engine won’t rev, bogs down.

[interoz]

Hello!
I’m having an issue with a 94 Honda Civic DX that I obviously need help troubleshooting! I replaced the cylinder head yesterday because of lost compression. Prior to this, it ran good. After replacing the head, I buttoned everything back up and it started up and idled great. But it won’t rev up without bogging!

Symptoms:
Engine starts perfectly, idles great….press the gas more than 5-10% and it wants to bog down/ die. Very lightly press the gas and it will rev to about 3-4000 rpm. As soon as I let off the throttle, it eases back into a smooth idle again.

I have checked the following….
-TPS- adjusted and functioning.
-Vacuum- Cannot hear anything/ checked with carb cleaner/ checked with gauge at a couple different spots, holds 22 in hg at idle.
-Replaced fuel filter
– checked fuel regulator…good
– Fuel pressure…seems to be fine. I don’t have a pressure guage but it starts and will rev so I assume it’s good.
– checked crank timing…perfect.
– checked ignition timing…pretty close, set by ear. I need to pick up a timing light.
– checked MAP sensor
-Checked every connection….twice

I’ve got about 12 hours of looking at this engine…I’m out of ideas! HELP!

Thanks

Topic

[EricTheCarGuy]

I would say the fuel pump is a dead end as Honda fuel pumps hardly ever go bad and with a reading of 71psi it’s WAY above anything I’ve seen and would not indicate a faulty pump, remember it’s resistance to flow that creates pressure and the pump creates flow, not pressure, are you sure you used a good gauge and checked it correctly? Perhaps this could indicate a restriction somewhere. I was with Jacob on the electrical connectors as I’ve seen that issue more than once, you can usually identify the correct connector because the connector and what it connects to should be the same color. I don’t think you have a fuel delivery problem based on your description, it still sounds like a timing issue. When you timed the engine did you short the connector under the dash or follow whatever procedure was outlined on the under hood sticker? If not the computer will try to correct for your ‘correction’ and you won’t be able to time the engine properly. Also are you 100% sure that the engine is in time correctly? If it’s not it could exhibit the symptoms you describe.

[jacobnbr1]

Fuel pressure specs are as follows:Controlled pressure [1]215 – 265 kPa (31 – 38 psi)Uncontrolled pressure [2]280 – 330 kPa (40 – 47 psi)Displacement222 cc (7.5 oz) minimum in 10 seconds[1] With vacuum hose connected at Fuel Pressure Regulator
[2] With vacuum hose disconnected at Fuel Pressure Regulator

Clearly if you took an accurate test you have way too much pressure. Take a look at under hood hose routing from the injector rail to the return line and see if it is kinked or something. Recheck the pressure test to confirm the pressure is again 71 psi and if so then replace the pressure regulator.(See Below)

Here is the service manual procedures:

1. Relieve fuel pressure.

• [li]Disconnect the battery negative cable from the battery.
• Remove Fuel Filler Cap.
• Use a box end wrench on the 6mm service bolt at the Fuel Rail, while holding the special banjo bolt with another wrench.

[/li]

Loosen The Service Bolt

• [li]Place a rag or shop towel over the 6mm service bolt.
• SLOWLY loosen the 6mm service bolt one complete turn.

[/li]

1. Remove the service bolt on the Fuel Filter while holding the banjo bolt with another wrench and attach the fuel pressure gauge.

Clamping Pressure Regulator Hose And Measuring Fuel Pressure

1. Reconnect the battery Negative cable.
2. Start the engine. Measure the fuel pressure with the engine idling and the vacuum hose of the Fuel Pressure Regulator disconnected.

PRESSURE AT IDLE SHOULD BE: 280 – 330 kPa (40 – 47 psi)

NOTE: If the engine will not start, turn the Ignition Switch on, wait for two seconds, turn it off, then back on again and read the fuel pressure.

1. Reconnect the vacuum hose to the Fuel Pressure Regulator.

PRESSURE AT IDLE SHOULD BE: 215 – 265 kPa (31 – 38 psi)

1. If the fuel pressure is not as specified, first check the fuel pump. If the pump is okay, check the following:

• [li]If pressure is higher than specified:

[/li]

• [ul]
  [li]Pinched, collapsed, or clogged fuel return hose or piping
• Faulty Fuel Pressure Regulator

[/li][/ul]

• [li]If pressure is lower than specified:

[/li]

• [ul]
  [li]Clogged Fuel Filter
• Fuel Pressure Regulator failure
• Leakage in the fuel system

[/li][/ul]

[380]

When your reving up the engine do u have the transmission in neutral or is it in gear.

[EricTheCarGuy]

I don’t know if I’ve said it enough but it’s awesome having you on this forum Jacob, thanks for the detailed info.

[Regnice]

Maybe a fuel volume check ?

[interoz]

After going back through every step and checking every hose, wire connection and sensor, the problem is finally solved!

After putting the car in the backyard for a while, apparently the pulsation damper was dying a slow but certain death. Each time I would mess around with it, the car was getting harder and harder to start. It finally failed completely that let me narrow it down…rather quickly.

Thanks for the help though!

[jacobnbr1]

What exactly is a pulsation damper?

[rice400]

does he mean harmonic balancer? If so, how would that effect the engine starting? I’m not being sarcastic, i genuinely dont know.

[dreamer2355]

Quoted From jacobnbr1:

What exactly is a pulsation damper?

+1.

[EricTheCarGuy]

Quoted From jacobnbr1:

What exactly is a pulsation damper?

It is a device mounted on the fuel rail similar to a fuel pressure regulator that helps to ‘dampen’ the pulsations created by the fuel pump to help create a balanced pressure in the fuel line. I’ve never known of issues with them on Honda’s however.

[dreamer2355]

Quoted From EricTheCarGuy:

It is a device mounted on the fuel rail similar to a fuel pressure regulator that helps to ‘dampen’ the pulsations created by the fuel pump to help create a balanced pressure in the fuel line. I’ve never known of issues with them on Honda’s however.

Thanks for the update Eric S:). Learn something new everyday on this forum!

[Author]

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