1979 Eldorado v8 350 no start

40

Asked by Sep 07, 2015 at 01:19 PM about the Cadillac Eldorado

Question type: Maintenance & Repair

V8 350 non diesel with port fuel injection. Ignition system OK after diagnosis
(fire all the way down to the plugs) so can a TPS sensor create a no start
situation?

14 Answers

63,315

Have you tried spraying some starting fluid down the throttle body? Will it run a few seconds on the starting fluid? If not, run a compression test to make sure it hasn't jumped timing. If all cylinders test low or zero. It's jumped timing. If I remember correctly these cars had 2 fuel pumps. The main pump in the gas tank and an auxiliary fuel pump mounted on the frame rail on the driver's side. HTH. - Jim

40

Have not tried the starting fluid yet and from what I have read I agree about the two fuel pumps. I am not sure it could have hopped time (the car has been parked for over 9 years and only started occasionally) So where I am headed next is to see if the aux fuel pump has power and go from there. Do you have any other suggestions?

1 out of 1 people think this is helpful.
40

Tried start fluid and the engine did start for a few seconds so I know it is fuel related. Any suggestions?

1 out of 1 people think this is helpful.
63,315

Check for fuel pressure at the fuel rail. If it's low make sure that both pumps are working and that the fuel filter is not restricted. To answer your original question. The throttle position sensor (TPS) on these cars was very primitive. More like an on/off switch. I doubt that it would cause a no start condition. Since it's a fuel problem, as I said, check the fuel pumps, fuel pressure, fuel filter, and fuel pump relay(s). HTH. -Jim

40

With my luck the main pump in the tank will be the problem and I get to drop the tank when it is full of gas LOL...Thank you Jim

1 out of 1 people think this is helpful.
63,315

You're welcome. Glad to help. You sound like you have the same kind of luck as me. Lol. - Jim

40

Hello again Jim. Scenario #2 Still no start and it has fuel (I pressed in the plunger on the test port on the fuel rail and fuel sprayed out quite substantially and when I put some gas down the throttle body it did start and run for around 1 second or so. Does the ignition control module control the fuel injector pulse? I have also done nada with the TPS sensor. At this point I am not sure the injector pulse signal is there or the injectors are not working for some other reason. Suggestion?

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Also, FYI I did take the ignition module out and had it tested and it tested OK.

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Another thought I had is that if the electrical checks out down at the injector can the injector itself go bad? Remember this car has been parked in excess of 10 years so is there some mechanical component in the injectors that can go bad?

63,315

Yes, that's definitely a possibility. The fuel injector opens and closes to provide the fuel spray. It's very possible that gum or varnish has the injectors stuck. The injectors receive the pulse signal from the ECU (Computer). If the crankshaft sensor is bad the ECU may not "know" that the engine is cranking. So it won't pulse the injectors. I'd check for pulse with a noid light at the injectors. These early Cadillac systems were pretty reliable. If anything I'd bet it's gummed up fuel injectors from sitting. HTH. -Jim

40

Thanks Jim for your suggestion and that is precisely what I am doing next. Would a 1979 Eldorado have a crank position sensor? It has the Oldsmobile non diesel V8 350 in it and is there a cleaner or procedure to clean out the injectors if it passes the noid light test?

63,315

I don't see a crankshaft sensor listed. If it passes the noid test I don't know of any procedure to clean the injectors. Unfortunately I believe that they'll have to be replaced. HTH. -Jim

40

Thank you Jim, you have been quite helpful. I am praying that the problem is in the electrical and not actually the injectors. Injectors for that car are expensive :-(

1 out of 1 people think this is helpful.
63,315

You're welcome. Glad to help. Keep us posted. -Jim

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