Kinda sounds like the fuel pumps are ok then. So, what happens to fuel pressure when you disconnect the fpr vacuum line????

 

I'm fairly certain everything with the pumps are alright. Not 100% but enough to try the regulator first. The fuel gauge has a bleed valve to take pressure off the system. Until this latest problem, with the engine running I could fully open the valve, get a full stream of gas out the drain hose and still carry 29-30 psi. The old fuel pump would lose pressure and the engine would shut off. If I take the vacuum hose off of the regulator the pressure goes to about 37 psi. I thought it should be higher. Closer to 40.

 

OK, good feedback on the fuel pressure going up to 37psi when the vacuum line is disconnected. Thats about what my 94 Taurus does, it goes up to 39-40 psi with the vacuum line disconnected & drops to about 29-30 with it connected. Sounds like your fpr is doing what it should, but its not yet clear exactally Why fp intermittently drops & the engine stalls. Will be interesting to hear what you find.

When it begins to act out, will it straighten out every time you thump the fpr????

 

It only recovered one time when the fpr was tapped. I have a fpr ordered but still not convinced that is the problem. If it gets replaced it will fix the problem or eliminate the fpr. I don't think it the pumps are the cause either. Definately not the hp pump. You can heard it run. Its almost too loud. The low pressure pump is really quiet with just a low hum. It does seem to quit berfore the hp but both run until after the engine quits. Out of sight out of mind is the fuel resevoir mounted on the frame. Mine has the taller bowl which is not suppose to have a filter. I don't know if it has any kind of strainer inside to help protect the hp pump. If it does there might be debris inside that collects on the strainer and shuts off the flow of fuel. When everything shuts down, it drops off allowing the fuel to flow again. I have been reluctant to pull the bowl off because I have heard they won't seal properly and will need to be replaced. Since mine is suppose to only be a resevoir and not a filter I have let it be. Probably won't get back to working on it until the weekend.

 

On the fpr not responding to a thump, had the Taurus fpr act the same way when I thumped it about 3 years ago when trying to trouble shoot a random engine stall.

Never could get it to do that again, so like you, after some fuel pressure tests & looking up the specified fuel pressure operating range, found where mine was operating at 1-2 lbs above the low side spec of 28 lbs on pressure, I came to the conclusion it was coincidence & Murphys Law messing with me on the fpr thump & it stalling.

After a lengthly 6 months long trouble shoot, with fuel pressure gauge, timing light & scantool showing nothing, I finally caught spark going missing when it stalled while driving down a hill, but I could hear the fuel pump still running, so it turned out the danged computer was going bad & randomly killing voltage to the ICM & that killed spark, so finally decided after that scenario to replace the danged computer.....so far end of story on those maddening random stalls, after which the engine would start right back up like nothing had happened!!! Point of story being, it could take a while to get lucky & run down whats Really going on, when the problem is random & no trouble codes set.

Will be interesting to hear what you find, so keep us posted on your trouble shoot & try to keep an open mind while doing it, let test Results be your guide.

 

Didn't get to work on it this weekend. I have read that a loud high pressure pump is an indication it isn't getting enough fuel. This is another sympton I have. Did some research and found out the fuel reservoir has two valves in it. One at the fuel inlet and one at the fuel outlet. If the inlet sticks it will cut off fuel to the system. If the outlet sticks if will send fuel to the return line and reduce the flow of fuel to the high pressure pump. Don't know if this is my problem but it is the only part in the fuel system that hasn't been replaced. When I purchased the truck there was some water in the fuel system and maybe it deterioated one of the valves. Anyhow, I have a reservoir on order and when it gets here I'll do a flow test both before and after install.

 

Will be interesting to hear what you measure for delivery rate. I believe I remember 1pt/15sec is the spec. Have you tried something like a 20oz dose of Techron Concentrate Plus in the tank before filling so you get good mixing & running most of the treated tank out???? It will lube the fuel pumps, fpr, injectors & tidy things up all the way from the tank to the combustion chambers.

EDIT: On the code 67, its probably the NS switch on the side of the tranny, or maybe the wiring to it.

 

I have used several different additives at different times. Techron and Seafoam are two of them.

 

Fuel reservoir was the problem. The fuel pressure is steady at 31psi at idle. I have been checking fuel pressure for the past year and it has always been 29 psi. Guess that one psi below spec was an indication something was amiss. Took the old reservoir apart and found an o-ring in the bottom of the canister. There is a spring loaded valve on the fuel inlet and it looks like the o-ring goes on the end of valve. Tried moving the valve and it appears to be stuck. Apparently the code 67 had nothing to do with the problem I was having.

 

OK, good find, fix, feedback & to hear you found what you believe is the culprit. Have the random fuel pressure drops & engine stall stopped????

 

At idle fuel pressure is within specs, steady at 31 psi. It use to be below spec at 29. No more stalling or bucking. Drives fine on the road. Can push the throttle to the floor in all gears and not a hint of a problem. Before the new reservoir it would stop running at idle. I have driven the truck about 10 miles since the repair and I'm confident it is fixed. Diagnostics on the code 67 indicate it might be more for vehicles with A/C, which mine does not have.

 

OK, well it sounds like your ready to pronounce this puppy cured!!!

 

The high pressure pump could be heard over the sounds of the engine and exhaust. This is no longer the case. Nothing more than a quiet hum. Drove it some more today and all is well.

If I'm reading the part numbers correctly, the reservoir I purchased has a superseded 1990 part number FOTZ-9K044-A. The original was E7TZ-9K044-A.

 

Did you ever get this figured out?

 

Have a read from post 24 through 28 of this 11 year old thread for details that would likely answer your question.