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sprinkles08
sprinkles08, ASE Certified Technician
Category: Ford
Satisfied Customers: 21591
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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I have a 1994 Ford Explorer with really bad acceleration

Customer Question

I have a 1994 Ford Explorer with really bad acceleration after the vehicle warms up. No misfires. Just really bad throttle response.
Submitted: 4 months ago.
Category: Ford
Expert:  Super Mechanic replied 4 months ago.

Hello and thank you for using the site. My name is ***** ***** I will be happy to assist you today.

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Let me just say that any money that you paid, or if you have a subscription, that money stays in your account until the answers are rated, (positive) regardless of how fast or how long it may take to get finished. You can FOLLOW UP AT ANYTIME, even after rating.

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. *** A BAD RATING HAS NOTHING TO DO WITH ANY DEPOSIT YOU MADE *****

You will want to check the fuel pressure to see if it is too low. Also that the filter is not restricting the flow of fuel.

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Then if the fuel pressure and flow are good, the exhaust may be a little bit restricted. You can have a back pressure test done on it at most exhaust shops to see if the cat is clogged.

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If they are both ok, then you will want to take a sample of the fuel to be sure that it’s not contaminated.

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Please don’t forget to rate the answer, **** THAT IS THE ONLY WAY I GET PAID **** if you need any more on it, I will be here.

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Customer: replied 4 months ago.
I replaced the fuel filter, negligible change. The fuel pressure reading is at about 29-30 when running and does not go up during acceleration.
Expert:  Super Mechanic replied 4 months ago.

I see, thanks. Most likely the pump, that is pretty low pressure, thanks.

Key On Engine Off 35 - 45 psi

Key On Engine Running 30 - 40 psi

Customer: replied 4 months ago.
KOEO - 40 PSI
KOER - 29-30 PSI
Customer: replied 4 months ago.
Checking back pressure now. Does it matter which side I install back pressure tester too?
Expert:  Super Mechanic replied 4 months ago.

You will want to check it before the converter(s) on either side if possible.

Customer: replied 4 months ago.
There is 0 back pressure at idle and at 2500 RPM's
Expert:  Super Mechanic replied 4 months ago.

That's good. What is the fuel pressure when driving? (when the hesitation starts)

Expert:  Super Mechanic replied 4 months ago.

If you accept my additional service request for your email address, you can give me your email in a private info box and I'll send you the instructions in a PDF file, the file is rather large.

You will just have to accept the additional service offer and ENTER your email address in the “ENTER CONTACT INFO” section so that I can see it.

I do not have access to your email address,

Customer: replied 4 months ago.
I replaced the fuel pump and fuel pump relay. Slight change. The voltage at the fuel pump is 9.87v when the battery voltage is 12.5v
Expert:  Super Mechanic replied 4 months ago.

I see, thanks. That means that there is a voltage drop in the circuit. However after all of the time that I have in this case with no payment I will opt out and open it back up. Please DON’T REPLY to this post as that will lock the question back to me, also DON’T RATE THE ANSWER yet, someone should be along shortly, I’m sure, thanks and sorry I wasn’t able to help with it.

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*******YOU CAN ALWAYS GET A REFUND WITHOUT RATING THE ANSWER AS BAD OR THE SERVICE AS POOR ********

Customer: replied 4 months ago.
Any luck?
Expert:  sprinkles08 replied 4 months ago.

Hello and welcome to JustAnswer!

Do you still need help?

Customer: replied 4 months ago.
Customer: replied 4 months ago.
The fuel pump voltage is ok. The vehicle has no power under acceleration.
Customer: replied 4 months ago.
Fuel pressure is 31 psi.
Expert:  sprinkles08 replied 4 months ago.

How did you determine voltage to the fuel pump is ok?

Customer: replied 4 months ago.
Checked voltage at the fuel pump connector.
Expert:  sprinkles08 replied 4 months ago.

What procedure and equipment was used and what was the result?

Customer: replied 4 months ago.
I used my Snap On multimeter, started and ran the engine, unplugged the connector and checked voltage going to the new fuel pump from the vehicle. Voltage was 14.35.
Expert:  sprinkles08 replied 4 months ago.

A voltmeter shouldn't be used for checking a power feed because it won't tell you if the circuit can support a load, and the meter is definitely inaccurate in any event. It couldn't have had 14.35v without the engine running. What you need to do is set up a headlamp bulb across the connector terminals for the power and ground feeds, crank the engine and see if the bulb lights as brightly as if connected directly to the battery (physically compare it).

Customer: replied 4 months ago.
I will do that.
Expert:  sprinkles08 replied 4 months ago.

Let me know how it goes!

Customer: replied 4 months ago.
Light is bright as can be.
Expert:  sprinkles08 replied 4 months ago.

I'm a full time tech and at work this afternoon, I'll get back to you as quickly as I can.

Customer: replied 4 months ago.
Thank you
Expert:  sprinkles08 replied 4 months ago.

Do you have a scan tool to monitor data?

Customer: replied 4 months ago.
Not for a 1994 Ford Explorer
Expert:  sprinkles08 replied 4 months ago.

Have you not checked for fault codes then ?

Customer: replied 4 months ago.
Have not
Expert:  sprinkles08 replied 4 months ago.

What is fuel pressure if the key is cycled a few times with the engine off?

Customer: replied 4 months ago.
40 then drops to 30
Expert:  sprinkles08 replied 4 months ago.

In what period of time does it drop that far?

Customer: replied 4 months ago.
I will double check tomorrow
Expert:  sprinkles08 replied 4 months ago.

Ok.