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1987 porsche 924s starting problems
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eugenechris  



Joined: 13 May 2008
Posts: 34
Location: oregon

PostPosted: Sun Jun 01, 2008 5:32 pm    Post subject: 1987 porsche 924s starting problems Reply with quote

ok i posted this in the regular 924 section a have not had many responses so ill post it here

I'm having a hot start problem with my Porsche.

i understand its hot out now so there could be vaporization in the lines. took a look under the hood lines seems to be covered mostly. when I'm having the hot start problem i can spray starter fluid into the intake and it will sputter a little maybe die once then start just fine. i have been reading allot about the problem for the last few days

tomorrow I'm going see about getting a pressure gage i can hook up to the injectors and measure the pressure then shut the car off and see how much the pressure drops and if it keeps drooping. any ideas on the numbers i should look for read some where they should be 300 running and 150 for 15-20min after. check that first then do the same thing but clamp the fuel lines before the injectors and see if the pressure drops still if it does then its the injectors if not then its my fuel pump.

another question i have is when im having the problem and i turn the key on i don't seem to hear the fuel pump. I'm going to go out now and see if i can hear it when the car is cold. if the fuel pump is not coming on during the hot start what could cause this a relay some where and where would i find it on my car. i have checked all my fuses and they are all good.

let me know what you guys think i should try and figure this thing out this is my daily driver and really sucks only going one place and waiting for some time ya know. thanks chris
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JSilverman  



Joined: 16 May 2006
Posts: 93
Location: Burke, VA

PostPosted: Mon Jun 02, 2008 12:06 am    Post subject: Reply with quote

The fuel pump relay is under the dash by the fuse panel. Its a cheap part ($25 I think, buy 2 so you have a spare as they are common failures) Your problem could also be with the reference/speed sensors on the bellhousing.
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Paul  



Joined: 02 Nov 2002
Posts: 8909
Location: Southeast Wisconsin

PostPosted: Mon Jun 02, 2008 12:49 am    Post subject: Reply with quote

A lot of good info HERE
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jrrhdmust  



Joined: 19 Mar 2008
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Location: Middle Georgia

PostPosted: Mon Jun 02, 2008 12:03 pm    Post subject: Reply with quote

I have been dealing with a cold start problem:

With the pump running, the car not, the fuel pressure should be 36+-3 on the pressure rail.

With the car running it can drop to 29.

After 20 minutes after discontinuing the pump there should be 14 psi at least on the rail

As far as the pump running, you probably will not hear it. It runs when you turn the starter over, and will run constantly once the engine is running at least 200 RPMs.

You can slowly pinch the return line and watch the pressure if it goes above 59 it is not the pump

The Bosch Fuel Injection & Engine Management book by Probst says to chech the residual pressure, fuel pressure and the air flow meter
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eugenechris  



Joined: 13 May 2008
Posts: 34
Location: oregon

PostPosted: Tue Jun 03, 2008 7:03 am    Post subject: Reply with quote

ok i ordered a new dem relay but still waiting on it now there is alot of relays under my dash will it be labled which one it is? if not i can take a picture and you guys can point it out for me. lol. i hope this works but it does sound like this is a common problem with the porsche.
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eugenechris  



Joined: 13 May 2008
Posts: 34
Location: oregon

PostPosted: Tue Jun 03, 2008 7:39 am    Post subject: Reply with quote

also would this pump work for the 1987 924s

http://cgi.ebay.com/ebaymotors/1987-PORSCHE-944-951-TURBO-BOSCH-INJECTION-FUEL-PUMP_W0QQcmdZViewItemQQcategoryZ33555QQihZ001QQitemZ110258620583QQrdZ1QQsspagenameZWDVW

if not i gues i will buy the $160 pump. if changing the relay does not work.
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jrrhdmust  



Joined: 19 Mar 2008
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PostPosted: Tue Jun 03, 2008 2:46 pm    Post subject: Reply with quote

did you hook up the fuel pressure gage?

If so cover the return line, clamp it slowly, with the pump jumpered and the pressure will climb, if it goes above 59 the pump is good.

If you touch the DME Fuel Pump relay while turning the ignition switch to run, you can feel the relay activate. If it doesn't activate it is bad
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eugenechris  



Joined: 13 May 2008
Posts: 34
Location: oregon

PostPosted: Tue Jun 03, 2008 5:53 pm    Post subject: Reply with quote

no i have not hooked up the gage yet planning on it the next couple of days will this pinch thing also tell me if the valve is bad in the fuel pump?

also since today its no longer a hot start problem went to get in my car to go to work and nothing. sprayed starter fluid in the intake and started up and ran good stopped at the gas station on the way turned it off went back out nothing foot to the floor gave a couple cranks and started up. i made it to work.

let it sit for two hours its cold out now I'm in Oregon and its raining and after two hours nothing when i tried to start it. got off work and it started right up so no longer a hot start problem now its only starting when it wants to. does this still sound like the pump relay? I'm not thinking its the pump because after it starts in runs just fine never died on me or nothing. I'm waiting for the relay now i ordered it off ebay


and which one is the fuel pump relay?
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eugenechris  



Joined: 13 May 2008
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Location: oregon

PostPosted: Wed Jun 04, 2008 8:05 am    Post subject: Reply with quote

ok i found this under the hood two wires look to be bad i guess to sensors could this be it? also seem to not get gass i pulled off the lines going to the injectors and no gas was coming out when i tired to start it now it wont start at all still waiting on the relay



this is my fuse box which one is the fuel pump relay


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bcblase  



Joined: 23 Oct 2007
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Location: Winchester, VA

PostPosted: Wed Jun 04, 2008 1:16 pm    Post subject: Reply with quote

I think those damaged connectors go to the reference sensors on top of the flywheel bell housing.

The fuel pump relay is #2 - the tall one, 2nd from the left in the back row (not shown very well in your photo - it is barely visible in the upper left)

BC
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eugenechris  



Joined: 13 May 2008
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Location: oregon

PostPosted: Wed Jun 04, 2008 5:44 pm    Post subject: Reply with quote

when i turn the key i do feel it click in the second sensor

i opend up the fuel lines and im getting gass to the injectors the lines i pulled last time must of been vacume lines. lol. but im getting lots of gass

so i got my volt meter out and check the coil have power going to it and from it checked coil wire good then i did not have power at the wires checked at the distrubtor cap nope checked inside the cap where the coil wire connect to the rotor had power just not getting to the wires. i hope this was my problem all along but this could just be another problem. i hope not. so im going to see if i can get a rotor and distrubtor cap locally and hope that fix it. i will let you guys know.

the this that gets me why would it do this when it was hot. and why when i sprayed starter fluid in it a few times it started up? dont know but will change the two for a start.
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eugenechris  



Joined: 13 May 2008
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Location: oregon

PostPosted: Thu Jun 05, 2008 7:23 am    Post subject: Reply with quote

i will have my cap and rotor tomorrow before twelve. just to be clear the firring order is 1-3-4-2 is this right? let me know

and i wanted to say thanks for all who has helped so far and all the info i have found on the board. this is a great place for a Porscher
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Paul  



Joined: 02 Nov 2002
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PostPosted: Thu Jun 05, 2008 8:48 am    Post subject: Reply with quote

1 3 4 2 is the correct firing order.

If it runs with starter fluid, your issue is not the cap and rotor.

The frayed wires are the connections for the ref mark sensors. They would be the next thing to fix since the car will not start if they are bad.
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White 986 on its second motor. "Christine"
Arctic Silver 986 with 3.6 liter/325 hp. "Frank N Stein"
Polar Silver 996TT. "Turbo"
Owned and repaired 924s since 1977
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eugenechris  



Joined: 13 May 2008
Posts: 34
Location: oregon

PostPosted: Thu Jun 05, 2008 6:30 pm    Post subject: Reply with quote

Paul wrote:
1 3 4 2 is the correct firing order.

If it runs with starter fluid, your issue is not the cap and rotor.

The frayed wires are the connections for the ref mark sensors. They would be the next thing to fix since the car will not start if they are bad.


it was starting with the fluid but then it stoped and was not starting at all that was when i started checking to see if it was geting spark and found out the rotor and cap was bad. im hoping that was the problem all along. but could just be another problem at the same time

ok new rotor and cap on still no spark at plugs i have 11.5 volts all the way to the roter but no spark getting to the plugs. bad coil?
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jrrhdmust  



Joined: 19 Mar 2008
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PostPosted: Sat Jun 07, 2008 11:39 pm    Post subject: Reply with quote

Are you getting 12V to the Fuel Injectors?

That is my problem, when the Fuel injectors are connected the voltage drops to 3V. I think it is a wiring problem. I am still working it.
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