6.5L Turbo - Mobilehome - Lift pump Voltage
 

Hello everybody, I new here, have a or have not a problem with the lift pump voltage.

As I have ever and ever again had shut-offs of the engine, mostly going uphills, I have investigated this for over 2 years now.

(as well as no-start due no Diesel injected and other issues like under ceratin load SES lamp going on)

So far i found and solved:

The PMD was replaced by a DTech relocation-kit including new DTech PMD.
But unfortunately it was forgotten to take out the resistor of the original Standadyne-PDM and to put it in the new DTech PMD.
That i have just done now.

As the lift-pump does pump (I took off Dieselhose directly at inlet of Injectionpump and ran Lift-pump with booster) i checked then the voltage going to the pump while engine is running (soldered 2 wires onto lift-pump power supply cabel, after the plug, layed cabel till driverseat, connected multimeter) and found that the lift-pump only gets 7,3 Volt.

Then I soldered another wire to lift-pump relay directly to see if there is more (as I understand while cranking this relay supplys the voltage to lift-pump; when running Oil-Pressure-Switch supplys voltage to lift-pump) > it's the same, 7,3 Volts.

Now I am sitting here and are wondering: how can that be?

Can anyone understand this or has a idea how to approach further?

thanks in advance

Thomas

Corrosion in the circuit?

Burnt contacts in the OPS causing high resistance?

The LP voltage should be battery voltage when running so 14.5v or so from charging system.

Also AC Delco ONLY for OPS replacement-aftermarket OPS are often bad out of the box.

Google "OPS relay mod" for long term reliability.

Thank you for swift help Diesel Wrench :-)

Now that I now that also the lift-pump lust get the max. Alternator-chargin voltage during running of the engine i know what to hunt for.

So i will go and hunt from approx. Wednesday on this "whatever-source-of-voltage-drop"

Thank you indeed Diesel Wrench. Have a nice weekend

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Meanwhile i found "the answer to my desires" >

Engh Motors - USB-to-ALDL Interface Cable

:-)

I have just yesterday placed a order.

Then I will install a Laptop as "Boardcomputer" and then I will have great fun learning this Software and technology, reading out all the sensors.

What I will do as well is checking all the ground's; the one going from the Batt. - to tha Chassis (just below the cooler) i redid already, the next at the back end of the motor i found already, the others i will need to search for.

Instead of swapping the OPS, you can add a lift pump relay - recomended - you can do both, but I would definitely add a relay to be triggered by the OPS - oil pressure switch.
I have 2 vehicles running with bad OPS's. With the relay, the OPS only needs to send out enough voltage to trigger the relay. Then you run a fused wire to feed the power to and from the relay.

Google "dual lift pump relay upgrade".

You should find a schematic by Buddy on some threads. I do not know if the schematic is on this forum. But it would be a good add. IMHO, it's a must do for any vehicle that came stock with the LP running off the OPS.

Since you already have the prestart lift pump relay, you only would need to add one relay as apposed to the dual relay upgrade.

You can show full voltage to the lift pump and still not have it work when sourcing off of the OPS for power. You can have full voltage but the OPS switch sometime will not carry enough amps to run the lift pump. It's easier to diagnose in your case since you are showing low voltage.

As with the OPS use only an AC Delco lift pump if going with an OEM style pump. Get a lift pump for a 1993 - they are supposed to have a little higher flow.
The aftermarket lift pumps do not have a great track record for longevity

Hello jrsvoie,

Thank you for forwarding informations, I do appreciate your advice very much.

After reading true hundreds if not tousends of pages i found so many unlocigal non-corresponding informations about the matter "which Lift Pump for a 1995?" and "which PMD-Resistor number to be used?" that I really have been confused.

For sure I came to the conlusion:

If LP must be replaced it is - from the technical point of view - very wise to use a ACDelco Lift pump.
My findings where that the originally intsalled ACDelco Lift Pump is a Model EB309; so next I have to find out the ACDelco type for a 1993 > jrsavoie do you have any information about the ACDelco Model for a 1993?

As I have shown in the youtube videos I did take out the original Resistor from the original PMD. Most interesstingly it was a Resistor number 6.
Up to my limited understanding of the functioning/influence of this Resistor it is so that it can be used to kind-of "fine calibrate"/"adapt" the supplyed ammount of Diesel to the InjectionPump in accordance with the vehicels main-use (for example towing; snow pushing . . . ) and the Area the vehicle is mostly driven in (for example Flatlands like the Salt Desert in Utah compared to hilly Areas like for example San Bernardino Los Angeles).
As this Mobilehome has always been in Switzerland since 1995 i would have expected to find a Resistor number 9 installed as overehere it is rather hilly Area.
So I am a bit confused now of this.

Furthermore i am facing the challenge that I have to do ANY and ALL work OUTSIDE at any weather with extremly limited space (Switzerland is a very very very very little and a narrow Country, finding somewhere only a parkingsspace is a constant challenge - even to find a fuel station where i can - without bloking all traffic - fill the 226 Liters Diesel is a challenge).
However, so far I managed during the last winter to undertake lot's of repairs/maintenance/modifications (we had a loooooong winter, temparaturs to minus 18 degrees here) somehow.
So all and everything takes overhere a little longer while for me to do.

The diagnostis software/cable should arrive this week, the widening of the parkingspace I should have finished by then too, then I can repark, level that Baby and continue my investigations.

jrsavoie thank you again for your support

Ok the 93 AC Delco LP is the best flow/pressure available for a 6.5td stock replacement LP.

The PMD resistor calibrates IP output to a common baseline,all IP's are not created equal and some fine tuning is required at build/rebuild time to equalize the fuel they meter out.

The resistor has nothing to do with hills or flatlands or how the vehicle will be used.

Thanks Racer55 for your explanations; helped me understanding things better.

Meanwhile i have received and connected GMTDScan.
I have permenantly "49 - Service Throttle Soon Lamp circuit fault"

The engine started and was running OK (no driving) since the installation of the missing PMD-Resistor.

Everytime i started the engine i have noted it in order too see what happens after 50 starts.
Today now i went on to check further on the chassis-grounds.
The one on the leftbside motorblock i redid (0,0 Ohms now) annother one in the P30-chassis-extension as well) Both I have filmed and out to my youtube-channel (channel name: thomas kammermann).

Meanwhile 50 starts have taken place > engine starts no more again (no diesel coming on injectior).

This might be a coincidence or not, i do not know.

However, first i think i should get rid of this "49 - Service Throttle Soon Lamp circuit fault"

Each time I delete this Error withnthe GMTDScan Software it comes back immeadeatly - no matter if engine is running or not (ignition is on).

I appreciate every single idea-of-further-approach - so far i found only this chassis-to-motorblock flatband-woven ground cable (see youtube video) - is there annother one.

On the regular trucks the rear passenger side of the engine just behind the intake manifold there should be a stud holding a water block off plate-it should have 3 ground wires from the harness fastened to it,2 on 1 ring terminal and 1 with it's own ring.

Your truck may be different but the grounds should still be fastened to the block somewhere close to the harness.

The STS light code could just be a blown bulb in the instrument cluster?

You can force a resistor relearn with scan tech by doing a timeset command.

Thank you racer55 for your ongoing support; I appreciate it very much, thank you.

I will tomorrow search for the mentioned 3 wires on the passenger side, rear end of engine (towards automatic transmission).

I redid later on today the ground connection of the ground wire coming from the IP solenoid going which is connected ontop of the IP-casing.

If I understud you you correct you say it could as well be the light bulb "Service Engine soon" which is blown causing the 49?

If have just now re-checked the SES light on the Cluster > the light/lamp is actually lighting up when "Glow plugs" is performed ("no-Belt" - "Park" - "Service Engine Soon" - "Glow Plugs" are ON during Glow Plugs-period).

Do I need the full version with license of scan tech to do a timeset command?

THank you again and Best regards

Thomas

As far as I know you do need the full version of scantech to do TDCO relearn but I am unsure if timeset will work in the free version?

You miss-understand me about what light may be burnt out-there should be a service throttle soon light in the dash,and if it is burnt out it could be the cause of the code?

Thank you for your reply and your patience with me-newby racer55.

In order to make sure that I have understud you correct:
There should actually be a Light installed in the dash named "Service throttle soon"?

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Thank you again for your ongoing patience and support Racer55.

Meanwhile I found the Light "Service Throttle soon" > the light-bulb had bad contact > took it out, cleaned it, put it back > works (now @ IGN it shows during Lamp-test also "Service Throttle soon" for a short while).

Scantech shows now no more error-codes @ all :jump:

Thank you very much racer55.

Glad you got it solved.

Hello to all sou helping minds.

I have meanwhile refurbished all ground connections.
It seems as by now the retrofitted (previuois owner) DTech PMD ( installee witha 70cm cable extension harness) has died.
The new orignal (upgraded grey version) Stanadyne PMD has meanwhile arrived from US - - and annother650.- swiss francs have left my vallet which looks like swisscheese altead.

Within the next 14 days i will install it.

Let me share this with you:
I am a very expirienced Tchnician for Co2 high power lasersystems.
Especially i am a expert on transmission of all kinds of PWM/PPM signals (Puls Widh Modulated / Pulse Pause Modulated) signals.
I can assure you: a cable extension harness to install within such a signal circuit it nothing wise to be done at all. And if done it must be done in a very specific and accurate manner, the longer the extension, the more accurate and specific.
I ordered therefor the upgraded original Standadyne PMD as replacement of the seems-to-be-dead PMD.

I thank you for your interest and your ongoing support.
After the engine does run again i will keep you informed about the result of redoing the grounds in regard of the lift pump voltage AS well of my findings in regard of perhaps existing OPS-Contact problem.

Kind regards
Thomas

New, grey Standadyne PMD including Y-Harness
 

Today i tried to install the lately from USA arrived original Standadyn PMD.
See attached pictures and Doc's.

The Plug on the short end of the y-harness does not fit the connector on the engine.
You will see on the pictures the existing connector as well as the connector from the new y-harness.

Well, no luck so far.
I am now in contact with a official Standadyne Partner overhere.

i'll keep you posted.

Best regards

Thomas

Jipiieyeyjippieyey! :jump:

Hello Everybody,

Meanwhile I have received a adaption cable (one side plug for old-style-black Stanadyne PMD ---- other side plug for new-style-grey Stanadyne PMD) which I installed today on the existing DTech-PMD cooling bracket.
This adapter harness i ordered from accuratediesel.com.
THe harness I ordered is 6ft. long (even tough i am not fan of long PWM-signal cables).

1.) The DTech cooling bracket is that much bended that the PMD (no matter what type) does not touch-dowm on the entire surface of the cooling bracket.
It is that much bended because - i believe so as a professional precisionmechanic - they must have milled out the cooling ripples after they milled that side on which the PMD is mounted. (in order the aluminium bracket to remain flat it MUST be the done the other way around: first milling out the ripples THEN milling the side where the PMD is to be mounted).

2.) Between the DTech PMD and the aluminium cooling bracket they install a syntetic/plastic/rubber-kind-of "heat transfer pad" >> I have NO idea how such a plastic heat transfer pad shall work in any other way than isolating the heat)

So:
First i did flatten the side of the aluminum bracket where the new-style-gery Stanadyne PMD is mounted.
With the the new-stale-Stanadyne-Kit comes a metal heat-transfer-pad (as it should be), this I installed covered with a thin layer of heat-transfer-compound (which i also use on Lasers for thermal sensors).

Well,then I installed the new-grey-style Stanadyne PMD (mounted of the cooler) in the mobile home.

Then I powered the lift-pump with a booster, bleeding the filter (opening filter cap).
One injection line i loosend on one injection nozzle on each side.

As you can see on my prevous post the motor was not running since July 2013.

I tunr the key, GLOW PLUGS and .. . . . . motors just starts as it should :jump:

My conclusion:

As I had this stalling/shutting-off while driving/not beeing able to start since the day I bought the mobile home (an even the garage who sold me the thing had this problem for several months - that's why they installed the DTech thing - forgetting to also install the resistor) i am 100% sure now that the DTech-thing was faulty from the beginning.

What a f***-up!
See, I am living in CH > I cannot just go around the corner to get any part @ Autozone or so; I cannot even find a mechanic which knows even as little as I about this motor, I must order all-and-everthing in the USA; paying fright cost which blow ma a** off.
And claiming warranty? No chance!

I for myself - as a technician not only for laser for many many years - I never ever ever ever buy 3rd party replacement parts, never did, never will.

The official Stanadyne partner in switzerland (which has a pump revision center - but as I found out only on their webpage located in switzerland) i useless: Cashing 700 bucks (!) for the part and having NO idea the slightest what they sell; nill support, nothing)


Well, however the motor runs and I am rather happy man.

Most interesstingly the lift pump has still only approx. 7 Volts AFTER the connector plug.
As I have also ordere a new AC-Delco lift-pump this will the next to investigate and solve.

Thank all of you again for your ongoing support and I hope any of my Info does also help someone else.
I will continue on the 7Volt on the lift-pump soon.

Kind regards
Thomas

Lift pump voltage still only approx. 7V
 

Hello Everybody,

Could please someone study the attached electrical diagram of the lift pump relais?

I did measure it out and have written the values in the diagram.

Wherever there should be 12VDC i measure only approx. 7VDC.

As far as i understand the situation the lift pump relais is activated during ignition/crancking; when the engine is running the lift pump gets the 12DC from the oil pressure switch.

So theoretically when the OPS contact is damaged I should still measure 12VDC while Ignition/Crancking?

Can anyone tell me where this 12VDC going to the lift pump relais are supplyd from?

Thank you for your time and help

Kind regards

Thomas

The LP fuse is often located very near the relay-any corrosion around it or the fuse holder?

Here is a suggested modification list for 6.5 diesels that also includes a 2 relay lift pump/OPS modification that was put together by Buddy from Buddy's multi-tune chips.
Have a look at the diagram on page 6.it includes longevity mod but might help answer you question?

Thank you for your swift reply and the pdf racer55, I appreciate your support very much.

I will a.s.a.p. go hunting the LP fuse you mentioned (as the engine is in a Thor Columbus Mobilehome things are very often "just somewhere" located) as well as I will study the OPS-bypass-relais schematic.

Thank you again racer55, kind regards from Thomas

leroydiesel.com is a good place to order PMD's and such.

I had 2 bad gray Standyne PMD's and gave up on them. I only use Flight Systems PMD's now.

I made the mistake of buying one from Pensacola diesel and feel hosed. It looks to be a Dorman. Which I would never buy. And the PMD resistor box was empty

Hello Everybody,

Finally I could solve the too low voltage @ the Lift pump.

As probably expected by some of you it was in fact the Oil Prssure Switch contact.
It took me a while to verify because the wiring diagram printed on the Lift pump Relais did confuse me as it is not correct - so also the wiring diagram I draw mayself in Post 16 is wrong.

However, I did modify the LP power supply by the means of the OP-Switch-contact bypass according the wiring diagram from racer55 in Post 17.
That solved the problem, now there is 12V power to lift pump as it should be.

THank you all for your support and help, I have learned a lot.
Hopefully my videos where also help for anyone else.

Best regards

Thomas