Starting Device Trip


Thread Starter


Since November last year, after a MarkV HMI upgrade, sometimes when we start, the Detroit goes through its two minute warmup and then just as its starts to accelerate, it might get to 55%-65%, and it suddenly cuts back to idle.

At times we've had a Starting Device Trip come up, but mostly we get no indication as far as alarms or events go. If we leave it for 10 minutes or so it'll ramp up properly the next time.

We looked at the Diesel Accelerating 4-way Solenoid as we thought it might have been dirty hydraulic oil making it stick, but that was OK.
We looked at the throttle assembly, actuator arm and fuel racks, and it all seems to move freely.

Any ideas?
Does the diesel get an analog signal output from the Mark V to control speed? Or is it just a solenoid output that controls the fuel rack?

Have you taken any data using one of the VIEW tools to try to see if the problem is being caused by some problem with the logic? If so, what does it tell you about the outputs driving the diesel?

Or could there be some problem with the relay outputs driving the solenoid (intermittent)?

Are there any Diagnostic Alarms being annunciated prior to or during this failed start attempt?

Are you sure there isn't something restricting the fuel flow-rate or the fuel rack?

Were PROM upgrades done during the HMI upgrade? If so, it might have been necessary to "convert" some sequencing elements and maybe something wasn't completed properly. If PROMs were upgraded, which PROMs were upgraded?
I don't know what kind of clutch you have but this can be caused by a clutch limit switch being set just on the edge. The vibration caused by the engine accelerating can open the switch and cause the described symptoms
Thanks Bob,

We checked the clutch limit switch and it was a bit loose. After we retightened it, we had two attempted starts and both failed. It looks like the limit switch has a fair amount of travel before disengaging.
Another possibility is the diesel engine lube pressure switch, usually something like L63QDN. If the actual lube pressure falls as the engine starts to accelerate, or if the switch changes state for some reason, the symptoms could be like you have. Really the problem needs a good analysis of the diesel logic to see what is happening, acceleration is usually controlled by logic L20DAR, which then picks up the 4-way valve, somehow it looks like it is picking it up and losing it again. Can you run a VIEW plot on the major logic? or simply even a Real Time Plot of the major logic to try and see what is happening?

since there is no alarms you have to check hydraulic pressure switch 88HQ or 88QA or the loop of ready state. this loop is wired at the junction box

from zoheir
good luck.

Bob Johnston

I'm sorry, but this is very confusing. 88HQ/QA are the Hydraulic & Lube Oil Pump motors. I cannot see that anything on either Hydraulic or Lube pressure could be associated with this problem
As far as i know, we face the same problem in GE 6FA with markVI. after sorting out we fine that there was some signal which causes trip in SFC. so by changing the value of the parameter the SFC works fine after ward, but it should be remembered that the signal parameters for both mark6 and SFC should be same

The starting scheme and sequencing for a Frame 6FA with a Static Frequency Converter (SFC) and a Frame 6B with a diesel starting means, torque converter, and clutch are very different. So much so as to be incomparable.

I have been in contact with GE and they assure me that all the necessary PROMs were replaced and the LOGIC wasn't and didn't need to be changed during the upgrade.

Something else was noticed this morning using VIEW2. As the Detroit was accelerating, L14P1 (Diesel Starting Device Above Minimum Speed) flicked off for 0.1 second and then on again before the Detroit cut back to idle. Can a faulty speed sensor be the cause of this problem?

Process Value

Diesel engine Problem

well, ok as it has been a long time since i posted here, and it would be old school if i came back with a overly long post.

background information.

The machines i have worked with all have cummins make diesel engine of 600HP. A 125V DC motor is used as a starter for diesel engine. MARK-V/ MARK VI controller according to startup sequence controls the diesel engine acceleration. Suction air system is turbocharger after cool type. Torque converter connects diesel engine and hydraulic clutch gear assembly, it will engage when slip speed reaches minimum value. When GT speed reached 55% (GT self sustaining speed) the hydraulic clutch disengages automatically.

Working of the diesel engine during the starting time.

Diesel engine starter motor will be switched .On for 5 seconds. After engine starting, the warm-up timer (T2DW) keeps the engine at warm-up condition for 1.5 minutes. And speed of the engine kept around 700rpm, during this period turbine will not rotate due to torque converter pump oil pressure not sufficient to engage hydraulic clutch. After Diesel engine warm-up time of 1.5 minutes, Diesel engine accelerates, which causes the torque converter, engages the GT shaft. (Diesel engine speed raises from 700 rpm to 2100 rpm with in 15 sec. This is achieved by energizing diesel engine acceleration solenoid 20 DA-2. At the end of 15th sec 20DA-2 De-energized. After 1.5 seconds, acceleration holding solenoid 20 DA-1 energized during this 2.5 seconds, speed of engine reduces to 1700rpm & maintained at this level up to firing).

I have uploaded a large pic here which shows the PID of the diesel engine and how it works during the starting time. It is divided into four diagrams.

pic1 - gives the general PID of the diesel engine setup and introduces the oil circuits , the nature of the solenoids during energized and non energized states , the piston movement during acceleration and idle conditions etc ...

pic2 - gives the state of the diesel engine from idle run to acceleration

pic3 - gives the state of the machine from transition from acceleration to hold

pic4 - gives the state of the diesel engine from hold to disengage

Please read through the above to know how the diesel engine works. your application code might be different but not my much , only the control constants may change. worst case you have a electronic governor for diesel , but you did say that you "looked at the Diesel Accelerating 4-way Solenoid" so i am guessing that you will have a similar setup.

now to your problem.

you have two problems at your site

a. Diesel engine falls from acceleration speed to idle , ie diesel engine not sustain during the start up

b. Diesel engine disengages fast , below 45% speed leading to starting diesel engine trip.

the first problem is mainly due to the problem with the acceleration hold solenoid. if the accleration hold solenoid does not port oil properly , you can see in the diagram , there will be a pressure reduction to the upward part of the piston , this causes the piston to move upward thus causing it to idle. This is a fairly frequent problem with the diesel engine. refreshing or replace the acceleration hold solenoid you will get this right. and yes it might be also that the acceleration hold solenoid is not functioning at all. check this possibility.

for the second one of diesel engine disengaging prematurely. This is mainly caused due to the age of the diesel engine when the diesel engine performance becomes reduced. The diesel engine disengages when the GT back torque becomes greater than the diesel engine torque. One solution is to give your diesel engine a overhaul. this almost always works. the work aroung in this step is to give more fuel to the diesel engine. you can do two thing

a. Increase the accleration timer by a little amount ( in the eg from 15 sec to 17 , you will see in your old diesel engine that even after 15 sec the engine speed will not have reached 2100 , so you will have to adjust the constant to get it around the 2100-2200 mark)

b. Reduce the deceleration timer, by a little amount ( in the eg a 2.5 sec timer is given , this is to cut back the speed from 2100 to 1700 odd , in your diesel engine , adjust this timer so as to get 1700-1800 rpm as the accleration hold time.)

do the above and your machine will start well. I do not know your machine standard speeds , check it with the plant operation personnel before the tuning.

the disengaging of the diesel engine is not a problem of diesel engine alone , the torque converter malfunction will also affect this. In the torque converter circuit , the failure/under performance of the torque converter charge pump , passing of the suction relief valve VR23 will have a similar effect.

so that's it folks , further discussion is always welcome.
We replaced the GE speed pickup sensor and have had three for three good starts, so unless its coincidence it looks like that was the problem.
Thanks for the feedback!

It's always good when troubleshooting a problem to understand what changed just prior to the start of a problem, but when doing so one needs to evaluate the likelihood of any event causing the problem being investigated. While HMI upgrades can be complex and difficult to understand, if there were any other problems/alarms being experienced the upgrade wouldn't be the likely cause of a single problem like this.

Again, thanks for the feedback! "It's the most important contribution!"(c) and it's what makes forums like really useful.

At one of our sites, there is Detroit Deisel Engine 8V92 series currently we are facing issues during startup.
Frame size-6B
Controller- Mark V
The fault is actually during cranking it's not starting. The cranking motor is starting for 5sec and stoping since there is no combustion.
Activities are done for fault finding
1. Checked the fuel pump during cranking there is suction
2. Changed new air filter, oil filter, and fuel filter
3 Checked the pressure also it is good
4. Changed the three-way valve and fuel pump also
5. Checked the solenoid valve also
Still, we are not able to find the fault.

Thank You

The Mark V only sends a signal to the diesel to start (it actually operates a 125 VDC contactor which sends 125 VDC to the diesel starting motor). Because it's a diesel, it doesn't need a spark or any electric means of igniting the fuel. It's the heat of compression that ignites the diesel fuel and keeps the diesel running after the starter is de-energized. If the diesel uses a hydraulic cylinder to move the fuel rack then it gets a signal from the Mark V to move to one of a couple of positions (idle and crank, some units have a slightly higher "acceleration" diesel speed, but not many.)

Diesels, just like gas turbines, and just about every other internal combustion engine, require fuel, ignition source (heat or spark) and air. If any of those three are lacking, then it ain't gonna start and run. Very simple. Again, a diesel uses the heat of compression to generate the heat required to cause the diesel fuel to burn (combust). SOME diesels (though not one I've ever seen on a GE-design heavy duty gas turbine) do have something called "glow plugs" or something similar that are energized during starting in very cold weather (think Siberia or the arctic/ant-arctic poles, or other mountainous and snowy, COLD parts of the world).

Having said that, if the ambient temperature (or the temperature in the Accessory Compartment where the diesel is located) is cold enough, the heat of compression won't be enough because the cylinder walls and the block are too cold to support combustion. In this case, it is necessary to do something to warm the Accessory Compartment--OR, to shut off the vent fan which is keeping the Accessory Compartment so cool as to make it very difficult for the diesel to start.

Another problem I have seen is that if there is water in the diesel fuel it can cause the paper element in the fuel filter to swell up and prevent any flow through the filter. (How does water get in the diesel fuel you ask? Well, it does. It comes from the tank the supplier uses to fill the diesel fuel tank; or sometimes diesel fuel is put into a barrel to get close to the Accessory Compartment and the barrel has rain water in it. It's things like that which result in water in the diesel fuel. Those and unscrupulous vendors which sell contaminated fuel (contaminated with water).)

But, the Mark V is not to blame. This isn't a controls problem. It's a diesel fuel "firing" problem. Either the engine is too cold (caused by the Accessory Compartment being too cold), or there is a problem with valve seals on the diesel, or the piston rings, which are not allowing the pressure to build up high enough in the cylinders to burn properly (this can be checked with a compression tester),. Low compression will usually result in white smoke coming from the diesel engine exhaust. Or it could be a problem with the fuel injectors (water in diesel fuel can ruin fuel injectors, too!). Carefully remove the diesel fuel filter and dump it out into a clean container. You will see if there is water in the diesel fuel. If there is water in the diesel fuel, it's very possible the fuel injectors are damaged or becoming damaged.

You need to observe the fuel rack to see if it's moving to cause the injectors to actually put fuel into the cylinders. Sometimes there are pressure taps where gauges can be installed to monitor fuel pressure to the injectors. It could be a faulty high-pressure fuel pump.

If you can't solve the problem with the above., get a knowledgeable diesel engine mechanic to come to site and assist with the issue. The diesel engine is a "standard" diesel engine in almost every respect--the only major difference is that the fuel delivery system (with the hydraulic rams) is different than many diesel mechanics have probably seen.

MOST diesels used on GE-design heavy duty gas turbines as starting means have a method to shut them down manually in the case of an emergency. Most people don't know the emergency trip method exists. It's nothing more than a damper in the inlet air flow that closes when unlatched by a human being pulling on the handle. The damper closes and completely shuts off the flow of air to the cylinders--thereby removing one of the three things required for an internal combustion engine to operate: the air. I have been to a couple of sites where the damper somehow got unlatched and because no one knew it existed they didn't know to re-latch it to open it and keep it open. Not a common occurrence, but it does happen. AND, everyone at the site should know the emergency diesel shut-off exists and where the handle is to unlatch the damper door is, and how to reset it. (One of the reasons no one knows it exists is because the yellow labels which indicate where the release mechanism is are usually painted over by the painters at the factory where the diesel is installed in the Accessory Compartment. Sometimes there is masking tape over the labels which didn't get removed by the factor painters/personnel after painting and before shipping, but usually the painter don't even put tape on the label....)

Lastly, some Mark V-equipped units were shipped with electronic control modules which took a 4-20 mA signal from the Mark V (doesn't sound like your unit is so equipped) and those have been known to fail with some alarming regularity in the early days of their use, but the manufacturers almost use them exclusively on just about every diesel engine in existence these days (new ones) and they have become much more reliable.

Hope this helps! (See; this wasn't so bad, was it?)

Thanks for your support and strong knowledge. We started the diesel engine and the fault found was with ECU Governor control for the diesel engine. There was loose connection in the JB which was triggering not to start the diesel engine. After rectifying ,the diesel engine has been started..

Thank you