fuel pressure problem

[oneqwicksho]

1990 ford Taurus sho, mtx 105,000 miles new fuel pump and fuel filter

before and after pump and filter i have a wine noise coming from the gas tank. if i slap the tank with my hand it will change tones. slight to medium throttle car runs great, WOT runs poor, KOEO 28psi--KOER 32psi--WOT spikes to 35psi-- then right to 28psi-- FPR vacuume line pulled 38psi. it don't make no sense to me i put a fuel pump in my brothers SHO and at WOT pressure shoots to like 46psi and his car glues you in the seats over 4k. so i don't know

any help appreciated:thankyou:

 

[deercrusher]

faulty wiring to fuel pump?

 

[oneqwicksho]

faulty wiring to fuel pump?

i don't think the car would even run if i had that problem

 

[oneqwicksho]

No one has an idea?

 

[deercrusher]

i gave you an idea - it's not always black or white, work or not work with wiring. you could have a bad ground for instance, that when you go WOT it the wire's ground capacity is limited due to corrosion or anything else - and it's only showing up when the system is put under stress. I wish you luck.

 

[oneqwicksho]

All wire and connections look brand new and I have checked the grounds plus I don't think it is a corrosion issue you can eat off my car top or bottom its clean no rust. Its just driving me nuts because I can't figure it out. Well I think I might just replace the FPR and see what happens

 

[oneqwicksho]

Ok new pump again new filter, and a good set of fuel pressure regulators, and still max pressure at wot is 40psi and idle is 34psi. I even put a newer computer in cause I wanted it and, was wondering if it would help any.

Even after all that when I shut the car off after driving it, there is a wine noise coming from the tank. The wine got more quiet after the replacement of the FPR.

I am loosing my mind I can't figure it out! Is there a sensor I need to replace? Or something?

Please someone help my S.H.O

P.S. I checked the wiring and grounds again everything looked ok.

 

[1bad98SHO]

im not sure but does the SHO use a different pump than the SLO? If so maybe you got the wrong pump?

It sounds to me that the reason its wining so bad is due to insufficient voltage. Check voltage from the ignition to the fuel pump relay. Then check voltage from the relay to the pump. Somewhere you are losing some juice. Could be a faulty relay and it could be the wiring. To test the ground you can splice into the ground wire at the fuel pump and run a wire straight to the battery.

 

[oneqwicksho]

im not sure but does the SHO use a different pump than the SLO? If so maybe you got the wrong pump?

It sounds to me that the reason its wining so bad is due to insufficient voltage. Check voltage from the ignition to the fuel pump relay. Then check voltage from the relay to the pump. Somewhere you are losing some juice. Could be a faulty relay and it could be the wiring. To test the ground you can splice into the ground wire at the fuel pump and run a wire straight to the battery.

How do I Check voltage from the ignition to the fuel pump relay and, check voltage from the relay to the pump.

And, before the fpr I could hear the wine from fifty yards or better away and, after the fpr I can barly hear it. I have to put my head under the car just to hear the slight wine. I thought that would be a clue but, as I said I'm lost I will try anything now

Thanks

 

[1bad98SHO]

let me get you a wiring diagram sir.

Here you go. It looks to me as if you will need to follow this step. At the CCRM there should be what appears to be a pink wire with a black tracer. This should be the wire that goes to the fuel pump. Just use A DMM and check the voltage on that wire with the car running. Check it coming out of the CCRM(ICM) Then check it back at the inertia switch. Then check it at the fuel pump itself. Look for any voltage drops. along the path of the wire.

Also try running a ground wire from the battery to the ground at the fuel pump if the voltage on the pnk/blk wire to the pump checks out.

If the voltages check out fine. If the ground checks out fine. You have tried 2 pumps. you should have a new fuel filter on it as well. and you know you have the right pump then you probably have gotten 2 bad pumps. Its hard to believe but it happens.

If anything I am willing to say that either your CCRM is going bad or your ground is not sufficient.

 

[AREA 91]

FYI: 89-90 SHO's have a 2 speed fuel pump. The resistor is white ceramic located on the firewall.

 

[St Louis SHO]

Yup, the resistor could be bad, its a white two wire dealy on the firewall.

 

[oneqwicksho]

Ok found it on the fire wall I have a couple questions thou A: is there a way to check if it is bad? and, B: if bad where do i get a new one? or used? And, is there a way to hot wire it so it works like a 91 and newer sho

thanks

 

[1bad98SHO]

Didnt know there was a resistor in the Older SHO's. Learn something new everyday. Setup the same way the grand prix GTP's are then with the 2 speed pump.

 

[St Louis SHO]

Ok found it on the fire wall I have a couple questions thou A: is there a way to check if it is bad? and, B: if bad where do i get a new one? or used? And, is there a way to hot wire it so it works like a 91 and newer sho

thanks

I dont see why you cannot just bypass it. But please be aware, I've never done it...

 

[oneqwicksho]

Ok engine running battery: 13.8v CCRM pink/blk wire: 13.8v inertia switch: 13.6v fuel pump: 13.3v couldent find the ground and I'm getting no reading on the resistor.. Should I? I Will run the jumper wire from pump to battery this weekend. And one thing I noticed, I started the car with the resistor un pluged and then pluged it in and drove home, shut the car off and the wine is worse, I wonder if the check valve in the pump is shitin the bed? Hopefully this will help so we can figure out what's next Thanks

 

[1bad98SHO]

Im not sure how to bypass the resistor on the Older SHO's. On the GTP's you can bend a tab over on the relay so the fuel pumps runs in high speed all the time.

 

[oneqwicksho]

Well another new pump, strainer, filter and still same pressure problem. running new ground tomorrow and, doing some more tests then next thing is new FPR and, swaping a ccrm

 

[SHOZ123]

FWIW the 40 psi at WOT and 34 psi at idle are right on the money.