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Porsche Crest Fuel pump? No start.

Hi all,

I love this forum.

Got a new toy for my son yesterday and he is very excited, even though it is not running he actually teared up when I told him it is his.

It is a 84 Porsche 944 with no maintenance history other than a recent battery, fuel filter, and DME relay.

Description of problem: No fuel.
1-Cranks over (new battery).
2-got good spark
3-verified reading (ohms and AC) of both RPM and TDC sensors...seems good and I get a tach bounce during cranking.
5-disconnected one injector and tried to start car. No change. No fuel.
6-replace DME relay with new. No change, No fuel.
7-Jumped pins 30,87,87a. No change, No fuel.

I am now thinking problem with the fuel pump. I will get under there today and verify power to the pump.

Any other tips/tricks?

Thanks in advance.

I now this topic is constantly coming up. I have read up on this problem both on this forum as well as Clarks Garage. Watched some video's as well. Just want to make sure I am headed in the right direction before I drop $200 bucks for a pump. Luckily, Pelican is just around the corner.
Old 08-01-2018, 10:06 AM
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If you jump the DME relay and don't hear the fuel pump pumping, then that's at least one problem you have...
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Old 08-01-2018, 10:34 AM
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There are some good knockoff fuel pumps on the market these days IMO. They also last a long time so if you need one a 100K mile used pump is a reasonable option.

That said, the usual problem in this situation is that the fuel injectors are full of evil spooge from neglected gasoline and they need to be removed, backflushed, cleaned, etc.
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Old 08-01-2018, 10:41 AM
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Quote:
Originally Posted by kdjones2000 View Post
If you jump the DME relay and don't hear the fuel pump pumping, then that's at least one problem you have...
Since troubleshooting the "no fuel" issue, I have not heard the fuel pump once turn on. Nor have I had fuel pressure at the rail.

I forgot to mention, I also check all the fuses and they are good.

Would all this lead up to the fuel pump or wiring associated with the fuel pump? Just want to make sure there isn't any other little (easy) tricks or checks to do before verifying wiring and fuel pump.

Thanks
Old 08-01-2018, 10:46 AM
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If the car has sat for any appreciable length of time, then the fuel pump is probably locked up. Pumps get varnished by the gasoline that was in the tank when it dries out.

You might try Rock Auto for assorted fuel pumps to use in the car. Bosch is the OEM fuel pump supplier.

Last edited by Pauld_94S2; 08-01-2018 at 06:24 PM..
Old 08-01-2018, 11:12 AM
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You do not usually hear the fuel pump as it's covered by the noise of the engine cranking. If you jumper the DME relay though it'll run all the time (fireball mode). You should hear it run then.

-Joel.
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Old 08-01-2018, 11:37 AM
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I just revived my '84 944 last fall after seven years of storage and the fuel pump was locked up by gasoline varnish, rust and and tar. I bought a new pump on e-bay for about $30. It is a little louder than the old one but has worked fine.

Before you put a new pump on, drain the tank and unscrew the fuel strainer from the fuel tank sump and see what kind of trash is in the sump and screen. Then, go from there depending on what you find. I found my sump full of rust, gas varnish and the screen was plugged with a very viscous black tar. Use spray carb cleaner to clean the strainer screen and don't scrub on it, as it is very delicate and costs nearly $100 to replace.

I wasted a lot of time, money and effort trying to clean the tank by flushing it with gas and acetone, but only succeeded in plugging 3 fuel filters and my refurbished injectors. I finally bit the bullet and dropped the transmission and fuel tank and had the tank professionally blasted and coated inside and out. It cost north of $400 for the tank but it is well done and has a lifetime warranty against rust and leaks. (New tanks are still available but cost $1800.) Have had zero problems with mine since then.

Good Luck

Last edited by Spring44; 08-01-2018 at 02:12 PM..
Old 08-01-2018, 01:50 PM
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it's the pump! Replaced with Bosch unit from Pelican and problem solved...well, one of many. It runs, kinda.

Found a vacuum issue and many others. Thanks for the help.
Old 08-01-2018, 03:13 PM
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Quote:
Originally Posted by Spring44 View Post
I just revived my '84 944 last fall after seven years of storage and the fuel pump was locked up by gasoline varnish, rust and and tar. I bought a new pump on e-bay for about $30. It is a little louder than the old one but has worked fine.

Before you put a new pump on, drain the tank and unscrew the fuel strainer from the fuel tank sump and see what kind of trash is in the sump and screen. Then, go from there depending on what you find. I found my sump full of rust, gas varnish and the screen was plugged with a very viscous black tar. Use spray carb cleaner to clean the strainer screen and don't scrub on it, as it is very delicate and costs nearly $100 to replace.

Good Luck

I will definitely do this, no telling whats in there.
Old 08-01-2018, 03:16 PM
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I was going to say that if you pull the tank sock, you should put a hose clamp on the neck first to keep from extracting the threaded metal tank insert along with the part you are trying to remove. However the early 944 has a metal fuel tank I think and this may not be an issue in that case.

But anyway for future searchers going after the in-tank screen filter who might have the plastic tank, keep that in mind.
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Old 08-02-2018, 07:46 AM
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Quote:
Originally Posted by Jfrahm View Post
I was going to say that if you pull the tank sock, you should put a hose clamp on the neck first to keep from extracting the threaded metal tank insert along with the part you are trying to remove. However the early 944 has a metal fuel tank I think and this may not be an issue in that case.
Yes, my '84 has a full metal fuel tank. Do you know when Porsche switched to the plastic tanks?
Old 08-02-2018, 11:56 AM
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So...

I just tried to remove my strainer with all my tricks and I can't break it free. The 17 mm nut was rounded of (prior to me touching it) so I tried some channel locks on the outer rim and I tried vise grips on it as well. No luck. Can't use any heat, can't cut or drill on it...

Any tips?

Last edited by DeltaBravo; 08-02-2018 at 01:58 PM..
Old 08-02-2018, 12:59 PM
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Quote:
Originally Posted by DeltaBravo View Post
So...I just tried to remove my strainer with all my tricks and I can't break it free. The 17 mm nut was rounded of (prior to me touching it) so I tried some channel locks on the outer rim and I tried vise grips on it as well. No luck. Can't use any heat, can't cut or drill on it...Any tips?
Use a small pipe wrench on the large outer diameter of the strainer housing.

Last edited by Spring44; 08-02-2018 at 09:32 PM..
Old 08-02-2018, 09:28 PM
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Maybe backflush it and leave it be? Siphon out any spooge and keep on truckin'.

It's not a filter that gets impregnated, just a screen.
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Old 08-03-2018, 04:28 AM
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