Losing fuel pressure??

[RonD]

Yes, some year V8s did just have ONE fuel line, so FPR was on the IN line, in that case you can't test it
Just have to flip a coin, FPR or fuel pump, lol
Most change the FPR because its WAY EASIER, but if that doesn't fix it then have to do fuel pump

 

[svtcards]

My fuel line isn't connected to regulator it's on fuel rail on both pressure and return side.im assuming just disconnect it from rail your meaning?my psi only hits 30 psi with key on the run position at the moment.35 max when idling.my fuel lines r braided stainless.not sure if I can actually crimp them without damaging it.your thoughts on that?

Yes, some year V8s did just have ONE fuel line, so FPR was on the IN line, in that case you can't test it
Just have to flip a coin, FPR or fuel pump, lol
Most change the FPR because its WAY EASIER, but if that doesn't fix it then have to do fuel pump

Ok good to know.you don't think one of the injectors could be the cause?

 

[RonD]

No, you would smell fuel after shutting the engine off as injector leaked fuel into the warm engine, lots of fuel vapor which is what you smell, like in the summer when filling up
Also would be misfire and Rich code on that bank

Also pressure would be a steady drop to 0psi wouldn't hesitate at 10 or 15psi, just drop to 0psi

 

[rusty ol ranger]

I think its the checkball

 

[svtcards]

I think its the checkball

On the fuel pump? I just put the old regulator that I replaced that was in donor car to c if results were the same.the results were the same.pressure drop to 20psi then slowly to 15 psi.then slowly down to 0 a after over an hr or so later.when I 1st turned key on to run position when I finished installing the whole fuel system last fall the fuel pump made a small priming noise then start right up.now it makes like a knock sound with the prime noise.maybe that Xtra knock could be check ball or something?when it was Dyno tuned he said it was running rich. he showed me the fuel air ratio he usually likes to see which he got it to that point.ran great the whole time.if I left issue the way it is. hard cold starts runs fine after that will I damage anything if pump really is the issue?

 

[svtcards]

No, you would smell fuel after shutting the engine off as injector leaked fuel into the warm engine, lots of fuel vapor which is what you smell, like in the summer when filling up
Also would be misfire and Rich code on that bank

Also pressure would be a steady drop to 0psi wouldn't hesitate at 10 or 15psi, just drop to 0psi

No fuel smell after engine shut off

 

[svtcards]

No fuel smell after engine shut off

And I'd see fuel in the oil also if it were some of the injectors Leaking by correct?

 

[RonD]

Maybe but that would depend on engine temp and if that one injector's intake valve was open
Gasoline evaporates pretty fast if it leaks into a warm engine, which causes the smell and would not make it passed piston and rings in liquid form, certainly possible just not likely

In the old days with a carb leaking, it would be more likely to get liquid fuel and fuel smell in the oil

 

[svtcards]

So If the issue is the pump and I leave issue the way it is with the hard cold starts and runs fine after that would that cause issues down the Rd?

 

[RonD]

No, no issues as long as its not pinging/knocking from running Lean

Cycle key on and off 3 times before cold start, that builds back up lost fuel pressure

 

[svtcards]

I decided to go ahead and change the in tank fuel pump. The place I bought it from sent me a new one for free so what the hell I changed it and it solved the problem.started right up right after 2nd cranking.holds 35 psi no problem with engine off.thank God it worked.it seems like everytime I take a step forward I take a step back.pain in the ass to say the least.rearend rebuild is next in may and hopefully I can enjoy it this yr.

 

[svtcards]

I do have 1 more question.should there always be fuel pressure in a cars fuel system?or does it eventually go back to down 0 psi?how long should it take for a system to depressurize if just sitting there?

 

[alwaysFlOoReD]

Pressure should stay same for years.

 

[RonD]

+1 ^^^

In Rangers and most Fords