77 924 Martini's alive! but need some help - Page 2

Ian Kowalczyk · 03-10-2008, 08:18 AM

Nice Car. Needs a paint restoration though. I think this car is great-I don't understand why Porsche disowns it.

The handling is great, and these are very fun to work on. I have to replace the pump on mine as well.

Rock solid transmission, and engine. Great Car.

-Ian

DMRK · 03-11-2008, 07:25 PM

Yea it needs a few things. The paint looks a little better now that it is cleaner. Pretty impressed with it so far.

I got the fuel pump this am. It was as advertised! A Pierburg pump and a Beck/Arnley PN. I am goining to install later when I get home.

DMRK · 03-11-2008, 07:26 PM

How about some pics of yours Ian?

924RACR · 03-12-2008, 05:52 AM

Excellent! Please be sure to share your source with the 924board - we're always looking for good leads on those pumps!

DMRK · 03-12-2008, 09:07 PM

I learned the source from post on the 924board.

Got the pump in, now to do more checks. Hope to be able to drive this weekend to see how everything else checks out.

Thanks for all the help.

DMRK · 03-17-2008, 05:36 PM

Update

Well I hooked up the gauges. Not sure if I hooked them up right or not, the Haynes manual wasn't the clearest. I just removed the line that comes out of the WUR from the top of the fuel distributor and connected that to the side of the gauge with the valve on it. Then I connected the other side in to the top of the fuel distributor where I removed the line from. Is this correct? I measured a system pressure of 65 psi. The control pressure was the same (maybe the WUR dosent open). I am not sure if I am doing this correctly, any help would be appreciated.

924RACR · 03-18-2008, 05:00 AM

That is correct, for the hookup. Only other thing you didn't mention was to be sure that the gauge is installed between the valve and the fuel distributor. Doesn't sound like you did that properly, as I think 65 psi sounds about right for a control pressure, but not for a fuel pump delivery pressure (which should be higher as I recall)...

924MartiniRossi · 03-18-2008, 08:30 PM

I might just be making some correct martini strips soon. I had the Martini that is features at www.924.org

Michael

DMRK · 03-18-2008, 08:51 PM

Quote:

Originally Posted by 924MartiniRossi

I might just be making some correct martini strips soon. I had the Martini that is features at www.924.org

Michael

I would be interestedin those. Let me know.

I had the Valve hooked to the WUR, and the gauge to the Fuel Distributor.
I didn't get the time to work on it much, so I will keep on it. Also figured the vacuum lines out and am fixing those.

924RACR · 03-19-2008, 05:50 AM

OK, well you should see much higher pressure with the valve closed than with it open. This does raise the question what the potential limitation here might be, if you cannot get the pressure higher from the pump (with the valve closed, gauge on the FI distributor side). It's possible, though unlikely, that the pressure regulator (in the FI dizzy) is not adjusted properly, or dirty - this is set by shims in the spring, and can be adjusted by adding/removing shims. Presumably pressure could be raised by adding shims.

Other possible sources, if that doesn't turn up anything, would be to check the pump and filter. Make sure the filter is correctly oriented, and reasonably new, check voltage at the pump, etc, make sure the pump isn't dying...

DMRK · 03-24-2008, 09:05 PM

Checked the pressure regulator and it is clean.

Played with it for awhile on Saturday and found that my pressure starts off good but after a couple minutes will decrease and it runs poorly. Now if I shut it off for a second and restart it, it runs fine for afew more minutes and everytime I restart after that. It does not matter if it is hot or cold. So I think maybe I have a restriction some where? Accumulators? Any Ideas?

Thanks, Dave

924RACR · 03-25-2008, 06:17 AM

I'd be looking first into power supply to the pump... electrics on these cars aren't the best after 20+ years... have you cleaned all the grounds? For the pump too?

Ian Kowalczyk · 03-27-2008, 02:06 PM

Quote:

Originally Posted by DMRK

How about some pics of yours Ian?

Sure I can have some pics sometime soon. Needs work, but very minor, (as all I know a the moment, and can ownly hope)

. I need to get it running. Funny thing is, it is my first car too.

DMRK · 03-28-2008, 07:05 PM

Well I put my meter on the pump while it was running and it was 12.8-13V to start. The voltage dropped to 11 V as the pressure dropped and I could hear the fuel pump slowing down. So I am thinking the relay is bad. Only other thing in the circuit is the switch that picks the relay that is inside the airbox. I took apart the relay and cleaned all contacts in and out to no avail. Hopefully a new fuel pump relay will get her going. Any thoughts? Thanks, Dave

924RACR · 03-29-2008, 05:00 AM

I would be more suspicious of the wiring to and from, including fuse and fusebox. Look for corrosion, etc. But you're on the right track!

What ground did you use for the test - the other terminal on the pump or a good chassis ground? Your fuel pump ground may be poor...

Buddy · 03-29-2008, 06:47 AM

Good idea checking the grounds. On a car like this, you want to clean every single ground you can get your hands on, especially the ones under the hood and under the dash. Even the fuse terminals since corrosion on the fuses can reduce the electrical flow.

When I replaced my interior a few years ago, I polished all the grounds inside the car. Ran like new and the gauges responded better. Sometimes, it's enough to just unplug and reseat things like the relays and fuses. Moisture gets into the interior pretty easy and the corrosion forms on connectors. You'll be amazed at how much better everything runs after a thorough inspection and cleaning of your electrics.

Good luck on this one. Good to see another saved from the crusher.

DMRK · 03-30-2008, 04:17 PM

Well I ran it with a jumper in place of the relay and same problem, so it is not the relay. Put the meter on the pump terminals (not gnd) again and the meter was reading 13 volts steady untill the car ran poor enough it died. The fuel pressure had dropped below 50psi at this point. On the previous pump voltage test my meter leads might not have had a good connection or I have multiple problems, but the pump voltage is good now. I have been cleaning every contact I can, even taking them out of the connectors to do so. I also took apart the fuel pump relay and cleaned the contact inside as well as the spades on the outside.

Now what else could account for my fuel pressure gradually falling? I think I have something clogging the line some where between the tank and the fuel filter in the engine bay. The PO said he cleaned out the tank, I think I'll check his work. Is it possible/probable for the fuel accumulators to get full of crap and maybe slowly block off fuel? Also I read in the Haynes manual about the compatibility of accumulators to certain fuel distributors, could this cause my problem? I think that maybe someone replaced the distributor at some point which has the new PN and I have the old 2 accumulator set up. Well thats where it stands for now, thanks for everyones help so far.

924RACR · 03-31-2008, 04:56 AM

OK, good, yes, now sounds like you've pretty definitively ruled out the electrical problems, so yes, I'd be questioning the pump and it's ability to move fuel.

Just on the off chance - are you building up a vacuum in the gas tank? Sometimes the return lines get clogged. Then again - you'd expect to see a rise, not a drop, in delivery pressure, so that's probably not the issue. Yes, I'm sort of leaning towards a clog in the supply to the pump.

It's quite possible that further work with the car has dislodged more crud in the tank, requiring more cleaning/rinsing. This would also be supported by the pump getting hot as it has to work harder.

You will be able to see into the tank if you remove the sender from the top - it's accessed under the hatch carpet, and unscrews on your car with a bayonet-type fitting.

Might need to remove the hose from the pump and drain the tank, flush it through a few times, see what you get out. If it's all clean, that would kinda support the idea that your pump is dying.

Another test would be to see what happens if you pump from a fresh can of gas, instead of the gas tank, after the car loses pressure. Obviously if the pressure comes back up, then your blockage is confined to the tank, rather than the pump or further plumbing.

I believe there is also a sock-type filter/strainer in the tank, which could be clogging up and releasing. Looking inside the tank should confirm/deny this. IIRC, there is a port on the bottom of the tank, held on by 6 screws, which when drained should allow better access for cleaning, etc. But I'd try running the pump from a clean can of gas first.

HTH...

DMRK · 04-01-2008, 08:17 PM

I did check the return line and can blow though it and hear the bubbles in the tank.

I too thought of running it out of a gas can, we'll see what happens.

I installed the new pump so it should be good.

I was wondering if it had some sort of strainer/sock in the tank. I'll look in and see, and clean it all.

Another thought I had was that the accumulators had a diaphram inside and maybe floating around inside and clogging the line. Is there a way to bypass the accumulators (if it will run without them)?

Thanks, I think we are getting close.

924RACR · 04-02-2008, 06:57 AM

It would seem that you could bypass the accumulators and run without them, yes, if you can rig some high-pressure fittings safely. I'm not sure what a long-term impact of running like this would be, though.

Usually they just leak, though. I've never heard of one needing to be replaced for any other reason.