This is now becoming a real burden. I had a fuel leak on a rubber fuel line which began slowly than progressively got worse. I finally traced it (Open hood, found a stream of fuel potruding upward) - I replaced the hose and thanked the good grean earth that I fire didn't start due to the close proximity of the headers.

Went to the rear, lifted the carpet to expose secondary fuel unit. What I found was that the pressure was so great that it pushed the twist top upwards causing it not to seal as it should.

I figure - Okay. release pressure (open fuel cap) twist off then twist back on. Wrong! -

The damn thing is on tight. I figured I could borrow a "large wrench" to get some trq. I'm concerned that I'm going to damage the threads and or fuel unit.

Why do I have so much pressure in the tank?.

Is this normal?.

If not, any suggestions to trace the problem. I did a archive search but came up short.

TIA
Any suggestions to diagnos my problem?.

 

Drew,

The problem may not be pressure, but vacuum. This would also explain the resistance of the gas cap to open and may indicate causality for your fuel leak. ( I realize this is inconsistent with the "pushed up top" but bear with me...)

Check your fuel pressure regulators, and your damper. If unused fuel is not being returned to the tank as it should, you can create a condition where the tank pump overpressurizes the fuel line (causing a weak line to start leaking) and depressurizing the tank, thus "sucking" the gas cap down. Hard. Especially in a euro LH car, which "should" have 2 fuel pumps.

The other thing that could preclude fuel return would be a pinched/clogged fuel return line.

Carefully open the fittings at the end of each reg and see if fuel comes out. Listen for the famous Ross Perot "giant sucking sound". If you have no fuel outlet, you may have your issue solved. Check also for vacuum going to the individual items, suck them down (gently) with a MityVac.

I have never seen this happen on a 928, but without digging through the fuel line diagram, I don't recall anything to prevent it from being the problem. And somebody pulled my diagram out of my manual. Ugh.

BTW- What do you mean by "secondary fuel unit"? Under the rear carpet is the access for the fuel tank level sender unit - is that what you are referencing?

If you are worried about damaging anything, you can just pull the return hose off the fuel level sender unit, thus de-vacuuming/pressurizing the tank. Be sure to cover with a shop rag.


Greg

 

BTW- What do you mean by "secondary fuel unit"? Under the rear carpet is the access for the fuel tank level sender unit - is that what you are referencing

Yes - The level sending unit. Which is also acting up.

Thank You for the feedback -

I could probably do the work, since I have the manuals, but let me tell you - I have a low tolerance for gasoline fumes and I think I'm going to send her out to a shop.

Drew

 

Drew,

That sucks big time! Just recently I started getting a gas smell blowing thru the main central vent. Not sure were to even start backtracking that problem.

On top of that bad news, the power company kept turning the neighborhoods power on/off last Tuesday, it fried my cable modem, router, and some cable wiring thru out the house. Those bastards

 

Red UFO,
Check out the Y connector near the charcoal cannister. It is located toward the rear of the front passenger side wheel well. You will have to remove the liner to see it. There is a good picture here.
http://members.rennlist.com/v1uhoh/underww.htm

 

Drew,

Hope your up and running soon, regardless of who fixes it. I would suggest that it might be a good idea to de-pressure/vacuum that tank asap just so as not to strain it - it is old and it was never designed to be a pressure/vacuum vessel. And whatever the condition, part of your fuel injection is overpressured, which is also not a good thing.

Good Luck,

Greg

 

Ed thanks for that link. I did a search in archive but didn't see that one. I recently replaced both fenders so I know right where that spot is. I'll be checking this weekend.

 

Well, Instead a fudging with it, I made an appointment w/Exotic MotoWerks.

Red - Yeah Bud, it does suck. Not only am I in fear of a gas fire, I'm in fear of vapor poisoning. Which has happened to me before, hence the low gas tolerance - If I even remotely smell gasoline - grab me a bucket because I'm going to blow.

On top of all this BS - I almost had an electrical fire this morning. I shut the car down - And there was a nice cloud of smoke coming from the stereo console - Besides that my amps are running in the red -

I hope Dan squares me away. The bad thing is that, I have track event at Firebird this weekend and plus our gathering at AMP - Looks like it's the bike or the altima for me.

BabyBlue will be there in Spirit.

Still waiting on directions to AMP - Shouldn't't be too hard to find.

Gbyron - Thanks for the heads up w/the pressure. Dan at Exotic is a 944 guy who has started working on sharks. His knowledge of the 44 is impressive, besides - The Desert Gang Captian (Rich Andrade) reccomends Dan without Hesitation. I feel I'm in good hands w/Exotic.

peace

 

Damn,

The first thing I bought for the shark is a fire exstingisher. Why? Because on Rennlist I saw people posting pics of Ebay sales of 928 that caught fire. I figured my shark was worth investing a $10 small fire exstingisher incase something like you described happened. I could save 'most' of the car and fix it or sell for parts if that happens. Otherwise it could just burn up and be worth nothing.

I hope to make it to the track this weekend, my brakes are running hard again after the clutch incident. I might unplug the battery and reboot. Too freakin hot here to work on the shark, been programming some C++ and getting close to importing my 3D shark into a racing sim very soon now.

Sharks, you love'em, then sometimes hate'm, then you love 'em again while you spend your last dollar on it. I think drugs are cheaper than a Porsche habit.

 

Found my fuel leak. While putting in new sPark plugs I fired it up and saw fuel dripping near the 4th spark plug on drivers side. The gas was dripping out of a fuel line that goes into the carbureator. I had to tighten a clamp and it took care of it.

It really scared me to think if I went on a long trip this gas dripping on the header could have burnt my shark to the ground.

Now that I"m high up on my to do list the shark shows a few more things to do to it.

 

Drew,
The Euro S2 only has the one external fuel pump..............FYI

 

Hey John -

Yep - I know. Thanks for the heads up.

Red - carburator?. What carburator?. Did you switch over?. There was a shark that was running weber carbs - or was it dual quads?.

Owners claims it ran better than FI.

Never made it anywhere last weekend. New Job and 12 hr shifts makes me real tired. Thought I could swing but .........

 

Drew,

Any resolution of your pressure/vacuum issue? Inquiring minds want to know...

John,

FWIW, I do recall the euro S2 only has one pump, but I have seen 2 euro '84 LH (S3) cars semi-recently and they both had in-tank and outboard pumps. I assume Drew's car is an S3 (ergo, LH), as it is an 84. The in tank pump may not have been factory installed, but it's an easy upgrade that is known to be helpful on any higher output 928. That's why I suggested looking.

Greg

 

gbyron -

Thanks for asking. She's still waiting to hit the shop. My appointment is set for Wednesday AM at Exotic Motowerks.

The "unit" which is in the tank does have a fuel line leading from it, it also has a six pin connector for the fuel level sending unit. At time I here the pump working from in the car - when there is so much pressure its expanding the tank and pushing the cap upwards (along with the strong fuel smell)

With the "notion" that I do have a secondary pump - Is it OEM or is it an upgrade?. Anyone know of a way too find out for sure?. When I get home from work, later this morning, I'll take some pics and post them on the board.

As soon as I get word from Exotic, I'll post the info.

Thanks again for the all the help and suggestions.

 

Drew,

Sorry for any confusion, I just remember what I work on, and sometimes the factory does weird things for different market RoW cars - i.e. open loop Lambda on Swedish 84 LH cars. 100% factory, 100% weird. I think every other LH car in the world was closed loop (O2 sensor adjusts mixture) but not Sweden.

If you have the 'upgrade', you would see a pair of wires on the outlet from the tank. The in-tank pump actually screws into the bottom of the tank just like the screen filter, and feeds the output hose, which feeds to the fuel filter and primary pump.

If you have it, (or want it), it can be done with 100% factory (Bosch) parts.

The required are simply 1 intank pump, and a short wiring harness that's parallel to the primary pump harness (same circuit).

If you have the extra $150 or so, for an in-tank pump, it is a "nice to have'. The factory installed it on really early CIS cars, and also on later 4V cars, because the main fuel pump can't alway provide the correct amount of pressure at full throttle. The in-tank pump feeds the primary pump, which helps keep fuel pressure high when the captain signals the engine room for more power using the long, skinny pedal.

HTH,

Greg