fuel pump or egr?

[trinistylez]

I could really use some help guys, It'll save me a couple hundred dollars. I went to a shop today, lately the car has been having "flat spots" in acceleration where it hesitates. I have an after market fuel pressure regulator, and we thought it might have been the cause of the issue, the mechanic thought that the car was not getting gas. So we used all the original stuff, uninstalling the aftermarket regulator and using the original and the car ran like crap. When he squeezed the return fuel line, the car revd up fine. He suggested that the fuel pump may be bad... this is after trying two original fuel pressure regulators.

prior to my car having this trouble or hesitation in acceleration, I used a bottle of forumula1 carb cleaner, an additive that you put in your tank...I'm thinking carb build up in the egr as result of the additive. The mechanic also said that the egr would not cause the car to act up as in hesitation and accelerating. What do you guys think from your experience, should I go ahead and replace the pump or clean the egr first?

[deevergote]

I doubt the EGR is the problem, but cleaning it can only help.

Install a fuel pressure gauge, and see what your pressure is.

Are you using brand new stock FPRs, or used ones? If used try new.
Have you replaced your fuel filter?
Another possibility would be the injectors. Try having yours professionally cleaned and balanced, or at least swap them out for known good ones.

The pump is possible, but I haven't seen any situations where the pump provided weak fuel flow. Usually when the pump fails, the car just cuts out and won't start.

If you live in an area that sees a lot of rust on cars, changing the fuel pump could be a HUGE hassle. The tank has to come down, and all the hardware holding that tank up will likely be rusted. You'll have a rough time getting it all off, and you'll have to replace the straps and bolts.



Another "flat spot" culprit is the o2 sensor. It can cause problems without throwing any error codes at first. I had a problem with mine, where the engine would lose all power from about 2500 RPM to 3000 RPM, then it would run fine.

[trinistylez]

We used regulators that we knew was working fine. We pulled it off a car that was using it. Just for testing purposes. The aftermarket fuel pressure regulator at idle reads 23-25ish. I can not turn it up because if i adjust it anymore. The return line will pretty much be closed off.

[deevergote]

Weird...

So what about the filter?


If you can remove your gas tank easily, with no rust problems, then replacing the pump wouldn't be a bad idea. Even if it doesn't fix the problem, it's still replacing an old component that would fail eventually anyway... if you can afford it, anyway.

[trinistylez]

I have not done the filter yet. Wouldnt hurt to do that anyeays. I got a pump but it cost me a lot so if i can return it that would be great. You mentioned the 02 sensor was giving you trouble and took a while to come up. I might try the sensor and filter. Seems everytime i get paid. This car drains my wallet. Im still lost as to what it could be if not any of those things mentioned.

Now im second guessing the pump. As you said. Ive never heard of them starting to fail. It either works or it doesnt..

[deevergote]

It doesn't mean it CAN'T fail that way, though... I just wouldn't assume it based on what we know so far.

If the o2 sensor is old, spend the $35 or so from RockAuto.com for a new Denso unit, and replace it. Just like cleaning the EGR, it can't hurt, and it might help.

Look at it this way... as long as you're replacing old, worn out things that would eventually need replacing anyway, you're only getting yourself ahead of the game!

[Bad_dude]

What did you guys do to test that you are not getting gas? Check the vacuum line on the FPR? What about air interruptions? Check timing? First replace the fuel filter. I don't know how much your mechanic knows about Hondas but if you have clogged EGR ports or a defective EGR valve, you will get hessitation on accelerations. Did you ever clean the ports?

[GeoffM]

When I was diagnosing a problem, I cranked the engine for a few seconds. I removed the number 1 spark plug and saw the cylinder was wet. I cranked it again with the plug removed and saw a mist shoot out of the cylinder hole. It won't tell you if you have the correct fuel pressure, but it's better than nothing

[trinistylez]

It doesn't mean it CAN'T fail that way, though... I just wouldn't assume it based on what we know so far.

If the o2 sensor is old, spend the $35 or so from RockAuto.com for a new Denso unit, and replace it. Just like cleaning the EGR, it can't hurt, and it might help.

Look at it this way... as long as you're replacing old, worn out things that would eventually need replacing anyway, you're only getting yourself ahead of the game!

the o2 sensor is ordered and on its way. my engine and computer are out of a 95 jdm prelude, so I ordered the o2 sensor for that car... or should I have ordered the regular accord one?

What did you guys do to test that you are not getting gas? Check the vacuum line on the FPR? What about air interruptions? Check timing? First replace the fuel filter. I don't know how much your mechanic knows about Hondas but if you have clogged EGR ports or a defective EGR valve, you will get hessitation on accelerations. Did you ever clean the ports?

I will clean the egr valve tomorrow. Absolutely no time lately, but I will do it tomorrow and see how it holds up. What he did was he removed the aftermarket fuel pressure regulator. Connected it with a stock fuel pressure regulator and the car would not rev up properly, it was back firing. When he pinch the return line, it ran fine. When he removed the vacume line, it also ran fine, and that is without having to pinch the return line to build more pressure.

I adjusted my fpr yesterday, i swear the thing is almost completely closed. but its running somewhat better. When the engine is cold, it runs fine, when its warm it starts to hesitate, and the check engine light comes on. I have two codes. 36 and 12.

By monday evening the new o2 sensor should be in, as well as the egr cleaned, and the fuel filter replaced. Then I will see about doing the fuel pump.

[cloudasc]

For the o2 sensor, you should get the o2 sensor for whatever engine harness your using (most likely the cb one), as its what decides what the connector for the o2 sensor is (unless someone botched the wiring during the swap).

Also a quick test to see if its the o2 sensor causing all your problems, is to simply unplug it. If it drives perfectly with it unplugged, no hesitation etc, then the problem lies with the o2 sensor. Unplugging it will cause the CEL to come on, just clear the codes after the test.

[trinistylez]

For the o2 sensor, you should get the o2 sensor for whatever engine harness your using (most likely the cb one), as its what decides what the connector for the o2 sensor is (unless someone botched the wiring during the swap).

Also a quick test to see if its the o2 sensor causing all your problems, is to simply unplug it. If it drives perfectly with it unplugged, no hesitation etc, then the problem lies with the o2 sensor. Unplugging it will cause the CEL to come on, just clear the codes after the test.

I will give this a try. Like I keep saying, monday seems the only day Ill be free to do anything. I was just driving around and the symptoms seem to get worst, very very low and rough idle, hesitation got really bad, seems the warmer the engine is, the more hesitation.

[Bad_dude]

Well your CEL codes, 12 is with the EGR valve. Test the valve first, then clean it if it passed and also clean the holes below it. You can see the runner path below it too. You might not reach through the entire path but you could use a straw that those carb cleaner comes with and spray it through and let it soak.
Good luck.

[trinistylez]

Well your CEL codes, 12 is with the EGR valve. Test the valve first, then clean it if it passed and also clean the holes below it. You can see the runner path below it too. You might not reach through the entire path but you could use a straw that those carb cleaner comes with and spray it through and let it soak.
Good luck.

how do I go about testing the valve? I know cleaning it would be a simple matter of taking it of the intake manifold and get down and dirty with some carb cleaner. But how do you test it?

[trinistylez]

So I seafoamed the car this morning and it worked wonderfully. I guess it had to of been that formula1 stuff I put in the tank. I am not doing that again. Car still has some power loss. But I am going to clean the egr and replace the o2 this week coming.