Cough, sputter, cough. Dead fuel pump?

mr.bch · 07-19-2003, 11:04 PM

81 SC 3.0L. Went to start it up to drive to a wedding today and it started fine, but wouldn't rev and wouldn't accept throttle imputs without slight backfiring in the airbox and a general sound of lack of fuel. (Had to drive the VW to the wedding, not nearly as much fun)

Last week my fuel pump started making a real loud whine when ran below 1/2 tank. So, of course, I have kept it above that level since and it has ran fine. After the wedding, I came home and started tring to see what is up. Filled the tank, no change. I can get it to rev up but only after feathering the throttle past it's dead, dry spot of 1000-3500 rpm and with lots of airbox popping. After that, it revs freely in the upper ranges with small throttle openings.

Anyone recognize this symptom? Is my fuel pump not providing fuel? I would think that if it would die, it would die altogether and not provide any fuel. The car is less than 1000 miles off of a valve adjustment and full checkout my the Porsche shop.

If the pump is going to be replaced, what shoudl I replace it with? The $400 Bosch OEM P - pump? The $260 Murray's liftime Carter pump?

MY83SC · 07-20-2003, 05:53 AM

Keeping an eye on this thread! I had a simular problem. I was driving and my car began to sputter, as if running out of gas. Same symptom on restart as you described. I had a bad fuel pump relay. I ended up replacing the relay, fuel filter and the fuel pump. I used the OEM pump from pelican. Also, I cleaned out my tank and screen. Runs like a charm now. Good luck!!!

Mike Kast · Mike Kast's Garage

mr.bch, How did you resolve this issue? Here's one-

Does a fuel pump give any warnings or does it just stop and leave you on the side of the road? How is it supposed to sound? When it is dying can it cause a stutter under load? Would it be intermittent or constant.
Please post any experience you may have had with pump failure.

mr.bch · 10-12-2003, 05:49 PM

Yes, by accident, I clicked submit post twice, so search on the same thread and there is the one with the resolution. I believe once a fuel pump is dead, it is dead. Not very intermittent. My case ended up being an electrical glitch. I replaced my pump anyway, though because it was getting very noisy and loud.

RoninLB · 10-12-2003, 06:46 PM

my fuel pump was suddenly 1/2 dead.. meaning it was like running on 3 cylinders.. I drove it like that on I-10 in Texas till I found a place to fall down about 120mi later in NM. I don't trust a fuel pump with over 75k miles anymore.....Ron

Mike Kast · Mike Kast's Garage

Ronin LB,
did it slowly deteriorate? Or did it suddenly turn half bad?

Leland Pate · 10-12-2003, 08:40 PM

MIke?
You having trouble with the fuel pump?

Mike Kast · Mike Kast's Garage

Hey Lee,
I don't know what the problem is. Oh man... it's a long story, but to sum up, I was having fuel starvation problems that came on like wildfire and I had no clue what it was...yadda yadda yadda $1000.00+ later the mechanic changes out the fuel regulator. couldn't find anyone to agree with that one. Anyway, I talked to enough people to be convinced the source of the problem was coming from the tank. I dropped the tank and the last quart that came out looked like salad dressing. Cleaned out the tank, blew out the main line that runs from the tank to the accumulator blew out the accumulator changed the filter and had a great improvement but still intermittently sputtering under exceleration.
Fuel pump was probably taking a beating from all the sediment. Injectors could be cloged. I have run bunches of techron through but I'm not sure if I have done it since I dropped the gas tank or not.
It's good to see you Leland. Are you car shopping?

Leland Pate · 10-12-2003, 11:35 PM

Holy CRAP, Mike... I had no idea you were having running problems with the car.
I never experienced "that" problem.
So it has a rebuilt fuel regulator on it now?
Hmmmmmmmmmmmmmmmmmmm... I'm trying to think.
I know the pump was replaced at one point... it's in the records... DO you know how to test the injectors? The procedure is in the Bentley manual and the factory manuals.
It's the "under acceleration" part that has me stumpted. Damnit, what could it be...
YOu are talking about: fully warmed, normal driving, press the pedal and the engine "stumbles"? Does it stumble for a moment then smooth out?

Have you checked the plugs to see if one particular cylinder is running lean or anything?
I'm here to help.
Damn, I'm bummed out now. I was really hoping the car wouldn't give you any headaches.

RoninLB · 10-13-2003, 05:37 AM

Quote:

Originally posted by Mike Kast
Ronin LB,
did it slowly deteriorate? Or did it suddenly turn half bad?

the pump wasn't the quietest it had ever been.. so I'm on I-10 and stop to take a wizz.. so I try to re-start and no-start.. it's late at nite and I hang for an hour and still nothing.. I fall alseep to sunrise and try again.. it re-starts and it's running all broken up.. I dare to chug along to the next town in nowheresville. It took a couple of hours to confirm a bad pump on arrival.. I get the car to the famous city digs' parking lot where I wait out the weekend waiting for a pump delivery.. I pay the local wrench $100 to get me cement blocks, some wood, rags, and anything else I may need. I'm close to the border and a constant parade of HP, Customs, Feds, you name it.. I'm in the middle of Drug Import City and the locals are wondering what this NY'er is smuggling.

pookie · 10-13-2003, 06:17 AM

I am having this exact same problem right now, from what I saw on this thread and the other one it may be an electrical problem? I took off my fuel accumulator and filter this weekend, drained the gas out of them, and sprayed some air through them. No sedimont of chunks came out. So I put them back on and I still have the probelm. I can hear my fuel pump whine and it doesn't sound any different than normal. I will check my fuses and clean them all, it just seems weird that it would be electrical and not fuel related. But as long as it works I'll try anything. Also If I decide to drain the tank how do I clean it out? I don't want to put water in the tank do I? Would the water cause more rusting and problems down the road?
If anyone comes up with anything else please let me know.
Thanks
Ryan

Mike Kast · Mike Kast's Garage

Oh boy... Cleaning out the tank...
This is what I did. I ran it to fairly close to empty.
Removed the fuel gauge float in the top of the tank. And siphoned as much of the gas out that I could. Which was tough because the car is so low. I had some 1/2 inch clear hose laying around and I ran it into an oil pan running the hose over the front bumper to keep it as low as I could. After all the fuel I could get out that way was out, I jacked the front of the car up as high as I could (Typical jacking precautions of course) and disconnected the fuel line that runs between the tank and the pump. I ran the rest into another big oil pan. Maybe another gallon and a half or so came out. I don't remember getting much if any on the floor. The whole time I was chain smoking so I didn't want to spill.
Naaaaaaaaaa
Now there is maybe a half gallon left in the tank. And that is where the nastiness was lurking. Disconnected the other line that feeds back into the tank and the fill line (That one is a little tricky) And I forget what else It really wasn't that hard.

Then I removed the clips from the tank and did the board under the tank and jack it up to break the seal trick. It popped out very easily. Then I dumped out the spooge

that was left and I am pretty sure now after Leland's post that my injectors are most likely still suffering.
Anyway, if you do this, find a radiator shop in your area to power wash the tank. That's what I'll do next time. I got the POR15 tank sealer and used their cleaner. I didn't go with the sealer though because there is plastic in the 911 tank that the POR15 won't adhere to.
So yes. The short answer is there was much water involved. But not with the tank in the car. I think that might be a bad thing.
And Leland, Thank you very much if you can help. I tried (Lamely) to contact you when it all started. But I felt funny about it. I was torn between HELP! and "This guy just sold a car, there was no warranty that I recall" So I let it go. Plus, your a busy boy so I suffered in semi silence...lol... My concern with the pump was more if it had been damaged by the spooge than if it was old. But the truth is I didn't look at the reciepts yet. I'll look now. And check the manual cause I was hoping to get some carb cleaner on them some time before I leave for Atlanta this weekend anyway...
Oh and yes, Fully warmed up. Stumbles in the middle of hard exceleration, intermittently, Sometimes at 3500 RPM sometimes at 5000 RPM... It's random. just a split second miss. Sometimes more than others... I'm chipping away at it Lee. Plugs look good. I just changed them again. 2nd time

mr.bch · 10-13-2003, 03:55 PM

Cough, sputter, cough. Dead fuel pump??

here is the thread showing what I went through. In short, I checked my tank (perfectly clean), pulled injectors and cleaned, new injector and sleeve orings, new fuel pump, new filter, etc., etc., etc., Turned out to have faulty contact on fuse #4, I think it was.

Mike Kast · Mike Kast's Garage

mr.bch ?
what year is your car? What do you think Lee? I'll take a look.
Thanks mr.bch. How come there are 2 threads with the same name? lol
How'd ya do dat?

mr.bch · 10-13-2003, 04:58 PM

I have an 81 SC, mostly stock 100,000 mile motor, freshened about 35,000 ago.

I clicked the POST TOPIC button and nothing happened, so I hit is again. WHoopsie.

Mike Kast · Mike Kast's Garage

Just going trough my receipts it looks like the fuel pump relay was changed about 50 times. Fuel pump was changed at 153,468 miles. We are now at the ripe old age of 234,866. My trusty calculator tells me that it's been 81,398 miles. According to Ronin LB I'm past due.
Leland, The fuel injectors are original aren't they? I don't think I saw them in the long list of motor items. It is quite a list. And whats with the break caliper paint? You bought it 3 times? And what about that $1700 car trailer reicipt? How come that didn't come with the car? lol

RoninLB · 10-13-2003, 05:54 PM

Quote:

Originally posted by Mike Kast
My trusty calculator tells me that it's been 81,398 miles. According to Ronin LB I'm past due.
? lol

yeah Mike.. mine went at about 100k.. so I started looking into it before my computer world started.. and I was told, and read, to not trust them past 75k.. like I told my brother to flip his 911 pump, which his wrench did.. and he's sending it to me for my smugglers box storage/ back-up.. he doesn't turn wrenches so he doesn't need it.. try getting stuck in Nowheresville where the nearest Porsche shop is over $500 away to flatbed........Ron

Leland Pate · 10-21-2003, 08:17 PM

Sorry for the late reply, Mike.
We just moved up to Montana and are still in temporary housing. I brought the PC in so I could see what was going on on the board.

I've been thinking about your problem. But first, yes, the injectors are about 2 years old. It could be time for a new pump but I just don't see that being the problem.
I'd think that the fuel filter would stop anything from clogging those injectors. When you say a mechanic replaced the "fuel regulator" are you refering to the fuel pressure regulator?

One other suspect part I'm thinking of could be the fuel distributor.

You can pull out each injector from the intake runner and with the air filter removed and the car off, press up on the air meter plate and a uniform cone of gas should spray out of each injector. That procedure should be outlined as well in the manuals I gave you.

Please keep me posted.
Also, pm me and I'll give you my cell number. Call me ANYTIME you think I could help with something. I told you that when I sold the car to you and I'm telling you again!

Mike Kast · Mike Kast's Garage

Hey Lee, Welcome back to the great north west!
Did I say fuel regulator? hmmmmmm...Anyway, It was the fuel distributor that was changed. From what I remember in my readings, when the fuel filter gets filled with crap it has a bypass. Is that right? I don't know but I checked the injectors before I left for Atlanta and they didn't make the misting cone spray. They didn't look to bad when I pressed lightly, but when I lifted up hard they started spitting and squirting from the sides. Some worse than others. Which may explain the missing under hard exceleration.
I thought they were old anyway so I ordered 6 new ones and a new pump. Only 2 years old huh? Damn!
What is most confusing to me is the crap in the gas tank. I wonder if something in the fuel in NC let a bunch of stuff loose in the tank. By the time I got the car here it was March so the oxygenation was already out of the fuel by then.
Its weird. Whatever it is I am pretty sure the last of it is in the injectors now because I have cleaned about everything from the injectors to the tank. Hopefully the injectors will solve it.
Thank you sir!

Langers · 10-21-2003, 10:59 PM

Aah I get it...this is all just an evil plan by Leland to keep "his" car in good condition so he can buy it back

Very clever

muawahahahaha