No power issue 1990 2.9lXLT...need advice

[Maggrett]

Hey everyone,
I need some help diagnosing a loss of power under load for my 1990 2.9l Ranger XLT.

Issue: low throttle response while driving and will not deliver power on highway enough to go uphill. This is fairly new.

What I've done:
Replaced tfi with new
New fuel filter
New spark plugs
Timing checked and in spec
Wheel bearings and brakes good
New air filter
No codes at all

Vacuum at idle is 16hg then goes immediately to 0 then back upon wot
I am at almost 5,000ft above sea level, so I think the number is normal

There is no pressure at the shrader valve in rail on drivers side while sitting a short time. Barely comes out right after shutting engine off. When I replaced fuel filter, there was high pressure right after turning engine off, but then went back to little to no pressure afterward and same issue.

Where do I got next? I apreciate your help and time!!

 

[rusty ol ranger]

It idles fine just has no ass?

 

[Maggrett]

It idles fine just has no ass?

Yes. Starts a little slowly, but idles perfectly at 750. Seems to bog down at wot. No misfire though.

 

[Uncle Gump]

Have you checked fuel pressure?

 

[Maggrett]

No, just bled the shrader. Litterally nothing most times, just a dribble a few at engine off. Will get a shrader coupler for my vacuum gauge and report numbers.

 

[Bear in the woods]

Sounds like trash in the tank. Starts stopping up more as you drive it. Then sett when you shut It off

 

[Uncle Gump]

You just have to start there honestly. Without correct fuel pressure... nothing else matters.

Losing pressure after key off... it happens. My 2.9L will hold for several hours.

You also want to ensure the pressure regulator works properly... and isn't leaking. First check the vacuum hose at the regulator for fuel... if it's wet... regulator is bad. Regulator should also increase fuel pressure during periods of low vacuum.

 

[Maggrett]

Thanks! Will try both shortly and report back.

 

[Maggrett]

You just have to start there honestly. Without correct fuel pressure... nothing else matters.

Losing pressure after key off... it happens. My 2.9L will hold for several hours.

You also want to ensure the pressure regulator works properly... and isn't leaking. First check the vacuum hose at the regulator for fuel... if it's wet... regulator is bad. Regulator should also increase fuel pressure during periods of low vacuum.

I am getting 31 lbs at idle, 39 at wot, dips to 28 releasing the throttle, then back to standard 31 lbs.

Unplugged fuel.pressure regulator, no gas coming out, slight idle increase.

 

[Uncle Gump]

That sounds about right... a tad low but not the problem you have now.

Checking fuel pressure doesn't always tell you what the problem is... but will tell you what it isn't.

Did you check base timing with the spout disconnected?

Google exhaust restriction testing and use your vacuum gauge for another quick test.

 

[Uncle Gump]

I'm also guessing you didn't put some oversized tires or something when this problem started.

Has it just run fine until it didn't?

 

[Maggrett]

I checked the timing and it was right on. I aready did the vacuum test- seemed good at 15-16hg then zero blipping the throttle.
Nope, got the same size tires I've always had, though they are new.
The problem kind of was slowish in appearance; going on the highway having more and more trouble getting uphill. The final straw was the truck not even being able to reach 75 mph in windy conditions. Hovered around 55-60 with no response from the throttle...floored. It takes forever to reach speed. Idling and blipping throttle while parked seems perfect. I am going nuts trying to figure this out.

 

[Maggrett]

Also, when I pulled my plugs the showed signs of running hot and lean. No fouling at all. Burnt looking.

 

[Maggrett]

The oil pressure gauge reads a bit low as well when this started happening. It would normally be past the "m", but now dips down to the "o".

 

[rusty ol ranger]

The oil pressure gauge reads a bit low as well when this started happening. It would normally be past the "m", but now dips down to the "o".

Dont put much stock in that gauge.

Athough do your other gauges drop or anything during the event?

Wondering if you got some sort of odd electrical issue fucking with the ECM or something.