Car stalling after 10 to 20 minutes of driving?? (long)

[SIR70t]

All,

Symptoms

The 70T started to lose idle then stall after 20 minutes or so of driving. The first time it stalled was after approximnately an hour in traffic in the 35 degree heat in Sydney the other weekend.

You could restart the car after a 30 minute 'cool down' time then drive for 10 to 20 minutes and it would basically lose idle and power.

Diagnostic so far

My mechanic has replaced points, checked the fuel flow and pump.
CDI is still making the whine sound on ignition.
The coil is realtively new, last 3 years (completed only 6000 miles since)

From the little piece of resaerch I have done on the Pelican site it could suggest the CDI may have come to its life end, although Warren's posts seem to indicate there are a few more steps in a cleaning and connector type check prior to completely writing it off.

Opinions please?

A new CDI may be required, what are the thoughts of the board? I'm not too concerned about having and origianl Bosch unit, and I have looked at the MSD 6AL and this looks reasonable.

The MSD change looks to be a straightforward 'bolt in', however I haven't completed all the research.

Are there any other possible causes???.. (I have spoken to Lisa and Ryan for some general advice)

Does anyone have a spare CDI that they are willing to sell / part with.

Regards and thanks
Shane

[JD]

Hey, go with the M&W CDI not the 6AL

http://www.mwignitions.com/main.html

Benefits:
:arrow: its Australian made
:arrow: its put together in Sydney (so you can hassle the maker) and not in Mexico
:arrow: and its black vs red with the MSD (so less noticeable)
:arrow: people have had issues with the 6AL and tacho working

Who says I am biased? :wink:

[SIR70t]

looks like the spell check was not working

In any case, we may have found the problem..

We originally checked the fuel pump and it seemed OK, however it now looks like it is the culprit..

The interesting thing is the T (with Zeniths) has had an MFI pump installed in the past, and from what I understand it provides the benefit of being quiet in its operation...

As an interim step I'll be putting a 'little ticker' for the next 12 months or so, until I source another unit..

Shane

[lisa_spyder]

Shane,

Should I say it? Yes I think I will seeing it's you :wink: ...I told you so!

The symptoms you describe are really indicative of a fuel pump issue and as I said to you on the phone that would be the first thing I would check. Trouble with these things is that the repairer has to make it happen to them on a roadtest or in the shop and Murphy is usually working his forces against the poor repairer in these instances :wink: .

There are other things that can cause the problem - distributor, coil etc, but the most common by far (after points closing up) is the fuel pump. Just how low have you run the tank down? You know the pumps hate getting hot and when the fuel tank is low the pump works harder to draw the fuel and literally cooks. Sometimes, they just die of old age...but usually they are helped along by not keeping enough fuel in the tank.


If you're looking for a stopgap, a Facet pump should get you through. We've used something else too but I need to ask Mike as I can't remember what exactly...guys with MFI; you cannot run a Facet or anything else - Factory Bosch pumps for you only.

Cheers,

Lisa
Cheers,

[SIR70t]

Lisa - yes you did tell me so, you are adorable!!!.... funny. Yes the repairer had to experience all the right conditions to get the right answer, well the good news is that we have come to that answer.

The bit below has confused me a little, from what I understand we are going to put in a facet pump (little ticker as I understand)..... on one hand you say it should be OK on the other hand you say 'you cannot run a Facet' .. Maybe I have mis read this???

Cheers

Shane

And would welcome the name of another appropriate pump for the Zeniths if it come to mind...

"If you're looking for a stopgap, a Facet pump should get you through. We've used something else too but I need to ask Mike as I can't remember what exactly...guys with MFI; you cannot run a Facet or anything else - Factory Bosch pumps for you only. "

[lisa_spyder]

Sorry Shane,

Too much info is one sentence....MFI engines cannot use Facet pumps; you will be fine on carbes. They don't last a lifetime though, so do treat it as a stopgap for a few months.

I'll get back to you on an alternative. From recollection those Facets are getting difficult to purchase.

Drinks on you next time I see you! :lol:

Cheers,

[Spyder Automobiles]

OK,

I'm detailing this info as a sponsor post as it could help someone else in the future....


There are 2 Facet pumps:

Cylindrical type, delivers at a higher pressure and greater volume.
Silver top: 5-6psi delivers 28gallons per hour, rated to 200hp
Red top: 6-7.25psi delivers 36gallons per hour, rated to 300hp
Silver top is fine....

The other is a square box shape which has a lower rate of flow and pressure but will still work OK.

They both tick as you obviously already know (little tickers :lol: )....

The alternative is to use an EFI pre-pump. Just a garden variety universal EFI pre-pump. Delivers about 7psi and more than adequate volume...oh and it's quiet too - but very allergic to running out of fuel!

All these pumps are available from good accessory shops, Repco, Bursons etc.

Cheers,

Lisa

[SIR70t]

Lisa, Excellent!! thankyou,

I'll line up the 'cowboys' when ever you like
:shock: :shock: :shock: :shock:
Shane

[72911S]

Lisa...I'll ask the painful question...what is the current price for an OEM
pump for an MFI engine. Any point in getting the dud pump rebuilt?? :cry:

[e72phil]

Andrew,

I think Porsche will charge you around $1200 fro an OEM Bosch MFI electric pump.

I recently bought some from the USA where they were around US$450 ea.

I will look up the supplier and send you a PM of their website. it was original Bosch and the correct pump. I keep one in the 911E as it not something that the local Repco in Albury might keep on the shelf.

[Paul W]

Hi guys,

Had to have a chuckle reading this post. My 8yo fuel pump died after a fuel tank resto I had done late last year, which I should add had nothing to do with the repairer, they just don’t like being left dry.

Drove Mike @ Spyder to distraction trying to trouble shoot the problem as the car would run strongly for 10-20 mins then die on the side of the road – yet it wouldn’t replicate the fault regularly. Pump pressure tested fine as well. Mike ended up plumbing a second pump in the system and drove the car until it stopped – switched on the new pump and all was good. Pump has since been replaced and the car runs like a dream. I had Mike replace the OEM pump with a generic version as per Lisa’s earlier suggestion and its worked like a dream.

Good Luck

[lisa_spyder]

Andrew,

Don't forget our board sponsors aPorschapart and Bob Whyms Automotive - they both stock and sell these pumps. Hopefully Craig can jump in with a current price from Bob Whyms.

Cheers,

[72911S]

Thanks Phil and Lisa,

E and S run the same pump I assume

Also....I guess you have to work from the tank inwards when trouble shooting this problem. No good having a new pump sucking from a clogged tank.

[OBRUT]

since this is fast becoming THE fuel pump thread i thought i would also mention that you should be careful using a pump with too high a supply pressure.

from memory, carbs only need about 3.5 psi supply pressure and if you run them, for example, with a mfi pump you will beat them to death in short order.

one option is to use an adjustable regulator (eg. holley) and if you want to look really cool you can put a little pressure gauge next it in the engine bay...

[spydr32000]

Ryan, your right, the specified pressure is approx 3.5 lbs. As with most carby fed engines they will quite happily live with up to about 7psi I know of a few cars using this much pressure, providing the needle and seat can hold that pressure you will not have a problem.