Fuel The fuel pump doesn't stop priming and I can hear a hissing noise on the lower intake area (passenger side).

[Trilldev123]

Well??
Don't just ask and run!!
tell us what you found.

Haven't gotten around to it guys, sorry. Work is kicking my a$$. I will for sure come back and have an explanation when I fix it. I just need a free/non-exhausting day. I'm gonna figure out where all the hot wires in the fuel pump relay are and go from there. I probably have things hooked up to a constant hot wire which keeps the pump on. My signal wires trigger the relay(s) every time but I'm hoping to remove the factory relay and just use the one that came with the painless harness. Right now I'm running both relays so I don't mess up the inertia switch routing lol. I haven't deleted any wires. Just added a "fuel pump wire" that I believe is a signal wire. It's been a confusing process but I'm determined to figure this little issue out. It's been a while since I asked the question but I won't be like every other forum that leaves you without an answer lmao.

 

[Trilldev123]

Yes, during normal operation the pump runs all the time at one speed. They fuel travels to the rail and meets resistance at the fuel pressure regulator. The rail (and injectors) are kept pressurized at 30-39psi (depending on vac load) and all excess fuel is returned to the tank

During priming, the pump runs for 1-2 seconds and then switches off if there is no tach signal indicating a running engine

Thanks, everyone for the continued help!!! I won't leave ya'll hanging

 

[General karthief]

Thanks, everyone for the continued help!!! I won't leave ya'll hanging

Better not.
Membership dues will double

 

[Trilldev123]

Hey guys, a further question. (As a last resort) Since my fuel pump is staying on when the ignition is turned on, could I run a toggle switch in-between the FP signal wire to "ON/OFF" the fuel pump when I need to shut the car off? (my inertia switch is still working in the circuit) I will be keeping the key (ON/OFF) ignition part of course and turning the car off by the key then shutting the fuel pump off by toggle switch. I'm wondering if the fuel pump being running at all times is necessarily bad if I start and turn things off at the right time? And my pressure regulator being replaced, working correctly (further explained below).

With that method could I still use the stock DA1 ECU or should I go ahead and install my mega squirt gen 2 ECU if going with this method. I DO NOT want to fry the ECU's. I'm not sure if I sound like I don't know what I'm doing with wiring but I'm new to the fox body game and want to do things right with the painless harness. The last owners had their way with the wiring. I'm in this project deep and I'm not turning around. I'm determined to learn everything mechanical with this car myself so don't say "Take it to a shop". I sat in the car tonight and looked at the wiring to refresh my memory of how things are and since the Painless is a stand-alone harness just for the 302 engine itself. IF I install the aftermarket gen 2 ECU. Could this toggle switch idea work?? This method is only a last resort. I still want to figure out why the pump is staying on and try to get it back working like factory ( meaning ecu priming for 5-10 seconds before starting). But if I don't I want to know about the toggle switch idea

Also, I believe my Diagram in my regulator is shot and is staying closed not holding pressure, causing the gas to just shoot back into the return side of the fuel rail back to the tank (If that's how it works).... I did spray it with carb cleaner when I had everything removed. Could that ruin the rubber diaphragm inside? Fuel pump regulator/ fuel rail noise will be the next task after figuring out what I can do with the fuel pump itself.

Thanks again.

 

[Mustang5L5]

I'm wondering if the fuel pump being running at all times is necessarily bad if I start and turn things off at the right time? And my pressure regulator being replaced, working correctly (further explained below).

The pump running all the time points to a potential ECU issue, either bad capacitors or a burned pin 46 trace.

Before wiring in any cut-offs, open the ECU and inspect the capacitors. Verify that there isn't any sort of green discharge from the bottom.

FLip it over and inspect the traces near the 60-pin header. See if there are any burned traces like this

This frequently happens when the harness trans type doesn't match the ECU trans type. AUtomatics and manuals are wired slightly different and using an AOD ecu in a manual harness car can burn up the ECU. Since you have an aftermarket harness, unknown how it's wired. Another good check is to pull the computer out, and test pin 46 to ground on the harness and see if you have any voltage in key on, and crank position.

DA1 is an automatic ECU

 

[Boostedpimp]

I've had the issue with the fuel pump running constantly and it ended up being a burnt trace in the ECU just like mentioned above

 

[Trilldev123]

DA1 is an automatic ECU

Oh wow, I didn't know that. I thought it was the correct ECU since it's the one that came in the car when I bought it. This is a 88 GT 5spd manual car as said when I looked up the vin #. This car never ran right, I was able to drive the car but it always fell on its face at high rpm and backfired out of the exhaust when you gave her some gas. I saved this car from just going to the junkyard 5 days before I bought it since the previous owner gave up on the car and I have been trying to get this car going smooth ever since.

I'll pull the cover off and do what you stated above and I'll have some pictures of what I found. Since I have a manual car would I basically have to go ahead and install the mega squirt ECU since the DA1 is useless with a manual car?

 

[Trilldev123]

Heres what I see as we speak. Im not seeing any obvious burn marks but Im not quite sure if Im looking correctly. And Im not seeing any green discharge but I do see some yellow chunky stuff at the bottom of the third picture.

 

[Trilldev123]

Closer pictures of all four corners of the ECU. It has some weird brownish yellow residue coated on it. Looks like thick honey when you scratch it.

 

[Mustang5L5]

Yellow stuff appears to be flux residue. I wouldn’t worry about that. Rest of board looks clean. I’ll look tomorrow on a bigger screen.

Test for continuity from pin 40 to 46 and 60 and 60 to 40. You should have it.

 

[Trilldev123]

Yellow stuff appears to be flux residue. I wouldn’t worry about that. Rest of board looks clean. I’ll look tomorrow on a bigger screen.

Test for continuity from pin 40 to 46 and 60 and 60 to 40. You should have it.

Okay, will do. I'll test them tonight and let you know tomorrow

 

[Trilldev123]

Yellow stuff appears to be flux residue. I wouldn’t worry about that. Rest of board looks clean. I’ll look tomorrow on a bigger screen.

Test for continuity from pin 40 to 46 and 60 and 60 to 40. You should have it.

Okay I tested the pins as you said and I'm getting continuity on every single one, so that still works.

 

[Trilldev123]

Since this is a DA1 computer (for an automatic), I can't use this anymore with my setup, right? and I'll have to use the aftermarket ECU I have for my 5 spd. What puzzles me is that before the harness swap, the fuel pump did the normal prime for 3-5 seconds and then turned off.

 

[Trilldev123]

But I guess the missing factory harness stuff changes things completely. I'm thinking this harness is basically set up for a person who's wiring in the fuel pump, etc to individual switches like a drag car correct? running a constant hot through the harness for switch provisions and you add in your own ground wires? So it leaves the consideration for the ECU priming the system out of the picture when you can just flip a switch?

But again, that goes back to my previous question. If I wire in a switch for the fuel pump, Is the fuel pump staying on constant necessarily bad in my case, if the fuel pump regulator holds pressure and returns fuel back to the tank correctly? (When I order a new one) especially in a stock engine car?

sorry for the bundle of questions at once but now that the DA1 ECU seems to be fine, it opened my mind up to new questions.

Thanks again!

 

[JimProfit]

Anxiously awaiting the resolution. I am also experiencing a similar problem including the “hissing”.

 

[Mustang5L5]

Since this is a DA1 computer (for an automatic), I can't use this anymore with my setup, right? and I'll have to use the aftermarket ECU I have for my 5 spd. What puzzles me is that before the harness swap, the fuel pump did the normal prime for 3-5 seconds and then turned off.

It's not an easy question to answer because you are using an aftermarket harness. Typically you can use an AOD ecu only with AOD specific wiring. Is there a wiring diagram provided for the harness? part number?

CHeck for voltage on pin 46 with the ecu pulled during key on and cranking. Ensure that you have zero voltage on this pin coming from the harness. (unsure if you tested this). However the aftermarket harness may not even be wired like this so it may not be a concern at all and a lot of these suggestions don't apply.

 

[General karthief]

Anxiously awaiting the resolution. I am also experiencing a similar problem including the “hissing”.

Your stuff may be different than the stuff this member is using, he has installed an aftermarket wiring harness which may or may not be his problem.
Start a thread with info on your car and the problems you are encountered in the tech forum

 

[Mr.Kelley]

I am using that harness in my Falcon. In the instruction booklet it tells you how to wire the different ECUs (auto or std) to work correctly. I have a 5spd Ca emissions ECU but I'm running a 4R70W with a stand alone controller. Do you have the Painless Install Guide. If not I can send you a PDF copy

 

[Trilldev123]

I am using that harness in my Falcon. In the instruction booklet it tells you how to wire the different ECUs (auto or std) to work correctly. I have a 5spd Ca emissions ECU but I'm running a 4R70W with a stand alone controller. Do you have the Painless Install Guide. If not I can send you a PDF copy

The painless guide is very vague and the page for the ECUs shows only 2 ECU types (A9P and A9L). This car came with a DA1 computer which is an Automatic computer which I didn't know until these guys told me. My car is a 5spd manual car.

 

[Trilldev123]

It's not an easy question to answer because you are using an aftermarket harness. Typically you can use an AOD ecu only with AOD specific wiring. Is there a wiring diagram provided for the harness? part number?

CHeck for voltage on pin 46 with the ecu pulled during key on and cranking. Ensure that you have zero voltage on this pin coming from the harness. (unsure if you tested this). However the aftermarket harness may not even be wired like this so it may not be a concern at all and a lot of these suggestions don't apply.

This harness is the 60510 painless harness https://www.painlessperformance.com/Manuals/60510.pdf
if that was what you were referring to when asking about part number.