Low fuel pressure (EFI) - bad pump, bad plumbing or ?


Help Support 7173Mustangs.com:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Yea, I’m not sure of Spectra’s fuel unit. I can tell you, I followed the tutorial and now have a nice return setup on my 73 EFI system. Only change from the tutorial is the intank pump for EFI vs carb; the tutorial’s pump is for a carb. If you get interested in this low cost intank EFI system, PM me and I’ll pull the paperwork for the pump you’ll need.
Thanks Steve. Going to do one last test this afternoon just to triple check that it is the pump that's failed. Assuming it is bad, I am interested in doing in tank.

I do think that if I go in tank, I'd be doing it from the current sending unit location if I can figure out the logistics. If I head down that road, I'll hit you up for that pump info but I'll figure out what I'm planning first before I ask you to waste time on this.

Either way I need to get this sorted as it's finally gotten cool enough to drive this thing so I need to get it back on the road ASAP!

Thanks again for the feedback on this.
That’s cool. I used the original tank pump outlet as my return line. 3/8” line in and 3/8” return. For what companies want for intank EFI systems, this is a wonderful cost savings. If you have detail questions on the mod, hit up Kilgon; it was his original hack. He’s a great guy.
So I ended up replacing the pump with another similar pump for the time being and I'll revisit doing an in-tank pump over the winter.

Thanks everyone for the great feedback on this.

One other fuel related thing I'm wondering about. I've been using these little filters because something like that came with the EFI when I got it.


The thing is, these things are tiny and not cleanable and for me when they start getting plugged they just lock up but it's one of the few reasonably priced 10 micron, 3/8" filters around. I've had a couple of times now where I had to limp home and it ended up being the filter clogged up enough to make me lose pressure very quickly.

It finally occurred to me that maybe I should just use an OEM style filter as virtually every car on the road today is using large, cheap 10 micron filters.

So I'm thinking about using something like this (or an OEM equivalent) https://www.amazon.com/gp/product/B00CTA0YZU with these quick connects https://www.amazon.com/gp/product/B000E323JO. At first I thought the quick connects would be a bad idea, but now I'm thinking it might make it easier to swap out filters once a year or so.

Any disadvantages to doing something like that? It won't look as pretty and I don't know how the quick connects will deal with vibration (and maybe heat) as this would be up by the throttle body. But seems like the much larger element might keep me from ending an outing before I want because of a clogged filter.

Thanks for any feedback.
Thanks. I dig that you can clean them and was assumed those little Earls filters were, but after breaking one in half, I don't think they are meant to be opened.

I do need 10 micron though for the EFI and at the moment still using 3/8" barbed fittings. Actually have a couple of these on the way, but am thinking about doing the quick connect / OEM thing that way it's a filter I can get anywhere. And since it seems like I need to change filters pretty often, the quick connect thing might hold up better than removing a barbed fitting? No idea if that's true though.

I have two filters. One coming out of the tank and one in the return line before going back in the tank

I got both from Holley during a warehouse sale. I think they were earls and cleanable
I have two filters. One coming out of the tank and one in the return line before going back in the tank

I got both from Holley during a warehouse sale. I think they were earls and cleanable
Thank. Same. I have a 100 micron coming out of the tank and before the pump and a 10 micron before the EFI. I think I'll spend more money and get bigger/ better filters so hopefully I won't have to deal with this again.
I’m using the factory Ford quick disconnects, mounted at the tank, and I’ve had no problems with it failing. No fuel flow issues either. From your first post, looks like you have room at the tank.
My thinking all along has been, if it works on stock 1980’s Ford cars, it will likely be an improvement in ours. My fuel filter is the stock one that was on an 1989 Mustang with a 5.0.
Totally agree. Just wish I would have realized that a couple years ago.

I have the new filter in up by the EFI for the time being. I'll relocate that down by the tank when I rework the plumbing again this winter.

Thanks again for the feedback
Last edited: