Im troubleshooting my fuel system, and was going to stick a hose on the inlet of the high pressure pump, and hang that hose in a bucket of gas, then try to see if the truck will run off of that. Does anybody know if it will work or not? Just trying to narrow down my problem, and was curious before i go out to the garage this weekend and take the time to do it, if it might work.


86 302/aod 4x4 efi

 

No. It's only a booster pump.

Edit for below: Not reliably, but for a test fire, I could see that.

 

I know the from experience that the engine will start and run without the low pressure tank pumps working. The HP pump will struggle and whine some and the engine may buck and cutout at higher speeds or loads. So it should work fed from a bucket.
At the same time you should test the LP tank pump(s) by running them into a bucket.

What kind of problems are you having?

Here is a link to my page with fuel system troubleshooting on my '86

http://75.95.181.105:86/F150/Dual%20...0Selector.html

or
http://75.95.181.105:86/F150/Dual_Tank_Selector.html
.

 

That's a pretty good write-up you made there.

 

Clickable link no good for us non-mods....

 

Try this:

http://75.95.181.105:86/F150/Dual_Tank_Selector.html

Had spaces in filename. If link does not work then copy an paste.

 

Thanks. I was answering the same questions over and over on another forum which prompted me to do the writeup.

 

I have run the low pressure pumps into a bucket, they both run fine. the valve switches fine. If i unhook the inlet to the high pressure pump, fuel comes out, but if i unhook the outlet and turn on the pumps, nothing comes out. The pump does run, and if i pull the pump out and stick one end in a bucket, and put power to it, it will pump out fine. It doesnt make any sense.

 

Let us know what caused it when you figure it out? Given your description, it sounds to me like the electrical has been dorked with (HP pump) and it's running backwards....

 

That was my thought. Does it look like the HP pump has been replaced? Lots of foam padding and skinny pump? There will be a + and - on the pump, if it's wired backwards, it will run backwards.

 

i hadnt even thought about the possibility of the pump being backwards, but funny story.....the pump was running backwards. I noticed that above the quick connect connector going to the high pressure` pump, there were two but splices, taped up where i could hardly see them. the p6ump had been replaced and i had replaced it when i got the truck, and i guess when i hooked it up to the new pump about 6 years ago, i hooked them up backwards (new pump had same size connectors. Then, when i was troubleshooting, i got a pump from a jy, a factory bosch pump with the different sized connectors, and plugged it up. I knew the pump worked, but now that i had the correct pump in the truck hooked up correctly, it was backwards. I switched the wires, pump fed fuel up and truck cranks up no problems. Now if i can just figure out all this emissions stuff. can anybody help? what all does the truck HAVE to have hooked up/working for the computer to actually go into the close loop/open loop (always get those confused) and to have the most power. The truck does not have a check engine light, and the egr is blocked off, but the evp and valve is still hooked up, along with the vacuum line and the evr solenoid.

BTW, i dont have to pass emissions, and dont have a CEL, so im not worried about what codes it will throw if the engine will run and perform at its best potential. Thanks for all your help!

 

I did the same thing when I replaced the pump in my 93. It had a different connector and pigtail so it had to be spliced into the factory harness. I did it backwards and had your same symptoms. That's why I asked you to check polarity in your other thread. At least yours wasn't an in tank pump like mine was, I pulled the thing three times before I figured out what I had done. It doesn't always pay to follow the written instructions, especially when they are wrong.