My 1980 ZX was becoming increasingly hard to start. New injectors didn't fix the problem, which I had assumed was the fuel rail losing pressure after shutdown, which is often due to "drippy injectors."

I finally got off my lazy butt and put a fuel pressure gauge on her. Good pressure, (36-39). After shutdown, fuel pressure would intermittently go to zero. Other times it would hold @ 32psi or so.

Clearly a drainback problem.

(As a side note, if I disconnected the pump, the engine would continue to run all the way down to 12-15psi before beginning to rumble and stumble.

The fuel pressure regulator was indeed working. Disconnect it, block the vacuum line, and fuel pressure stayed rock-steady at 36 regardless of revving it.

The most logical explanation is that the check valve in the fuel pump was intermittently being jammed by rust or other debris coming from a 30 year old tank.

I didn't however, feel like popping for a replacment $130 pump, and/or dropping the tank and cleaning it out, expecially with good fuel pressure.

So I bought a fuel check valve from NAPA. Part # ECH-AR269. By Echlin. Along with two 90-544 hose barb fittings. (1/4" barb for 5/16" fuel injection hose) and a pair of new 3/8" fuel injection clamps. Total was under $30.

I spliced this BETWEEN my fuel filter and the fuel rail. This way any crud/debris will be caught by the filter BEFORE it has a chance to contaminate the new check valve.

After letting it sit for 4-5 hours, it started instantly. I'll report on how it does tomorrow morning.

Interesting. I tried something similar in the past, but on the FPR side because I had an Aeromotive adjustable FPR which didn't hold pressure (none of the Aeromotives do). I didn't really like the check valve I found though.

Yours looks interesting but the part number comes up as a relay on the NAPA site.

Interesting. I tried something similar in the past, but on the FPR side because I had an Aeromotive adjustable FPR which didn't hold pressure (none of the Aeromotives do).

I wish I knew this about 2 months ago...

I'm currently replumbing my whole fuel system and selected/installed an Aeromotive adjustable FPR. I haven't fired it up yet but I will keep this in mind when I do.

Yours looks interesting but the part number comes up as a relay on the NAPA site.

Yeah, that's really the Echelin part # off the box. But NAPA should be able to cross-ref for you.

It's an Echelin Ignition Part. Guess I can dig around the Napa site if I really want to find out.

http://m.napaonline.com/Tablet/parts/ProductFinder.aspx?k=ECH-AR269&interchange=false

I wish I knew this about 2 months ago...

I'm currently replumbing my whole fuel system and selected/installed an Aeromotive adjustable FPR. I haven't fired it up yet but I will keep this in mind when I do.

Yeah, sorry about that. I actually had an e-mail exchange with one of the technical guys down there to confirm that it was normal and followed up by suggesting that they add some text to the web page or the instructions about it, to save people time trying to diagnose a "problem" that's actually caused by their product. He said they had some stuff in the works but it never happened. That was about a year and a half ago. I assume the marketing department (or marketing person, who knows how big they are) realized that they were better off to leave it unsaid. Caveat emptor...

Updating this thread with correct part #'s.

Here are the correct NAPA part #'s. This valve can (reportedly) be found at places besides NAPA, since NAPA online really sux...

AFP CV8000 check valve

90-544 hose barb fittings. (1/4" barb for 5/16" fuel injection hose

3/8" fuel line clamps (2)