Vannin' Home Forums Ford Troubleshooting Poor idle, poor fuel pressure, power loss

Van was driving fine then suddenly it idled fine but over 20mph, big power loss then stalling.
1978 E150 / 351W Mid gas tank only.

2 Years ago I dropped the tank, it was perfectly clean inside. Replaced fuel pump. Added fuel filter.
Replaced rubber fuel line with new rubber. Blew out steel lines with compressor. Ran fine for a long time.
Pulled some bush stumps with the trailer hitch and somehow damaged the carb.
Local shop installed new carb and set everything up. Ran fine for another year.
Suddenly I'm getting the power loss at 20mph. Less than 600 miles on new carb and new fuel pump.

Tested alternator and battery at local battery shop. Both are fine.
I just replaced the fuel pump again. Fuel filter was perfectly clean. Replaced the fuel line (braided stainless with anodized fittings) from pump to carb and added a fuel pressure gauge.
Fired it up and it barely idles but revs with foot on gas pedal.
I checked fuel pressure gauge and it reads 1psi during idle. Fuel pressure I'm reading online is supposed to be 7psi idle with manual fuel pump.
Air filter is new.
Don't know if the new fuel pressure gauge is actually working correctly.
Fuel pump must be working because it revs when I hit the gas pedal in Park.

Feels like I just did all this work for nothing, and I'm basically where I left off before replacing the fuel pump.

I probably should have replaced the fuel lines from the fuel pump to tank when I dropped the tank to inspect it.
Checked air flow with compressor and the fuel lines seemed fine.

Should I drop the tank again and replace the fuel line from the tank to fuel pump?
What else could be causing low fuel pressure?
If the manual fuel pump lever wasn't seated under the cam correctly, seems like it wouldn't idle or rev up at all?

Any ideas before I drop the tank again and replace the fuel line from tank to fuel pump?

Check rubber connection at fuel sending unit, sounds like the hose is collapsed or split, maybe a squirrel or mouse got hold of it. That is where I would start.

MufflerMan Mike, you may be right!

I dropped the tank 2 years ago and I can't remember how it all sets up.

Isn't the sending unit where the rubber fuel line goes in, at the top of the tank?

Do I have to drop the entire tank to see where the fuel line connects to the sending unit?

I should have video documented the entire process because I can't remember what that looked like!

Carb may have a bad or sticking power valve....

Pretty sure I just figured it out!

Crawled under from the passenger side.
Found the rubber fuel line where it attaches to sending unit.
It's right above and in line with the drive line.
Looked fine no cracks or kinks.
From there I could see the spot I installed a fuel filter meant to filter before the fuel pump.

From that angle I could see that there probably was a kink.
Crawled back under the drivers side where the fuel filter is.
I already opened and inspected the fuel filter, it was the 1st thing I looked at and the filter was spotless.
Could not see the kink because the kink was facing the frame. There is an awkward slight bend in the steel fuel line.
I really needed to feel the short rubber section between the fuel filter and steel fuel line.
Totally missed it. The rubber was installed slightly too long, between the clamps, allowing it to kink over time.
It worked fine during the winter. When it warmed up, the rubber softened up and kinked!

I loosened the clamps and pushed the rubber further up the steel fuel line and worked it around until there was no kink.
The kink left a memory dent in the rubber so I put another clamp right at the kink to support the hose there.

Van is parked too close to neighbors house on the street, so I will fire it up tomorrow and it should be good to go.
If I'm seeing 7psi at the fuel pressure gauge, then I should be good to go.
If I'm good to go then I can redo the rest of the fuel lines later or put in a braided heavier line at that spot.

Muffler ManMike was on the right track, with the fuel pressure gauge reading 1psi it had to be the fuel line.
Glad I didn't drain and drop the tank again. This was easy, didn't even get my hands dirty and these vans have so much clearance, I didn't even have to jack up.
It only took 10 minutes.

Started up like normal. Idled like before all the stalling started.
Let it warm up and I was confident enough to put it into drive and try and go around 1 block.
Boy was that a mistake, it stalled 12 times going around 1 block and I thought I was gonna have to call AAA for a tow.

Fuel pressure gauge is doing a weird flickering thing and does not read over 1psi.

I have a new set of spark plugs coming Sunday so I will pull a few and see what they look like,
possibly toasted white hot from too lean a mixture due to pinched / kinked fuel hose?

I also found some brass fittings online so I an test the fuel pressure gauge on the garden hose and test city water pressure,
and verify the darn thing works. It had over 2K 4.5 star reviews and how hard is it to build a manual fuel gauge in 2024?

Just a thought. To eliminate possibilities? Maybe hang a gravity fed container to your fuel inlet, Bypass the FP. See what happens. Test fuel pump function same thing, run a line from the temp container to FP. Dominate Steve! Good Wrenching!!

So just a heads up the filter in the back is a good pre filter at 100 Microns, "CatFish". Process of thought, "Wedgy" A fuel can duct taped to something and feeding the pump, normal practice. I am guilty of this, divide and conquer. The new fuel at the pump is so clean a 100 micron filter may be useless, a post filter at 6 microns may help. At first thought 100 is better than 6, but a particle of 6 is smaller than a particle of 100, I almost did this. I got lucky and say this online and went with the 6. If you can run it in the upper end your lower circuits in the carb may be clogged.

Spark plugs looked normal. I'm guessing it's either a clogged carb or another blockage between the fuel tank and fuel pump.
I tend to think it's not the carb because it revs like normal at idle. And it idles like normal.
Since the fuel pressure gauge is not getting a solid 7psi reading, I'm guessing it's somewhere in the fuel line, possibly another kinked rubber section that I can't see.
I found this really cool electric fuel pump on Amazon. It's showing up in a couple days. $23.99
I can alligator clip it to the battery and connect it to the line going to the tank and fire it up and see if it will pull gas into a bucket.
This will detect any blockages from the tank to the pump. If I'm only getting 1psi then I can safely drop the tank and replace any and all the other fuel lines.
I can also put it inline and replace the manual fuel pump connected to the engine block and see what the fuel gauge reading is in comparison to the manual fuel pump.
This will be a heck of a lot easier than dropping the tank again just to find out it's not that at all.

I'm gonna take jcd74's advice and add a 10 micron filter between the pump and the carb.