I posted this problem twice before, first time about two months ago and the second time about a month ago. I am still having a problem when I start up the vehicle when it is below freezing outside or when the vehicle has sat overnight. If I crank the engine without applying the throttle it will start and then stall a second later. This will happen about four times before the engine will keep running. If I use full throttle the engine will start up normally and idle normally and smoothly at 700 rpm for about four seconds and then, all of a sudden rev up. All this time I have the pedal floored. It is almost as if the engine does not know that the throttle pedal is floored and it takes it about four seconds to realize that the pedal is floored. It will occasionally run a little rough at the end of the four second period before it picks up speed but it runs very smoothly during the four second period. Here is some more info. It is parked outside in the cold. The grid heater works normally. I am using Howes Diesel Treat. I am pretty sure that the fuel is not gelling. Somebody suggested, on my second post, that the injectors might be leaking and that I replace the O-rings. So, last Sunday,I replaced the injector o-rings, the copper washers and the connector tube o-rings and it made absolutely no difference. The tach works normally, so I think the ESS is working properly. I have tried powering up the lift pump for about five minutes before I crank the engine to eliminate any air and it makes no difference. I have also inserted a clear vinyl hose in the fuel supply to the VP and there are no air bubbles. I have 15 psi fuel pressure. This brings us to the APPS. On my truck it is at the bottom of the throttle pedal and there is no throttle cable at all, on Dodges I beleive it is different. I have the Cummins manuals for the ISB and they do not mention any APPS reset procedure at all, so I haven't tried it. There is no problem during a warm or a hot start. I have checked the overflow valve in the drain line and it appears normal. I forgot to mention that there are NO CODES. I am stumped. HELP!

 

Could a Moderator please move this thread to the HELP forum. I think that is a more appropriate forum for this thread. Thanks.

 

Sounds like a cold engine that hasn't been plugged in to me.

 

mine does the same thing if it's cold out and wasn't plugged in. it's just a cold start thing as far as i'm concerned and i wouldn't worry about it. however i'm not sure i'd be holding my foot to the floor on a cold engine. i give just a bit of throttle to keep it running for 20 or 30 seconds and then it should idle on it's own. full throttle on that cold a diesel is just asking for trouble.

 

I have had the truck for over six years and it has never been plugged in, not ever, and it has been much colder and I have never had this problem before. As far as full throttle on a cold engine is concerned the pedal has absolutely no effect on the engine speed, it still idles at 700 rpm. I do not think that any extra fuel is being injected from stepping on the pedal, and therefore I do not think any harm is being done to the engine. I did read in the Cummins ISB manual that a protection feature is available in the ECM that, if enabled, will not let the engine rev above low idle until oil pressure has been established. However the truck has not been in to a shop in a long time, so it is a mystery to me how that feature got enabled. My problem first surfaced two months ago, prior to that the throttle always had full control over the engine from the instant the engine started.

 

hi,
i am having similar symptoms on my 97 2500 ctd. weird thing is, it starts right up no problem at all, runs normally for anywhere from a few seconds to almost a minute then just dies! this has only been happening this winter, so it's been cold, but not always really cold and i always plug in the block heater for several hours b4 starting. never happened last winter. sometimes, if i give it enough throttle, it won't stall out, but it does stumble like it's about to. when the stumbling stops i let off the throttle and after a few seconds of this it will idle and respond to throttle normally. after these start-up episodes, it starts and runs fine all day long. so far, this only happens after sitting overnight or longer, never happened twice in the same day. my tentative theory is that i have a fuel line leak that's allowing air into the system, but that's just a beginner's guess. ????? i have also tried manually pumping the lp until i hear the overflow valve opening. doesn't seem to make a difference; maybe slightly less cranking time to re-start, but can't say for sure. maybe there's already air trapped in the injection pump??? anyone?

 

On the Freightliner with the ISB check to see if you have a fuel heater. Some did, and most do not. Given as far north as you are I would suspect you have a fuel heater. On the commercial medium duty engines, the fuel heater should be an external canister mounted system located before the fuel filter - most are commercial types from manufacturers like Racor. Check to see that the heater is cycling. What this sounds like is the fuel heater is not functioning, or the prescreen in the heater is plugged. The other likely problem area is the fuel prefilter. Most Freightliners have it mounted right up in your face when you tip the front off, and it usually has around ten feet of fuel hose between it and the OEM transfer pump that feeds the primary fuel filter.

If you have never had a fuel heater, and the fuel filters are clear, and the problem never occurred prior to this year I would start shopping for a new VP44. A checked or eroded delivery valve will exhibit the same cold start symptoms.

The 97 Dodge with the cold start stall is likely a plugged screen in the fuel heater, or the fuel heater not functioning at all. Again, check it to see that it is cycling.

In both cases I assume the fuel hoses are nearly new and not the originals.

 

(97 2500 ctd) i have recently (last summer) had my lp and fuel heater out; replaced a failing lp and cleaned out the heater. i don't remember a screen though? could be the saki, but if there was one i would have cleaned it. wanted to replace the heater unit just as a precaution cause it's old and i had it out but the part is no longer available, as far as my cummins shop (north denver) says anyway. so i really don't know if it's functioning or not. there is a fluctuation in the voltage meter (and lights etc) during cold weather, so i had assumed the fuel heater was functioning, but i suppose it could be drawing power but not heating fuel up sufficiently??? would a bad heater explain these symptoms though? it happens even when it's not that cold and my diesel is treated for cold

 

oops.. forgot to mention...i don't know how old my fuel hoses are. have had the truck less than 2 yrs. that's why i was guessing at a fuel/air leak

 

On the 97 you have a fuel delevery problem, I am assuming that you have already changed the filter and overflow valve if you haven't you need to, and also try changing the fuel lines. Have you ever cleaned the fuel heater screen if not try that to. What kind of injectors are you running?

 

I had this problem on a 97. It ended up being a grid heater relay. I would check into it.

 

farmer dave,
do you mean the air intake grid heater or the fuel heater relay?
thanks

 

oooooh, i remember the screen now. i put a new one in when i changed my lp, but between then and now there's been some really cold weather, so if the fuel heater's not working, ther could be wax crystals plugging the screen? and the filter too, i guess. does anyone know, once those crystals form, what temperature is required for them to return to liquid? the only reason i wasn't thinking this is because i have had this problem before and when the fuel filter is plugged up, it won't run well at all at any time or speed. always feels bogged down and low on power and if it's really bad just won't run. currently however i have a normal idle and full throttle response once the initial start-up episodes are over. i will try changing my fuel lines, filter, and overflow valve. hopefully one of those will be it.

 

ps. stock injectors as far as i know

 

I was talking about the air grid heater. It wasn't the grid heater that was bad, it was the relays. You might have a bad relay. You need to check the voltage at the grid heater when the wait to start is on. I am not sure what the voltage should be though. Maybe someone else knows the answer to that.