loss of accel when pedal goes too far! Can it be diagnosed?

[MarkgM]

I have an '87 Accord LX, 2 bbl carb, auto trans. This is my first time here, got the link from someone I met at alt.autos.honda.

I did a simple rebuild of this carb (main gaskets, needle valve) about 20,000 miles ago. Recently, I had an aftermarket fuel pump in line to the carb just after the aux. filter. The reason why I did that was because of an intermittent electrical problem to the fuel pump. Sometimes it was Ok, sometimes it stopped completely.
I changed the ignition wiring, and got rid of the extra fuel pump, I was worried about too much fuel pump pressure causing problems.

So, here's the problem. It's running fine until I push the gas pedal down more than half way or so, and then, no more power, it may be described as sputtering a bit (but not really sputtering). It won't go faster if the pedal is too far, but lighten up and it goes back to good accelerating behavior. I can't test it at speeds higher than around 35-40 mph right now, no vehicle reg. and I'm on a residential street.

Without any other changes, I stuck a pressure gauge on the fuel line to the carb, and it showed 2 pounds of pressure. The Haynes manual says remove and short a couple of lines to the fuel pump relay, but I haven't quite figured out which one is the fuel pump relay just yet. Anyways, how could not enough fuel pump pressure cause a problem that reproduces itself right away?

The accelerator pump, when not running, give it some throttle, and it shoots gas into the first barrel Ok. I connected manifold vacuum up to the Throttle Control Diaphragm, and that made it rev up well when at idle (with the other line 28 plugged). The dist. vacuum advance also appears to be responding to manifold vacuum Ok at this point.

For tools, I can measure vacuum or pressure, but I don't have a pump to create vacuum or pressure of a specific amount. I have the Haynes manual, but it appears to only (partially) document a 3 barrel carb -- ?? The problem now is what am I in for? If I go to a shop, surely they will have to change the (in-tank) fuel pump, and rebuild the carb, before they "narrow it down", or some such thing. I'm on a shoestring budget, and don't know where to look next. Any ideas? It would be nice if I could determine if that second barrel is working Ok.

Do you think the fuel pump has to be changed - does the carb have to be rebuilt? Could that aftermarket pump have mucked something up? Thanks for any help--

- newbie (Mark)

[shepherd79]

well lets start with fuel pressure. you say it 2lb, well it should be at least 2.4psi.
actually it should be between 2.4 and 3.4psi so you may want to check your fuel pump first. i would say try to run at 3psi at least.

[MarkgM]

Hmmm... I had this problem with the aftermarket pump, and that was between 4 and 7 psi. I don;t know if that creates more pressure with the existing pump still in line, but what do you think?

[shepherd79]

well, with 2psi it sounds like your carb is not getting enough fuel at full throttle.
the other thing, check your vacuum lines for leaks, but i bet fuel pressure is your problem.
two much pressure won't do any good eather. you are not looking for high pressure sustem, you need to find a pump that will pump that can pump a lot of galons per minute.
how many fuel filters do you have?

[doug]

most aftermarket pumps I've read about here are installed closer
to the source (tank). also, the intank pump is removed. Maybe the stock pump is obstructing flow and with the aftermarket up front it has a hard time with flow?

[MarkgM]

I have 2 filters - changed both of them. And an in-tank pump. Another thought on the pump. THe Haynes manual says remove the fuel pump relay and jumper pins 1 and 2 before measuring the fuel pump pressure. Think I need to do that first?

Also, locally, I can get a fuel pump, $139, and I'd have to wait a week.

[jb2wheels]

Try the jumper and see if pressure goes up. That 2.4 psi lower limit is serious - I had one at about 2.2 one time and car would barely run - would actually stall at anything more than idle.

[MarkgM]

Will have to do. Have to find that fuel pump relay! Bit of a hurricane today, hope to be able to check it tomorrow.

Anyone know - is the pressure supose to rise with reving it? It stays at 2 psi when reving in (parked).

[jb2wheels]

Pressure should not change with RPM unless you have an electrical problem.

[ACCORD EX]

does your accelerator pump move ?? secondry opens ??

Mike !

[A20A1]

Booster venturies?

[MarkgM]

Well, reving or not, I don't really see the 2nd barrel opening. That had me kind of curious.

By that I mean the throttle.

[A20A1]

You wont see it open unless you open the throttle all the way really quickly, cause the is not as much resistance to the rpms from the transmission.
Have soeone push the gas for you, bu make sure they stomp it and don't just gradually increase the rpms.

anyways... like i mentioned before... check for a loose booster venturi.

https://www.3geez.com/showthread.php?...ooster+venturi

details in link above

[ACCORD EX]

ask a friend to rev give a full throttle for an eye blick ! and you look at the secondry connection ( vacuum dash pot ) at the right side of teh carb facing the car from front ! if it doesn't check vacuum lines for leak and vacuum ! and clean with a carb cleaner !

Mike

[A20A1]

blick?

... sorry... nevermind... I guess you ment blink... right?

[MarkgM]

Will do. I wll check the blick. And I will see if I can feel some wiggle in the little brass venturi part.

[MarkgM]

Well, just jumpered the 1 and 2 where the fuel pump relay plugs in, turned ignition to on, and voila, better than 3 psi, close to 3 1/2. Looks like the fuel pump is Ok.

Wiggled with the venturis, and they don't have any looseness about them.

Had a friend stomp on the pedal while I looked, and saw a little bit of movement in the second barrel (throttle). Only for a moment, only a bit of movement there.

I'll have to get an electrical tester to test the fuel pump relay. Maybe I should test drive the car with those leads jumpered as it is? Hee hee Boy, now I'm really running out of ideas!

[MarkgM]

Registetred the car today, and got a chance to really take it out on the road. The symptoms are becoming a little more clear to me.
Today, I had the car running smoothly at 70 mph down the highway. It appears that at any speed if I push the pedal too far then the transmission disengages. The engine still revs - in fact, it will rev up a bit while the drive is disengaged! Let the gas pedal back down a bit, and it engages again. Any ideas about that one?

[A20A1]

Check the TV cable.

[MarkgM]

Took it to the mechanic to diagnose it. I found a mechanic good enough to diagnose without rebuilding the carb first. Thank god for that, the others would charge a thousand bucks before figurnig it out.

After some diagnosis, it was found there was a vacuum leak in the hose the PCV valve plugs into. Also there was another small vacuum leak. Also, the valves on #4 needed adjustment, and there was some kind of air hose for the valve? Was replaced. Timing adjusted, and voila, she's running allright.

#4 was running itself so lean in the end that it was making a big problem, and the loss of vacuum was no help. Go figure. Runs pretty good now. Cost about $200 to diagnosis and fix.

I've also started using gas cleaner, and that seems to help a great deal. The idle was still a little rough, and running the cleaner ("Outlaw") seems to have also smoothed that out.