have you checked your fuel pressure regulator?

 

Replaced yesterday . . .

 

There is a check valve in the fuel pump and it's sole purpose is to keep fuel from draining back into the tank for easier starts. If you are going to pull the fuel pump, might as well replace it....

 

There is no code for low fuel pressure. There is a code 43 for Fuel Supply, but it is really an O2 sensor performance code. Not sure if it would indicate anything w/ low fuel pressure.

Frankly I am surprised it will start w/ only 10 psi fuel pressure. Are you sure you aren't leaking fuel pressure from test setup? Any chance fuel pressure gauge is faulty?

I looked for a spec on fuel supply volume per unit time but did not see anything in shop manual. Ebay suppliers suggest 100 liters/hr is stock fuel supply volumetric rate. That works out to ~270 ml in 10 secs or 1 liter in 36 secs. If you're falling short of this volume delivery then low fuel pressure is consistent.

If you're confident fuel pressure is correct, then it's time to replace fuel pump.

I've done a fuel pump on my 94EX and it's no fun. Car has to be elevated on jackstands and/or ramps (front and rear). I elevated rear on ramps and front on jack stands. This allows enough room to work underneath and extract fuel tank. A box or foot stand is handy to support tank while disconnecting fuel lines and electrical connects. I disocnnected lines at access port on pax side and fed them through opening to simplify. Be sure tank is as emply as possible as handling the empty (solo) is difficult enough.

Somewhere I've seen a video or post about cutting a hole on driver's side to access the fuel pump w/o dropping the tank. This may be an option, but brings it's on set of problems (position for hole, sharp metal edges, etc).

good luck

 

I am now beginning to think it might be the fuel pump. Most of the time pumps just quit. But once in while, the pump may operate at 1/2 pressure, like the pump is "gummed up" a bit.

Have you tried replacing the fuel pump relay? Also, the check valve is something to look at too.

 

I'll see if I can swap pressure test kits at OReilly to get a "second opinion". Haven't checked the relay because relays are basically glorified on/off switches. But DC motors can act funny without the right amount of juice, so it's possible that a power drain somewhere could reduce pump speed. Beats dropping the tank, so it's worth a check!

One nagging detail is this thing about getting the car running with a shot of starter fluid and then having it continue to run. At least with carbs, the engine is sucking mixture into the cylinders. Is it possible the engine was drawing enough fuel through the injectors to do the same thing with what little pressure was in the line? Once the revs dropped, so did the fuel supply and the thing died again.

When we get this sucker running, the first couple rounds are on me ;^)

 

An injector/s stuck open might cause low fuel pressure and difficulty starting. When you measured fuel pressure did it drop to zero as soon as pump went off? This would indicate a leak somewhere. It could be check valve in fuel pump, fuel pressure regulator, an injector/s, or a leak to outside perhaps along fuel rail. Gas leaks are surprising hard to spot, but smell will usually find them.

I don't know any way to test for leaking injectors except to pull and test injectors one by one for stuck open condition.

good luck

 

Testing with a second pressure gauge was exactly the same - 10# that bleeds down after the initial system charge and then goes back to 10# in starting mode. No visible leaks or extraneous gas smells. All plugs look and smell the same, so not likely it's a single injector. Looks and feels like pressure loss somewhere. List is getting shorter with fewer sensor circuits involved.

 

Been awhile, but I got back to the no-go Honda and found a very strange answer to the puzzle. I dropped the tank and was pulling up the pump but it wouldn't come out easily, so I looked inside and the pump was completely off the bracket and barely attached to the output hose! It all pulled apart completely as I lifted it through the top of the tank. When did this happen -- and why? And why now? Has it been like this since it was installed? It's #AF195130-2580, which looks like a Honda pump. There's at least a 1/2" of hose (and a clamp) that should have been attached to the pump output -- how did the pump pull out of this -- or stay attached in the first place? It explains why I was only reading 10# of pressure because the rest was dumping back into the tank. WTF?
Also, with everything accessible, should I replace the pump or anything else? Any aftermarket pumps to use or avoid, or are they all the same at this point?
And to anyone who's stayed with this saga long enough to reach the end: Thank you! I have a mechanical solution, though definitely not an explanation, but it's one more question and answer for the Honda troubleshooting gurus.
Attached is a photo of the pump coming out of the tank. At this point, the pump has pulled off the hose and is completely loose.

 

The fuel pump sits in the bracket that is attached to the upper flange closure. Looks like it was mis-assembled by someone who removed/replaced fuel pump. Hopefully no parts are left in tank!

I have no info on performance of aftermarket fuel pumps. Check amazon for reviews, but this is weak indicator because parts are generally new when reviews are written. I would be tempted to stay w/ OEM considering work to replace pump. However when I did this job I used aftermarket (don't remember brand).

good luck