98 v85.0 hard starting when cold

[jerryls]

I have a 98 explorer V8-5.0 with 150K miles on it. When it's cold it cranks and cranks but doesn't start. If i finally get it to start in runs fine. If i warm it up and shut it off it starts up right away. It's only when I let it sit overnight or for a long period it doesn't start. Another clue may be, but then it may be unrelated,.. it now sometimes has the temp gauge go up beyond normal. This isn't consistent, so I'm thinking I should change the thermostat.

I tried changing the fuel filter as I don't think it was ever changed, but that didn't help. Any suggestion would be appreciated.
Thanks

[shorod]

You should try pressing down on the accelerator pedal slightly next time you attempt a cold start. If it seems to start easier that way, the Idle Air Control (IAC) servo is probably the issue. That's a pretty common issue. With the engine running you could also turn the steering all the way to one of the locks and see if it bogs the engine down or even causes it to stall. If so, that's another indication the IAC is not working as well as it should be.

If holding the throttle open slightly doesn't offer an improvement, then the Engine Coolant Temperature (ECT) sensor may be the issue. Cold starts require a different air/fuel ratio for efficient starting. Don't automatically draw a connection between this comment and the temp gauge though since Ford typically has a sensor for the PCM and a separate sending unit that feeds the gauge.

-Rod

[jerryls]

Originally Posted by shorod

You should try pressing down on the accelerator pedal slightly next time you attempt a cold start. If it seems to start easier that way, the Idle Air Control (IAC) servo is probably the issue. That's a pretty common issue. With the engine running you could also turn the steering all the way to one of the locks and see if it bogs the engine down or even causes it to stall. If so, that's another indication the IAC is not working as well as it should be.

If holding the throttle open slightly doesn't offer an improvement, then the Engine Coolant Temperature (ECT) sensor may be the issue. Cold starts require a different air/fuel ratio for efficient starting. Don't automatically draw a connection between this comment and the temp gauge though since Ford typically has a sensor for the PCM and a separate sending unit that feeds the gauge.

-Rod

Thanks Rod,
I tried all sorts of things with the gas pedal, pumping it, flooring it, not touching it etc, and it doesn't matter, so maybe it's the ECT sensor. About how much does that cost and is it difficult to change? Is it an electrical connection that I can disconnect to use default values to see if it starts better?

Also, out of curiosity what does the steering wheel position have to do with the IAC?
Thanks Again,
Jerry

[shorod]

The ECT is probably around $20 at your local auto parts store. It has an electrical connector and is threaded in to the head and is directly in the flow of coolant.

The IAC increases throttle to compensate for varying loads on the engine, as well as the cold idle function. With the steering at one of the lock on a car with convention hydraulic power steering causes the pump to load the engine. The IAC should increase bypass air to compensate for the load and prevent the engine from stalling.

-Rod

[jerryls]

Thanks Rod,
It's cheap enough to change. Should i try disconnecting the ECT first to see if the car will start?
Thx,

[shorod]

I'm not a big fan of suggesting people just shotgun parts. If you have access to a scan tool with a datastream mode it would be pretty easy to see what the ECT is reporting for coolant temperature. If you were to check the coolant temperature on a cold engine you should be withing probably 10 degrees of the outside air temperature.

Since all those positions of the throttle didn't improve the way the engine started, did you try spraying some throttle body cleaner in to the throttle body to see if that will cause the engine to act like it wants to start? If that makes it sputter or start, then find a fuel pressure gauge with the Ford adapter and check the fuel rail pressure. If the fuel rail pressure is within specification, you might want to look in to the crankshaft position sensor (CKP).

-Rod

[jerryls]

Rod,
Thanks- im not a fan of the shotgun approach either. There's nothing more frustrating then changing a part and finding out it wasn't the problem. i only have a scan tool that reads the fault codes. I'll try the spray to see what happens. Would the CKP sensor only cause it to not start cold though? Recall when warm it starts right up.
Jerry

[shorod]

The cold start issue seems most indicative of an IAC issue, but you have come close to ruling that out. The CKP is a hall effect sensor. Thinks contract when cold, expand when hot. If there were a solder joint or broken wire in there, when cold it could contract and go open circuit. The same can happen when hot, and seems to be a more common failure mode, things expand and no longer make good connection. Similarly, fuel pumps can fail or not work quite correctly during temperature excursions. From my experience they tend to act up more when hot and after being run, but that's not to say they will never show signs of failure when cold. You're kind of in a situation where you can buy more tools to reduce the chances of buying parts that are not needed - and having the tools for future troubleshooting, shotgun parts, or take it to the shop and pay them to use their tools to diagnose it. I do appreciate that you are applying logic and asking good questions versus just changing out parts starting with the least expensive.

I trust you've used your code reader to check for pending diagnostic codes.

-Rod

[jerryls]

Thanks- As soon as I can get it in my garage to work on it, I'll check all this and let you know what it was. It's too cold out here it NJ to work outside. i appreciate all your detailed repsonses!

[jerryls]

hi Rod,
I finally got to look into this and although I havn't solved the problem, I think it's the fuel pump. I am not getting any gas. if I spray starter fluid in the air intake it starts and runs as long as I keep spraying. I checked the 20A fuse and pump relay and it checks out. I then went to the collision shut off connector and measured the voltage. It measures only around 9.2V when cranking. I see the volatge on the pink and black wire that goes directly to the pump. I jumped 12V directly to the pink wire(with the connector disconnected) and I don't hear the pump running. It seems to me like the pump is bad, but please comment on this.
Thanks

[shorod]

It's certainly sounds like the fuel pump is the culprit, but it might be in your best interest to check for fuel pressure when you jumper battery voltage to the fuel pump just to be sure the fuel pump isn't running.

The low voltage at the pink/black wire could be due to a dirty connection. What voltage do you measure to the inertia switch on the dark green/yellow wire with the switch disconnected and the key first turned to the run position? Now with the connector plugged in to the switch, what voltage do you measure on the dark green/yellow wire for the first second after turning the key to run? If you are getting considerable drop through the switch, that could be your problem. If the fuel pump is causing a huge drop in voltage, there's either a bad connection somewhere or the fuel pump is faulty.

-Rod

[jerryls]

[quote=shorod;6873058]It's certainly sounds like the fuel pump is the culprit, but it might be in your best interest to check for fuel pressure when you jumper battery voltage to the fuel pump just to be sure the fuel pump isn't running.

The voltage is 12V on the gr/y wire, until I connect or jumper in the pump. I tried swapping the fuel pump relay also. I'll check the wiring and connector to the pump, but I already purchased a new pump for $66 from RockAuto, since the car has over 150K miles anyhow. I'll let you know after I change it. Hopefully that's it.
Thanks Again,

[shorod]

Good luck!

Do you happen to have a current meter that you could use to determine how much current is flowing to the fuel pump? The fact that voltage at the inertia switch drops concerns me a bit that it could be due to a poor connection. However if you were the find there is 7 amps or something flowing to the fuel pump that would help convince me that the wiring is not the problem and the fuel pump is the likely culprit. However if the voltage is dropping and the current draw is only 0.1 Adc or so that would strongly point to a poor connection between the source and the pump.

-Rod