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  #1  
Old 08-03-2007, 12:03 AM
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1972 280 SE 4.5 V8 - Stops Running When Warm

Hello,
Has anyone else experienced the same problem??

I have replaced the Ignition Control Unit, Fuel Pump, and Relay, Ignition Coil, ThermoTime switch and all of the usual Tune-up parts e.g. Plugs, Wires, Fuel Filter, Air Breather, PCV Valve(Cleaned)

The strangest thing is that after the motor stops running and it sits for appx. 30 - 40 minutes it starts right up and runs fine.

Could the two Resistors mounted on the lower left Fender cause the engine to stop when warmed??
Also, I did notice a somewhat frayed Fan Switch wire.
Does the ECU monitor the engine temperature and if/when the Electric Fan does not kick in could the ingition system stop?

In addition, I spell lots fuel when trying to re=start the warm engine.
If you have any suggestions of where to look next let it would be greatly appreciated before I take the car into the shop.


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72 280 SE 4.5
73 BMW 2002
79 BMW 733i
79 Camaro Z28
88 Corvette - 35th Anniversary
88 Turbo Coupe T-Bird
95 F150 Pick-Up
05 Lincoln LS V8
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  #2  
Old 08-03-2007, 01:09 AM
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Location: beautiful Bucks Co, PA
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The ignition control unit usually causes the problem you have. Did you fit a new or used repalcement?
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  #3  
Old 08-03-2007, 02:34 AM
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Location: Santa Clara, California
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try the resistors

I had a dead stop backing out of the driveway with front wheels in the gutter and rear wheels halfway to the crest of the road. Pushing this thing out of that and to the curb is another story. . .

I had the resistors replaced. Garage I used tried hammering the fuel pump while I was there to show how smart they were. It didn't work. Ha ha. They traced the problem down to the resistors. I believe they replaced only one.

Have you replaced the radiator? My car cooks up pretty fast and I'm debating that this would be the next step.

Hope it helps and good luck w/ this car. It is a fun one to drive!
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'72 280 SE 4.5, over 100,000 miles
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  #4  
Old 08-04-2007, 01:53 AM
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Thanks for sharing Chase and Tviano:

I purchased a Remanufactored unit from Programma (FL), a few months ago (I still have the old one as well).
Re: Radiator; I took it to my favorite Radiator shop (Radiator Master - North Hollywood CA- I've been taking all of my other car radiators since the 90's) Steve cleaned, pressure tested etc both Radiator and Oil Cooler 2 months ago)

I'm thinking Resistors too. The last Mechanic I talked to in Concord CA stated those resistors must be tightend and grounded to the fender as well.

Hey, I love the car I would just like to drive for once in comfort and not stay on pins and needles if/when it will cut off or not..

The engine technology on this car reminds me of a 80's GM product.
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72 280 SE 4.5
73 BMW 2002
79 BMW 733i
79 Camaro Z28
88 Corvette - 35th Anniversary
88 Turbo Coupe T-Bird
95 F150 Pick-Up
05 Lincoln LS V8
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  #5  
Old 08-04-2007, 10:32 AM
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Take a bottle of water with you. Next time it dies, use the water to cool the ignition unit. If the car fires right up, you pretty much found your problem.
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  #6  
Old 08-04-2007, 01:42 PM
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Hey thanks for the tip. (The Control Unit is still under warrenty) Also, I just ordered two new Resistors ( Mercedes Benz Parts Diresct). W'l post an update on the progress . Thanks again.
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72 280 SE 4.5
73 BMW 2002
79 BMW 733i
79 Camaro Z28
88 Corvette - 35th Anniversary
88 Turbo Coupe T-Bird
95 F150 Pick-Up
05 Lincoln LS V8
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  #7  
Old 08-18-2007, 12:35 AM
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1972 280 SE 4.5 V8 - Stops Running When Warm - Update !!

Hi folks..

Well, I changed the two ignition resistors and I drove it three days straight with no problems at all! (I drove it in 100+ degree temperatures, rush hour traffic, trips back and fourth to LA 120 miles each..... etc) However, last night I backed down my driveway to go to the grocery store and sat outside for about 3 minutes and it stalled; It would not start back up, and it was not even warm (<175 degrees). So we left the car and walked to the store..lol. Then, my wife goes out this morning and it started then she moved it back in our driveway. (Figures it would start for her).

Anyway, it won't start at all now.. (Actually I'm kind of glad) I'm tired of this Intermittent stuff.. At least now I should be able to get to the root cause.

I do notice the following: Extensive unburned fuel smell like I'm flooding out a carborated engine etc..

The Fuel Pump(New) is pressurizing when key is turned on.

Since, I have replaced the Ignition Control Unit, Fuel Pump, and Relay, Ignition Coil, ThermoTime switch and all of the usual Tune-up parts e.g. Plugs, Wires, Fuel Filter, Air Breather, PCV Valve(Cleaned)

I'm starting to think what's left?? Cold Start Valve, Fuel Pressure Regulator, Trigger Points??

Any suggestions??? Thanks...
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72 280 SE 4.5
73 BMW 2002
79 BMW 733i
79 Camaro Z28
88 Corvette - 35th Anniversary
88 Turbo Coupe T-Bird
95 F150 Pick-Up
05 Lincoln LS V8
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  #8  
Old 08-18-2007, 01:39 AM
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When you try to restart it are you getting a spark, if not you have an ignition problem. If so I would put a fuel pressure gage on at the rail. The pressure should hold at about 30psi even after it has stalled. If the gage says zero the pressure regulator may have failed or an injector or cold start value stuck open. By the way do you smell gas before you try to restart it?
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  #9  
Old 08-18-2007, 01:50 AM
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1972 280 SE 4.5 V8 - Stops Running When Warm - Update !!

Hi Bill,

Thanks for sharing... I will check the car out in the morning and I'll check.... Thanks..
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72 280 SE 4.5
73 BMW 2002
79 BMW 733i
79 Camaro Z28
88 Corvette - 35th Anniversary
88 Turbo Coupe T-Bird
95 F150 Pick-Up
05 Lincoln LS V8
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  #10  
Old 08-21-2007, 11:24 PM
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1972 280 SE 4.5 V8 - Stops Running When Warm - Update !!

I believe the cause is my old Wiring!!!

I pulled the distributor plug from the coil (Bosch 3 months old) and I was not getting any spark at all. Since I still had the old one in the trunk I put the old one (Generic Brand) and the car started right up!

Frustrated, I didn't think I had a bad new coil so I put the new coil back in and the car started right up again.

BTW.. Fuel pressure in the injector rail 35 -37 Pounds (Plenty high)

After further inspection the wire from the Silver Resistor to the Ignition coil was frayed and cracking. In addition, the other wires to the coil are in the same condition.

I know the car spent most of it's life in Marin County CA (Near the Ocean).
Perhaps being in the High Desert w/no Humidity is drying thing out.

I probably need to have someone go through the wiring for continuity / voltage checks etc..

Hopefully this is my real problem.

Thanks for all of your help...
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72 280 SE 4.5
73 BMW 2002
79 BMW 733i
79 Camaro Z28
88 Corvette - 35th Anniversary
88 Turbo Coupe T-Bird
95 F150 Pick-Up
05 Lincoln LS V8
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  #11  
Old 08-21-2007, 11:44 PM
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Quote:
Originally Posted by 1972 280SE 4.5L View Post
BTW.. Fuel pressure in the injector rail 35 -37 Pounds (Plenty high)
Too high. It shouldn't be above 30, you can flood the engine with pressure that high!
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  #12  
Old 08-22-2007, 12:58 AM
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You can adjust the fuel pressure regulator by turning the bolt on top. Don't know which way to turn it to reduce the pressure. But play around with it using your pressure gage.
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  #13  
Old 08-22-2007, 07:22 AM
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Will Do .. Thanks Tomguy and Bill
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73 BMW 2002
79 BMW 733i
79 Camaro Z28
88 Corvette - 35th Anniversary
88 Turbo Coupe T-Bird
95 F150 Pick-Up
05 Lincoln LS V8
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  #14  
Old 01-28-2008, 02:34 AM
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Hey Folks I'm Back... I tell you this car can drive you crazy... After all of the other parts replacements etc... It started doing it again.. Stalling when warm.. I went ahead and replaced the Fuel Pressure regulator.. This seemed to have done the trick.. I drove it everyday for about 3 weeks w/no problems.. Now a new problem has developed.. It wants to stall only when it is Cold (Below 175 degrees). Go Figure! I'm guessing it could be the Cold Start Valve?? It looks pretty bad but not leaking.. Also, I mentioned I replaced the Thermo Time Switch as well.
I thought I read somewhere the Cold Start Valve is controling things up until 175 degrees and the cut over to the FI system controlled by the Thermo Time Switch.. Any thoughts???
__________________
72 280 SE 4.5
73 BMW 2002
79 BMW 733i
79 Camaro Z28
88 Corvette - 35th Anniversary
88 Turbo Coupe T-Bird
95 F150 Pick-Up
05 Lincoln LS V8
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  #15  
Old 01-28-2008, 08:55 AM
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The thermo-time switch is just that: Runs the CSV ONLY for X amount of seconds at Y° (I have a chart at home somewhere). It will NOT inject when the car is above 50F I believe (maybe cooler) and it will NOT inject for more than 2 minutes at any temp. The CSV and thermo-time switch can easily be ruled out.

Your problems are probably not related. D-Jet, when finicky, can be a pain to diagnose and you may think things related. I would look at your aux air valve. Make sure your throttle plate and linkage are adjusted correctly or you WILL have all types of issues!

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