new 044 and still not running right

[krasuskyp]

installed the replacement 044 yesterday

car still cuts out with any throttle, especially if any hint of boost builds, lift and feather and it 'runs' "OK"

new FP now making same noise

need some help thinking this thru - what happened and why / where to look?

scenario:

• car running GREAT
  
• 2gal of fuel left last Fri, drove 3mi under light throttle, filled tank, drove 3mi home under light throttle
  
• drove 2mi under light throttle later that evening, 2mi back home under light throttle (quick errand)
  
• next morning, start car and hear rear FP sounding loud ("squeaky")
  
• car runs like crap (as outlined above) for 40mi drive, parked for 4hrs
  
• car runs like crap for a few miles, then suddenly all is fine - it's back to normal for remainder of drive home
  
• start car next morning, FP sounds loud again and again runs like crap
  
• replace FP yesterday, new FP sounds loud and again runs like crap

WTF happened here???

To me... the timing of the fill-up with 2gal remaining and the 2 light throttle short trips seem too close to this onset to not be related, but why / how?

Did something in the tank get sucked thru and clog my fuel filter possibly?

I'm at a loss to know where to go from here, this is an odd one certainly.

Would really appreciate the insight of the brain trust here (Paging Doctor Fairman, white courtesy phone please! )...

TIA, gentz...

[Porsche 935]

I had bad running problem once, found filter in tank clogged.

[krasuskyp]

ugh, of course - I have a FULL TANK

once emptied, how do you go about finding 'that'? And once in there, is it obvious to see the clog?

thanks

It wasn't anywhere near totally empty (2gal) when I'd filled... but I've certainly run it to fumes and even out at least a couplefew times over the yearseses... maybe that's had an accrual effect on the in-tank filter and something finally broke the camel's back in there?

[jwasbury]

Paul. Your first step should be to check system and control pressure. You have CIS pressure gauges?

[krasuskyp]

yerp - will do TODAY!

[jwasbury]

if you have a mighty vac or something (could use a bicycle pump), you can check the warm control pressure and the enrichment (boost) control pressure. Obviously if system pressure in not in spec, your control pressures will likely also be fubar'd.

[krasuskyp]

riiiight - but - WHY???

all of the sudden

and what's causing my rear pump to complain?

I've got the gauges / Mity Vac ready... now just to remember how the heck to connect them 8-/

[JFairman]

I'd try removing the fuel supply line at the fuel head and stick it into a container. Then turn on the fuel pumps and see if they run smooth and relatively quiet when there's no fuel head or possible clogged return line restricting them.

Look to see how much gas is coming out of the hose. I've done that and with two 044 pumps it's a lot.

The original rubber fuel supply hose was too short to reach a big container I had down by the rear bumper so I pushed on another 4 foot long hose that fit snug over it and put the other end into a 2 gallon container to collect it.
Then I poured that back into the gas tank afterwards.

It's always good to keep a garden hose or fire extinguisher nearby ready to go when playing with gasoline.

[Norm K]

Originally Posted by JFairman

It's always good to keep a garden hose or fire extinguisher nearby ready to go when playing with gasoline.

I'm no fire-suppression expert but I'm not certain a garden hose should be among the tools you'd want to keep handy in case of a gasoline fire.



.

[krasuskyp]

THANKS JIM - knew you'd be (one of) the resources I'd want in on this! 8-)

OK I'll run that test and report back.

Frustrating.

Jah, I've got extinguishers mounted in 2 of the 4 corners of my garage ferfukkinSUREDLY...

[gsxrken]

CIS gauge is your friend here as our respected former 930 owner suggested. The intermittent nature of it, and the fact that new pump also does it, makes me wonder if a red relay or fuel pump fuse up front could use a cleaning, spreading, and general once over. I assume you cleaned the terminals at the FP when you changed it. I once had a loose relay from the trunk carpet pulling the fuse cover down and loosening one of the relays. Sort of sounded like your symptoms...

[turbo owner]

Originally Posted by krasuskyp

ugh, of course - I have a FULL TANK

once emptied, how do you go about finding 'that'? And once in there, is it obvious to see the clog?

thanks

It wasn't anywhere near totally empty (2gal) when I'd filled... but I've certainly run it to fumes and even out at least a couplefew times over the yearseses... maybe that's had an accrual effect on the in-tank filter and something finally broke the camel's back in there?

Tank thing is easy, I pulled mine to do it. You will need a special tool to remove the filter, I used a bolt with the right size hex head to fit the huge Allen head in the filter.

Double nut the bolt to remove the filter.

You will need to remove the spare tire, the alarm horn, 3 clamps hold the tank in and the Jack the front end up and undo the supply line to the pump and the return line from the tank. The fuel filler neck will need to be removed also, just slide the rubber hose up the neck for this. Unhook the fuel sending unit and remove from the tank.

It should be ready to remove.

Look in the fuel sending unit hole to inspect and see how bad things look.

Let it air out for a day or two and then get started.

I used a shop vac and air nozzle with about a 3 foot extension, harbor freight, $15.

Use the shop vac where the filter installs, bottom of the tank and the air nozzle in the sending unit hole to clean out the swirl pot. Gotta do this because the fuel line pickup is in there and chunks may be plugging the feed line to the first pump. Second pump could be fuel starved thus making noise in protest.

Your weekend is now planned for you.

[Ronnie's.930]

Originally Posted by turbo owner

Your weekend is now planned for you.

Paul's mistress sez that he has other plans!

[turbo owner]

Originally Posted by Ronnie's.930

Paul's mistress sez that he has other plans!

He's going baaaaahk for more

[Norm K]

Originally Posted by turbo owner

He's going baaaaahk door for more

fify

[IMR-Merlin]

Sounds like you have a pump that is cavitating. Either a clogged line or filter.

Just for the sake of saying so. Are you sure you wired the new pumps correctly and are running them in the right direction? I did mine backwards by mistake once.

[krasuskyp]

funny you ask on the wires

well, first - the car ran beautifully for exactly 1yr... so I ASSume they were wired correctly?

when I removed the rear pump last night, my wire crimps pulled off and I'd not paid attention to which was which

to install, I went with red wire to red terminal / brown wire to blue terminal - ASSume that's correct

but yes, that's the first thing I thought of... but... wouldn't make sense as like I said it ran good for 1yr then this

thanks tho

no time yet to hook up gauges, and any time I even glance at my car the wife promptly manifestoes with a dozen hebiitch manslave "things to do, dammit"... sigh

[icemann427]

Paulie, there is a fuel filter in the engine compartment, too. Left front side. They dirty up. Take it off and blow through it.

[WinRice]

Paul,

You really need to check the tank strainer, that's the first place any large debris goes before it hits the front pump. You don't need to pull the tank, just find a bolt head that fits the large hex on the bottom and grind a couple of flats on it for wrench, or have it welded to a piece of scrap metal about a foot long and you're good to go. In a pinch, get a long enough bolt so you can put a pipe wrench on the threaded portion while the head is in the hex. Make sure and have a couple of spare O-rings around, because the original is probably hard and smashed flat and won't seal.

Had a car many years ago that someone stuffed a rag in the tank. It would float around and randomly plug up the strainer. Some days ran good, other days like crap.

Checking CIS pressure is probably a waste at this point until you get the main fuel system sorted.

[WinRice]

Strainer and o-ring:

1987 Porsche 911 Turbo Coupe - Fuel System - Page 3

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