98 SLS NEED HELP PLEASE

[CTCADILLAC]

OK I HAVE A 98 SLS. SHE WAS RUNNING FINE ABOUT 3 WEEKS AGO, THEN I PARKED IT AND DIDNT DRIVE IT, BUT I WAS STARTING IT UP AND LETTING IT WARM UP EVERY OTHER DAY TO KEEP THINGS LUBED AND FLOWING. AFTER A FEW TIMES IT RAN OUT OF FUEL (STALLED), I PUT IN 1 GAL THE NEXT DAY THEN THAT RAN OUT (STALLED), SO THEN I PUT IN 5 GAL TO GET IT TO THE FUEL STATION, NOW IT WILL NOT START AND IT READS "SERVICE FUEL SYSTEM" IM HOPING SOMEONE CAN HELP ME ASAP! THANKS IN ADVANCE, AS IM STUCK DRIVING A MAZDA F'N PROTEGE I WANT MY CADILLAC BACK! LOL ;P BTW WOULD A BAD FUEL FILTER SEND THE "SERVICE FUEL SYSTEM" MESG.

[adallak]

When you turn ignition ON (engine not running) can you hear the fuel pump running for a few seconds?

There might be water in the tank. Intensive cranking might help to get it out of system. Do not overheat the starter though.

I cannot recall any single case when replacing a fuel filter solved a fuel delivery problem. When I replaced my fuel tank after 16 years and some 150.000 miles it was as clean as a new one.

Pull the trouble codes. They may provide some information.

[CTCADILLAC]

When you turn ignition ON (engine not running) can you hear the fuel pimp running for a few seconds?

There might be water in the tank.

I cannot recall any single case when replacing a fuel filter solved a fuel delivery problem. When I replaced my fuel tank after 16 years and some 150.000 miles it was as clean as a new one.

Pull the trouble codes. They may provide some information.

ITS HARD TO TELL AS I WAS BY MYSELF, I DO HEAR A PUMP BUT I THINK ITS THE SUSPENSION LEVELING, IL GET UNDER THE TANK AND LISTEN THERE WHEN MY WIFE GETS HOME AND LET YA KNOW MORE. ALSO I JUST HIT 156,000 I DONT THINK THE PUMP HAS EVER BEEN CHANGED, I KNOW I NEED A FILTER, DO YOU THINK AFTER 150 ITS DO FOR A PUMP CHANGE? WOULD IT BE A GOOD IDEA TO DROP IT, CLEAN & DRY IT, N CHANGE THE PUMP? HOW ELSE COULD I CHECK FOR WATER? BTW THANKX AGAIN FOR YOUR TIME!

[adallak]

When you turn ignition ON (engine not running) can you hear the fuel pimp running for a few seconds?

There might be water in the tank.

I cannot recall any single case when replacing a fuel filter solved a fuel delivery problem. When I replaced my fuel tank after 16 years and some 150.000 miles it was as clean as a new one.

Pull the trouble codes. They may provide some information.

ITS HARD TO TELL AS I WAS BY MYSELF, I DO HEAR A PUMP BUT I THINK ITS THE SUSPENSION LEVELING, IL GET UNDER THE TANK AND LISTEN THERE WHEN MY WIFE GETS HOME AND LET YA KNOW MORE. ALSO I JUST HIT 156,000 I DONT THINK THE PUMP HAS EVER BEEN CHANGED, I KNOW I NEED A FILTER, DO YOU THINK AFTER 150 ITS DO FOR A PUMP CHANGE? WOULD IT BE A GOOD IDEA TO DROP IT, CLEAN & DRY IT, N CHANGE THE PUMP? HOW ELSE COULD I CHECK FOR WATER? BTW THANKX AGAIN FOR YOUR TIME!

Leveling compressor does not kick in as soon as you turn the ignition ON. So you cannot confuse it with fuel pump. You can still hear the pump when you are in the car if it is quite outside.

There is a Shreader valve on the fuel rail. You can also release fuel pressure from there (wrap it up with a rag to not cause fire). It is an easy way to see whether there is any pressure up there.

My 1991 Seville went to junk yard (perfectly running) with original fuel pump and 175.000 miles on the clock.

[KHE]

I doubt the problem is the fuel filter. I have never seen those clog up.

Since there is a message displayed on the DIC (SERVICE FUEL SYSTEM), there has to be a trouble code stored in diagnostics. Enter diagnostics and write the trouble codes down and post back. That will provide a big clue to the problem.

[CTCADILLAC]

OK THANKS GUYS IL POST BACK SOON, THANKX FOR THE HELP.

[BodybyFisher]

I searched for Service Fuel System and did not find it, are you sure that is the exact message?

We do need codes as KHE said, if you are getting a message, a code is set

[JimD]

I searched for Service Fuel System and did not find it

His model has that message, Mike.

To the original poster:

There is no need to guess or take a shotgun approach. We need Diagnostic Trouble Codes (DTC) commonly refered to as "codes". Here's how to display the codes on your model;

http://www.caddyinfo.com/readingcodes.html

I echo the comments about pointing a finger at the fuel filter. Your fuel filter is not a scheduled maintenance item; leave it alone unless you have good reason to change it.

An empty fuel tank is a condensation magnet. Put some deicer fluid or a few ounces of alcohol in the tank to absorb any moisture.

And turn off your CAPS LOCK key.

[BodybyFisher]

Thanks Jim, I searched SI for his year and did not find anything on Service Fuel System

[Ranger]

I'd get a fuel pressure gauge on the schreader valve on the fuel rail and check the fuel pressure. You may have burned up the pump running it dry. Fuel cools the pump.

By the way, there is no need to get under the car. Have your wife turn the key on (no cranking) while you have your ear to the open fuel filler pipe. You should hear the pump run for 2 - 3 seconds.

[rockfangd]

sounds to me like one of a few things, either the low fuel level overheated the pump, or you had foreign material in the tank and it clogged the filter or sock. And the service fuel system will throw a code if you excessively crank the engine but it fails to start. If the starting issue was to be ignition related it would not trip the service fuel system indicator. I would bet on bad fuel pump myself.

Does anyone know the pressure spec for the 4.6 engine?

Good luck. I love my caddy for now lol

[CarlaValentine]

My manual says that the fuel pressure spec is 43.5 PSI at key on.

[CTCADILLAC]

Ok so I checked the codes today I got a P0231 Fuel pump feedback circuit low voltage, I think thats what it is. If so what could be causing this?

[BodybyFisher]

The fuel pump receives power from CKT 120 through the fuel pump relay. The PCM energizes the fuel pump relay for 2 seconds at key ON to provide fuel pressure for starting. After the 2 second fuel pump prime, the PCM will not power the fuel pump relay until 4X reference pulses are received indicating that the engine is turning (crank or run). The PCM monitors voltage on the fuel pump power CKT 120 to detect fuel pump voltage supply faults. DTC P0231 is set when the PCM sees the fuel pump not energized (2 volts or less on the feedback) with the engine cranking or running

Conditions for Setting the DTC

Fuel pump feedback 2 volts or less for 1.3 seconds.

Action Taken When the DTC Sets

• The Malfunction Indicator Lamp (MIL) will not illuminate.
• The PCM will command a message to be displayed.
• The PCM may record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records.

I can't copy the diagnostic tree but this appears to be related to the fuel pump relay, I would pull the fuel pump relay and look for corrosion on the contacts and socket

[JimD]

Ok so I checked the codes today I got a P0231 Fuel pump feedback circuit low voltage, I think thats what it is. If so what could be causing this?

P0231 - Fuel Pump Feedback Circuit Low Voltage

There are several items to investigate in the rear underseat fuse/relay box. One is a 20 Amp (yellow) fuse labeled F/PMP. Check the fuse with an Ohmmeter and be sure there is no corrosion on the fuse blades.

Another is the relay in position #39 labeled F/PMP. The easiest way to pass or fail a relay is to temporarily borrow a relay with the same number of blades from another position and see if the pump will operate and the engine will fire.

The F/PMP fuse and the F/PMP relay are adjacent to each other in one corner of the fuse box.

[CTCADILLAC]

Thankx guys, Im going to mess with it later on and keep you posted on what I find.

[CTCADILLAC]

Well I had some time today to check it out I found the#1 20Amp fuse was blown, I replaced it,cleared the codes then tried to start. No luck starting. So then I switched the #39 relay with the #40 relay (same relay, from parking lights) then tried that, no luck starting, but the code hasnt come back yet either. What do you think I should try next? Thankx for the time and advice!!! Btw what would cause the fuse to blow?

[adallak]

Well I had some time today to check it out I found the#1 20Amp fuse was blown, I replaced it,cleared the codes then tried to start. No luck starting. So then I switched the #39 relay with the #40 relay (same relay, from parking lights) then tried that, no luck starting, but the code hasnt come back yet either. What do you think I should try next? Thankx for the time and advice!!! Btw what would cause the fuse to blow?

A blown fuse means a short in the related circuit. It may be the fuel pump itself or the wiring. Could you hear the fuel pump running for two seconds after you replaced the fuse?

[KHE]

When the car wouldn't start after replacing the fuse, did you check the new fuse to see if it had blown? If it blew, there is definitely a short in the fuel pump circuit somewhere.

[CTCADILLAC]

Yes I checked the fuse after cranking and it is still good im playnig with it now il keep ya posted! Any and all tips are welcome. Thankx Alot Guys!!!

[BSchlossmann]

I Googled "Cadillac "Service fuel system"" and received to following information. Hope this helps...

Is your Caddy stalling out and not re-starting with a Service Fuel System Message? Getting a DTC PCM0231?.... It's a good chance your fuel pump relay contacts have loosened up. Follow these repair instructions:

Background: STS quit and I would get the "SERVICE FUEL SYSTEM" message on the DIC. With PCM0231 code. "Fuel pump relay low voltage". This happened once before and I had replaced the Fuel Pump Relay with a NEW OEM unit from GM. Worked fine for a couple months, then it started to quit again. Upon hooking up a fuel gauge, I was getting 48- 43 PSI with key on... no start.. It start up and run till I hit the FP relay with my hand/ or jiggled it a bit, car would stall and quit, fuel pressure reading drops to 0... I'd turn the Key off.. then back on and I still got 0...

If you are getting 43-45 psi on 1st key on....I doubt the fuel pump is the problem!! A bad pump will not show 45 PSI, plus if you had a fuel system leak, it would drop more than 5 PSI.....after a few minutes.

Please do this first before replacing that pump!!! I'd hate you see you fork over $170+ only to find out that was not the problem!!

Quote:

From ewill3rd:The contact must be tight or the current won't flow.

That is a fairly high powered circuit, the current flowing through that connection over time can heat up the metal and cause it to relax making the connection loose. This might leave you with a good cold start but when the heat builds up it will loosen like a bi-metal strip.

I usually use a male connector as shown in the second photo to check the "tension" of the female. If you can get a male terminal and check each female you'll "feel" the one that is not tight enough.

Compare the "drag" as you pull the male terminal back out. If you find one that is loose, that is the one you need to replace or repair.

I hope this makes sense. The fuel pump circuits are the worst place for this due to the high current used and the terminals are just slightly too small to handle it over a really really long time.

Here is what I had to do: (Seville SLS STS Version)

* Disconnect battery

* Locate the Fuel Pump Relay (Forward (engine) compartment, drivers side junction block).

* Remove the electrical center cover

* Disengage the sub-terminal block containing the fuel pump/AC relay from the main block. (disengage 4 clips at bottom - pull up)

* Remove the FP relay.

* Remove the blue terminal locking clip on the side of the sub block.

* Using a Terminal release tool, Release the female FP relay terminal pins from the sub block.(Release/repair & re-install one at a time to prevent mis-locating pins)

* Bend the clips in the pins toward the opposite side to decrease the gap. (Release/repair & re-install one at a time to prevent mis-locating pins)

* Re-insert terminal pins into the sub-block. (Release/repair & re-install one at a time to prevent mis-locating pins)

* reinstall blue locking clip.

* Reinstall sub block assy. to the main block.

* Using mini-pliers, very slightly twist each one of the male pins on the FP relay.

* Re-install relay. Re-connect Battery.

* Turn key to run, check for fuel pressure.

* Start car.

* Re-install electrical center cover.

* Enjoy the Cadillac!!!

In addition to the above, using a test light I checked for power at the heavy pink wire at key turn on to ensure power delivery before starting the above repair.

Most likely you can not see a loose contact(s).. I strongly urge you to hit/ jiggle the FP relay the next time you get it started... If it quits or the Fuel pressure drops, I'm willing to bet it's the FP relay contacts

[CTCADILLAC]

Thanks BS Il try that tomorrow didnt have much time today. Il post tomorrow.

[CTCADILLAC]

Well looks like the fuel pump is shot, I took off the cover in the trunk and turned key on nothing no noise, also no pressure at the shredder valve (Obviously) So now I got to get a new one, got 3 quotes 3-400$. Anybody know anyplace cheaper than this? Also I read a little about these after market Universal fuel pumps which are cheaper just dont know if they would do the job!Any input if you have used these would be appreciated! Thankx

[adallak]

Well looks like the fuel pump is shot, I took off the cover in the trunk and turned key on nothing no noise, also no pressure at the shredder valve (Obviously) So now I got to get a new one, got 3 quotes 3-400$. Anybody know anyplace cheaper than this? Also I read a little about these after market Universal fuel pumps which are cheaper just dont know if they would do the job!Any input if you have used these would be appreciated! Thankx

If the fuse, the relay and the wiring is fine, then it is the fuel pump. Have you checked out rockauto.com and gmpartsdirect.com. They usually have the best prices. Rockauto's customer service is outstanding. Cannot say the same about gmpartsdirect.com

[JimD]

Well looks like the fuel pump is shot, I took off the cover in the trunk and turned key on nothing no noise, also no pressure at the shredder valve....

It might be worth the time and effort to take a real close look at both halves of the chassis wire harness to pump wire harness connector with lots of light and a magnifying glass.

However, your original blown fuse is a pretty big clue favoring pump failure.

So now I got to get a new one, got 3 quotes 3-400$. Anybody know anyplace cheaper than this?

I have no idea about pump prices but I would give these folks a call

Palm Chevrolet Cadillac Saab of Gainesville

2600 N Main Street

Gainesville, FL 32609

352-376-7581

Cadillac Parts Department

Have your VIN available.

Mention that you are asking for web-sales price quotes.

Also I read a little about these after market Universal fuel pumps which are cheaper....

This is not a situation where I would use an unknown aftermarket replacement from an unknown seller. Spend the $$ for an OEM part.