Fuel pressure

You have a good point. Since the regulator is in the tank, I'll have someone else check the pressures again before tearing into it.

The return comes back from the fuel filter. There are three connection points on the filter. Two at the back which are the pump outlet and the other connects to the return on the fuel assembly in the tank. The third at the opposite side of the pump goes to the fuel rail.

The following link goes to the pump I have. You will see there are 3 connections. My information is that there is a fuel pressure damper. I have the advantage of having the old pump and rack to look at. There are various sources describing the system as non return. he ford manual I have shows the component on the front passenger side of the rail. There is no return line.

https://www.showmethepartsdb.com/bin/showmeconnectdll.dll?lookup=partprint&part=000566496&id=98756AXFPWEB&storeid=&userid=

Attached is a picture of the page in the book describing the pump. I may be using some terms incorrectly, but I think we are saying the same thing.

I agree with what you say. I was confusing non return with not return from rail.

Thanks again for all your input It sure made me think along different lines than I would have.

Ken, what is your opinion regarding running like this and effect on the cat converter or other components or will I get a check engine light before any major damage.

Ken, to recap the history. The truck died on me and would not start. Problem was diagnosed as fuel pump. New pump was installed and truck ran. Hesitated a little on acceleration in higher gears and took some time say 5 seconds after being shut down. Pump was checked and only running at 50 PSI. Pressure dropped to zero immediately when shutting off. Pump was seen as problem and was replaced with another new one. Same situation.

To confirm pump was OK, pinched fuel return line from filter and pressure immediately increased tom 80 PSI.

Contacted pump assembly manufacturer and he agreed problem was with pressure control valve.

Checked the old assembly with air pressure and it went up to 65 PSI and then released as indicated in manual.

Now in discussion with garage to replace pump third time and want to be sure that I do not damage engine if negotiation becomes a hassle.

Because of the cost of the pump I was charged, I am not going to give up easily so if they do not give in quickly, I want to be sure I do not further damage the engine as all in all it has served well for the ten years I owned the vehicle. And I want to run in for another 6-8 mos before replacing.

Starting and running as described. I have a relative with a garage a 100 miles from home and if I can't get satisfaction from the garage, I'll go to his place to replace it.

Again Ken thanks for all the help. If we ever meet, dinner is on me

When its all settled and done. I'll post the results. Mechanically, I believe it is quite simple now. You guys helped me get rid of nagging doubts that I was missing something and gave me the confidence to negotiate with the garage. If the problem had been resolved, I would be happy but since it wasn't and I paid what I feel was a premium price, I have incentive to push the case.

For what its worth, it is strange that two units had the same problem. The manufacturer may have a QC problem. I believe that just because two pieces of data are the same, it doesn't make them right they are just consistent.

Got the check engine light this morning. So pulled the codes. No surprise P0171 and P0174. System lean bank 1 and 2 This took 200 miles driving to show up.