears/leaks in the car?

The wiring harness between the PCM and fuse block inside basically goes up and over steering column and behind the instrument panel :/

Of course, unless I can find an actual pinout of what plug on the PCM and which DRKGRN/WHT wire is the correct one, I'm still not certain I'm testing the right place.

There isn't a fuse on the fuse box under the hood?

I've checked the power to/from the PCM1, PCM2, and IGN fuses in the underhood fuse box and all checks out fine.

Also, as curiosity, I tried jumpering the relay to power fuel pump, and the car still does not start when manually powering it. Tomorrow after work I'll check for power at the ignition module also. I'm curious if its just PCM failure, or maybe ignition switch power?

OK, I can only find the generalized schematic for 91-95, but Saturn tended not to change alot wiring wise b c it was too expensive to do so until they added the BCM iin 3rd Gens.

That being said:

The IPJB DRKGRN/WHT at F4 (F5 in later models I believe) is the input to the high side of the fuel pump relay coil; the other end of the coil comes out from the relay on pin A5 of the IPJB, on a BLK wire which goes into a splice pack --presumably to ground.

However, the FUEL PUMP AND PARK 10A fuses are upstream from the fuel pump relay and operating current for them comes from the RED/WHT wire that leads from the IPJB to the UHJB IP BATT fuse (UHJB Pin A, Connector 2239)


The fuel pump switch is of course normally open, but when the coil is energized, that part of the relay closes, and he current exits the IPJB through a GRY wire at IPJB D4 to the fuel pump.


Based on your description of events, I'm thinking one or some of the following

• the RED/WHT connection is intermittent at either the IPJB or underside of UHJB. I've read of many overheated torched connections under the fuse box.
• the IP BATT fuse, PARK fuse, F PUMP fuses are making poor electrical connection
• The fuel pump relay is bad.

My best guess is the IP BATT feed and connection on one end or the other (IPJB, UPJB) or dirty fuse contacts).

This scenario ties the two events (lights and fuel pump) together.

Most interested to see how this plays out.
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w/r/t being banned while online, it was done by neither Goalie nor I. Previous moderators of this forum were not fond of members joining without posting immediately thereafter (same session). I doubt the moderator had any clue you were online; probably just banning accts w 0 posts. For the record, new members are now sent a PM explaining they have 10 days to make 10 posts, etc.

No more grey area.

I don't apologize for other people's behavior, but I am sorry that this happened to you. Goalie and I have our email addresses in our signatures so you can badger us any time it becomes necessary.

The parking lights work all the time when they're supposed to though. It just seemed like having them on affected the process, but I'm thinking I was wrong with that assumption.

This morning before work the car cooperated enough to let me test during working conditions, and I was able to get the 2 second 12v feed at the PCM connection and the connection on backside of the interior fuse panel. So, at least I know its the correct wire and connections I've been looking at.

When the car is acting up I get constant 12v at the PCM connector, and nothing at the fuse panel. This leads me to believe its somewhere between the PCM and connection to interior fuse panel, but where is the question. Does the DRKGREEN/WHT wire for the fuel pump relay trigger go straight from one point to another, or does it connect somewhere else midway? I wonder this because even when its acting up and I manually jumper the relay to run the pump, the car still will not start.

Going thru the book of knowledge. Hopefully (because scanner won't connect to anything) my phone camera will make these readable. If not I'm sorry about potato cam

Please tell me if you need more information as I have most of the rest of the set, especially for the 99 cars. Now if the puppy will stop trying to absorb the book.

I won't have any time this evening to do much, but will look hopefully tomorrow when I do have a little time.

I did however manage to test the correct wire from PCM during normal operation and when its acting up. During normal operation I get 12v power for the 2 seconds before startup, and 14v running. When its acting up I get no power at the PCM connection. That was at 4am this morning before work in 25 degrees and ice.

Now I get to figure out why its not signaling as it should.

It's starting to sound more and more like something wrong inside the pcm. Maybe a solder point gone bad or something. If it's not showing up at the pcm that's gotta be it. I don't remember if pcms going bad was common. But the sucky thing here is you will need a 99 m/y pcm because of the secondary air injection unless it's a very early 99. Otherwise it will throw the service wrench. Single cam right? Hopefully someone will tell me I'm wrong , but when I needed to swap out the auto pcm for a manual one I found one I needed on eBay for under $100. Quick way to tell if yours has air injection is you'll find a little pump behind the pass headlamp, with a tube running to a check valve ontop of the a/c comp, and from there a tube to the header. You'll have the coffee can pee-cat too

I think we may be complicating this a bit too much.

If he fuel pump relay "trigger" coil INTERMITTENTLY grounds itself (shorts), it will lead to no voltage at the PCM when measured relative to ground because there is no resistance across which to develop a potential (V) irrespective of what the PCM wants that output voltage to be at that pin of the PCM.

If he fuel pump relay "trigger" coil INTERMITTENTLY goes open circuit, you would still see 12V at the PCM relative to ground, as the PCM is ready to supply current at this voltage, but when the coil opens up, that current path disappears, but that does not affect the potential V at the PCM.

So, after reading and re reading the posts in this thread, if you re 110% positive there is NO issue with the IP BATT feed on either end, then I will propose the theory that the coil inside the fuel pump relay is intermittently grounding out, thus opening the relay and killing the fuel pump.

I went out to try starting it after work and the fuel pump kicks on, but something else is keeping it from firing up. I get voltage at the ignition module pink wire, but I'm not sure if something else is complicating things. This weekend I'll have more time to devote to checking the IP BATT feed, looking over diagrams, and dig some, as right now I just don't have any daylight time to do anything but see if it starts. :(

Do you own a fuel pressure gauge? Hook one up at the rail and see what if any fuel pressure you are getting.

Also, pull the boots off the coils and see if you get an arc across each one. Test best done at night.

Since my last post I think I've narrowed it down to either the PCM, or wiring close by. A few times now when its acted up I've been able to point a hair dryer directly at the PCM for a few minutes on high and it activated the fuel pump correctly.

I had finally gotten the chance to test if it was getting fire during this problem, and when its acting up it isn't firing either. I was getting 12v to the ignition modules, but it wasn't sending signal to fire.

As far as testing fuel pressure, when the pump wasn't kicking on, I could test at the valve and there was no pressure. I know it wasn't a matter of the flow of the pump, it just wasn't getting juice.

A few weeks ago I had to change the crank sensor because during testing the fuel pump started working as it was supposed to, but I still wasn't getting fire, and at some point the crank sensor had gone bad as well. I tested it for resistance and it showed as open.

Sorry it took so long for a reply, we've been wrangled here with work and kid stuff lately and I've had to leave the car sit for a few weeks. For a couple days over new years weekend it started every single time I needed it to, but then monday morning when trying to leave for work it was crazy again. Thats when I finally took the hair dryer to the PCM and warmed it up.

What is the security system doing while all this is going on?

A bad CKP will kill spark and and fuel injectors. Not sure about fuel pump; would be redundant.

I'm not quite sure what security is doing when it does it. As far as I know the security system on a '99 doesnt lockout the fuel/fire like it does on a '00 and up. I've tried the security reset several time with no change. So far the only thing I can repeatedly do is take a hairdryer to the PCM and heat it up for a few minutes and it comes on as it should.

I asked about the security system erroneously thinking that the Passlock system was implemented in these cars in 99. It was implemented in 2000 as far as I know. Which explains why you can't tell me what the security system is doing because you have no security system status light.

Sorry.

Indeed it should just be a starter disable on the earlier models.

I'll have to look at a generalized schematic for the coupes and figure out which wires to wiggle/contacts to clean as a last ditch effort before condemning the PCM.

PCM failures in S cars are EXTREMELY RARE. I think I remember only 2 or 3 on this forum in the 11 yrs I've been on here -- but one of those was indeed diagnosed with a hair dryer.

Kevin,
Could you please update you signature to match the format outlined in my first PM to you? Thanks.

The format may seem a bit anal retentive but it keeps all of us from having to ask things like "where in the country are you" w/r/t diag of this problem. Are you in a state where the temp is 80 deg or 8 deg?

Sig done, I thought I did it before but probably got sidetracked and didn't 'save' it.

As far as wires go, I've tried fiddling all over around the area and moving every wire I could find, even wiggling the wires and connections in the steering column with no apparent change. Sometimes I could move things around and it would come on, but I could never repeat by moving the same thing, so I figure it was just coincidental that it activated properly at the same time I was doing that.

I'd like to rule out the PCM as the cause (I've heard too that its *very* rare for them to fail, but there is that small chance they still do), but so far thats the only logical thing I can think of that would be causing the problem and being 'fixed' by warming it up a little.

I've noticed that once I do heat it up, and get the car warmed up on those cold days, if I put the heat on high and just on the floor setting, it hasn't acted up while running. Getting it to that warmed up state to do this can be a chore though on some mornings at 4am when leaving for work.

OK,

One last thing to recheck.

When the fuel pump cuts out:

1) Does the dome light work 100% of the time?
2) If you turn the headlights on, then open the driver door to get out, does the chime sound 100% of the time?
3) Do you plug high current draw devices into the lighter for long periods of time?
4) Do you have an aftermarket head unit spliced into the feed going to the lighter?

Yes, these are all F5 questions. I know you said you checked it. But it may be a connector / terminal contact problem that you cannot see.

Also, I don't remember the outcome of the IP BATT feed check.

When the car is acting up, check the IP BATT feed at the inside fuse panel. This runs straight to the battery (99% sure) and has nothing to do with the PCM.

If the IP BATT has no V on it, then that is why you see nothing on the relay. The power feed to EVERYTHING is not there.

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The next time the car acts up, have a friend sit in the passenger seat and one at a time wiggle the crap out of F5 and the IP BATT incoming wire. This is more easily done w 2 people b/c the driver is trying to hold the clutch in, turn the key, and fiddle w wires all at once.

Also, instead of putting the hair dryer on the pcm, point it at the fuse panel while shielding the PCM from the heat. The heat should make any iffy contacts expand and become a more secure connection. It may be a terminal respringing is needed.

Please post back w results. I know I suggested IP BATT earlier but do not remember the response. I have a migraine, the screen is blurry, and I just can't read through it all right now.

I'm a stream of conscious thinker, so if it comes to me I have to write it down immediately or it's gone. Sorry if there are any redundancies

I'll see what I can check next time it acts up. Usually its very early in the morning and I'm the only person awake, or I'm driving somewhere alone and the only person in the car. Those factors usually rule out having someone assist with any testing.

Just a long shot idea, but see if there is any ground wire going from the frame to the tank, or fuel pump, maybe it has a corroded connection. Those are often exposed to the elements and can eventually make a bad connection. Not sure if Saturns have that or not.

You can most definitely check for dome lamp and chime functionality If you are alone. If they both still work, then we absolutely rule out F5 issues.

They both definitely work all the time. Lots of the time I have to pull the chime fuse when I'm trying to start it because I get tired of hearing the 'ding ding ding ding ding ding' every time I turn the key off and on again.

IPBATT when acting up?

Stumbled across this thread while searching for something else....

Kevin,

What was the outcome? Bad PCM?