'69 FI Squareback: The Continuing (Mis)Adventures

[Tram]

[D/A/N]

[raygreenwood]

Dan....Since I dont follow this thread religiously.....and I have limited time to go back through many pages....can you restate...what your current drivability issue is please?

Ray

[D/A/N]

[raygreenwood]

This is a standard sign...from what you described.....of the FI system experiencing a power loss....meaning feed power....but the engine runs on for a very short time because it has residual fuel...and still has ignition.

Open the system power relay and look for corrosion, burned contacts and damaged or corroded wires in the actuating coil.

This is also....the exact symptom of losing the ground to the power supply relay. This can be caused..depending on how your relay is set up....by losing ground to the panel or part the relay is attached to (check your main ground braids especially the trans tail braid)....or a poor brown ground wire that is usually grounded to the mounting strap of the relay with a ring terminal.

If the ring terminal has wire breakage inside of the insulation near the strain relief of the ring terminal, or if the ring terminal has corrosion between it and the panel or the mounting strap of the relay...or if the sheet metal screw is a bit stripped and not tight or if the paint needs to be scraped away underneath....or if there is rust on teh metal where the paint has been scraped away.

A long type back...because of this very similar problem regarding the grounding point for the EFI system power relay on my 412.....same issue...car cuts out....appears to still be running but the pedal does nothing....may cut in and out...hearing the fuel pump relay click and fuel pump cycle (which was the same problem and symptom caused by a different relay...in the fuel pump circuit)......which may continue the on again off again running scenario even though I am losing speed and pulling over.

The maddening thing was...that sometimes it started again right away. Other times...I fiddle with everything, touch everything...looking for broken wires and unplugged plugs....and it magically starts back up. I finally figured it out by getting the car running one day...and calmly going through everything while running in park at about 1800 rpm.....and jiggling everything.

Even though the system relay on the firewall was pretty tight...its ground wire had poor connection. Moving it just a little caused the engine to "blink"...basically...as the EFI system lost power for a second.

The other similar but fuel pump related problem I noted above...was the exact same problem....to the exact same part # relay....that is under the dash in the 411 and 412...and again...mounted on a thin piece of sheet metal (the pedal cluster) by a crappy little sheet metal screw. Its ground wire and ring terminal loop around and are held tight under that crappy little screw.

Through vibration, shifting, your knees bumping around...a little rust..etc.....it got an intermittent ground situation and would cut the pump out for a split second...sometimes several times in a row....relay clicking...car running like crap and slowing down....and each time it clicks and makes ground...the fuel pump goes through its prime cycle....because the ignition key is still in run position.


.....this was fixed by drilling a hole in the mounting panel in the engine compartment where the EFI system relay is mounted...and one on the pedal cluster where the fuel pump relay is mounted ....and installing a crimp-in threaded insert so I could use a real bolt instead of a crappy sheet metal screw to secure these critical parts.

I used metric stainless steel captive panel nuts from Mcmaster Carr. They press in from the back or front so they are invisible
http://www.mcmaster.com/#captive-nuts/=z1tqu9 about $8.70 for a bag of 25. Just need the proper size drill bit and use a bolt and washer to lock them into the panel.


This can also happen if the main injector ground bundles at the case centerline have intermittent contact.

While you know I of all people applaud new harnesses....the standard female connector type can have intermittent contact here for many reasons...vibration, heat expansion, just working loose....poor contact at the brass connector tree due to its connectivity with the case and potential corrosion or oil underneath.

I have found that using these type of female electrical connectors are the best for the ground bundles. They have a locking tension tab in the center if you look closely. They cannot be removed unless you squeeze the tab. They are also thicker and hold tighter with less issues.

Knowing what issues the ground bundles have and can cause...I make it a point to remove and clean them about every 3-4 months...and I use pro-gold circuit connectivity spray to make sure there is 0 chance of them ever growing corrosion.

The problem your are having cannot be caused by the MPS....yes you could get intermittent load sensing...but only if one of the soldered wires inside has connectivity issues or if one of the fine coil wires is cracked or corroded....but neither of those will cause the power cycling that is happening with your fuel pump.
While the TPS can cause some drivability issues...again...it does not have the ability to cause the power cycling issues.
Ray

[KTPhil]

One of the few things perhaps not checked is the harness leading to the pump up front. If those push-on connectors (either embedded in the plastic pump connector or those at the other end) are loose, it would explain why the pump may cut out, causing your symptoms, and yet the relays remain silent and functioning. Perhaps with heat soak the connector fails to make good contact. After a bit if jostling or cooling down, it may remake the connection enough to run the pump. I'm not sure where the pump itself grounds; it's not in the usual wiring diagrams.

[raygreenwood]

[Tram]

[raygreenwood]

Yes i agree....or as I noted....it could be a ground issue.

I will have to look at his exact wiring diagram.....but as you note....you can lose a cylinder pair due to trigger points themselves, a bad solder joint on that trigger pair, poor connection at the plug.....or downstream from that.....injector grounds.

Even though each injector has its own ground wire....cylinders 1 and 2 are paired and crimped together and cylinders 3 and 4 are paired and crimped together.....at the case. Enterline. The TVS also gets its ground via contact #14 that goes to this same ground lug and another ground paired with the TVS #14 ground wire.....also goes to terminal 11 on the ECU.

So....if there is a failure or intermittent ground issue at the multiple ground connection on the case centerline (#27 in the chart in Bentley for 70-72 models).....it could cause any number of partial failures to any of these ground links.

You also have to remember that with injector signal....there is upstream connectivity....and downstream connectivity.

By upstream....i mean injector signal between the trigger points and the ECU. This only tells the ECU when and what pair to fire. This is wires #21 and #22....with wire #12 as ground....which runs striaght to the ECU.....so in effect it gets its ground from #11....which gets its ground from the case centerline lug. Loss of that ground intermittently. ..would cause whichever pair of injectors that are process....not to fire.....which would cause the next firing cycle of the other pair not to arm. So you lose both injection cycles....which is all injection cycles....during the ground loss event.

So....on the upstream side.....you can have:
Bad trigger pair on one side
Bad solder joint on one side for either wire 21 or 22
Bad center ground solder joint at wire 12
Bad fit on any of those 3 female wire connectors inside the plug
Bad wires near a strain relief on any of those 3 wires
Bad plug fit in the trigger point assembly
Bad wire on any of those 3 wires between trigger point and ecu
Bad connection of any of those 3 wires at the ECU in the card edge connector

.....and it can cause a pair of injectors not to inject.

On the downstream side....short of issues inside of the ecu like cracked traces on the circuit board between components, you can have:

Bad connection of the card edge connectors at wire #'s 3, 4, 5 or 6....the outputs to the injectors
Bad wires between the ecu connector and the injectors
Bad connections of the female connectors inside any of the individual injector plugs

Note: since these are individual output leads.....the failure of any one will not cause injector failure in pairs

Bad ground wire female connectors at any injector, bad ground wires between injector and central ground lug

NOTE: this will not cause paired injector failure either

Bad crimping or corrosion at paired injector ground rimped terminals at the central ground lug.....which will cause failure of injectors in pairs.

Lots of stuff to go through. Just because the harness is new.....is no reason not to check to eliminate. But......outside of issues i mentioned earlier that would also cause system power loss and the off and on of fuel pump (relay issues)......the primary two things i have found that cause paired injector failures is connectivity at the three pin trigger plate plug and poor connectivity at the paired grounds on the case centerline. Ray

[D/A/N]

[raygreenwood]

The injector grounds can cause this exact issue....easily. There will be no relay clicking....jo lights on the dash...nothing......its like a switch gets thrown. Once the engine stops altogether....meaning power from the engine is gone....only switched power to battery and no rpm signal....everything lights up.

Thats when a whole ground bundle pops loose.

Since you have wire pairs crimped into single male/female terminals......any one or two could be screwed up at the strain relief.....have a weak crimp that lets in moisture causing hjgh resistance corrosion......or it could be the grounding of the brass lug itself with the three male connectors to the recess in the case....or it could be a loose nut.

Going all the way back to #11 and 12 at the ECU.....pull the plug,and clean all the card edge area on the circuit board with a pink eraser if necessary......or use deoxit solution. Blow clean...and then check the forked connectors to make sure the forks are clean and have tension.
Inspect the crimps on the wires.

You noted you have a new harness. Where did you get it? Ray

[D/A/N]

[raygreenwood]

He has good tools and knowledge and from what i have heard he builds great harnesses.

The ground quality may bkt becany reflection on the harness itself. Its a problematic location. It sees heat, vibration....possinly,moisture depending on location...which means corrosion. There are also several joints in that train of ground.......and the female terminal design can work loose.

I have been thinking of simply eliminating the issues when i put my harness back in by going to ring terminals and a locknut. Ray

[D/A/N]

I wasn't able to do everything Ray suggested but I got some tinkering done today. Unfortunately, there are no smoking guns to report. Heres what I've got:

--3 pronged ground is securely nutted down at the case parting line.

--One of the injector grounds was very loose. I wiggled it vigorously while the motor was running and it didn't cut out. I even removed the ground and the motor kept on running, just not very smoothly. I tightened up the female connector.

--We went through the engine bay and once again wiggled and tugged on every plug and connector and the motor didn't cut out.

--I pulled on each wire on the relay under the back seat, especially the ground and the motor kept running fine.

--Found big vac leaks at the injectors on the 1/2 side as well as at the intake runner to IAD. Should I just clamp up the ends or use substitutes for the stock boots? They lasted less than 20k miles. In terms of injector seals, on the other side, I've been using the green viton ones that Ray recommended somewhere and they've held up for more than 10k miles so I'm going to do that on this side too.

--Removed the plug from the ECU and found everything on the plug end to be okay. The end of the circuit board was a little dirty but I forgot to bring an eraser with me. I'll have to get back to that.

--I used the Bosch EFAW tester. I'm not quite sure that every button or function works b/c for every test that involved resistance, I got readings that made no sense. Thus, I'm going to have to check the injectors and the MPS with the VOM. Everything else checked out fine according to the book, including the trigger points though these aren't the same (potentially problematic) ones I removed and tested over the weekend.

--I still have to check the trans. ground strap and a few other things.

Naturally, we're reluctant to go for a test drive b/c it's not particularly fun to go for a drive when you can't be confident you won't break down on the side of the road. Plus, we've been able to drive many hundreds of miles between breakdowns so who knows?!??!?!?!?

[RocketA]

For real?

You've been working on this problem for like almost 3 months? You and your multimeter and all the experts and now a special Bosch machine and the thing still won't run?

[Tram]

[D/A/N]

While I guess divine intervention would be nice, it's clearly not going to happen. So we don't get further distracted, I'm going to repost what I had before Mr. Rocket's unhelpful intervention. If anyone's got any input, I'm all ears:

--3 pronged ground is securely nutted down at the case parting line.

--One of the injector grounds was very loose. I wiggled it vigorously while the motor was running and it didn't cut out. I even removed the ground and the motor kept on running, just not very smoothly. I tightened up the female connector.

--We went through the engine bay and once again wiggled and tugged on every plug and connector and the motor didn't cut out.

--I pulled on each wire on the relay under the back seat, especially the ground and the motor kept running fine.

--Found big vac leaks at the injectors on the 1/2 side as well as at the intake runner to IAD. Should I just clamp up the ends or use substitutes for the stock boots? They lasted less than 20k miles. In terms of injector seals, on the other side, I've been using the green viton ones that Ray recommended somewhere and they've held up for more than 10k miles so I'm going to do that on this side too.

--Removed the plug from the ECU and found everything on the plug end to be okay. The end of the circuit board was a little dirty but I forgot to bring an eraser with me. I'll have to get back to that.

--I used the Bosch EFAW tester. I'm not quite sure that every button or function works b/c for every test that involved resistance, I got readings that made no sense. Thus, I'm going to have to check the injectors and the MPS with the VOM. Everything else checked out fine according to the book, including the trigger points though these aren't the same (potentially problematic) ones I removed and tested over the weekend.

--I still have to check the trans. ground strap and a few other things.

Naturally, we're reluctant to go for a test drive b/c it's not particularly fun to go for a drive when you can't be confident you won't break down on the side of the road. Plus, we've been able to drive many hundreds of miles between breakdowns so who knows?!??!?!?!?

[KTPhil]

[raygreenwood]

I am going to recap some stuff here so bear with me:

Hi Ray.....Here's the problem

Way back in February and March the motor randomly cut out 3 different times. It didn't happen again until August. Now, it drives fine until out of the blue there's 1-3 misfires that cause the car to lurch.

OK...so when you say "misfire"....do you simply mean not running smooth....like lack of any cylinders firing at those 1-3 points....or is there a pop or backfire?

I ask this because a lack of injection for a couple of cycles....which is a "no firing" situation can feel just like this. That could be trigger points, ground connectivity or anything in the previously described upstream/downstream loops.

OR....an exceedingly lean set of injections can cause detonation or power loss that feel like a misfire. That can be due to either a bad connection internally or externally on the MPS...being caused by vibration usually (could be a cracked solder point inside the MPS or a bad connector in the plug).....

Or.....it can be the TVS. You have the two wire TVS...which is REALLY just an on/off switch. With age and wear, the gap between the leaf connector and the park position can be slightly too small....and the collet that fits the throttle shaft can be worn, loose or cracked. This can cause your adjustment...to be just barely enough to be adequate. As the parts heat up and vibration acts upon it....at small throttle openings (cruise)....you can end up with the TVS sensing closed intermittently...which will create a lean across the board condition.


The motor continues to run but there's no throttle response. As I'm coasting to a stop, the motor dies. Idiot lights stay on. As I try to re-start it, the relays click and the fuel pump primes. It doesn't restart right away but usually, after a few minutes it'll fire right back up and take me home.

So.....the motor continues to run....which means there is fuel (whether its enough or too much is still a question) and spark....does it "really" continue to run....or is the motor just windmilling in gear? meaning if you push in the clutch and step off the gas...does it idle...or flat out stall?

There are two items that have this exact INITIAL effect:
1. The breaker plate ground braid if its worn or poor can have the effect of literally shorting out or cutting off ignition at certain exact advance points where the plate moves to just the right point and you have no ground. But...its usually a classic misfire with a pop. and does not come and go so much. Once it starts...its almost a clockwork regular defect. Just going down the list

2. This exact effect is also what happens when the fuel pump is choked off by silt in the tank....or cavitates due to filter restriction or turbulence in the line. It may still be pumping SOME....but with reduced pressure and very incomplete injections you get misfiring under load....and the engine still runs....but you dont really have the ability to use the throttle because fuel pressure is dropping with every injection.

This also has the added effect...if its a clog in the tank, filter,etc....of causing the NEXT issue below:

Once it refused and left us stranded on the side of the road.

....lack of ability to re-prime the pump and start running again. It can or will eventually re-prime...as fuel running back out of the return line and the mains...flush just enough silt away from the sock or the inlet area to allow a usable re-prime. the other thing that can cause this...and it was notorious on many D-jet cars early on....and they made minor changes in the later pumps I believe .....is that a worn pump that is not ...say...ideal in its internal clearances and inefficiencies...will run HOT. When it does....the tolerances in the pump open up, fuel pump efficiency is lost, the pump cavitates, gets even hotter quicker....and you lose prime. The pump will not re-prime until it cools down. Each time this happens...the pump wears a little harder. The events will get closer together...and one day it will cease to operate.

Have you done a pressure and flow test on the pump? Have you removed that crappy and useless sock filter in the tank (replace it with an external strainer from Summit racing)....also...do you have the fuel pulsation dampener installed inline?

It never happens when the engine is cold.

If its a worn or cavitating/clogged pump...it WONT happen when the engine is cold...because the PUMP is still cold/cool as well.

Often, several weeks will pass between episodes and the issue will appear to have been fixed by replacing a part but it happens again. Last time, on the 8th of this month (it has been parked since), it cut out a second time maybe 10 or 15 minutes after the first time.

And here's the recap of what we've done:

We've replaced the spark plugs, checked the plug wires, changed points, used 3 different coils, tested the rotor, verified the cap isn't cracked, changed MAP sensors, tested the TP's, confirmed that the relay under the back seat isn't loose, confirmed that the dwell and timing aren't moving around,

verified fuel pressure,

This is not as important as verifying fuel pressure AT proper flow volume....and pressure stability during running and on acceleration. You can have proper fuel pressure....and have poor flow...which will mean a hot running pump and the inability to maintain fuel pressure in a stable manner.

[b]the fuel pump was rebuilt 2 years ago

Ditch the rebuilt fuel pump. I will say this again...and I dont care who it pisses off. There is no such thing as a FULLY rebuilt D-jet pump...either from a reman house or anyone else. Cleaning it, disassembling it, checking the motor windings and bearing and putting in new proper seals...does not remove the zillions of cycles of wear from the roller cell chambers or the rollers themselves. Polishing the rollers and chamber...(as some reman houses of yore used to do)...does not rebuild the tolerances. Replacing rollers and reusing rotor chamber (as some reman houses of Yore have done).....again...does not fix all of the worn tolerances. Still others have lapped the chamber plate to reduce lateral tolerances above the roller just like lapping an oil pump...which still will never give perfect tolerances.....and you still have an armature in the motor with a zillion miles and baked dielectric coating that has been sitting in fuel since the early 70's.

There is no useful reason to keep reusing these pumps unless you are building a museum piece and must have the car concors exact. There are just too many little issues that a refurb cannot address...that can rear their ugly heads. Every part has a design lifespan.

I for one will NEVER put up with "being scared to drive the car"....because of an intermittent problem. Because of the desire to never be in this position (and I was in my youth when I got my first 411...my first car)...there are many classic, original or reman parts I dont screw around with if I dont have to. Get the newest and best you can. In your case...it may very well NOT be the pump. Why risk it? Buy an E2000 or if you must...an NOS D-jet pump....and KNOW what its not.[/b]

Ray

[neena]

Thanks for the explanation Ray! Our misfire doesn't come with a pop or backfire. What happens is we'll be cruising along and it'll suddenly hiccup or blip and there'll be a slight lurch as if the engine stopped for a microsecond. The first time this ever happened it did this like 3 times over 45 minutes before finally cutting out after the last one. Each time since, the time between hiccup and stall has gotten shorter.