Difficult Cold Starts

[Banditt76]

I have a 2003 V6 Auto Mustang with a ProCharger 11 psi complete supercharger kit installed with BBK Shorty headers, BBK 65mm throttle body, 42 lb injectors, 340 lph fuel pump, off-road h-pipe, dual exhaust, SCT 90mm MAF and custom dyno tune. Since last November I have had trouble starting the car first thing the next morning after it has been sitting overnight for 12+ hours. I have done some maintenance such as replacing the battery, spark plugs, Royal Purple engine oil, ProCharger supercharger oil and K&N fuel filter. The first startup of the day sometimes takes up to five cranks to get the engine to fully turn over while also having to supply some gas pedal so it doesn't stall. The rest of the startups during the day startup just fine. I tested the battery and alternator and both are fine. Not sure if the cold weather overnight is the main cause or not. The car always sits outside as I do not have a garage unfortunately. It can get into the single digits sometimes here. I cannot change any tuner options with the SCT tuner as the dyno shop locked all those options out. Any advice on what else I should check?

 

[ttocs]

first I would check fuel pressure. I had a similar problem where it just wasn't supplying enough pressure.

Did the procharger kit require the battery to move to the trunk?

 

[Banditt76]

The fuel pressure looks fine at around 40 psi at startup. The battery is in the stock location.


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[ttocs]

Ok good. I have learned in my tuning education(I am not yet youtube certified) that giving it gas while cranking actually just adds air. If it were me on my holley efi I would adjust the IAC open a little more.

 

[Banditt76]

I adjusted the IAC, but it still has problems when overnight temps get into the 30s or below. Could this be a cold startup issue with the starter? It starts up fine after the first cold startup of the day. Can’t diagnose afterward until the next cold startup a day later minimum.


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[ttocs]

next time its cold try turning the key on and wait 5 secs while the pump charges, then turn the key off, and then back on for 5 secs. When you hear the pump stop priming then turn the key to start.

 

[Banditt76]

Tried that today, didn’t help at all.


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[ttocs]

so it shouldn't be fuel then. I wonder if the AIT maybe isn't reading correctly and throwing things off on the air/fuel mix when cranking, assuming there is spark from the start?

 

[skidoo]

next time its cold try turning the key on and wait 5 secs while the pump charges, then turn the key off, and then back on for 5 secs. When you hear the pump stop priming then turn the key to start.

Were you thinking fuel pressure was bleeding down? If fuel is bleeding down through an injector maybe it's dumping the fuel into the cylinder when it sits overnight? Is there a Schrader valve to put a gauge on and let it sit overnight, then check to see if it bled down?

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[Banditt76]

Were you thinking fuel pressure was bleeding down? If fuel is bleeding down through an injector maybe it's dumping the fuel into the cylinder when it sits overnight? Is there a Schrader valve to put a gauge on and let it sit overnight, then check to see if it bled down?

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I’ll try that. I think it does have something to do with the air/fuel ratio.


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[RAU03MACH]

Were you thinking fuel pressure was bleeding down? If fuel is bleeding down through an injector maybe it's dumping the fuel into the cylinder when it sits overnight? Is there a Schrader valve to put a gauge on and let it sit overnight, then check to see if it bled down?

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then the engine would hydro lock at that point

 

[skidoo]

then the engine would hydro lock at that point

I guess it all depends how many CC's of fuel leak down. 5 or 10 cc wouldn't hydrolock an engine if there's 74cc of combustion chamber, deck height and head gasket. But it sure could make it hard to start.

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[ttocs]

I thought that it could be leaking down but if charging the line 2x before starting it does not clear the air I am not sure how much is leaking back. That is why I considered the AIT. If it was not reading correctly the IAC would not be in the correct position which could be with cracking the throttle open a little gets it going. It could even just be the harness going to it as I had a problem with the harness on my tps sensor. Hell it could be the tps, if you have a volt meter its not hard to test that.

 

[TrickVert]

I'm going to weigh in on this with a discovery on my car. I've been having trouble for a long time with initial cold starts. If the car sets for a few days or a week, it will crank, crank, crank, crank, sputter, sputter, sputter, sputter..... then either catch and run normally, or die, and I have to crank again. Second cranking is less than the first, but it will usually still sputter a bit before catching. One day I figured I would just prime the sh!t out of it. I twisted the key from off to run to off to run at least 15 or 20 times. On the last one. I cranked it, and it fired right up! The next time I experimented, I listened closely to the sounds of the pump priming. For a number of cycles, I heard bubbling sound in the tank as soon as the prime cycle ended. Once that sound subsided, I cranked the car, and it again came to life immediately. Somehow and for some reason, my fuel rails/lines/something are ending up empty of fuel. I have no obvious leaks, but do occasionally notice a slight fuel odor in the garage several hours after returning from a drive, so one of my AN fittings is apparently seeping, but just barely. That should not by itself be enough to cause the lines to go dry, but if the fuel is vaporizing to some degree, giving that pressure somewhere to go before the fuel cools and re-condenses *could* be culprit.

 

[ttocs]

There is a small hose that is inside of the tank that goes from the pump to the hat that can get a leak in it and when it leaks it leaks back into the tank so you never see it. That sounds like this case.

 

[RAU03MACH]

I once had a 88 f150 that had a leaking problem soon as I hit the key
The engine turnd over and locked up
I started checking everything
I pulled the plugs and killed all the power on it
Turned the engine by hand lol fuel pushing out big time

 

[skidoo]

I once had a 88 f150 that had a leaking problem soon as I hit the key
The engine turnd over and locked up
I started checking everything
I pulled the plugs and killed all the power on it
Turned the engine by hand lol fuel pushing out big time

Yup we had a customer bend a rod from a stuck injector on a 4.0 ford.

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[TrickVert]

There is a small hose that is inside of the tank that goes from the pump to the hat that can get a leak in it and when it leaks it leaks back into the tank so you never see it. That sounds like this case.

If this is in reply to me, ttocs, BTDT, but I don't think that's the problem here. When that little hose split, it resulted in fuel loss at higher RPM, but not in normal driving. That was a PITA to troubleshoot.

 

[ttocs]

If this is in reply to me, ttocs, BTDT, but I don't think that's the problem here. When that little hose split, it resulted in fuel loss at higher RPM, but not in normal driving. That was a PITA to troubleshoot.

yes but the bubbling sound in the tank makes me wonder.