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Car fuel pump


756puller
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Got a 99 Mercury cougar I've been fighting for a while. When it's probably below 35 degrees it won't idle. I have to keep it wound up to keep it running. It's throwing codes for bank one and two are lean. I've checked fuel pump pressure and it's right at 30 psi at an idle. I'm at a loss of what to think next, I'm leaning towards oxygen sensor but I'm not 100 percent sure. Can a fuel pump throw fits when it gets Cold out?

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If the fuel pressure is at spec it ain’t the pump.  I had a fuel pump take a dump, it would act up more when hot, would idle just fine, part throttle was fine, ask for full power and the pressure would drop off, engine would cut out like the ignition was getting switched on/off.  It was a Nissan 5.6, and those infinitely wise nitwits don’t put a pressure test port on the fuel rail.  Idiots.

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23 years old hoses may be getting crunchy.  As NomoreJD says, you can spray brake cleaner or ether, careful with ether, on suspect areas including the intake manifold.

It's tough to do much troubleshooting with only a code reader as it tends to load the parts cannon to blast at it. I've got an inexpensive Autel that's been good enough for my kid's BMWs but they've been reliable cars so far. For GM I have a Tech2, which is bi-directional and pretty descent but obsolete after '13 so when we replace the current vehicles I'll need something newer/better.

There may be a forum out there for your vehicle/engine that may help.

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14 hours ago, 756puller said:

Already did a new EGR valve and new ignition coil. Started it up today when it was maybe 45 degrees out and it ran perfectly.

When it is cold out does it smooth out once the car warms up? I had an intake hose not in place underneath where I couldn’t see it, fortunately it caused running issues before I dusted anything, but symptoms were similar, it was causing MAF sensor to get all out of whack and lean things out. 

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39 minutes ago, 756puller said:

It does not smooth out when the car gets warmed up, seems like below 30 degrees I have to keep my foot on it so it will run, it wouldn't idle by itself.

 

39 minutes ago, 756puller said:

It does not smooth out when the car gets warmed up, seems like below 30 degrees I have to keep my foot on it so it will run, it wouldn't idle by itself.

Starting fluid or carb cleaner sprayed around will help you find your issue i bet

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On fords of that era the first step when you have a drivability problem is to clean element in the mass air flow sensor. They are very sensitive to any type of contamination and will cause all sorts of running issues. 

It's not a guaranteed fix but it's a very common fix, and its free.

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33 minutes ago, gearheadmb said:

On fords of that era the first step when you have a drivability problem is to clean element in the mass air flow sensor. They are very sensitive to any type of contamination and will cause all sorts of running issues. 

It's not a guaranteed fix but it's a very common fix, and its free.

And on some of them, you can lightly tap the mass air flow sensor and if going bad, engine will stumble, those early computers are in open loop mode when you first start the car, so they are really only looking at crank position sensor for timing and temp sensor for enrichment.  Vacuum for fuel pressure regulating, a cracked intake hose, or other lines be my first check.  Good luck 

Mark

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1217962610_Screenshot_20221127-121615_SamsungInternet.thumb.jpg.d2c29bdf964d34f29141564427ea9eb0.jpg

First step in diagnosis is getting something to see what sensors are reading what values. Without that info, you're just doing a driveby shooting. 

An adapter like above that works with whatever phone, tablet, laptop you have via Bluetooth, and a free app/program will get you said info.

 

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It is pretty hard to find a vacuum leak by listening for a change in engine sound when spraying ether or carb cleaner. The computer will compensate for the added fuel entering from the leak and cut back on the injector pulse width. If you have a scan tool to monitor the injectors you will be able to see when you find the leak.

 

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