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What does this damaged capacitor do??

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Old Feb 8th, 2021, 02:50   #31
142 Guy
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Originally Posted by ChasesDragons View Post
Thank you for your description on doing to 3 port to 2 port conversion. All the capitals following are to highlight terns not to hout;

Do I understand the three ports on the pump form FUEL FROM TANK, FUEL TO INJECTORS, RETURN FROM INJECTORS?

When you say the 2 port conversion involves simply blocking the hose, do you mean the hose that is the RETURN FROM INJECTORS? Essentially changing the system into a "DEAD HEAD" system? Would this mean a different type of regulator used at beginning of the fuel rail and the rail is essentially into the dead end (head)?

Or am I misreading? is the return line from the injectors now being sent straight to the tank?

Two Qs arise if not; are the injectors going to get hot as the relatively stagnant fuel absorbs heat? Can it also increase vapour lock?

The more we talk, the larger this can of enquisitive worms seems to be! 👀🤣
You are not incorrect; but, there may be some details that require elaboration.

The three ports on the pump would be
1) suction - fuel from tank
2) outlet - fuel supply to the injectors
3) internal overpressure relief - connects back to the tank by different means as per the following discussion.

On the diagram that you posted, you can see that the 3rd line (fuel pump pressure relief) from the fuel pump tees into the fuel return line from the fuel pressure regulator. You cannot block off the fuel return line from the regulator to the tank. That would make it impossible for the regulator to control fuel pressure. However, if you are switching to a two port pump you can cap the tee that connected to the pressure relief port on the pump. Or it may be possible to completely remove the tee making for a continuous line from the fuel pressure return port back to the tank.

The diagram you posted may or may not be physically 'exact'. On my 142 E, the tee is actually a fitting mounted on the front edge of the tank with the line from the regulator connected on one side of the tee and the line from the fuel pump pressure relief port connected on the other side of the tee. In my case, switching to a 2 port pump just required putting an NPT cap on the side of the tee that went to the pump - hence my reference to blocking off the line to the tank which was probably confusing as hell for 1800 owners if the tee is located in the fuel line. As noted, I am definitely not a member of the 1800 Cognescenti.

Last edited by 142 Guy; Feb 8th, 2021 at 02:59.
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Old Feb 23rd, 2021, 20:57   #32
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That was what I was hoping. The 3 port system looked So complicated, that it seemed like a direct line back to the tank would prove a disaster of some kind!


To add to my miseries, I started going through the sensors and found no resistance reading on the COOLANT TEMP sensor near the AAV (not sure is infinity or short - it just showed 1).

I Wonder if this might trigger overfueling....

Anyhow, I will look for a replacement and will previous advice to check the AAV (Auxiliary Air Valve).

The MAP sensors is giving all the right resistance values. I am going to get one of those cheapy Vacuum Testers from ebay and run vacuum checks just to make sure. iroll
motors quotes of 285 for reconditioned MAPS seen entirely more palatable than what I heard Bosch were quoting

Warmest Regards & thank you all, for helping rekindle my passions in older vehicles.
Udhi

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Or it may be possible to completely remove the tee making for a continuous line from the fuel pressure return port back to the tank.
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Old Feb 23rd, 2021, 20:59   #33
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Dead coolant sensor Bosch 0280130014 with expected values for both coolant and Air sensors.

Regards
U
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Old Feb 23rd, 2021, 21:10   #34
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If your tester reads the same value as when the test leads are not connected to anything then the sensor is open circuit. If the tester reads the same as when the test leads are connected together, then it is shorted. I expect you have an open circuit.

When the resistance of the sensor is abnormally high (open circuit being abnormally high) it causes the D jet controller to go into warm up mode and add fuel to help with operation when the engine is cold. This will result in the engine running with a low AFR and suffer from excessive fuel consumption and fouled spark plugs.
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Old Feb 23rd, 2021, 21:27   #35
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Well explained! Yes, the behaviour is exactly as you describe for the OPEN CIRCUIT condition.

So I will stop intervening at this point until a new coolant sender is installed. I still cannot resolve why the sensor is about 4 times more expensive than other modern ones....

Rest assured that I will be back!

Regards
U

Last edited by ChasesDragons; Feb 23rd, 2021 at 21:38.
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Old Feb 24th, 2021, 00:55   #36
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Quote:
Originally Posted by ChasesDragons View Post

To add to my miseries, I started going through the sensors and found no resistance reading on the COOLANT TEMP sensor near the AAV (not sure is infinity or short - it just showed 1).

I Wonder if this might trigger overfueling....
It could well do as 142 described - try changing the range on your multimeter to make sure you're reading in the right range for the temperature the sensor is at :



At 68F/20C it's reading a little over 2200 Ohms according to the graph and gets higher as the temperature drops - not sure what ambient temperature you were testing in but most multimeters go in ranges of 200, 2k, 20k, 200k etc so a simple range change on your meter might show it's working for the temperature it's at.




Quote:
Originally Posted by ChasesDragons View Post
Well explained! Yes, the behaviour is exactly as you describe for the OPEN CIRCUIT condition.

So I will stop intervening at this point until a new coolant sender is installed. I still cannot resolve why the sensor is about 4 times more expensive than other modern ones....

Rest assured that I will be back!

Regards
U
It's an old, niche sensor - not many cars had fuel injection back then, least of all electronic fuel injection. That means there was no commonality of parts to give the "economies of scale" and make the part cheaper by being mass produced.

However, looking at the temperature curve, it's not dissimilar to the later model CTS sensors - whether the thread sizes are different or not i couldn't say for sure. There might be a modern sensor with the right characteristics but finding it would be the hard part.
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Last edited by Laird Scooby; Feb 24th, 2021 at 00:56. Reason: Missng lettrs
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Old Feb 24th, 2021, 03:56   #37
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I Wonder if this might trigger overfueling....

Exactly what I experienced with a dead coolant temp sensor in my 71E, evidenced by poor MPG and a sooty tailpipe. You may have also checked the intake air sensor in the air intake housing from the air filter, if not, worth checking too. That can also affect mixture.
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Old Feb 24th, 2021, 16:09   #38
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The air intake sensor corrects for the change in air density as the temperature of the air changes so sensor errors will have a similar effect (higher resistance = lower air temperature = need more fuel to mix with dense air). However, the air density correction is based upon the ideal gas law so the change in density is based upon the temperature in absolute degrees (Rankin or Kelvin) so temperature errors have a smaller effect (a sensor reading 10 C when it is actually 30 C only creates a 303/283 = 7% error). Coolant sensor errors have a much bigger effect.

While poking around the sensors, carefully examine the plugs and the wiring at the sensor end. On my B20E I had to replace about 20 cm of the wire at the sensor end because the insulation had hardened and was crumbling and falling off. If this causes the wires to short this can lead to erratic operation. I also had heat damage on the wiring to the injector plugs so I replaced that wiring at the same time. Even though it is partially blocked by the intake manifold, 50 years of exposure to the radiant heat from the exhaust manifold that sits on the same side of the engine below the injector wiring harness does the wiring no favor.
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Old Feb 24th, 2021, 18:23   #39
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Again,
Thank you all for your help. I have two threads going and they are starting to converge. My apologies if it is causing any confusion.

Briefly,
I did set the meter to 20k. The sensor returned errors as described above. I was lucky to have the identical sensor in a w114 merc engine I had stored. Since that gave sensible reads, I installed it into the B20E. The problems are unchanged. I tried shorting the connector pins to replicate low resistance (warm engine) to stop the fuel enriching process from the Coolant sensor, but there was no change in the vehicles behaviour.

I will order a cheap vacuum tester to test then MAP unit in the car - it is passing all the resistance checks but I would like to be sure by checking changes to dynamic vacuum. The MAP has little microfratures over it. The two halves are also secured by screws which is inconsistent with sites stating they should be riveted.

I think the next step is to check the condition of the wiring running to sensors etc. I don't know how to do it, but I am sure there will be answers out there.

Warmest Regards and thank you again!
U
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Old Feb 26th, 2021, 12:32   #40
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Question.
Why not fit an aftermarket 'electronic' ignition? Not only do you virtually eradicate points wear as you're only switching low voltage & low current, but the quality of spark is infinitely better across the range and interference is also virtually eliminated too.
Just a thought ...
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