: How to clean out fuel system in a 96 Eldorado sitting for 6 years.

04-11-13, 04:40 PM
Hey all, I scored a 97 Eldorado from the In-laws and drug it to my house. It's been off the road for around 6 years. I just finished replacing the timing chains and slippers and then tackled the fuel system.

I drained the tank, changed the fuel filter and put about 3 gallons of fresh fuel in. When you turn the key you can hear the fuel pump prime the system. I turned the engine over with the ignition plug pulled for about 30 seconds to prime the oil system. Reconnected, squirted a bunch of starting fluid in there and she fired up! Of course she stalled right after that but I continued to let it run on starting fluid alone trying to clear the rest of the old fuel in the system. I went through a can and she still won't stay lit. I squirted raw fuel into the intake and it will run as long as I'm feeding it manually. It has around 10 minutes of run time on it now so I figured the old gas would be circulated through at least. Now I'm wondering what else could cause the engine to not get fuel? I'm hoping I don't have to pull the injectors and clean them but if that's what is next then that's that.

Any help would be greatly appreciated. Thanks all, NAES

04-11-13, 05:13 PM
Tedious cleaning - if the pump won't prime the system it could be anything from a totally clogged primary fuel filter (base of pump module, tank drop), secondary fuel filter, to the fuel lines themselves to the injectors, injector timing signal, FPR ..........

If the engine "runs" with starting fluid then ignition is not the problem.

If the engine has run on and off for 10 minutes or so (pray that the starting fluid has not broken [yes, broken] anything), use the sticky post "How to pull codes" and its proper section for the car to get any stored trouble codes, then go back and decipher the codes with the link with "obd2" in the address - depending on the build date the DTC's might be a mishmash of OBD-1 and OBD-II codes.

04-11-13, 05:28 PM
checking the fuel pressure might be a good idea
there's a service port on the rail, right Sub?

04-11-13, 05:29 PM
Well, you can hear the pump run, but when you try to start it you don't even get a pop or sputter? If you have any sort of pressure at all at the rail, even low pressure, it should at least TRY to start. If it doesn't, I'd focus my attention on the injectors and their circuits... injectors fuses in tact?

04-11-13, 08:48 PM
squirted a bunch of starting fluid in there and she fired up!
I squirted raw fuel into the intake and it will run as long as I'm feeding it manually.
Check the fuel pressure. It's obviously not getting fuel. Just because you hear the pump run does not mean it has enough pressure to run.

04-11-13, 09:37 PM
OK guys, thanks for the replies. I don't have a gauge to measure fuel pressure so I'll have to figure out a way to see if fuel is making its way to the engine.

Here's a little more information from when I originally posted. The fuel tank was about 3/4 full when I drained the tank. The gas was definitely yellowed from age but not nearly as crappy as I would have imagined it to look. The fuel filter that I removed on the drivers side body rail drained clean fuel through it. I even ran some cleaner through it and it came out without seeming as though it was clogged. I didn't cut it open to verify though. And up at the fuel metering unit I removed the top and examined the fuel screen. There was no contamination that I could see and the tiny bit of fuel inside the unit looked good. I didn't find any deposits up there.

Is there a fuel line up inside the engine bay that I could remove and put in a jar or something to see if fuel is at least making it up that far?

Thanks again everyone for the help. I'll get this little whip on the road soon enough!


04-11-13, 09:47 PM
Yes, there is a fuel service port on the fuel rail. It looks and operates just like a tire valve, but be advised that getting fuel out of it is just like getting air out of a tire. You know there's some in there, but you don't know how much. Imagine trying to check your tires by pressing on the tire valve and hearing it hiss. It may only has 5 psi, but it will hiss. Just because you get fuel from the service port doesn't tell you a thing, other than that the fuel pump is not dead.

04-13-13, 10:23 AM
Good point. I was just trying to rule out a complete blockage up to the engine. I'll see if I can find a fuel pressure tester to rent like at Autozone or the like.

Thanks again all. NAES

04-15-13, 03:25 PM
Alright. I rented the fuel pressure tester from Autozone and got to work. I depressed the schraeder valve on the fuel rail and nothing. No hiss, no fuel, nada. So I worked my way back to the fuel pressure regulator. I popped the top off of it and removed the screen. There was a little fuel sitting in there. I turned the ignition switch on hoping a big stream of fuel would shoot out of the regulator. Nope. I tried the switch a half dozen times with nothing.

So, the pump is running and I already changed the frame mounted fuel filter. I think the next step is to start at the source and work my way up front. I'll be going out to drop the tank in a while and then see what I find. I'll report back when I have something new to add.

Thanks again everyone for the help. NAES

04-15-13, 03:45 PM
i have a feeling you're going to need a new pump/module assembly

04-15-13, 09:26 PM
No fuel = no fuel pressure.
No fuel pressure = failed pump.

04-17-13, 03:57 PM
Dropped the tank today and found an interesting problem. The fuel feed hose had disintegrated above the level of the fuel that remained in the tank years ago. So, the pump was pumping as it should and shooting fuel directly back into the tank.

So now my question is, can I just replace that piece with standard fuel line and a couple of hose clamps? Will it be alright inside the tank? I don't see why not as it isn't a high pressure line or anything like that.

Attached are a couple of pics for your enjoyment. You can see how brittle this stuff has become. Hell, it'll be cheaper than a new pump at least!


http://i52.photobucket.com/albums/g40/southern_killafornia/2013-04-17_12-33-19_563_zps95aa4739.jpg (http://s52.photobucket.com/user/southern_killafornia/media/2013-04-17_12-33-19_563_zps95aa4739.jpg.html)

http://i52.photobucket.com/albums/g40/southern_killafornia/2013-04-17_12-32-27_882_zpsb98812b7.jpg (http://s52.photobucket.com/user/southern_killafornia/media/2013-04-17_12-32-27_882_zpsb98812b7.jpg.html)

04-17-13, 04:12 PM
It IS a high pressure line and it flexes on installation - your best bet would be to look in RockAuto and replace the entire fuel pump module/level sender/tank pressure sensor.

Curiously the entire DELPHI/UltraPower/Airtex assembly costs less that the level sender alone - find the best price.

(That inline fuel pump discharges directly into a 45 psi pressure head - the FPR insures that, and any fuel not burned cycles back to the tank: More fuel goes 'round and 'round than is burned ............)

04-17-13, 04:39 PM
Thanks for that super quick reply. Definitely saved me from screwing something else up!

I'll look at RockAuto and see what I can find.

OK, back under the car! NAES

04-17-13, 09:07 PM
Found a new pump on Evilbay. Should get here in a week or so. It's an Airtex. That should lop off another to do item.

Now a million more little things to do....


04-17-13, 09:29 PM
WOW! Never seen anything like that before.

I would bet it could be salvaged, but a new pump isn't that expensive and since it's already down, what the hell.

Perfect example of why hearing the pump run means nothing without a pressure test.

04-17-13, 11:29 PM
I thought about salvaging the pump but a foot of Gates brand submersible fuel line is $30 at Oreilly auto parts. I found the fuel pump on Ebay for $40 NIB!! How could I go wrong? I'll still keep the old pump for possible parts down the road but since it's already this far down, I might as well do it.

And yes, the old pump runs fine but that doesn't mean a damned thing as far as getting the thing to run! :yup:


04-18-13, 09:48 AM
Fuel pump only for $40 or assembly for $40 - the last "$50 fuel pump assembly" we saw in here from eBay was Chinese and would not fit............ and "fuel pump only" may not have that flex line - thus the advice to look in RockAuto for the deals on original GM parts.

04-18-13, 01:20 PM
The listing was for an Airtex Fuel Pump Assembly part number 3935m. Airtex isn't the worst brand in the world.

A quick search showed that it is in fact the entire assembly, not just the pump. I may have gotten lucky, if not I'll return it. The car hasn't run in a long, long time, what's another week or 2 going to hurt?

I'm sure you're just looking out for my best interest. NAES

04-18-13, 02:25 PM
Where did you get that part number?

my listings show E3913M as the Airtex part number for a 1996 eldorado

04-18-13, 09:34 PM
Sorry Chris that was totally my bad. The car was manufactured 9/96 and sold as a 97. I see now that 96-7 is a transitional year for the fuel pump. I didn't know that until I did a little digging today. So my guess is that I'll end up getting a 97 pump that truly fits the 97 manufactured year. The Airtex comes with the wiring harness so if the pump physically fits the tank then I'll play with the harness a little bit and see if it'll work. I don't see why not as they are both 4 pin connectors just arranged in a different plug..........I hope!

Wish me luck guys. I'll report back when I get the pump and start messing with it.


04-18-13, 10:24 PM
FWIW, The 1997 "model year" (or ANY OTHER model year) began/begins in about August/YR. My "2002" Seville series was built from 08/01 to 06/02.

Mid-summer is the production line reconfiguration time for the new model year. The onboard diagnostics (OBD) systems changed during 1995-1996.

04-18-13, 10:59 PM
and the 10th digit of the VIN will tell you the model year

04-25-13, 10:59 PM
SHE LIVES!!!!!!!................well sorta!

I swapped in the new pump and primed the system a few times. Depressed the fuel pressure relief valve to ensure I'm at least getting fuel up to the engine and let her rip! She fired after a couple of cranks and then settled in. I only let it run for about 2-3 minutes as I haven't changed the coolant yet and didn't want to get the engine too warm letting that old stuff circulate.

So next time around is some fresh Dex-cool and then I'll let her warm up and see how she feels. It's so awesome to get into a project that you know nothing about and be able to make your way through it. I want to thank all of you who replied and helped me out. It made the job so much easier.

I'll report back after the coolant swap. Anything else I should think about getting while I'm already in there?


04-26-13, 11:15 AM
Just drain and refill with 50/50 Dex and distilled water.

05-14-13, 06:48 PM
Hey all I'm back.

I took the Eldo to the (semi)-local Northstar "expert" for a once over. My list was tightening the front pulley to spec, fix the P300 code (engine miss firing), valve cover gaskets, plugs, wires, AC recharge and a general tuning for smog.

The 3 day job turned in to 2 weeks with no phone calls getting returned. I finally had the time to just drop by and get the car. It was in the bay and literally nothing had been done on it. He breezed through every reason in the book for not getting the job done or returning my calls. 2 weeks wasted. Still misses at idle so I put a new set of AC Delco plugs in gapped at 0.60 and wires are on the way from RockAuto. Still misses so I'm hoping it's the wires. Otherwise I'll go through the coil packs and see which one(s) might be bad.

The saga continues...............NAES