Date: Sat, 31 Mar 2007 09:03:07 -0800
Reply-To: Mark Drillock <mdrillock@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mark Drillock <mdrillock@COX.NET>
Subject: fuel supply testing
In-Reply-To: <de48c0be0703310915n6b0e4287wbcf184ebe636a054@mail.gmail.com>
Content-Type: text/plain; charset=us-ascii; format=flowed
Bentley page 20.29 has a procedure for checking whether enough fuel is
being supplied for the engine to run under full load.
Basically, measure the amount of fuel being returned to the tank while
the pump is running. NOT the amount coming directly from the pump but
instead the amount coming from the fuel pressure regulator return line.
The spec is about 1 quart per minute being returned to the tank.
Again, the only amount that counts is the excess from the pressure
regulator, while the pump is working against the regulator.
Mark
mordo wrote:
> I'm bumping this post in hopes for some diagnostic help.
>
> I thinkn calling this condition "surging" was inaccurate on my part. It is
> actually just momentary loss of power.
>
> The condition presents with the engine warm, and the engine under load. I
> have tested fuel pressure at the T and it is at spec.
>
> I am thinking that the throttle valve switch is a possible culprit. My
> question now is what is "full throttle"? If the switch is defective or
> misadjusted, would the switch out of adjustment cause this momentary dying
> condition under full throttle?
>
> I've just checked continuity and adjustment of the TVS and it appears to
> function properly. Given where the throttle is when the the swithc closes
> for full throttle, I would guess that the TVS is not related to this power
> loss. The throttle valve is open to its stop when the switch closes.
>
> To recap:
>
>
> - 2.1L wbx with Vanagon syndrome harness installed
> - Idles fine
> - Under load, at about 1500-1700 rpm, the egnine dies and then revs up
> to about 3000 rpm. Dies, revs. Dies, revs.
> - If I hold the throttle steady it does this very consistently
>
> I'm at a loss. Any ideas?
>
> Thanks,
>
> mordo
>
>
> ---------- Forwarded message ----------
> From: mordo <helmut.blong@gmail.com>
> Date: Mar 25, 2007 4:31 PM
> Subject: Surging between 1700 and 3000 rpm
> To: vanagon@gerry.vanagon.com
>
>
> I just went out for a drive, the third short trip of the day. The van ran
> fine the first two trips except on a fairly steep grade near my house. On
> this grade, the engine loses power and drops to about 1500 rpm. By
> feathering the throttle, I could get it to rev up again and get me home.
>
> This third trip, the engine consistenly surged between abot 1700 and 3000
> rpm at about 25-30 mph. This is an automatic 2.1L wbx. Feathering the
> throttle seemed to have little positive effect. Accelerate from a stop and
> rev up to about 3k rpm - it dies and drops to about 1700 rom and then it
> goes right back up to about 3000rpm. A moment later, it drops back to 1700
> rpm and so on.
>
> I would be willing to believe it is a clogged fuel filter but why would the
> surging be so consistent?
>
> The engine idles fine. The engine is warm, not full on hot.
>
> I checked the fuel pump wiring before this trip. A good wiggle on all
> connections did not produce any negative effects. The fuel filter is a
> clear
> plastic, round filter in frotn of the pump. It seems to have some strange
> muck at the bottom side of the filter.
>
> Any lucid insights, list?
>
> --
> mordo
> 1990 Carat
>
>
> --
> mordo
> 1990 Carat
>
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