midnite993

Hi All,

Just when i think I had the problem solved it came back even worse than before! The car died at an intersection and I had to wait a few minutes for it to fire back up again.

I guess the MAF cleaning was just a coincidence. This time however, I heard a loud grinding noise. I lifted the hood and listened near the gas tank and it was really loud. I shut off the engine, removed the DME relay and jumpered pins 3 and 7 as instructed in the factory manual. The pump obviously is having issues...makes a grinding noise and it sometimes oscillates its speed up and down. Once in awhile it will get up to speed and make a normal hum, but then it starts slowing down and grinding loudly again. I went and listened to the fuel pump in my wrecked 993 and it always had a normal fuel pump hum.

Desert European replaced the fuel pump just a couple weeks ago, however I don't want to have to drive way out there in this condition. Walter's Porsche is close to me...will they honor the part warranty of another Porsche dealer? I'm tempted to just do this myself so I can still go on my drive through the mountains. What could cause a brand new fuel pump to go bad if it's not defective? Wouldn't be the first time I'd gotten a defective new part from Porsche.

I've looked through the workshop manual and the DIY sites and I can't find any instructions for replacing the fuel pump. I can hear the pump under the hood near the fuel tank, but I remember reading that the pump is located under one of the panels under the car. Where is it located? Must I drain the fuel tank or is there a cutoff valve?

Thanks again for any help...

95C4VanIsle

I had my fuel pump replaced at an independent last fall. The pump is located behind the front right tire, about a foot in as I recall. It is covered by a protective shield held in place by 7 or 8 screws. I did not drain my gas tank for the pump replacement, but that may have been done at the shop. It is supposed to be a relatively easy DIY. Hope this helps.

Garth S

Yes, access is under the panel Bret mentioned: it is a very straightforward DIY .... but I cannot recall whether you need to pinch off the supply line from the tank. Regardless, if the 'new' pump is grinding, I would flow some gas through the supply line to assure that it is clear of crap - and gently pinch it off with visegrips if necessary. Also, flow back the line running to the filter - and preferably change the filter. If the Installer does not hotshoe a fresh pump to you ASAP, install your spare .... and enjoy the weekend!

1pcarnut

I wouldn't necessarily give up on it being the MAF. If it responded to cleaning I might try that again and clean the connection with electrical cleaner. Would also try substituting a known good one.

Regarding the fuel pump, how much gas is in your tank? You will hear more noise when your fuel level gets low, may not necessarily be bad. You may also have water in your gas, have you tried some Techron?

BobbyT

The odds of a new fuel pump being defective are low, and the problem existed with the old fuel pump as well. The noise the fuel pump is making now could be it struggling to suck the gas from the tank--maybe there is some serious contamination in the fuel tank, or the fuel filter in the bottom of the tank (part # 928 281 081 04) is plugged. To check this filter, you need to pump as much gas as possible out of the tank, then disconnect the fuel line from the tank filter to the fuel pump, and let the remaining gas drain. Then you can remove the tank filter and see if it is plugged, and what contamination remains in the tank.

If you decide to do this, of course you need to be clear of any ignition sources, including the gas water heater that may be in your garage.

The older 911s had a big drain plug in the bottom of the tank, and it was amazing how much crap built up in the tank over the years.

bill930p

A buddy of mine had a MAF problem (in his 996) that he could fix by cleaning it. However, it would always come back a few days later. He ultimately ended up changing it for a new one.

Try cleaning it again to see if it goes away again.

midnite993

>>The odds of a new fuel pump being defective are low, and the problem existed with the old fuel pump as well. The noise the fuel pump is making now could be it struggling to suck the gas from the tank--maybe there is some serious contamination in the fuel tank, or the fuel filter in the bottom of the tank (part # 928 281 081 04) is plugged.

Thanks for the advice Bobby...I was starting to wonder the same thing. I will do the steps you suggest as I seriously doubt that a new fuel pump would go bad. But the car did run awesome for the first week after I got it...and I ran it to redline at least once every day. It ran awesome after the MAF cleaning too. Wouldn't a clogged tank fuel filter cause a problem all the time? The inconsistent problem would make me think the fuel pump is having issues.

Unfortunately, when I thought the car was fixed I filled the tank up with $80 worth of premium. Don't know where I'm going to store that amount of gasoline...maybe I could siphon it into my wife's Civic. Will let you know how it goes.

Jay

ppashley

Careful with the gas.

BobbyT

If the tank filter is partially clogged, or if there is some serious junk in the bottom of the tank, it may restrict fuel flow intermittently, or reduce it just enough that the engine can't rev fully under load.

I'm not that far away, and I have three thirsty cars if you need someplace to dump the fuel. https://rennlist.com/forums/images/smilies/smile.gif

geolab

I am sorry but I do not agree at all.
The gas tank fuel filter will never clog in any 993.
If you have seen one, or changed it once, you will know that it would be impossible to clog.

1pcarnut

Trying borrowing someone's MAF and swap it in. Couldn't hurt since the car seemed to respond to the cleaning. How many miles did you go after cleaning it the first time before the symptoms came back?

midnite993

Problem solved again...this time for good! Took the cover panel off, looked up into the fuel pump compartment, and the source of my troubles is obvious. The installer of the fuel pump just jammed it up in there and kinked the hose tightly on the outlet side of the pump. I re-routed the hose a little and used some heavy duty zip ties to hold the line in its proper place.

While I'm annoyed that the installer wasn't more careful, it is pretty tight up in there! Does encourage my entrenched idea that I'll never let a dealer touch my air-cooled Porsches.

Car runs awesome...will post some pics of my fun run!!! Thanks again everyone.