Engine Hesitation, low power

jacks87ponycar · May 30, 2022

Please help!
I have my dads 87 Mustang convertible that has been siting in my garage for several years.
It broke my heart seeing it day after day not running.
I finally had an opportunity to put some money into it. I did a five lug conversion, high performance shocks, plugs, wires, air filter.
The car has been running great.
suddenly today, its was sputtering when I tried to accelerate. I had noticed it was a little more difficult to start. Doing some research I found out it could be a few things, a MAF sensor which my car does not have it has a different system to measure the air flow or it could be something to do with the fuel pump/gas tank/ filtering system.
The car has always had a loud fuel pump. I have been familiar with the car since it was bought brand new. I have noticed the fuel pump is not as loud. Fuel pump issue?
I really appreciate your help.
Jack

Noobz347 · May 30, 2022

Moved into its own thread.

General karthief · May 30, 2022

You should be able to 'borrow' a fuel pressure gauge from Autozone or similar parts house, it would also be a good idea to change the fuel filter, its between the fuel tank and the axle housing under the car. Locate the fuel pump regulator passenger side at the rear of the upper intake, should have 32-34 psi with the vacuum line connected and the engine running, 42-44 disconnected. The schrader valve to connect the gauge is on the fuel line behind the alternator.

Mustang5L5 · May 31, 2022

Have you pulled the engine codes?

If not, i would start there. Do you hear the fuel pump prime when you turn the key to on? I would borrow/rent/buy a fuel pressure guage and see if you have 39 psi with the vacuum line off and capped.

Code reader here since 87-88 does not have a functional check engine light
Amazon product ASIN B000EW0KHWView: https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW/ref=pd_lpo_1?pd_rd_i=B000EW0KHW&psc=1

jacks87ponycar · May 31, 2022

Sorry for repeating this post but I may have entered it in a spot where very few people will see it.
I recently decided after 12 years that I was going to put my 87 Mustang LX, 5.0 convertable back on the road. I converted the 4 lug wheels to 5 lug, installed new disc brakes ll around, larger wheels, a full tune up, wheel bearings, new top and a lot of new interior parts.
She has 75,000 original miles on the first year of a fuel injected 5.0 engine.
She was running great, as acmatter of fact I was amazed that before Iveven tuned her up, after fresh gas and a new battery, she started right up.
After my initial 80bmile drive after my alteraions, I discovered I needed a new radiator. I installed tge radiator and took her fir a 40 mile drive. No issues. The next day I took her out again abd noticed right away she was more difficult getting her running. Then I noticed a lack of power and sputtering. This care does not have a mass air intake sensor. I did notice that the fuel pump was a lot less noisy than usual. I have known this car since it was brand new, it always had a noisy fuel pump.
I read that there could be an issue with the fuel pump/filter assembly in the gas tank.
Any help is appreciated, where do Ivstart?

Willybill32 · Jun 4, 2022

jacks87ponycar said:
Sorry for repeating this post but I may have entered it in a spot where very few people will see it.
I recently decided after 12 years that I was going to put my 87 Mustang LX, 5.0 convertable back on the road. I converted the 4 lug wheels to 5 lug, installed new disc brakes ll around, larger wheels, a full tune up, wheel bearings, new top and a lot of new interior parts.
She has 75,000 original miles on the first year of a fuel injected 5.0 engine.
She was running great, as acmatter of fact I was amazed that before Iveven tuned her up, after fresh gas and a new battery, she started right up.
After my initial 80bmile drive after my alteraions, I discovered I needed a new radiator. I installed tge radiator and took her fir a 40 mile drive. No issues. The next day I took her out again abd noticed right away she was more difficult getting her running. Then I noticed a lack of power and sputtering. This care does not have a mass air intake sensor. I did notice that the fuel pump was a lot less noisy than usual. I have known this car since it was brand new, it always had a noisy fuel pump.
I read that there could be an issue with the fuel pump/filter assembly in the gas tank.
Any help is appreciated, where do Ivstart?

A minor correction…1986 was the first year for SEFI 5.0 Mustangs. You said it sat for 12 years before you got it running again. Did you clean the fuel system or replace the tank and filter?

Bill

jacks87ponycar · Jun 5, 2022

Hi,
Sorry for the mistake, I was only 23 at the time my dad bought the car. He had previously owned a 85 which I actually preferred the looks of. I liked the way the 85 grill and headlights looked over the 87. He was the one that told me he was buying the newer version because the new fuel injection had increased the horsepower from what he told me from 185 horse to 235. From what I have read after doing a lot of research in preparation of my pony project, it looks like the actual horsepower of my car is 225. I may have simply misunderstood him and assumed it was the first year.
I waited for some responses and then decided because of the age of the car and the somewhat inexpensive parts ($300 for tank and pump) and after reading some posts about a baffle in the tank of the fox body that commonly comes loose, I decided it was worth replacing the tank and fuel pump as preventative maintenance even if it did not correct the problem.
The day the problem started, I decided to fill the tank, with premium which is what I have always done, I had to deal with siphoning most of the fuel out of the old tank which was messy and a pain in the butt.
After removal of the tank and inspection, it was obvious that the baffle had come loose. I still was not sure that this was what was causing the problem but after I installed the new tank and pump, she runs great again.
As I had read in some post on replacing the tank, it in fact can be difficult to do alone. What I found was that getting the drivers side bolt started was not to difficult, with the one bolt started, I used a bottle jack and 2 x 4 cut so it caught the seam in the front of the tank to the side of the strap I was able to get the second bolt started, but the tank is tight! Also please note, you have to have the fill hose inserted into the tank BEFORE you start installing the bolts on the straps. This means having the tank close to its final destination but not completely installed. The fill hose can NOT be installed after tank installation. I found out the hard way and had to unbolt the straps, insert the fill hose and then reinstall the tank.
I have installed a few tanks over the years, do all gas tanks have this baffle?
It looks to me, the baffle helps keep sentiment away from the pump.
Also, I was surprised to find the wiring for the pumps sits right in the fuel. I find this particularly odd. That was the way it was when I removed the the old pump so I assumed it was perfectly fine. My pump did not come as a full assembly, I had to remove the old pump from the assembly and install the new one, not difficult but I found that odd. The new pump came with a new screen and those funky white plastic clips that hold the fuel line to the fuel pump. Although, the second line used a different fastener. I had read about somebody using a sharpy cap to remove the second line, it works! You have to split the cap down the middle lengthwise to wrap it around the line and then insert it into the fuel line connector. I am sure there is a special tool for this task.
Thanks for reading, hope my posts helps other readers.

Willybill32 · Jun 5, 2022

jacks87ponycar said:
Hi,
Sorry for the mistake, I was only 23 at the time my dad bought the car. He had previously owned a 85 which I actually preferred the looks of. I liked the way the 85 grill and headlights looked over the 87. He was the one that told me he was buying the newer version because the new fuel injection had increased the horsepower from what he told me from 185 horse to 235. From what I have read after doing a lot of research in preparation of my pony project, it looks like the actual horsepower of my car is 225. I may have simply misunderstood him and assumed it was the first year.
I waited for some responses and then decided because of the age of the car and the somewhat inexpensive parts ($300 for tank and pump) and after reading some posts about a baffle in the tank of the fox body that commonly comes loose, I decided it was worth replacing the tank and fuel pump as preventative maintenance even if it did not correct the problem.
The day the problem started, I decided to fill the tank, with premium which is what I have always done, I had to deal with siphoning most of the fuel out of the old tank which was messy and a pain in the butt.
After removal of the tank and inspection, it was obvious that the baffle had come loose. I still was not sure that this was what was causing the problem but after I installed the new tank and pump, she runs great again.
As I had read in some post on replacing the tank, it in fact can be difficult to do alone. What I found was that getting the drivers side bolt started was not to difficult, with the one bolt started, I used a bottle jack and 2 x 4 cut so it caught the seam in the front of the tank to the side of the strap I was able to get the second bolt started, but the tank is tight! Also please note, you have to have the fill hose inserted into the tank BEFORE you start installing the bolts on the straps. This means having the tank close to its final destination but not completely installed. The fill hose can NOT be installed after tank installation. I found out the hard way and had to unbolt the straps, insert the fill hose and then reinstall the tank.
I have installed a few tanks over the years, do all gas tanks have this baffle?
It looks to me, the baffle helps keep sentiment away from the pump.
Also, I was surprised to find the wiring for the pumps sits right in the fuel. I find this particularly odd. That was the way it was when I removed the the old pump so I assumed it was perfectly fine. My pump did not come as a full assembly, I had to remove the old pump from the assembly and install the new one, not difficult but I found that odd. The new pump came with a new screen and those funky white plastic clips that hold the fuel line to the fuel pump. Although, the second line used a different fastener. I had read about somebody using a sharpy cap to remove the second line, it works! You have to split the cap down the middle lengthwise to wrap it around the line and then insert it into the fuel line connector. I am sure there is a special tool for this task.
Thanks for reading, hope my posts helps other readers.

I bought my '86 brand new on 09/30/86, when I'd already seen pictures of the '87 GT and decided I liked the '86 better. I think the '85 5.0 was rated at 210 HP, but the '86 was rated only at 200 HP, and in '87 they went up to 225.

I don't know that a loose baffle would create a problem, but definitely having gas sit in the tank for 12 years creates problems, so it's always good advice to clean the old gas out of the tank and clean it before starting for the first time. You've accomplished that now with the new tank, pump, etc. Thank goodness there was apparently nothing that got into the fuel lines to clog the injectors.

Bill

Engine Hesitation, low power

jacks87ponycar

Member

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

jacks87ponycar

Member

Willybill32

But at least it's tight!

jacks87ponycar

Member

Willybill32

But at least it's tight!

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Engine Hesitation, low power

Member

Stangnet Facilities Maint Tech... Er... Janitor

wonder how much it would cost to ship you a pair

That is…until I whipped out my Bissell

Member

But at least it's tight!

Member

But at least it's tight!

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