92 EX hard starting when cold, no power in WOT

[masospaghetti]

Car turns over fine (starter engages) but takes a long time to start when it's completely cold. It will restart easily once its started the first time. I've done the standard tune up items (fuel filter, spark plugs, timing belt).

Also the car bogs down under WOT. It has more power on part throttle than it does in WOT.

My guess is a fuel delivery problem or clogged cat because a bad sensor would give a check engine light. I don't have a check engine light. Am I on the right track here? I figured next step would be to check fuel pressure and drop the cat. Thanks all.

[F22Chris]

Did you do the rotor and cap too? Recheck your timing.

[Fleetw00d]

There is a check valve in the fuel pump assembly that is meant to keep the fuel line full; if this leaks, the line can drain back to the tank. Try this: Turn the key to "ON" position (not "START"), let the fuel pump run for two seconds (the dash lamp test completes); turn the key to "OFF", Turn the key to "ON", then when the lights go out again, turn to "START". If the engine fires much quicker or immediately, then this check valve is likely leaking. When is the last time you changed the fuel filter or checked fuel pressure?

[masospaghetti]

Good idea, i'll try that. I've never checked fuel pressure but I just changed the fuel filter. I'm not sure if I have the right fitting for this car, i've done it multiple times on a Pontiac and a Ford but every car is different.

F22Chris: I did replace the cap and rotor too.

[masospaghetti]

I checked fuel pressure today. With key ON and engine off, pressure would not go above 20 psi. Obviously below spec of 30-38 psi (per Honda FSM).

I'll try swapping the fuel pressure regulator first since i have a spare. Any other way to diagnose if the fuel pump is bad? Do they "get weak" like this? I figured they would just die altogether. Would rather not drop the tank unless I really have no choice.

[masospaghetti]

Tried swapping fuel pressure regulators with a known good one. Same result. Here is the pressure reading with key ON, engine OFF:



Here is with key ON, engine ON:



First reading is definitely below spec. Second reading is barely within spec. Maybe low voltage to the pump? Next thing to test.

[sonikaccord]

There are ways to diagnose "weak" fuel pumps, but you'll need an ammeter or scope to really see what's going on. Typically, dc motors don't get weak. They get intermittent or dirty. Like your starter would usually just die immediately. It's not too graceful and typically inconvenient when it goes.

Anyway, try clamping the return line on the fpr and see what your pressure goes to.

[masospaghetti]

Just an update. No matter what I did, I couldn't get pressure to go above 20 psi with the engine off. It would go up a little bit (~26 psi) when the engine running, probably because of the higher voltage from the alternator. I even tried applying direct +12v from the battery straight to the connector in trunk.

Swapped in a known good pump + fuel tank and all is well, car runs like a top, starts easily, and fuel pressure is about 38 psi while running. Thanks everyone for the help.