Uh oh . . .

[anupaum]

Ok, it's been a while since I've been here, but now I have a PROBLEM!

My truck is having trouble starting when it's cold. If I can get it going, it will start repeatedly without trouble, but from a "cold soak," it simply won't fire up like it should. Of course, I can't post any codes because I'm no longer using the factory computer, and unfortunately, my laptop died two weeks ago, so I haven't been able to plug in to the Megasquirt to see what's going on.

It's getting spark, but I'm not sure about fue. I can hear the fuel pump come on when I turn the key. Is it possible that a clogged fuel filter could be causing this kind of trouble?

Any ideas?

robert

 

[Wicked_Sludge]

hmm, maybe try a little squirt of starting fluid in the morning. if it fires right up then you know you have a fuel problem.

i know my escort is a little hard to start in the morning due to valve seals leaking oil into the cylinders. take a little blip of the throttle to get it running and clear out the cylinders.

 

[anupaum]

Well, it's VERY odd. This morning I went out to try starting the truck again and after a couple of reluctant efforts, it fired right up . . . Once it gets going, it's fine and I can start it again without difficulty. This is really strange!

robert

 

[anupaum]

I think I may have narrowed down the issue to my fuel pump. If it won't start, but I turn the key to prime the pump two or three times, it will usually fire up. After 225 000 km and 14 years, it's probably due for a new one.

Can anyone tell me how to check this for certain?

robert

 

[Wicked_Sludge]

check fuel pressure at the fuel rail. you might also check your fuel pressure regulator...if its leaking then pressure wont build up in the rail when the pump primes.

 

[TireIron]

yea, if it works when you prime the pumpa couple of times then it sounds a lot like the fuel pressure regulator is starting go soft. It ends up not holding pressure overnight and takes a couple primes to get it back up to pressure so it can fire up... when you go out in the morning and its cold and wont start, check the schraeder valve to see if it still has good pressure (remember to keep the rag over it because it will spray if it does)

 

[Will]

That is the symptom my 4.0 EEC-IV had when the coolent temp sensor was faulty. It didn't go into cold-start enrichment because it thought it was warm.

 

[shadetree]

Engine coolant temperature sensor.
Throttle position sensor.
Vacuum leak. shady

 

[anupaum]

Ok, I'm still investigating . . .

Fuel pump: Once the truck is running and up to temperature, it doesn't hesitate under load. On Sunday I filled the bed with 500 kilos of barn litter and made it up the hill home without trouble. It seems unlikely that if my fuel pump was going, it would run so well. However, when it's not fully warm, it has trouble maintaining idle.

TPS: My TPS is new. I can check the values with my laptop, but my laptop isn't working right now!

FPR: This is possible. I haven't checked it this morning because I couldn't get it to start, and I don't have time right now to fool around with it. (I'm teaching online in less than five minues.) I'd like to check the fuel rail pressure, but that will have to wait until I have some time between classes.

CTS: Given that the truck has a tough time when it's cold, this seems like the most likely culprit. I COULD check this with Megasquirt, which will report the sensor values to me, but unfortunately, the laptop isn't working right now . . .

Ugh! What a time for the computer to go down! It makes diagnosing this MUCH harder!

Thanks for all the help, gentlemen!

robert

 

[Earl43P]

Well, all is certainly not lost.....

Do a resistance check of the CTS cold, then hot.

I don't know the ohm values for your year, but it should differ considerably from cold to hot. Heck, remove it and heat it in a pan of water on the stove and watch the ohms change, plunge it into ice water, etc.

If you get that, I'd rule it out.


Starts reliably if you prime the fuel pump several times before you crank?

Look for seepage from the fuel filter or FPR (as noted earlier).

Personally, I'd simply keep priming twice in the morning and call it a day. Kinda like my neighbor's clutch. "I can't get it into gear in the morning, then it's fine all day". I told him "Pump the clutch pedal 3x before you start it."

Two years later, he's still doing that. Didn't cost a dime. Still driving fine.

 

[Wicked_Sludge]

if you get the truck started, then turn it off immediatly and it will restart with no fuss, i would doubt its a CTS.

 

[anupaum]

if you get the truck started, then turn it off immediatly and it will restart with no fuss, i would doubt its a CTS.

No, it'll die right away. If I keep my foot in it for a second or two, it'll stay running. It has a bit of trouble idling until it's fully warm, then it idles just fine. It's become much warmer here than earlier in the week, so it's become somewhat easier to start.

I tried getting a pressure gauge on the fuel rail this afternoon, but it was too deep to work with my gauge. It would be NICE to have my laptop back . . . I could diagnose this a lot quicker! However, I'll try the ohm meter on the temp sender.

Thanks for the help thus far, gentlemen!

robert

 

[jdm90]

Anupaum, have you had any luck with diagnosis? I am having the same problem on my stock 94.

 

[anupaum]

Anupaum, have you had any luck with diagnosis? I am having the same problem on my stock 94.

Ok, I got my laptop up and running. After some trouble with the VERSION of the Megatune software I'm running, I got the laptalk to talk to Megasquirt.

My A/F ratio is wonky--it's running REALLY lean. The coolant temp sensor appears to be working. What's really strange are my TPS readings. They should be at 60 when the throttle is closed, but they're up over 200. Shady mentioned that this could be a problem . . .

Now, I have a new CTS and fuel pressure regulator, but I haven't installed either of them in the event that I could diagnose the problem properly. What I'm finding strange about the TPS is that it's the newest sensor on the truck. I'll check the voltage settings and post again when I have time, but I'm so flipping BUSY right now it's hard to find time.

robert

 

[anupaum]

The more I look into this the stranger it gets . . .

I checked the voltage of my TPS. With the throttle closed, it's reading around .9 volts, which seems bizarre given the ADS count from the Megasquirt this morning. But when I got back in and hooked the laptop up again, I got a completely normal ADS count and the injectors shut off when I went downhill, just like they should.

The A/F ratio is WAY off, though. It's running REALLY lean and the EGO correction is bouncing all over the place. The duty cycle on my injectors bounces in direct proportion, so now I'm beginning to wonder if my wideband O2 sensor is shot . . . (I'll try to recalibrate it, first.)

So the coolant temp sensor is working, and the truck is obviously getting fuel (otherwise I wouldn't be able to start it at ALL), but it's still tough to start when it's cold--despite the fact that Megasquirt is recording the engine going through after start enrichment.

I wonder if the wonky reading with the O2 sensor may be causing the truck to run in open loop mode. Does that sound like a viable theory to any of you?

robert