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Weird cold start issue; Truck starts fine, idles for a bit, then dies, then starts

M

mgray

Member
Messages
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Location
Vancouver, BC
So this has now happened a few times(like 3), and only this winter on cold starts(around 0c/32f). So it's not even that cold.

Truck will start strong and quickly on the first try, idle fine for a few seconds, then bog down and die like it's running out of fuel. I never push on the pedal to see if that makes a difference. I just let it die, then start it back up. Sometimes it takes a few try's to start again, but it will start again relatively quickly, then continue to run normally after. Sometimes it will start right up the second time I try.

I live in Vancouver, so temps don't really get too low, -5c on cold days, -15c on really cold days, but those are rare.

This issue I think has happened at temps above 0c, like 5c or so as well.

Doesn't really sound like fuel gelling as I don't think it's that cold, and she always starts strong and quick, it's just like 10-20seconds after start, it will run rough like it's running out of fuel, then die. Again, only about 3 or so times it's done this.

PMD is Heath, and this issue is only on certain cold starts, never hot. GP's are Bosch and I think the previous owner did them 3 years ago? Anyways, I don't think it's the GP's either as she always starts strong.

It's like something is restricting fuel or something after initial start.

This is the first year I've added 2 stroke oil, and I don't add much, like 230ml(I fill up a Stanadyne performance bottle 232ml I think). I think this problem has happened since I started using it. Not sure if it's connected.

Any ideas? Thanks in advance
 
IMO not glow plugs as it starts. It does sound like fuel gelling, summer fuel will gel at above freezing temps. One would have to find out what your fuel is rated for as it is blended throughout the winter months. Another possibility is the fuel filter, cold thick fuel may not pass as easily.
 
Thanks guys I'll check the filter, I think it's only at most 1.5yrs. Could bad OPS cause this? I get weird spikes on my dash OP gauge, especially when cold. But last time I checked LP(maybe 3months ago) flow was strong at idle. Maybe my fuel heater isn't working, or is weak?

I'm going to let it sit over night as it's another cold one for us here @-5ish. I'll try to crack the t-handle right after she starts in the morning and see what I get or what happens.

thanks again
 
In a 96 no, it has dual power OPS & PCM you have to lose both for that to be the cause, but bad or weak lift with a dirty fuel filter especially over 1.5 years since last change it a distinct possibility. Change filter and run lift pump checks would be my 1st course of action.
 
Turbine Doc said:
In a 96 no, it has dual power OPS & PCM you have to lose both for that to be the cause
Click to expand...

Not doubting you TD, but I've heard a few times 96 was a cross over year for the PCM with OBD1 and OBD2?? My built date is Dec 22 1995, so other than it being a holiday lemon(which I'm sure it is), is there a chance I still have some OBD1 systems?

I do get the cheapest fuel around so the filter is definitely suspect like you said, so I'll hopefully pull it tomorrow and take a look. I do regularly drain my filter and get little bits of crud out, but it still doesn't seem like much crud.

thanks again
 
1.5 yrs is fairly long between filter changes, most of the crud is most likely trapped by the filter.
 
mgray said:
Not doubting you TD, but I've heard a few times 96 was a cross over year for the PCM with OBD1 and OBD2?? My built date is Dec 22 1995, so other than it being a holiday lemon(which I'm sure it is), is there a chance I still have some OBD1 systems?

I do get the cheapest fuel around so the filter is definitely suspect like you said, so I'll hopefully pull it tomorrow and take a look. I do regularly drain my filter and get little bits of crud out, but it still doesn't seem like much crud.

thanks again
Click to expand...

Should be fully OBD II by then, when you have codes read are the 2 digit or 4 digit codes ? Jumpering the diagnostic port pins A-B to make check engine blink to capture codes 2 digit is OBD-I, if codes have to be read with a scan tool and get a 4 digit code you are OBD-II, also look at your PCM is the case solid or have a small opening so chip can be removed, if that is the case it's OBD-I, OBD-II is solid case and no chip access portal in the box.

Look for the lift pump test run jumper pictured in the fuel system testing thread in the TRL OBD-I doesn't have that jumper in the harness
 
mgray said:
I do get the cheapest fuel around so the filter is definitely suspect like you said, so I'll hopefully pull it tomorrow and take a look. I do regularly drain my filter and get little bits of crud out, but it still doesn't seem like much crud.

thanks again
Click to expand...

That is visible crud, if you have that much visible, then I'd surmise also some 5 micron stuff with it and that is the fine stuff that really clogs a filter for low performance/starvation, which is why I run/recommend a primary & final filter to let the primary to "sift" the big stuff 10 micron & larger so the on engine (5 micron) isn't battling all debris. The primaries are larger physically and have ability to hold more crud than the OEM one trying to do double duty filtering large & small stuff.
 
As usual TD, you are a great wealth of info and I really appreciate your knowledge!!

I was running a little late this morning so I didn't have the chance to set up properly for my fuel flow test on the initial start. Well same thing happened this morning tho. Started fine, ran for 20 or so seconds, started stumbling and died. I pushed the pedal this time as soon as rpms started dropping and it didn't do anything other than maybe make it die sooner. Took about 4 more try's (5sec cranks) before she started again. Once she was running again I jumped out and turned the t-handle. I seemed to have to turn it a bit more than normal to get flow, and the flow wasn't too strong, but it was flowing. No effect on the idle as I opened it, and no dirt was seen. Truck started and ran fine rest of day.

It's still below freezing here and being new years eve I'm not going to pull the filter today. Going to wait for a better day.

So the t-handle drains before the filter right? If it drains before the filter, lets say my filter is chocked full, and my LP is strong...wouldn't I get good pressure out the t-handle as the pressure has no where else to go(can't go thru filter as its full)?? With a new filter, pressure can now flow thru the filter, so my t-handle pressure would be slightly less than with a clogged filter, no?

Also the fact that I don't seem to have any performance issues makes me question if it is really the filter? Mind you I don't really tow or push it hard so it may not be showing itself this way.

I feel the cold is a main factor

Anyways, this is just all for discussion till I see what my fuel filter looks like

Thanks
 
I had the same problem. Stalling 25 to 30 seconds after a cold start. It did it everyday for 2 weeks. I took the piston out of the fuel shutoff solenoid and it hasn't stalled since. That was a week ago. I just took out the piston because I was too lazy to do a proper voltage test on the solenoid to check if it got enough power to open fully. No problems since, but I haven't run it all that much since I'm on vacation for the holidays. Now I'm changing the glow plugs, the controller and the harness. I'll probably test the solenoid when I'm done with that.
 
Awesome, thanks for that. I'll check it out as well, although I'm not exactly sure where the shutoff solenoid is, how it works, or how to test it with my multimeter?? If you could please tell me how to test it and what values I'm looking for that would be most appreciated. Sounds like we have the same issue, and as much as I'd like to think the fuel filter is the problem, something just tells me it's not.

Thanks again

PS. Again I'm not sure how exactly the fuel shutoff solenoid works, but if you took the piston out to prevent it from killing the engine, how do you shut off the engine??
 
So what does the plunger do? closes to block fuel when voltage is removed? I'm just trying to picture how cold would screw with this thing causing what I have?

And how else does the PCM kill the engine if the FSS is deactivated?
 
The fuel shutoff solenoid is redundant. It mechanically closes the fuel flow to the injection pump. But since the injection pump is electronically controlled, it if perfectly capable of shutting itself off and stopping fuel from going into the cylinders. It was necessary on mechanical fuel pumps.

The solenoid is very simple. If it gets power, it lifts a rubber plunger off it's seat to permit fuel flow. If the voltage is too low, or there is some other problem, the plunger will not lift high enough to let the fuel go by... thus stalling the engine.

This is not proven, but I think that the rubber plunger sticks to the seat, and when you start the engine, the prime cycle from the lift pump gets in a little fuel throuth the space between the rubber sealing face and the plunger shaft. This allows the engine to idle for a couple seconds. When that is all used up, the engine stalls. The vibration from the running engine unsticks the plunger frome the sealing face, but the negative pressure from the fuel pump is holding the solenoid closed. When the engine stalls, thee pressure releases and the plunger is free to lift off it's seat, so it starts up fine on the second try. Like I said, this is just my hypothesis on what may be happening.

The problem can be in the solenoid or electrical, but for now it runs fine with the plunger removed.

To remove the plunger, just unplug the connector, unscrew the solenoid from the injection pump and remove the small circlip that holds the plunger in there. Reinstall the solenoid and reconnect the harness to make sure the computer doesn't throw a code. It's a 5 minute job if have snap ring pliers with small enough tips. I didn't so it took me 10 minutes since I had to wrestle the snap ring out of there with the wrong tools.
 
Ok, seems that the problem wasn't with the fuel shutoff solenoid. The engine started acting up again last week-end and this week. In the last couple of days, It's been hard to start, but as soon as it catches, it runs good. Sometimes after 30 seconds, it would just die, but start right back up. If I left it for 10 minutes, like picking up the kids at daycare, it would need 10-15 seconds of cranking to start. Seems that the problem is still fuel related. Last week I changed the glow plugs, controller and glow harness. This week I changed the fuel filter. I don't have a fuel pressure gauge, so I just went ahead and replaced the lift pump also since I had one on hand. Now I have good flow at air purge and water drain. I can hear the LP running when I turn the key, and when I stop cranking, it keeps going 3 or 4 seconds until oil pressure drops back to zero. The starter spins the engine fast, but it won't smoke or cough like an engine that's too cold or too slow to catch. It's just not getting fuel. I even tried cracking an injector line to check for fuel and got nothing. So that means that I may have a bad FSD or a bad IP. I'm going to take the FSD out of the bumper and try it direct on the IP harness to test if the extension is the culprit. If it still won't start, I'll have to order a PMD as I don't have a spare.

I'll post back with results later.
 
Yeah I gutted the FSS and changed fuel filters and it's still doing it. Only when temps drop to freezing, and only first thing in the morning. If temps are 6-10c it won't do it.

Any more ideas?
 
How about the fuel heater, when its cold out your oil and your fuel can become sludge. Try turning the ignition on, letting it cycle the glows but leave the ignition on for a few minutes without cranking. Go see if the fuel filter manager is warm, and then try to start it, cycling the glow plugs again and cranking.

It is also very possible the stepper motor is sticking and not advancing the injection at all, a scanner would show you this in the seconds that it is running if its advancing.
 
Sometimes I need to give a little throttle to trigger high idle (stepper advancment).....can stepper motor be changed?

Or.....what would be the problem, other then sticky stepper motor?

sorry for the hijack
 
Sometimes the PCM gets hung up as well on the rpm table for idle and to get it into cold idle you have to tap the accelerator, so it relooks at the idle table for the temperature the CTS is showing.

The stepper motor for advance itself can be changed, its external, exposed to elements. Although something inside the IP may also stick, someone that has taken one apart could comment on that more. Reving the engine can correct it as the additional IP housing pressure affects the stepper, and the PCM commands greater advance. On a scanner, you would be able to see desired injection timing and compare that to he measured injection timing value. Sometimes the measured could be stuck at base timing until stepper comes to life.
 
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