My 91 crx w/ b16 has had multiple fuel related issues for the last 2 months, currently the issue is, fuel pump primes, CEL goes on then off, pressure goes to 50 (on fuel rail), but then drops immediately back down to 10ish. Unplugging the Fuel regulator line to manifold has no effect. Car cranks but wont start.

I pulled each sparkplug and primed pump to look in cylinder and didn't see any fuel, so guessing injectors aren't leaking?

I've replaced the following:
1. Fuel pressure regulator
2. Main fuel relay (twice)
3. Fuel filter
4. ECU repair and full refurb (p28 w/ hondata s300)
5. Ignition switch

The last thing I can think of is replace the Walbro 190 fuel pump.

Im guessing it should have a 1 way valve thats failing?
Going to try to call walbro tomorrow (they only have mexican or japanese phone #'s) to confirm.

But wanted to get opinions, before I spend another $150 and a day dropping the gas tank, for it just to be something else I'm not thinking of.

Thanks all!!

 

clamped the return line on Fuel pressure regulator and PSI goes to 90 on rail, but then falls back down to 10 in 1-2 seconds.

 

Emailed Ron from https://autoperformanceengineering.com/ , as all their numbers are disconnected or "busy"
He informed me that the Walbro 190 does have a check valve in it "You can see it if you look in the outlet nipple. It's the little tire--valve looking thing"
and he believes its not holding pressure because "It's probably the little piece of hose that runs from the outlet of the pump to the metal tube that exits the tank. those tend to break-down over time (its been 10 years)"

I'm going to try one last thing before buying pump and dropping tank.
After researching about this issue, I saw someone on another forum installed a banjo bolt on the fuel filter that has a 1 way valve in it. As they too couldnt hold fuel pressure after priming.
but if I do have a leak in that outlet hose, will probably need to drop the tank and replace the whole thing in the end anyways. Will update after swapping the banjo bolt.

ordered this

M12 M12x1.25mm Metric Banjo Bolt Check Valve Diesel Oil Fuel Fitting Boat L-Gi | eBay

Bolt Thread: M12X1.25. Check Valve: One Way Flow from Bottom to Middle Opening.
www.ebay.com

 

I dunno

 

well.. feeling defeated. even with banjo bolt Its not holding pressure on my fuel rail gauge, and still no start.
To troubleshoot further, I took the tank return line off the fuel pressure regulator and primed pump and about 4oz of fuel was bypassed through the FPR. I believe I've read that is a normal amount, but searched and couldnt find anything.
Also, to make sure my gauge wasnt bad, I rented a pressure gauge from Autozone, which replaces the banjo bolt and it does pressurize to 40 at the fuel filter (but the guage has a check valve, if I press the release it drops down to 0) but still no start.

Can anyone tell me if after priming your car (not starting), it should hold fuel pressure? I've google searched and found a lot of contradicting info, or most people can still start their cars. So now I'm wondering if I've gone down this fuel rabbit hole, and its actually something else?

previously I took my plugs out and grounded to the frame and got spark on all 4, so that made me believe it wasnt a spark issue, but that was before I had my ECU rebuilt, so maybe things have changed? I dont know where to go from here. I can replace my fuel pump but I'm worried thats not going to fix anything.

 

Found out from Facebook groups that it should hold prime before a start so ordered a new fuel pump and going to replace soon. Hopefully that fixes the issue