Mondial 8 weird start issue -- relay related

Thanks guys! So I had a little time and made some nice discoveries (BTW, the fuel pressure tester came sooner that is why I made progress...)

1. Voltage to fuel pump is 11.5 to 11.6 (with car turned off of course)
2. it took the pump about 30 seconds to build up enough pressure before fuel came out of the FD (return line to tank)
2. FD to fuel tank (return line): dumps MUCH LESS than 1 liter in 30 seconds. More like 0.25 liters.
3. Control pressure between FD and WUR is 40-42 psi. Weird though when I close the valve on the tester, and should be reading system pressure, I also get 40-42 psi (yes the valve in pressure tester is on the side of the gauge connected to the WUR). However, maybe I did something wrong...
4. The pressure coming out of the FD for one of the injectors: ~40 psi
5. the pressure AT ONE of the injectors is: 15-20 psi (!!!!!!!!!!!!!!) ... needs to be about double as per the manual for the injector fire.
6. I removed all injectors and put small bags at end of tube -- when pump is on, fuel comes out but very irregular in quantity and it "spits" every once in while
7. So, I removed all the fuel injector lines from car and cleaned them with carb cleaner and then pure fuel injector cleaner (using my air compressor to force the liquid through).
8. I reassembled and connected 7 injectors. That one open line still has fuel coming out VERY irregularly and spitting every once in a while

I did not have time to re-measure pressure etc...

A. I probably should connect the fuel pump (with a T valve) to the pressure tester to make sure it is generating enough pressure.
B. I should read carefully to make sure I do get enough correct system pressure... and how to do so.
C. I might discover fuel pump is too weak, but maybe more likely that the FD is dirty inside and fuel simply does not come out well.
D. I will try connecting long tubes to each fuel line at the injector (with no injector present) and then run the fuel pump for a while to see if that helps to clear the lines.
E. Previously, I tried cleaning the FD by forcing air through it and each injector outlet as well (closing other ports with screws).
F. I could contemplate forcing pure injector cleaner through the FD using my air compressor and some custom contraption, but maybe this is delaying the rebuild of the FD
G. If step "D" fails, then will need to crack open the FD (and might as well the WUR as well). I already ordered rebuilding kits for both...

Thoughts?

 

All, super thanks!

So more progress...I directly connected the pressure tester between the fuel pump and the inlet to the FD.

1. first time in morning when turned on I got 78 PSI (got this reading only once) while keeping the ball valve in the tester closed so that I measuring directly the pressure from the pump; pump sounded like pump but a bit irregular and it took maybe 1 minute or slightly more for it to each this pressure.

2. if I open the valve and press the air vane and pump on, I get 40 PSI which then goes down to 5 PSI.

3. if I open the valve but remove safety switch and pump on, I get 20-40 PSI (sometimes got 20 and very slowly rising, and sometimes close to 40 rather quickly)

4. Then, I repeated test "1" and I could never get 78 PSI again....never more than 40 PSI. I repeated step 1 about 3 times.

5. I tried multiple combinations of valve open, valve closed, air vane down, safety switch off, and basically I never see more than 40 PSI at the inlet and when the air vane is down I always get ~5 PSI eventually.

6. With all injectors off, fuel only spits out very irregularly from the lines in all cases.

7. Recall that previously I got about 0.1 liters coming out of the fuel return line to the tank (in 30 seconds)

8. Recall that when I thought to be measuring system pressure using the line from FD to WUR, I also got about 40 PSI. I think my tester was correctly connected.


** My conclusions: **

A. fuel pump and/or accumulator is bad (most likely pump, but maybe just replace both to be safe); I already checked back of accumulator no fuel comes out; I do hear a water running sound after pump is off...and *maybe* during pump running....maybe this is just fuel returning to tank from the FD?
B. above was mentioned the primary pressure regulator...where is this? is it the placed horizontally inside the FD and I can only see the screw head on one side of the FD...in a sense it is placed traverse to the FD return line and lines to/from WUR...is that it? if so, or not, can I easily just remove it to inspect?

I will order a new pump and accumulator. I have the pump with the check valve inside. I think I saw I can order the same pump, might as well.

While waiting, I might as well rebuild the WUR (kit arriving soon)...that should be a relatively easy task, right?

I am tempted to open up the FD and do a simple rebuild but maybe I should wait...

Thoughts?

D.

 

Thanks!

This is all getting complicated A development: I found a place in US, DeLorean Auto Parts, which I have seem referenced on FChat, that has rebuilt FD and WURs. Basically, I mail them my core and they return a rebuilt one to me, takes a week total or so.

Pricewise not bad, $470 for FD and $270 for WUR.

Maybe just do that? been using lots of time on this already or am I just throwing money....?

That rebuild of the FD I suppose will include ensuring the pressure regulator is good...

So, I will have
-new pump ($100)
-new accumulator ($100)
-new fuel filter
-rebuilt FD and WUR
-AAV I have disassembled and inspected, maybe ok; cold-start valve (a US thing) is inspected, maybe as recommended by Birdman I should remove
-new injectors

there are some relevant thermoswitches and I have no clue if they work...handle later...

Fuel system should be ready!

Thoughts?

D.

 

All,

So I installed a new fuel pump and fuel accumulator...however pressure after fuel filter is just 20 PSI!?!?!?!

Some items:

1. I did not record to which of the openings of the fuel accumulator does the pump go. The accumulator has a center port and an offset-from-center port (both on the front face of it, of course). As I could tell from diagrams and Google searching, the center port should go to fuel filter (meaning that gas comes into the fuel accumulator by that offset-from-center port and then gas goes from accumulator to fuel filter using the center port. Is that correct?

2. When I removed the pump I noticed there was no gas in the tube from tank that connects to it. It was sitting all night but shouldn't there by even residual gas there. Does this mean the filter "inside" tank (as Guido wrote) is almost clogged? I did not "remove and clean fuel tank" after my car's 8 year hibernation, but I did remove all fuel using the tank's drain plug. I "blew air" into the gas tube from gas tank to "clean it"...just a short squirt. Gas DOES come to FD and to ports (not very much as before) so some fuel is coming to pump...can it be that "not enough" to build the 120 PSI pressure?

3. can something else be wrong? I did measure 11.7-11.4 volts at pump while running...

4. am I going to have to remove fuel tank from car and inspect that other filter??

 

In the diagrams, I see item 116404 .. can this clogged? can I remove without taking out the tank?

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I did not get 70 psi with old pump....reliably got 20-40...

I think it’s connected as you indicate....hmmmm have to inspect when I get some time....




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All,

Finally got some time and made progress!

1. I directly connected that back of the fuel pump to a 5-gallon fuel tank and immediately the pump when on had 80 PSI and I could get gas to squirt out of the injectors! (only tried one -- various things are partially disassembled) -- great news!

2. I removed the inline fuel filter that is inside the tank and it IS FULL OF CRUD/DIRT/VANISH --- so that was the source of my problems! (at least a major part). It took some effort to remove the filter, but I did. By sticking thin things inside that hole and the drain plug I can feel/pickup lots of "gunk", so I think my tanks need a thorough cleaning.

3. To remove the fuel tanks, I think only the metal straps need to be loosened from the engine bay part, and the line to the gas-filling-line disconnected (and the hose between the two tanks to be cut), then it seems they will just come out, right?

4. I am not sure exactly how to clean the tanks but once out I suppose I can find someway to flush them with pressure...

Stay tuned!

 

Many thanks all for your help! Finally, got the engine to start!!!!!!

1. The fuel filter inside the tank was basically blocked. I cleaned it. I could not remove the tanks so I washed them with water in place. Let dry, flushed with some gas etc. I changed all the rubber fuel lines around there too (inclusively the one between the tanks, whose removal made it easier to wash tanks).

2. Put it all back together, measured pressure at inlet to FD (was 80 PSI).

3. Changed all injectors.

4. Removed cold-start-valve (US only add-on), as per Birdman's website.

5. It just started! I had to play with idle settings, but all good.

6. Went for a drive (about 35 miles, or 50 kilometers)! and slowly started to up the RPMs, and periodically checked the engine bay. Wonderful sound!

7. At the end "something happened" and I lost lots of power and had to slowly limp home...not sure what. Maybe one bank went dead?

8. After it cooled down a bit, I disconnected one of the ignition coils and it seems that is what it was like when had no power. I did with other bank as well. Seems good now, but did not try again (had to leave for my day job ).... next I will test each spark plug (remove individually and see if it affects performance -- it should). Plugs are already changed. Cables are not.

Many thanks to Guido and Spicedriver for all your help!!!!!

If I cannot fix my powerloss problem, I'll be back...hopefully is something simple. Macroscopically I guess can be:

a. bad ignition coil/cables/Marelli's?
b. bad speed sensors (there is one per bank right?)
c. more fuel crude which got lose in WUR or FD (I never opened them up, though I did squirt cleaner through the FD at high pressure)

 

My current other car is a Porsche 944 Turbo, which is currently working quite well. Had a track event recently and all great. Have another one coming on May 19-20 and wanted to take the Mondial during the slower-speed touring laps, to see how it feels....I hope to have it ready by the 19th!

I'll have to read-up about the ignition module....not sure what they are. Also, I am not sure its a cold bank, need to spend some time. First was going to check cylinder by cylinder. Speed sensors I read you can just check with an ohm meter...

 

On another thread I read:
"I also had a couple years ago a bad crank sensor which was causing the car to malfunction, but not backfire. It would stumble, or lose power, then come back. I didn't figure it out until another fchatter riding in the car noticed that the tach went nuts when it happened. I looked at the schematic and saw that the tach was driven off only one of the digiplexes which showed that it was the crank sensor on that digiplex."
(by Birdman)

The tach DID HAVE A PERIODICALLY crazy RPM meter, but the large every once in a while motion of the tachometer did not correspond to what the engine was actually doing...so could the speed sensor be bad? I believe there are 3 sensors. One for tach and one per bank. If the tach one is bad, this should not affect the banks. But if bank sensors are bad too (a sign of age), then the Digiplex would be screwed-up periodically and I could see loss of power, backfires, etc (all of this occured during my so-called "limping trip back home".

??

 

More progress but no solution...

1. I drove last week 25 miles in one outing, seem powerful and I upped the RPM slowly, never quite got to go "all out" but at some point suddenly had to limp home for 5-10 miles. I did notice now RPM gauge jumping around periodically
2. I changed all my spark plug wires (the accel kit as per Birdman's website); nice red wires
3. definitely both coils are firing; and 99% sure all 8 cylinders are regularly getting spark
4. symptom now is still not much power, even after cable change; also idle is irregular meaning that if I adjust to 1000, then after some accelerator presses it goes to 2000, or to 500; also, sometimes if I accelerate too much then when I release the accelerator it goes to nearly 0 RPM, and often turns engine off; though I can re-start it easily; if I use my foot to keep the RPM from slowing down to fast then all ok.
5. could it be speed sensors? would that cause this? I am not sure where they are; the workshop manual indicates 3 such sensors (TDC sensor, TDC sensor, sensor tachometer); I think I see a rear one, on the side of the bell housing (near transmission system), not sure which one it is; seems like easy access but did not remove; had a hard time following the cable; I did see a round 5-pin or so connector underneath the car, with easy access; I disconnected and put electrical cleaner in there; as per workshop manual that should not be the connector, but I cleaned just in case. I cannot see the other two sensors.

** can some one point me to the where the 3 speed sensors are for a Mondial 8?

** any other suggestions ?

 

Thanks for the suggestions! I found all sensors and measured them cold to have about 750 ohms each. It seems they have been worked on. One of the TDC is a white wire one. The other TDC is a black wire one. The tach sensor is a black wire one with no connector -- just crimped wires together (I added a simple plug connector).

I cleaned all those contacts. I also uplugged and cleaned two large electrical connectors near the fuel expansion tank and the two Digiplex input connectors.

I also changed all plug wires, as I said previously.

In the end, the symptom is the same and maybe more stabilized. Engine sounds good and went cold to warm I think the power curve is good (only sitting in garage). However, when I drive around the block and the engine warms up eventually it seems to lose power and misfires and I have to limp home.

So, it *seems* that upon warm-hot range the engine is getting confused. I do not think the engine is "very hot", but definitely beyond "can touch the key metal areas".

Can this be the TDC/tach sensors getting hot and then not working well? I have not removed them to inspect -- I was thinking of ordering some new ones and if I am going to remove, I might as well change...

Understood about arcing extenders...the cables are new, but not the extenders (they do not seem easy to find locally, right? saw them on ebay), however them starting to cause misfire when warm/hot does not make...wouldn't it be always?

I will check for vacuum leak with your method (nice one!) I changed some/most of the vacuum lines (I think just missing are the ones to the Digiplex boxes).

NOTE: mine is a Mondial 8 so there is no ECU....just the Digiplex's I believe.