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  #1  
Old 07-28-2021, 01:42 PM
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1988 w126 300SEL starting possible fuel issue

Hi,

Can't get my 300 SEL started, here's what I have done so far.
The fuel pump wasn't working so I replaced the fuel pump with an old one laying around.
The car still wasn't starting, so I jumped the relay. Ok, so now the fuel pump works and the car still would not start.
I then removed the main line to the fuel distributor and fuel comes spraying out when the relay is jumped.
I then removed the first fuel injector line closest to the radiator and no fuel reaching the injector with pump running.
Any thoughts on what would be between the fuel distributor line and the injectors that would impede the fuel from reaching the injector.
Am I troubleshooting this wrong, any ideas?
Issues first started today when I went out, turned the car off then and I went to start the car and no go. There were no issues driving to the store. The car then sat for about 15 minutes as I waited for a tow truck and it then started and ran fine and I was able to get home. I turned the car off, waited a few moments and here we are. Car cranks fine, just no start.
There were no issues before the car not starting today.
Thanks, Dwayne


Last edited by junker68; 07-28-2021 at 01:53 PM.
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  #2  
Old 07-28-2021, 03:38 PM
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Quote:
Originally Posted by junker68 View Post
I then removed the first fuel injector line closest to the radiator and no fuel reaching the injector with pump running.
Any thoughts on what would be between the fuel distributor (FD) line and the injectors that would impede the fuel from reaching the injector.
1) Remove an injector line as before. With the pump running, push down on the air flow meter plate. Does fuel appear at the injector?
2) Between the FD inlet line and the injectors is, in fact, the FD! If there is no air flow the fuel flow path through the FD is closed. Pushing down on the air flow meter plate simulates an engine-running condition, and hence, air flow.
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Old 07-28-2021, 05:16 PM
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Frank, I'll check it out and get back - thanks.
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Old 07-28-2021, 05:31 PM
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Frank, prior to following your suggestion, I jumped the relay and the car started right up and ran fine.
I then shut the car down and then followed your suggestion, lowered the air flow plate and fuel came out of the first injector with the relay jumped.
Put the injector line back on and attempted to start the car again and no start.
Thanks, Dwayne
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  #5  
Old 07-28-2021, 06:23 PM
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Odds are that there is an ignition system fault. When you next have a no-start event, check for spark. The flywheel trigger/pickup is often the culprit in a temperature related situation, though it is by no means the only possible culprit.
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Old 07-28-2021, 07:02 PM
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K, thanks
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  #7  
Old 07-28-2021, 07:29 PM
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Removed the first spark plug and grounded it against the exhaust manifold and no spark. I hope I did it right, but with that being said the engine is cold.
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Old 07-28-2021, 11:16 PM
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In checking the ignition system it may be helpful to work backward from the spark plugs.
The distributor cap, rotor, and the shaft seal behind the rotor have gained notoriety over the years. Deterioration in that area is easy to see.
If the distributor seems OK, putting the coil secondary lead close to ground to check for spark would be next.
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  #9  
Old 07-29-2021, 12:41 AM
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An easy way to safely see if you are getting spark is to connect a timing light.

I know it is not a Mercedes and Members of this forum are repulsed at using Stating Fluid. But it is effective to determine if you are not getting fuel or ignition.
If it won't attempt to Start with starting fluid you usually have an ignition issue. If it starts right up with starting fluid you usually have an issue of not getting fuel.

"You could hear the Fuel Pump running but I had my Wife crank the Engine while I sprayed in a bit of Starting Fluid. If it attempts to start like that you know your are not getting fuel in the normal manner. If is does nothing like that you know you are not getting Ignition."

Note that a running Fuel Pump does not mean your Fuel Pressure Regulator is working as it should.

https://www.peachparts.com/shopforum/off-topic-discussion/412403-trouble-shooting-no-spark-1986-chevy-cavalier-4-cyl.html
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Old 07-30-2021, 08:40 PM
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To all,
I double checked, and I am convinced I've eliminated the fuel problem, so it seems to be ignition - no spark.
I double checked with a timing light, as I cranked the engine and there is no spark.
I also replaced the ignition coil with a coil I know to be good and the same issue. No hot start. It started fine when cold.

"The distributor cap, rotor, and the shaft seal behind the rotor have gained notoriety over the years. Deterioration in that area is easy to see.
If the distributor seems OK, putting the coil secondary lead close to ground to check for spark would be next."
All checked out good.

Frank, what and where is the "flywheel trigger/pickup." I did a few searches and I can't find it - thanks

Any other thoughts would be appreciated - thanks in advance, Dwayne
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  #11  
Old 07-30-2021, 08:59 PM
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Is the flywheel trigger pickup commonly known as the Crank Sensor - thanks
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Old 07-30-2021, 10:25 PM
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Quote:
Originally Posted by junker68 View Post
Is the flywheel trigger pickup commonly known as the Crank Sensor - thanks
Yes.
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  #13  
Old 08-02-2021, 12:33 PM
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Quote:
Originally Posted by junker68 View Post
To all,
I double checked, and I am convinced I've eliminated the fuel problem, so it seems to be ignition - no spark.
I double checked with a timing light, as I cranked the engine and there is no spark.
I also replaced the ignition coil with a coil I know to be good and the same issue. No hot start. It started fine when cold.

"The distributor cap, rotor, and the shaft seal behind the rotor have gained notoriety over the years. Deterioration in that area is easy to see.
If the distributor seems OK, putting the coil secondary lead close to ground to check for spark would be next."
All checked out good.

Frank, what and where is the "flywheel trigger/pickup." I did a few searches and I can't find it - thanks

Any other thoughts would be appreciated - thanks in advance, Dwayne
It should not be hard to verify if the Coil is getting voltage from the Ignition Switch when it is on. On mine I verified that and I also swapped a coil and still no spark. (I also verified that the distributor was actually rotating.)

All that was left electrically was what ever triggers the spark and the Ignition Module.

There is a sign at the local AutoZone that claims the test Ignition Modules. I don't know if that is on the Car, you need to pull the whole distributor and bring that in or they are speaking of the bare ignition module.
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Last edited by Diesel911; 08-03-2021 at 05:58 PM.
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  #14  
Old 08-26-2021, 04:13 PM
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Update...
Replaced the camshaft sensor (front - realized later, it's just diagnostic) and the crankshaft sensor (in the rear, by the flywheel).
Replaced the rotor and distributor cap.
Replaced the coil.
Same exact issue...starts when it's cold - when the above was replaced.
When I shut it down and try to start it back up, for a "millisecond" it feels like it wants to start and then after a few moments it just the starter cranking.
Thanks in advance for any additional thoughts.

Dwayne
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  #15  
Old 08-26-2021, 06:21 PM
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Do a residual fuel pressure test. The system should hold pressure for 30 minutes. If not the fuel in the lines can vapor lock. I don't know what the exact pressure should be ~ 2.5 to 3 bar for thirty minutes. You will need a fuel pressure gauge kit for this test- no guessing.

Working back from the injectors, the culprits could be-
Leaking fuel injector(s)
Leaking cold start valve
leaking o ring that seals the Fuel distributor piston- on the bottom side of the FD
Fuel accumulator
check valves by fuel pump

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