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  #16  
Old 12-09-2018, 06:11 PM
irox irox is offline
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Re: Trunk Fuel Resistor

Hi,

I got a chance to pull the trim and check the resistor.

I get 1.3 Ohms, with the leads providing about 0.3Ohms of that.

So, seem like it's a 1 Ohm resistor.

Hope that helps!
Ian.
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  #17  
Old 12-09-2018, 11:52 PM
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Trevor Trevor is offline
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Re: Trunk Fuel Resistor

Quote:
Originally Posted by irox View Post
Hi,

I got a chance to pull the trim and check the resistor.

I get 1.3 Ohms, with the leads providing about 0.3Ohms of that.

So, seem like it's a 1 Ohm resistor.

Hope that helps!
Ian.
Special thanks Ian, removing the trim must have taken some time.

The reported problem:-

(1) “When I got the engine running normal, I would unplug the fuel control module from under the deck lid, yet the car would continue to run normally.”

(2) “Yet when I unplug it (The resistor), the car starts. When its plugged in it does not.”

Ian, unfortunate that I have to call on you again but only then can we move forwards as the situation is completely confusing.

I must ask you to please confirm that the resistor was disconnected when it was measured.

Again thanks, Trevor.
.
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Last edited by svxcess; Yesterday at 09:45 AM.
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  #18  
Old Yesterday, 10:53 AM
irox irox is offline
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Re: Trunk Fuel Resistor

Hi Trevor,

the resistor was unplugged when I took the measurement.

Cheers,
Ian.
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  #19  
Old Yesterday, 04:22 PM
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Trevor Trevor is offline
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Re: Trunk Fuel Resistor

Quote:
Originally Posted by irox View Post
Hi Trevor,

the resistor was unplugged when I took the measurement.

Cheers,
Ian.
Thanks Ian this has been a tedious process as you will understand.


(1) “When I got the engine running normal, I would unplug the fuel control module from under the deck lid, yet the car would continue to run normally.”

Therefore the resistor is completing the pump ground circuit.

(2) “Yet when I unplug it (The resistor), the car starts. When its plugged in it does not.”

Therefore when the only the modulator is in circuit and the pump is running at a controlled speed and pressure the car starts, but when the resistor is connected in parallel with the modulator it does not start, possibly due to high pump speed and abnormal fuel pressure.

The final power transistor in the modulator is NPN and is switching on when the driver PNP is switched on via the ECU at c14. The ECU ground switching circuit must be OK as the pump relay is operating OK.

Conclusion:-

A short to ground within the resistor housing would result in the pump always running at full speed and this would account for the strange situation as per (1), the failure to start as per (2) and also other erratic engine behaviour. Furthermore the pump must draw a lot more current than one would expect.

Alternatively, both resistors measured are faulty and have reduced in value, which would be extremely unusual and unlikely but not impossible. Unfortunately the correct specifications can not be located.

Check the resistor for an internal short to ground.
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  #20  
Old Yesterday, 09:00 PM
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theflystyle theflystyle is offline
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Re: Trunk Fuel Resistor

Wow, I did not check quickly enough to see all the posts that I have missed.

Ian - Thank you very much for this tedious check. It is not lost on me how much effort is involved and once again I want to thank you.

Trevor - I am extremely fortunate to have such a methodical and detailed member assisting with this trace-down.

If I am following you correctly, because the reading of Ian's resistor off the car measures in-line with what I observed, you believe it to be an internal grounding issue within the resistor. I also agree that it would be very unlikely that both are faulty - but as these similarly aged cars are compared it could happen.

I messaged Huskymaniac regarding a thread he created in 2017 about a dropping fuel resistor and his homemade fix. I was looking for updates and feedback regarding his fix and if he noticed any non-reported side effects. I am between replacing my resistor with another used one or build my own as Huskymaniac presented but would love to hear any feedback from the forum.
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  #21  
Old Yesterday, 11:07 PM
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Trevor Trevor is offline
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Re: Trunk Fuel Resistor

Quote:
Originally Posted by theflystyle View Post
Wow, I did not check quickly enough to see all the posts that I have missed.

Ian - Thank you very much for this tedious check. It is not lost on me how much effort is involved and once again I want to thank you.

Trevor - I am extremely fortunate to have such a methodical and detailed member assisting with this trace-down.

If I am following you correctly, because the reading of Ian's resistor off the car measures in-line with what I observed, you believe it to be an internal grounding issue within the resistor. I also agree that it would be very unlikely that both are faulty - but as these similarly aged cars are compared it could happen.

I messaged Huskymaniac regarding a thread he created in 2017 about a dropping fuel resistor and his homemade fix. I was looking for updates and feedback regarding his fix and if he noticed any non-reported side effects. I am between replacing my resistor with another used one or build my own as Huskymaniac presented but would love to hear any feedback from the forum.
You wisely and rightly say, "but as these similarly aged cars are compared it could happen." If my one and only old eye is seeing right, Tony used a 20 ohm resistor which is exactly what I would have expected to be the value involved as per my previous comments. One ohm makes no sense at all.

Quite a long time ago I corresponded with Tony by email and have his email address. He is a good guy and knows what he is about. I will shoot off man email and hope that it will reach him.

Meantime we must now ask Ian as to whether he is experiencing any problems with his car. The plot thickens, is becoming extremely interesting and has many ramifications.

Cheers guys, looks like a merry Christmas.

P.S. Unfortunately my email to Tony has bounced due to the address I have no longer operating. I have sent a personal message and hope for a reply as it would be very sad to have lost touch.

P.P.S. It is clear from the photo that Tony used a 20 ohm resistor as it is definitely marked 20R and this value could be made up from four common 5 ohm wire wound 10 watt or even 5 watt resistors, connected in series and these could be temporarily installed and checked for heat prior to making up a permanent set up. Tony knows what he is about and he must have researched the correct value.
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Last edited by Trevor; Today at 02:09 PM. Reason: P.S. Added
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