Crank, No Start: Fuel Delivery Issue?

[mwjscn]

Hi All!

I've been trying to solve an issue with my Mystique for quite a while now and was wondering if anyone on the forum has had a similar experience, or can lend their knowledge toward fixing the issue.

Vehicle:
2000 Mercury Mystique GS
Zetec Engine
85.5k miles
Auto Trans

Issue: Crank, No Start

Presents itself as an issue only when temperatures are below about 40 degrees F.

If the car turns over successfully, it is characterized by a rough idle and surges around 1,000 or 1,500 rpm (coincidentally, the car usually has a very cold start idle of about 1,800) for a couple minutes.

If the car does not turn over, it can be started with starter fluid sprayed directly into the throttle body (still not easy, though. Sometimes it may take more than a single attempt). Car may idle rough until it gets slightly warmer.

Issue is extremely intermittent. Does not happen consistently, even at colder temperatures (does not happen at all during the summer or warmer weather). Sometimes at cold temps it will start and idle without issue.

The in-line fuel filter (under passenger side) is new and was not clogged previously. The car had in excess of 7 gallons in the tank this morning and the engine has never been starved of fuel. The battery is good and the cranking is strong (no dimming of lights or other accessories). A/C is turned off and excess engine belt drag is not an issue. Timing and Serpentine belts are very new. Air filter is new and clean.

Conjecture: I believe the issue lies somewhere in the fuel delivery system, mostly because starter fluid will get the car running. However, the fuel pump can be heard priming the system when the key is turned to On (sometimes I cannot hear it, but in 5 cycles of the ignition to On I could distinctly hear it 2 times this morning). The problem can be somewhat mitigated by priming the system while the car is hot (park, turn off car, cycle ignition a couple of times to have the fuel pump prime the system), but is not a surefire fix and may still result in the momentary rough/surging idle.

The issue at hand simply seems like a fuel starvation issue (no fuel to start car, surging idle is intermittent delivery of fuel). I can only really imagine, even though it seems to be somewhat operating, that the fuel pump is the issue. Are there any other items I should confirm before attempting to swap a new fuel pump in? Are there any relays, connectors, or other electric gubbins that could fit into the description of this issue (I doubted so, since the issue seems mechanically related to temperature)? Could it be an issue with the fuel injectors? If they are dirty and cold will they seize the flow of fuel? Assume everything in the car is original unless otherwise noted.

I have the Ford Workshop manuals and some simple hand tools (medium/small sockets, wrenches, multimeter, screwdrivers, allen keys, etc), so my ability to diagnose everything is somewhat limited.

Thanks in advance.

 

[cclngthr]

I would check the fuel pressure with it cold. If the pressure is low when the pump is cold, it could be that the seals in the pump are not sealing correctly and not allowing the pressure to rise. Also check the IAC valve. Cold start issues sometimes are related to the IAC not working as it should; possibly it may be clogged?

 

[mwjscn]

Thanks for the reply, is there any home remedy to check the fuel pressure level? I would imagine you may need some sort of tool given that the vehicle doesn't have a gauge for that.

Forgot to mention: the vehicle isn't throwing any codes and the CEL has never turned on for this issue. That being said, I'll still look up the IAC in the Ford Manuals. I can check the ohm rating of it with a multimeter and see if it is within the spec. Still doubt that to be the issue considering it idles fine occasionally and never has a problem when warm, but thanks for the feedback!

 

[cclngthr]

Thanks for the reply, is there any home remedy to check the fuel pressure level? I would imagine you may need some sort of tool given that the vehicle doesn't have a gauge for that.

Forgot to mention: the vehicle isn't throwing any codes and the CEL has never turned on for this issue. That being said, I'll still look up the IAC in the Ford Manuals. I can check the ohm rating of it with a multimeter and see if it is within the spec. Still doubt that to be the issue considering it idles fine occasionally and never has a problem when warm, but thanks for the feedback!

No, you need a fuel pressure gauge, which hooks up to the fuel rail at the Schrader valve. You can get those for home use, but they need to be taken care of carefully.

It may not throw DTC's, because the PCM needs time and a consistent trouble issue to throw a code. That said, a flight record of live data using a high scan tool showing fuel trims may show your trim to be at a higher percentage than it should be. With intermittent issue, it won't set codes.

 

[amc49]

There may well be no schrader valve to check fuel pressure as Ford started dropping them on cars around year 2000 or so. The later ones deduce pressure from a pressure sensor rather than a regulator since the regulator is the fuel modulator unit. It speeds up and slows down pump on demand. You either must rig your own entry into the fuel system or electronically read the fuel pressure with a scanner.

Might wanna check the PCV rear hose where it enters low at the back of the intake on a zetec, they commonly can suck a small hole in the side when fuel residues settle in the hose to bubblegum up the rubber. You can then have a small leak that comes and goes over and over to be vacuum leak. That could make some of your symptom there if hole is small enough to still be in hot idle trim available but not cold. Common on zetecs around that year.

You MUST be able to hear that pump initialize EVERY time key turned on or something wrong there. Maybe intermittent power to pump or pump dying.

 

[cclngthr]

There may well be no schrader valve to check fuel pressure as Ford started dropping them on cars around year 2000 or so. The later ones deduce pressure from a pressure sensor rather than a regulator since the regulator is the fuel modulator unit. It speeds up and slows down pump on demand. You either must rig your own entry into the fuel system or electronically read the fuel pressure with a scanner.

Might wanna check the PCV rear hose where it enters low at the back of the intake on a zetec, they commonly can suck a small hole in the side when fuel residues settle in the hose to bubblegum up the rubber. You can then have a small leak that comes and goes over and over to be vacuum leak. That could make some of your symptom there if hole is small enough to still be in hot idle trim available but not cold. Common on zetecs around that year.

You MUST be able to hear that pump initialize EVERY time key turned on or something wrong there. Maybe intermittent power to pump or pump dying.

Solving the fueling issue from key off to key on with a gauge is generally recommended. Most Fords with the pressure sensor also have the Schrader valve at one end of the fuel rail, and if it is not there, techs can remove the sensor and put an adapter for a fuel pressure gauge there to check fuel priming and pressure.

If the pressure is good, the problem may be elsewhere down the line where the A/F ratio is overly lean at first startup. If a vacuum leak is present, the fuel trim readings will show an abnormally high percentage in all conditions. Trim levels should be between -5% and +5%. Normal readings for LTFT is about 2.3%

 

[BrApple]

I would also agree that there is a chance of a vacuum leak.

 

[mwjscn]

Thanks for the great feedback guys, I will try and check for vacuum issues. If you have any more ideas for me to try, feel free to leave them as well. Thanks again!