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.

If the regulator is in the tank, how were you able to close off the return?

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.

Nothing is making any sense on this truck. Alldata says the regulator is on the fuel rail. If you have a return line at the filter, then the filter has to be the regulator because if it was in the tank, it would return right back into the tank, It wouldn't be piped out of the truck.

I Googled the regulator and all but one pic shows the rail regulator below. One pic showed an in tank assembly with a regulator.

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=

A damper and a regulator are 2 entire,y different things. The damper merely smooths out the flow. This system is returnless from the filter to the engine but the pump is a return type pump. The filter has to be the regulator.That pump has a fuel out, a fuel in and a vapor line.

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've seen that page. Like I said, they are totally confusing this system but it has to be what I explained. The pump assembly has a return line si it cannot be returnless.

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.

Glad we can help, way to hang with the problems guys, please use 2Carpros anytime, we are here to help

Best, Ken

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.

Yep i read through the post and conflicting information is tough to work with, it will hurt the cat for sure if it continues, can you post some pictures of the engine and fuel system so we can see what we have to deal with?

Best, Ken

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.

The engine should be okay, what is the truck doing now? thanks for the pictures they help.

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

Please let us know what happens so it can help others, I wish we could have helped out more, its a weird problem that's for sure.

Best, Ken

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.

Yes these things happen, we like to push OEM parts and this is why. When you need to redo a job it takes the fun out of it. Glad we can help please get back to us with the results

Best, Ken

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.

Yep, this could be because of misfire issues,, here is a guide that can help you

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

Let me know what you find.

Best, Ken

Well the problem has been resolved at long last. After going through multiple replacement NEW fuel pumps, I finally found a used fuel pump from an identical model truck which I fully tested prior to installing and found to meet operational specs regarding flow and pressure. Took the trouble to pressurize it and check the pressure next day and found it did retain pressure (lower but pressure indicating gas would be at fuel rail) Installed the pump a week ago and truck is running fine. No running lean codes. The lesson learned here I would say is that for the work required to remove and replace a gas tank for a fuel pump problem I will in the future test the replacement pump to assure that it will met the required operation. Additionally, just because it is new and just out of the box it is not good to assume it will function properly. Thanks for all the advice that kept me from giving up on this. If anybody wants tips on checking fuel pumps, I have some experience I am willing to share.

Good to hear, that's what this site is all about to share our knowledge.

Please use 2CarPros anytime we are here to help.