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AMEDEE
AMEDEE, FORD TECHNICIAN
Category: Ford
Satisfied Customers: 26083
Experience:  ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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I have a 97 ford aspire. I have replaced MAF and TPS. The

Customer Question

I have a 97 ford aspire. I have replaced MAF and TPS. The engine starts fine and idles beautifully. The issue is when I step on the gas. If I gently feather the gas pedal, the engine will rev up just fine. However when I put the pedal at WOT, the engine sputters like it is not getting the correct mixture of fuel and air
Submitted: 9 months ago.
Category: Ford
Expert:  AMEDEE replied 9 months ago.

Hello and welcome!

My name isCustomerand I can assist you with your question.

Expert:  AMEDEE replied 9 months ago.

This condition is caused by an engine breathing issue or severe lean condition. You would need to run some tests to see which one is causing this condition. Checking engine vacuum and fuel pressure would be the first two steps/checks you should do.

Expert:  AMEDEE replied 9 months ago.
Good afternoon. I see you have viewed my last reply but have not responded back. I am just checking in to see if you have any further questions or to see if you still need help with anything? If so, please let me know as I will be happy to help. If I have answered all of your questions, please dont forget to honor the good faith rating system to complete this conversation. Thank you and have a great weekend!
Customer: replied 9 months ago.
any easy way to check fuel pressure without the proper equipment? I assume that that all I need is a pressure gauge to connect to the fuel rail. what is the acceptable fuel pressure range
Customer: replied 9 months ago.
one other symptom that might confirm fuel pressure, when I have my obd reader in view data mode and go to WOT state, I get a fuel system open condition
Expert:  AMEDEE replied 9 months ago.

There is no way to check fuel pressure without a fuel pressure gauge.

Fuel pressure specs are 38 to 46 psi on this engine.

YES< it sure sounds like a severe LEAN condition causing this issue.

Customer: replied 9 months ago.
I got a fuel pressure gauge and the pressure was running steady at 38. I then unplugged the vacuum line to the fuel pressure regulator. if it was working correctly the car should have died as the regulator closed. It didnt. the car continued to run the same. So I have ordered a fuel pressure regulator. I will update you when I get it in and installed.
Expert:  AMEDEE replied 9 months ago.

Hello!

Thats incorrect. The engine will remain running with the vacuum hose removed from the regulator. The only thing that should have happened is the fuel pressure should have gone up a few psi.

Keep in mind, you need to check fuel pressure UNDER A LOAD WHEN THIS PROBLEM OCCURS to do the test properly.

Customer: replied 9 months ago.
I took your advice and looked into proper testing of the fuel regulator. You are correct, the fuel pressure went up from 38 to 40 when I removed the vacuum line. I was able to put a vacuum tester on the regulator and watch the fuel pressure increase as I increased the vacuum. So the regulator seems to be fine. How do I test it under a load as you mentioned above
Expert:  AMEDEE replied 9 months ago.

You would either need to do a brake stand (put the engine under a load in gear) while an assistant watches the gauge or simply get a fuel pressure gauge you can hook up to the fuel rail under the hood and that allows to you view the specs while inside the vehicle while driving down the road.

Customer: replied 9 months ago.
under a load, what range should the fuel pressure be at
Expert:  AMEDEE replied 9 months ago.

The same as it should be with the vacuum hose removed from the regulator.

Customer: replied 9 months ago.
I remove the vacuum line and then run it under a load. the expectation is that the fuel pressure remains at 40 (where is went to when the vacuum was removed). If fuel pressure drops off under a load, what is that telling me? bad fuel regulator or bad fuel pump
Expert:  AMEDEE replied 9 months ago.

That would tell you that the fuel pump is bad/weak and needs to be replaced.

Customer: replied 9 months ago.
or do I do the load test with the vacuum line attached to the regulator
Expert:  AMEDEE replied 9 months ago.

Either one would work. Because the regulator is not working or out of the picture with no vacuum going to it (hose removed or under a load)

Expert:  AMEDEE replied 9 months ago.

Hello!

It'sCustomerand I just wanted to check in to see how things are going and to see if you need any further assistance?