I finally give up, Taking my D Jet problem to real mechanics |
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I finally give up, Taking my D Jet problem to real mechanics |
dralf |
Jun 22 2019, 01:20 PM
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#1
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Member Group: Members Posts: 230 Joined: 24-January 04 From: Dayton, Oh Member No.: 1,597 |
Yesterday was my final straw at trying to resolve my sporadic engine stalling issues. Over the past few months I have been replacing various components in an effort to resolve my intermittent engine runnability. The primary focus had been coil, wiring, distributor and ignition parts. Thanks to many helpful tip from this site I narrowed the problem down to the fuel pump not getting current on occasion. My relays seemed OK so I thought the problem might be coming from the ECU occasionally thinking the engine RPMs had dropped below 100. My understanding is that this is fuel cut out is to prevent some engine issue. Using my volt/ohm meter in the cockpit as pictured I attached a lead to Pin 3 on the relay board to see if the ECU would occasionally drop the ground on the fuel pump relay circuit. To my confusion I was getting erratic measurements as I took a ride down the street. The car was bucking and surging and stalling. About a mile away from home my intermittent running issue became a full-time problem. I could activate the fuel pump as I turned the key just like it is designed to do but once the starter engaged the engine only ran for a few seconds apparently from the initial fuel pressurization but the that was all she wrote.
I limped home and it looks like by hot wiring the fuel pump I will be able to drive it to a local import car shop that has a mechanic familiar with D Jet systems. Despite my frustrations and throwing in the DIY towel, I am glad that this problem is continuous which should make it easier fix. I will post what it took to resolve this problem once I get it back. My shop appointment is 3 weeks out yet.... Attached thumbnail(s) |
mzalanka |
Jun 22 2019, 01:55 PM
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#2
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Member Group: Members Posts: 116 Joined: 11-July 11 From: Portland, OR Member No.: 13,300 Region Association: None |
You gave it the ol' college try. Good for you for handing it over to someone else to puzzle out.
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Porschef |
Jun 22 2019, 02:06 PM
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#3
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How you doin' Group: Members Posts: 2,165 Joined: 7-September 10 From: LawnGuyland Member No.: 12,152 Region Association: North East States |
Your fuel pump issue could be as simple as a bad ground wire, maybe try that...
(IMG:style_emoticons/default/idea.gif) |
Rand |
Jun 22 2019, 02:08 PM
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#4
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Cross Member Group: Members Posts: 7,409 Joined: 8-February 05 From: OR Member No.: 3,573 Region Association: None |
Please keep giving this the college try. It's fixable! I honor those who decide to fix it rather than swap to carbs or some other cop out. The answer is usually simple. Some just give up and swap. They lose. There is an answer.
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Spoke |
Jun 22 2019, 02:31 PM
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#5
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Jerry Group: Members Posts: 6,978 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
...Using my volt/ohm meter in the cockpit as pictured I attached a lead to Pin 3 on the relay board to see if the ECU would occasionally drop the ground on the fuel pump relay circuit. To my confusion I was getting erratic measurements as I took a ride down the street. When you say erratic measurements, what were you seeing? Normal operation is pin 3 would be zero volts. Keep in mind that a VOM has a hard time following a moving signal and will display all kinds of numbers. Sounds like the ECU is dropping pin 3 and cutting out the fuel pump. I assume you checked the contacts on the distributor? The ECU has no idea how fast the engine is turning thus needs the contacts to operate. QUOTE I limped home and it looks like by hot wiring the fuel pump I will be able to drive it to a local import car shop that has a mechanic familiar with D Jet systems. Despite my frustrations and throwing in the DIY towel, I am glad that this problem is continuous which should make it easier fix. I will post what it took to resolve this problem once I get it back. My shop appointment is 3 weeks out yet.... If you hot wire the fuel pump, how does the car run? I'm with Rand; keep at it and you will find the issue. I don't like giving up on an issue. Being an engineer who's job is to debug boards/systems I can't give up. |
FlacaProductions |
Jun 22 2019, 02:55 PM
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#6
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Senior Member Group: Members Posts: 1,568 Joined: 24-November 17 From: LA Member No.: 21,628 Region Association: Southern California |
You have 3 weeks to keep trying with a backstop on the horizon - keep at it!
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thelogo |
Jun 22 2019, 05:56 PM
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#7
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Senior Member Group: Retired Members Posts: 1,510 Joined: 6-April 10 Member No.: 11,572 Region Association: None |
If you could build a time machine
And go back in time when people knew how to work on fi And parts were available then youd be all set |
Mikey914 |
Jun 22 2019, 07:16 PM
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#8
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The rubber man Group: Members Posts: 12,648 Joined: 27-December 04 From: Hillsboro, OR Member No.: 3,348 Region Association: None |
Wondering if an intermittant short is the issue by chance?
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mark04usa |
Jun 22 2019, 09:03 PM
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#9
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'70 1.7 Tangerine Group: Members Posts: 351 Joined: 14-September 09 From: Austin TX Member No.: 10,805 Region Association: Southwest Region |
Please keep giving this the college try. It's fixable! I honor those who decide to fix it rather than swap to carbs or some other cop out. The answer is usually simple. Some just give up and swap. They lose. There is an answer. (IMG:style_emoticons/default/agree.gif) I went to carbs many years ago, and after experiencing the lack of performance and drivability issues with carburation, I went back to original FI, sorted it out, and have had a great running car since. (IMG:style_emoticons/default/beerchug.gif) |
GregAmy |
Jun 23 2019, 07:43 AM
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#10
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Advanced Member Group: Members Posts: 2,277 Joined: 22-February 13 From: Middletown CT Member No.: 15,565 Region Association: North East States |
I rarely repeat myself because, hey, I gave you my advice and it's your choice whether to use it not*. But...
...this is fuel cut out to prevent some engine issue... You are incorrect. Except for the ECU turning off the fuel pump when it is not seeing spark at the coil, there is no magical "oh, there's a problem, turn off the fuel pump" logic in the ECU. If all wiring is solid, and the engine is turning resulting in the coil creating spark, the ECU will keep the fuel pump on. QUOTE Using my volt/ohm meter in the cockpit as pictured I attached a lead to Pin 3 on the relay board to see if the ECU would occasionally drop the ground on the fuel pump relay circuit. To my confusion I was getting erratic measurements as I took a ride down the street. The car was bucking and surging and stalling. ...indicating that you have a fuel pump and/or distributor wiring problem. QUOTE ...it looks like by hot wiring the fuel pump I will be able to drive it to a local import car shop that has a mechanic familiar with D Jet systems. Indicating you have a wiring problem. Thus, allow me to be redundant and repeat myself (but I digress). See Post #8 in the other thread. Can't speak for Jeff's Post #10 follow up (I've never used it) but you should consider it. If nothing else, let the mechanic know this so you aren't spending $125/hr for someone to diagnose a wiring problem (in this case, collapsed and/or corroded male pins at the replay plate and/or relay and/or a bad relay plate that are causing intermittent electrical connection.) Good luck and let us know how it works out! *That's become my career mantra. I used to get all upset and follow up later with "Hey, I told you so" but that proved to be career-limiting. Now it's "here's my advice" and then let them go their own way. They can use that all they want, no matter how they hold their hands while declaring it. |
dralf |
Jul 12 2019, 03:15 PM
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#11
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Member Group: Members Posts: 230 Joined: 24-January 04 From: Dayton, Oh Member No.: 1,597 |
They found it ! My intermittent running issue has finally been solved ! My local repair shop worked on my issue for about two hours and determined that my engine would sporadically shut down due to a poor ground connection inside the ECU. The problem was fixed by using another ECU that I had recently obtained for one of our members. I can only say thanks to all who helped try and guide me through this problem. I now am looking forward to some fun drives through town with the top down and the radio blaring.
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Vysoc |
Jul 12 2019, 03:36 PM
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#12
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Vysoc Group: Members Posts: 586 Joined: 27-August 09 From: Young Harris, Georgia Member No.: 10,737 Region Association: South East States |
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Tdskip |
Jul 12 2019, 03:48 PM
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#13
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Advanced Member Group: Members Posts: 3,686 Joined: 1-December 17 From: soCal Member No.: 21,666 Region Association: None |
Good to hear, thanks for letting us know what it was and that you are back on the road.
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Literati914 |
Jul 12 2019, 04:38 PM
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#14
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Senior Member Group: Members Posts: 1,443 Joined: 16-November 06 From: Dallas, TX Member No.: 7,222 Region Association: Southwest Region |
Can the ground inside the original ECU be fixed, to carry as a back up? - 'cause remember the new ECU is still 45 years old!, with a chance of the same.
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FlacaProductions |
Jul 13 2019, 10:18 AM
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#15
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Senior Member Group: Members Posts: 1,568 Joined: 24-November 17 From: LA Member No.: 21,628 Region Association: Southern California |
Fantastic! Hopefully the "old" one can be repaired and used elsewhere.
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Ansbacher |
Jul 13 2019, 11:15 AM
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#16
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Senior Member Group: Members Posts: 689 Joined: 4-July 14 From: Tampa Bay, Florida Member No.: 17,589 |
Please keep giving this the college try. It's fixable! I honor those who decide to fix it rather than swap to carbs or some other cop out. The answer is usually simple. Some just give up and swap. They lose. There is an answer. Carburetors were used with great success on automobile and airplane engines for decades prior to fuel injection. Utilizing a tried and proven method to get gas into your cylinders is hardly a "cop out". My twin Dellortos work just fine, and they do not present head-scratching, unsolvable problems, when something does go wrong. I guess this argument will go on ad infinitum. Ansbacher |
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