Newbie with 1990 Bronco II 2WD


Cees Klumper

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Thanks RonD. Well that clamp (not sure now without looking at it again whether it's on the return or on the incoming line) does do something, because when I remove it altogether from the line, the car has 0 power above idle. But after that it becomes a crap shoot: adjusted one way the pump starts making a constant high pitch noise, it almost stalls when cold at idle, but once warmed up there's a lot of oomph to the engine and the car is really quick. Adjust it to 40 psi at idle and it runs ok but less power. Real sketchy! It did 'sail through' the California smog check last month with this setup, so the PO managed that at least.
 


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RonD

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FPR is most likely bad

It has a spring inside that holds the diaphragm closed below 43psi, at 44psi it is pushed open and allows fuel to flow back to gas tank until pressure drops below 43psi again
A vacuum hose on the FPR is used to reduce that springs pressure to about 35psi, so at 36psi fuel flows back to gas tank

This vacuum line stabilizes pressure to 32-38psi
At idle vacuum is high and fuel demand is low
Under acceleration vacuum is low and demand is high

So vacuum assist stabilizes pressure so computer doesn't need to adjust injector open time as much

He may have pulled and plugged that vacuum line and was just using the clamp to reduce pressure to a stable point but as demand changes while driving........................well you got what you got, lol
 

Cees Klumper

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I thought something like that as well - except, the FPR looks brand-shiny-new. Although would not be the first time a new part is bad out of the box. I will try the new fuel pump first, then see if that solves things, if not then move onto the FPR. I hate just throwing parts at it without knowing the cause.
I am also waiting for the code reader to arrive, so I can hopefully get some more data about what's going on.
 

RonD

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I would get a fuel pressure gauge and test FPR that way

Engine running vacuum line attached, should show 35psi
No vacuum line 43psi

With vacuum line connected and at steady 2,000rpm(approx.) stable pressure around 32-34psi, not slowly dropping
 

Cees Klumper

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I did pick up a pressure gauge yesterday, that's how I tweaked that clamp on the hose to get the idle pressure (engine running) to 40 psi. Will try removing the vacuum line, see what difference that makes, and check the pressure at 2,000 RPMs, thanks very much for all that information, that really helps me get this sorted out.
 

RonD

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If pressure holds steady at idle, but slowly drops at 2,000rpm then fuel pump is most likely weak, i.e. higher fuel demand shows low volume from pump, but can be dirty fuel filter as well, same symptom, low volume flow
 

RonD

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NICE, NICE, and NICE
 

Cees Klumper

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I ordered all new lights as well as NOS wheel caps for that new look. Also some spray paint in the original Colonial White (YY) to touch up some areas. The original paint has come back really well, after lots of elbow grease. I'm more concerned now about door dings than on our 2011 BMW! And the compliments from neighbors here in the marina (we live on a boat) just keep coming.
 

bobbywalter

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....seems like its giving you troubles....can i have it?.....
 

rusty ol ranger

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I would drive the shit outta that thing.
 

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