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[Leonardo]

I drive a 1991 xr2 82,000 miles,  began stumbling like running out of fuel or ignition cut out.  Replaced, fuel filter, plugs, wires, cap, rotor, checked timing but still does the same.  Any ideas on what might be wrong?

[Capri-guy]

when does this happen? when the engine is cold or warm? does it run on very low revs (like it's almost stalling) or does it rev at normal idle but in a rotten way?

wires connected correctly?

[Leonardo]

The car idles, but when you drive away it starts to stumble (almost cut out). If you accelerate it runs fine but as soon as you let off the gas and try to cruise it starts to stumble.  Wiring is correct.  At first I thought it was cross wire firing, that is why I replaced the plugs and wires.  The cap and rotor had some corrosion so I replaced them.  Next I changed the fuel filter just because I was running out of ideas.

[Capri-guy]

ok.
next option:

vacuum hoses?
fuel pressure regulator at the end of the fuel line?

maybe this will help:

http://perrya.hubpages.com/hub/Testing-for-1991-94-Mercury-Capri-Fuel-Related-Issues

[Leonardo]

I just pulled the fuel pump.  I noticed I did not have much pressure when system was powered up.  The strainer did not look too bad but to play it safe and since it is all apart I had decided to install a new Airtex pump and strainer.  Just over $100 at Advance Auto Parts.  Should have it back together this afternoon and will update my post.  HOPE this takes care of the problem.......I think it will.

[blueamber]

I gotta say that these fuel pumps seem to work or not work, getting a weak flow is a prostate problem that doesn't usually affect our cars...so are our cars girls???

'If you accelerate and it runs fine' means the pump is delivering plenty of gas, accelerating is when you use the most gas.  Remember, these are electric pumps, in the old days the pump ran off the engine, and a faster engine meant more gas available, not so with the Capri...

Doesn't sound like a fuel issue, more like vacuum leak or bad sensor or lots of other stuff.

Try disconnecting the o2 sensor or the tps and see what happens.  Lots of folks leave the o2 disconnected, not great mileage but the car can run better...Chris

[Leonardo]

Well the new fuel pump and strainer did not help.  The strainer did need changing but probably not the pump so if anyone needs a good used pump for a fair price let me know.  I'll try the o2 sensor tomorrow.  Wanted to take the car to a car show but not running like this.  I'll have to take my bwm with sidecar.

I checked all the lines over for a vacuum leak but everything looks healthy.

[Leonardo]

Well, not the o2 sensor nor TPS.  I'll keep playing with it and hope I figure it out.

[350boatracing]

I'm having the opposite problem as you. It runs fine when cruising but if I stop and put the car in neutral the rpm's jump from 500 to 1000 continuously. As soon as I put the car in any gear even at a complete stop the jumping stops and idle is fine. something screwy.

[Leonardo]

The last thing I tried seems to make it run better.  I disconnected all the sensors, relays and any other thing under the hood and applied a small amount of dielectric grease to improve the connections.  I did find some light corrosion and cleaned that off before reassembly.  Car is running much better now but not yet perfect.

[Leonardo]

I should have added when changing the fuel pump you must change the tank gasket.  I found out the hard way, with age the gasket gets brittle and will not form properly to the tank....you will get a leak when filling up.  I removed the old gasket and installed the Carter PTS2000 gasket and it worked perfectly.

[Rocketman]

I'm having the opposite problem as you. It runs fine when cruising but if I stop and put the car in neutral the rpm's jump from 500 to 1000 continuously. As soon as I put the car in any gear even at a complete stop the jumping stops and idle is fine. something screwy.

Check to make sure the bump-stop on the throttlebody is not holding the throttle plate open. This can cause an oscillating idle.

[Rocketman]

The last thing I tried seems to make it run better.  I disconnected all the sensors, relays and any other thing under the hood and applied a small amount of dielectric grease to improve the connections.  I did find some light corrosion and cleaned that off before reassembly.  Car is running much better now but not yet perfect.

Maybe try cleaning all the grounds on the engine & engine bay?

[Leonardo]

That was the first thing I did plus added dielectric grease to the attachment points.

[Leonardo]

Well I have it running better but it still stumbles a little.  Mostly when the engine temp is below 175 so I am figuring there must be a cold position sensor or control that needs adjustment.  Any ideas?