mdrouillard1983

Hey guys, I recently picked up a brand new Walbro 255LH pump, installed it into my '90 CRX. When I first took it out for a spin, it was bogging bad. I realized I was running on empty.

I put about 10 litres of fuel in and it ran better, went around the block; pushed it a bit and took it back home. But overall didn't have too many issues, but it was running rough still - lot's of engine vibration, some bogging but it would go when I put my foot on the throttle.

Next day my car barely starts, it starts and then eventually bogs out - runs for 45 seconds or so, and rough idle. Here is my diagnostics:

1) I just put a brand new fuel filter in.
2) Brand new pump, re-used OEM sock.
3) Hard feed line and return line broke when I dropped the tank, so I replaced with rubber fuel line and clamps.
4) Tank maintains pressure when I take off gas cap.
5) Fuel pump primes in #2 position, I even tested bu running a fuel line from the fuel pressure regulator into a bottle; fuel is delivered when primed. I had an adjustable FPR on there, it would read about 40 and drop when priming.
6) I was thinking maybe it was the FPR so I put the stock FPR back on, same issues.
7) Spraying starter fluid directly into the intake manifold allows the car to run a bit longer before it bogs and inevitably stalls.
8) I re-set timing and checked for spark on all four cylinders and I have spark.
9) Compression results are 140 - 150 - 150 - 159, relatively low I know - but this is with Vitara pistons and eagle rods (75mm)
10) Right after I installed the pump idling seemed fine, it wasn't until AFTER I took it out for the road test that it is acting up. What could this be? I have a chipped P28 ECU with a turbo basemap, and we did hit about 5lb of boost when I took it for the test in about 2nd gear.
11) Throwing NO codes CEL is off.

Oh also - if I put the pedal down or open the throttle up at all during start up, it stalls immediately like it is starved for gas but it eventually stalls out on it's own anyway.

Could I have damaged the pump by taking it around the block ONE TIME on a low level of gas? Seems very unlikely... And it is very strange that when I got it back after the road test, it idled fine; pulled it into the garage and next day when I come out it is acting up, wtf?

My question is, is it possible for my brand new Walbro pump to be defective? It primes so I know it "works" sort of and the car runs for a few seconds before stalling.

Could it prime with pressure and when the car is running, not supply the proper pressure for some reason? What the hell is going on? MAP sensor or ECU?

Thanks guys! I hate to have to drop the tank again, I figured since the pump is priming - main relay is not a issue and pump works, I think? But then again whats happening here it supplies fuel when primed but as it's running seems like its not or something to that effect.

RanCRX

I'm honestly not too sure since I never went that route. But from what I know and heard is that people with walboro fuel pumps need to have their gas tank over 3/4 full or something like that, I can't really remember. Look up some threads about it. I remember someone saying that improperly positioning the sock or something will cause a vacuum or something in the pump and make it to where it won't run well and stall out. As we all know the fuel cools off/lubricates electric fuel pumps and is the reason why people say keep your gas tank 1/4 full and over because it will fry out the pump. So I'd make sure your gas tank stays full until you can figure the issue

I know the walboro fuel pump throws out more psi, if your motor is stock then its not really beneficial.

br8crumb

have u tried putting more gas in it to fill like half the tank... and have u tried to prime 3-4 times in a row then start directly after? could be losing fuel pressure somewhere down the line also.

to many things done at once to really backtrack and guess. just double check everything

mdrouillard1983

I thought maybe main relay, so I went and purchased a new one - just installed it and the exact same issue.

-Fuel pump primes.
-Crank and it starts but runs rough.
-As soon as I put my foot on gas pedal, stalls.

I tried priming repeatedly like 5-6 times, and then crank to start; it starts but eventually dies and always dies when I put foot on pedal.

-- One observation I made, the fuel pressure jumps to about 40psi when the pump primes; needles then drops to 0. When its running (while it is for the few seconds it does before it cuts off) the pressure reads zero.

There aren't any fuel leaks in the lines, I suspect I would see dripping or smell gas in/and around the tank. No leaks around fuel filter either..
Anyone know what's going on?

mdrouillard1983

Can somebody here confirm it isn't the fuel pump? If it primes, it is working and wiring is all in good order correct? (Priming pumps fuel momentarily, it is only once I try to start the car, the pump doesn't seem to be on)

I'm thinking Ignition switch or ECU but need some more senior members input on this before I proceed.

mdrouillard1983

OK, this is almost retarded. I fixed the problem.

I think a certain sensor was grounded when it shouldn't have been and related to my OBD0->OBD1 conversion.

Basically, you know the black wire that ran tot he single manifold mounted O2 sensor for OBD0? I spliced that into my Air/Fuel Guage signal wire along with the wire to the O2 sensor (4 wire)..

The wire I spliced it into was the black wire on the O2 sensor which I thought was ground so have no clue what was happening, right now my 4 wire is wired directly into the P28 ECU.

Anyone know specifically why this would of happened? Anyway it is disconnected and it continuously runs, but I have a feeling my O2 sensor is NOT hooked up properly.

br8crumb

probably isnt. i dont use o2s on my obd0 though. only symptom is slightly rich which i can live with