Stumped!

[Will Help]

Fuel molecules becomes denser in cool weather and not only pumps better that way but performs better in the engine. That is why racers use fuel cooler cans, that the fuel line runs through ice in coils, to keep the fuel in optimum temperature range.

Hot fuel is less dense and even vaporizes in hot fuel lines sometimes resulting in vapor lock at the engine. The pump cannot pump vapor as it compresses too easily. Kind of like having enough air in a tire to mke it round and then putting the car on the ground and the air gets pushed to the other side leaving one side flat.

If the pump is weak, the fuel pressure is less when the engine is running because you have open the other end of the system by the injectors squirting fuel and the pump may not be able to keepup/maintain the same pressures.

[shorod]

Additionally, electric motors tend to have more issues when they are warm, either from connections or windings expanding and going open circuit, or from the short brushes making intermittant contact. Starter motors failing when hot may be a more familiar example....

-Rod

[82Stang]

So do you think changing the fuel filter will affect anything or is it pointless since the fuel pressure is what it is?

Don't want to keep throwing money at it if I don't have to. I'd rather concentrate on getting a fuel pump.

Thanks for the responses!

[Will Help]

Always good to change the fuel filter when changing the pump anyway. Distrubing the lines and tank ifyou drop it can compromise a questionable filter. Start with a clean slate!!!

[danielsatur]

Originally Posted by Will Help

Any body out there think the Cat could be plugged???

Check back pressure on Catalytic coverter,by taking the pre oxygen sensor
out of CAT and checking back pressure.

There should only be a few lbs. of back pressure.

If it's plugged ,it's like trying to drive a car with a potato in the exhaust pipe. ''No Power''

Will Help - knows what were talking about!

BAD CATALYTIC CONVERTERS:

If its plugged - it will not throw any codes.
Converter gets very hot,loss off Pwr,and stalling.

If it's Blown - Catalyst effeiciency error P0420/P0430
Poor EPA Emissions + fuel economy.

MCGIVER

[Will Help]

You can also listen at the tail pipe. A plugged cat/muffler gives a sound like trying to force air through a bent straw. Kind of like pressing your lips together and blowing hard. Doesn't have that nice hollow, clean flowing sound.

Sorry that this process is taking so long to fix your problem. It isn't as easy to trouble shoot when all we can touch are computer keys. I'm a kinda hands on mechanic myself. All we can do is work with your information and we all know that heresay information won't stand up in court!!!!

[82Stang]

Originally Posted by Will Help

You can also listen at the tail pipe. A plugged cat/muffler gives a sound like trying to force air through a bent straw. Kind of like pressing your lips together and blowing hard. Doesn't have that nice hollow, clean flowing sound.

Sorry that this process is taking so long to fix your problem. It isn't as easy to trouble shoot when all we can touch are computer keys. I'm a kinda hands on mechanic myself. All we can do is work with your information and we all know that heresay information won't stand up in court!!!!

Well thanks for those suggestions. I am a hands on mechanic myself, but been struggling with this intermittent problem for some time. Plus, I just got the right tool, that helps. I'll check the exhaust out anyway, sure it's fine though. But how can I be sure it is one and not the other(i.e.fuel pump or cat)?

[danielsatur]

Some fo these discount AutoParts will rent tools cheap!

Focus on Cat 1st.
1) Need a compreshion Tester guage. (Rent)
2) Jack-up/Rampup frnt of car.
3) Remove oxygen sensor on pre Cat side (the one closer to Eng.)
4) Screw the compreshion Tester guage in the oxygen sensor hole.
5) Start car Engine,and than turn it off.
6) What does the guage read?
7) How many lbs. ?

Note: My hearing isn't as good as will help too!

I guess it's like your car trying to Fart.

CAUTION - If your stuck in traffic behind one of those cars,turn
your Air-Cond to recycle cabin Air or you will die.

Hey!
After so much gas,you might want to change your shorts too!


MCGIVER

[82Stang]

Ok, got a used fuel pump/sending unit assy from the boneyard. Had to go with the $20 version vs the 200+ for new. But being smart about it before I do install it. How do I test this fuel pump out of tank to make sure it is good before going through the whole process of putting it in and hoping it works? Can I put power to it to make sure it works?

Knew the pump was low so started with that because I can check the exhaust later. I didn't experience any problem over the Winter months at all, that's why I'm thinking it is fuel related when the weather turned warmer.

Thanks

[Will Help]

If the car you got it from was there as a result of an accident, you can be 90% sure it is OK because the car was running at the time of the accident. If there was no damage to the car, then the mechanics of it become questionable. Why is it junked???

You can test it by temporarily jumping it just long enough to see if the pump runs. Make sure there is no gas in it that could be ignited by a spark.DO NOT LET IT RUN DRY FOR LONGER THAN A SECOND OR TWO!!!Running a car out of gas is a major cause of fuel pump failure.

Even though the pump may run dry is still not an indicator that the impellor assembly is working properly. Wet test would be best. DON'T STICK IT IN A BUCKET OF GAS!!! They will pump water though. You can temporarily stick it in a bucket of water for a short ( couple of seconds again ) test and drain it as best as possible before installation.

[danielsatur]

Hey!
Don't forget what elements you need for a Fire!

If that CAT is plugged,you won't get oxygen for FIRE.

Try to run up a hill with your mouth close (Exhaust) and fingers up your nose (MAF),and see how far you get.!

Keep it Real on AF!

If you need a pix,see DEI system :Automotive Forums > Mercury > Grand Marquis -
New gas saving devise.

Lets get to root cause,so we can close thread.

MCGIVER

[shorod]

If we are going to get to root cause and find a catalytic converter is the problem causing the poor running now, there will be something that caused the converter to fail. They shouldn't fail on their own, but rather due to an improper air/fuel ratio.

-Rod

[Will Help]

Shorod, think back to the beginning of this. It is a 96. A cat is typically suppose to last 100,000. This one is at least 12 years old. I have a 2000 with 165,000 and a 2002 with 181,000. Could just be old age.

Kinda like at home...only so much gas can pass before the trouble starts!!!

[82Stang]

Well, after I get the pump in and road test, I'll post back with the results!

[danielsatur]

Didn't you say it's your Mom's car?
What kind of driving Highway/City?
How many miles are on the car?

We put EGR,and PCV Gase's back in the Intake,and the catalyst is the CAT.
This is a simple Test, and it costs around $20 @ a muffler shop.
I would do it yourself just for the experience.

If this isn't,the problem than we can focus on possible fuel related problem.

The car is getting older & Ain't ''AS GOOD AS ONCE WAS'' - Toby Keith

MCGIVER