Note that an '87-'88 model without an in tank pump uses a different main pump than an '89-'95 with an in tank pump. The main pumps in the '89-'95 models do not like to suck fuel....but like fuel fed to them. Generally, they will be noisy if they are forced to suck.

If you are going to play engineer and remove the in tank pump, you will find that the '87-'88 main pump is what you need.

Keep in mind that it cost money for Porsche to put that in tank pump back into the vehicle in 1989. If the strainer and the '87-'88 pump was the "hot ticket", they would not have made this change.....

 

UPDATE: I was able to get the in-tank pump to operate by tapping on it. However, it doesn't sound all that healthy. Rolling it over causes its smoothness to change and it sounds and feels unbalanced in certain attitudes. It's staying out regardless.

The next item of interest was the fuel line between the pump and the filter. It was badly kinked in one location and slightly kinked in another. The really bad kink is just after the banjo fitting and it appears to be bad enough to restrict fuel flow. The other kink doesn't appear that bad.

For giggles I dunked the in-tank pump into gasoline to see its flow rate. It really just barely supplies any pressure or flow of fuel. I dunno, maybe that's intentional as the discussion on this pump seems to indicate that it's just there to keep fuel from vaporizing in hot climates.

Additionally, when I got the fuel connection line off, there was some calcified junk in it and one fairly large grain of something that looked like a small pebble. I said, "What? In the fuel line?". So is there some silica-mass in the pump, causing it to cut out? Is it excessive sucking that the pump has to do and it gets worse over a period of time, each time the car is driven? Is the kinked fuel line adding to all this? (I'm sure it's not beneficial)

Inquiring minds want to know---

I have a replacement fuel line on the way and other parts as well.

Will try to post photos of the findings so far.

89FP

 

I may be a minority of one, but I like the intake pump-- with an updated hose. In hot mountain climes, the vapor pressure of gasoline can get quite close to ambient pressure-- and pushing fuel, rather than pulling, makes a lot more sense.

The intake pump, pushing a head of roughly a foot, should pump gushers-- many times the 2.5 liter/min spec for the external pump.

Replace it, it is not expensive and doesn't usually survive the PO's attempt to get it loose without the right tools (flare-nut wrench for the flare nut, and an end-wrench for the counter-hold).

Cheers, Jim

 

Some photos:

 

"The intake pump, pushing a head of roughly a foot, should pump gushers-- many times the 2.5 liter/min spec for the external pump. "

Not even close. It's more of a trickle.

 

I would also replace the rubber hose to the pump the hard line you have pictured and the 3 sealing washers and if your using your old outside pump a new check valve,

NOTE you should consider Gregs info about using a different pump,
if your going to go with the single pump version,
if so the new pump will come a new check valve.

 

This may sound like a dumb question, but how on earth do kinks like that happen? And why would somebody leave it that way?

 

the kinks happen when you try to remove the cap nut and the check valve comes loose instead,
then the cap nut is turned and the line then hits the mounting assembly and starts bending .
Its quite possible that whoever did this didnt know that a new line could be purchased,
after they damaged it.

Also a critical point always use new sealing washers and dont over tighten the cap nut,
as it will deform the end fitting thus causing a leak ,
and then a new line needs to be installed with new sealing washers.

 

Not dumb at all. Has to do with character, diligence, a whole slew of traits that are usually hard-earned along with in the genes of the person who has them. Looks like the PO liked getting a "fast job done cheap" instead of a "good job done right".

I'll admit that using a second-hand part is cheaper than finding new, or having one made, but I agree Bill that certain things are just unacceptable. And I've driven the car for six months is the funny part. (I mean funny queer, not funny ha-ha [Carl Childers, Slingblade])

Naturally, it puts the rest of the car into shady territory and how maintenance was conducted. But, it was an affordable replacement to the one that burned. It looks and drives fine...or did before this and, like so much else in my life, I'll just have to undo the buffoonery that someone else has done.

I restore old sailboats as a hobby as well and finding the rat's nests and "fixes" that people have done is a real education on the human species. I've known for years what people do to cars, but they do it to ALL pieces of machinery to include weapons and airplanes as well.

Substandard work by people who think "It doesn't matter" is a good way for that person to wind up in a hospital due to their own negligence. Never seems to work out that way though the "Darwin Awards" shows that it does sometimes come right back at them.

 

I've seen slight kinks in this area, probably for the reasons Stan mentioned, but these kinks are unbelievable. So, I had to ask.

 

what does the fuel check valve look like?

iam thinking my cold start up issues maybe related to that check valve as once started for the day, restarts are no problem, its always that first start that i have to use fluid carb in intake.....

 

Latest Update: Fuel pump (high volume pre-'89) and filter and hard line are changed. In-tank pump removed/replaced with screen filter.

It has a new MAF.

Car runs but intermittently goes into "limp home mode". Sometimes when I floor it, sometimes "just because". I drove it around yesterday with only three occasional limp mode occurrences at first then it cleared up and didn't do it for four hours. Shutting it off and re-starting it stopped the problem. I figured the MAF was still "learning".

Today though it just is acting up. Wondering if Ignition Relay X needs to be replaced, which is an item on the to-do list anyhow. Plus, fuel pressure regulators are going to get changed as well. Last on the list is a new LH computer.

Sometimes the car runs fine, sometimes it goes into four-cylinder mode. Sometimes shutting it down clears it up, sometimes it doesn't. But at least it re-starts each time so I guess that's some kind of progress.

Deeply annoying and when cruising along suddenly not developing any power is a PITA. Pull over, shut it off, start it up. See if it runs smoothly. Couple of revs....if it's smooth, head on down the road. Then...does it again. Then, a long period where it doesn't do it.

If I didn't know better, and I don't....I'd suspect something electrical on the board. Either the relay is not cooperating or it has intermittent connections here and there or any number of permutations.

Currently looking for a cliff to make an insurance claim (Kidding, I'd never abandon the car).

Addendum: A key factor here may be that I failed to change relay XXV which supplies power to the LH board. I'm only guessing but having replaced it, the limp home mode has not appeared and it runs fine, accelerates fine, etc. IOW runs normally. Don't know why I failed to change that relay, don't really care though it seems it was "educational" to say the least.

The old 53 relay that I took out was in pretty sorry shape and, again, guessing, that it had intermittent connection. When off, with a bad MAF, the car wouldn't run at all, even with the fuel pump running. With new MAF...maybe that made it revert to limp home mode, but again, I'm only guessing.

Fuel pressure regulators, fuel lines and ignition relay will be changed soon.

Will keep this thread updated.

89FP

 

swap out the 4 running relays , they are all 53 relays
and inspect the coil wire ends for corrosion, and make sure that they are not rubbing on any part of their run.

Inspect the temp sensor releay with the green and red LEDS if either color is illuminatibng when the engine goes to limp home then you may have a bad exhaust temp sensor

WARNING limp home is a misnomer,
it should be the pull over and shut it off mode.

Running in Limp home can shear the driveshaft,
and cause the cats to glow orange and then catch fire

 

Thanks MrMerlin, I have the carpet pulled back and when the cylinders went to four, no lights were on. All three relays have now been replaced. As I mentioned, I somehow FAILED to change the LH relay when I was doing them. I probably got distracted and thought I had done so.

I wouldn't drive the car in the degraded mode except for a few seconds to get to a spot to pull over and try re-starting it. After changing the LH relay, it has seemed to be just fine. Normal acceleration, no hesitation, no cutting out, no reversion to the limp home mode, I drove it for several hours just now and just got home.... I will still change the fuel pressure regulators and possibly the ignition relay. Relay X, the fuel pump relay and XXV have been changed. The black one with the fuse tester has not. But all the 53's that could be related have been swapped with new ones.

New MAF
New High Volume external fuel pump
New Fuel filter
New hard line between filter and pump
New #53 relays for fuel pump, Ignition Relay X and LH relay
Replaced in-tank pump with screen filter
New fuel hose from tank to pump.

Etc, etc.

Seems to run fine now. Crossed fingers and I'll hold my tongue right and maybe it's in much better shape than before.

 

Hope you've nailed it! Just think of the peace of mind you now have after changing all that other stuff!